CN103619423A

CN103619423A - Tennis racket and method

Info

Publication number: CN103619423A
Application number: CN201280015576.4A
Authority: CN
Inventors: R·A·布兰特
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-01-26
Filing date: 2012-01-18
Publication date: 2014-03-05
Also published as: AU2012209400A1; JP2014503337A; MX2013008630A; RU2013138629A; CA2825530A1; EP2667951A4; WO2012102924A1; EP2667951A1; ZA201305683B; BR112013018946A2; US20120214625A1

Abstract

A tennis racket is provided that has a rectangular ball striking face with rounded corners. The racket is formed of a carbon fiber sandwich with light material mounted therebetween. A strip of carbon fiber is attached to the outer edge spanning the two carbon fiber top and bottom sheets. The rectangular frame is formed with outwardly bowed sides so as to be pulled into a straight sided configuration by the string tension. Locking grommets of various constructions are provided to hold the strings at predetermined tensions. Testing equipment and methods are provided for testing tennis rackets.

Description

Tennis racket and method

The cross reference of relevant application

It is the rights and interests of the U.S. Provisional Patent Application of submission on January 26th, 61/436,259,2011 that the application requires series number, and this application is incorporated herein by reference.

Technical field

A kind of tennis racket of relate generally to of the present invention and manufacture tennis racket and the method for giving tennis racket stringing.

Background technology

In U.S. Patent No. 6,344, in 006 B1 and U.S. Patent No. 7,081,056 B2, R.Brandt instructed have in vertical and horizontal direction all equal in length, or the advantage of more generally clapping the tennis racket of the bat line that line vibration frequency is equal.In patent document, will further develop and improve these designs, and will show for the manufacture of the building method with this racket of test.

Summary of the invention

The invention provides a kind of method of tennis racket and manufacture tennis racket, this tennis racket provides a kind of structure, by this structure, equal bat line length and the bat line vibration frequency of the expectation when hitting tennis are provided can to the bat line of tennis racket, to the batting performance of improvement is provided.In a kind of preferred embodiment, tennis racket comprises that thread-protected tube sets up and maintain the bat line length of expectation and clap line vibration frequency.In another kind of improvement project, for racket structure provides hierarchy, preferably with the form of carbon fibre material sandwich.The racket head of embodiment comprises a bandy side, and these sides are configured to be drawn as straight configuration when being subject to clapping line tension.In this racket, use one clap line or many clap line can the vicissitudinous density of tool to obtain the bat line vibration frequency of expectation.It is a kind of for testing the method for racket structure that the present invention also provides.

In more detail, by the bat line construction opening place at racket, using thread-protected tube to obtain may structure and method for realizing bat line length and the many of frequency of expectation.Thread-protected tube is at the structural detail of clapping the side edge of the face that line passes.The invention provides for keeping and clap the locking thread-protected tube of line and be provided for utilizing thread-protected tube that the algorithm of tension force is set.The present invention also provides polytype thread-protected tube, for example, by Teflon or other low-friction material, formed, by elastomeric material, formed, or have adjustment height, and these thread-protected tubes contribute to obtain bat line length and the frequency of expectation.A kind of configuration of racket head is provided, and this configuration is quantitatively set up side bandy degree before threading of face, to clap line length after threading, will become equal.

In another kind of improvement project, the invention provides for the manufacture of the method for racket in accordance with the principles of the present invention.In a kind of preferred embodiment, whole making body is made by carbon fiber sandwich.Compare with other racket structures, this structure provides good intensity and simplicity.Determine the size of carbon fiber racket embodiment, to be optimized for racket intensity and the ratio of weight.The present invention is also provided for testing the intensity of racket constructed according to the invention and other racket structures and the method for performance.Intensity to the intensity in racket bight and thread-protected tube bat wire maintainer is tested.The performance of racket by experiment chamber measurement is tested.Laboratory tests provide data, and these data are used for confirming that racket structure according to the present invention is superior to the performance advantage of other structures.

Generally speaking, according to reduction tennis racket of the present invention and step, be applicable to the tennis racket of rectangular shape, but within other shapes also can be contained in scope of the present invention.At various embodiments of the present invention, comprise: (1) is used for the outwardly-bent profile of the derivation that compensates curving inwardly, and to outwardly-bent for optimal performance, when be necessary determining; (2) for the bat line tension by with different and/or bat line mass density, obtain equal level and vertically clap the device of line frequency; (3) on difference is clapped line, maintain the use of the locking thread-protected tube of differential tension, making to clap line can be with equal frequencies vibration without equal length, and makes it possible to regulate or change each root and clap line; (4) for determining the derivation of the algorithm that the initial bat line tension that equates bat line frequency is provided; (5) specification of the embodiment with sandwich of rectangle racket, every pound of intensity of these rectangle rackets is approximately the twice of every pound of intensity of the conventional racket of being made by tube element; (6) specification of the embodiment preferably with mesa structure of rectangle racket, the every pound intensity of these rectangle rackets on the side of face is almost identical with the embodiment with sandwich, and there is the bight that intensity is larger, for packing material provides better protection, and allow structure easily unprecedented; (7) use of cantilever mode, estimates the stress on racket bight to analyze ground; (8) design and implementation of the device of the intensity in the side girders of racket and bight being tested.

Accompanying drawing explanation

Fig. 1 is the top view that having of a preferred embodiment of the invention is roughly the tennis racket head of rectangular shape;

Fig. 2 is the curve map that the amount of deflection of racket element when applying bat line tension is shown;

Fig. 3 is according to the curve map of the amount of deflection of Fig. 2, but vertical axes is exaggerated to illustrate better the amount of amount of deflection;

Fig. 4 is according to the top view of the tennis racket of one embodiment of the present invention, and this top view is based upon the size of describing in description;

Fig. 5 a to 5j is according to the schematic diagram of the cross section of the numerous embodiments of the bat line thread-protected tube using in the preferred embodiment of tennis racket of the present invention;

Fig. 6 is the schematic diagram of a beam, and this beam is supported and is applied with along this beam in its end power that regular intervals opens and in order to demonstration, putting on the power on the side of racket of line;

Fig. 7 is the schematic diagram of the beam of Fig. 6 amount of deflection in the situation that being subject to threading power;

Fig. 8 is the cross section of hollow cylindrical tennis racket frame, and the threading power acting on this cross section is shown;

Fig. 9 is according to the cross section of the tennis racket frame of principle of the present invention;

Figure 10 is according to the top view of the tennis racket of one embodiment of the present invention;

Figure 11 is according to the schematic diagram of the tennis racket of another embodiment of the invention;

Figure 12 is the amplification detail drawing in the bight of rectangle net racket, shows the line power of clapping;

Figure 13 is the schematic diagram that is applied in the beam of power;

Figure 14 is the viewgraph of cross-section of the side of the tennis racket in a kind of preferred embodiment;

Figure 15 is a kind of amplification detail drawing in bight of rectangle net racket of preferred embodiment;

Figure 16 is according to the schematic diagram of the sandwich of the material using in a kind of manufacture of tennis racket of preferred embodiment;

Figure 17 is the schematic diagram of the tennis racket made as described;

Figure 18 a and 18b are respectively according to a kind of top view and side view of tennis face of preferred embodiment;

Figure 19 a, 19b and 19c are according to a kind of top view of handle portion of tennis racket of preferred embodiment, side view and end-view;

Figure 20 is the schematic diagram of a kind of force measuring device of using in the method according to the invention;

Figure 21 is the stereogram of the testing equipment as used in the method according to the invention;

Figure 22 is the close-up view of overlooking of measurement device;

Figure 23 is the sketch of frame prototype that is made into demonstrate the proof of design;

Figure 24 is the stereogram of frame prototype of Figure 23 of acceptance test;

Figure 25 is another view of the frame prototype of acceptance test;

Figure 26 is the top perspective view of the racket that is configured to of instruction according to the present invention; And

Figure 27 is the view of the testing equipment for tennis racket according to the present invention is tested.

The specific embodiment

With reference to accompanying drawing, present invention is described.The first factor that will consider is the vibration frequency of the bat line when hitting tennis.For the factor that generally will consider of clapping line frequency, comprise following content.

Clap line frequency

It is an important challenge that the performance of given tennis racket is calculated, because all bat lines interact when colliding with tennis.Such calculating is documented in U.S. Patent No. 5,672,809 and U.S. Patent No. 6,344,006 in, and Main Conclusions is that the rectangle face racket with bat line equal in length in each direction provides optimal performance.The reasons are as follows.

A) the equal bat line of length (and tension force and density) vibrates with same frequency.Therefore their billiards that as one man crashes are reacted, thereby maximum bounce is provided.

B) when ball collides with two unequal parallel bat lines of length, this ball is subject to the different power of clapping line from every, causes unexpected bounce-back direction.When all parallel bat lines all have equal length, this error is eliminated.

C) when ball and bat line when collision away from Pai Xian center, this ball is subject to the unequal power from each side of the bat line being depressed.Clap line length shorter, this effect is larger.For rectangle face racket, every clap line have identical (maximum) length and therefore this error source be minimized.

D), for given racket weight, rectangle face racket has the moment of inertia around longitudinal center's axis more much bigger than conventional racket.Away from the collision of this axis therefore by cause racket with for the situation of conventional racket, compare much smaller degree and rotate away from collision ball.Therefore the angular error and the speed that have greatly reduced to produce are subdued.

E) because rectangle racket has the angle rotation less than conventional racket, therefore reduced the sportsman's arm causing due to off-center hits injured (being generally known as " lawn tennis arm ").

If length is not to equate completely, but clapping line vibration frequency equates, obtains the main benefit that equates to clap line length.It is given by following equation that the frequency of line is clapped in the vibration with anchor portion:

f = \frac{1}{2 l} \sqrt{\frac{T}{m}}

(equation 1)

Wherein, l claps line length, and T is at the tension force of clapping on line, and m is the linear quality density of clapping line.For conventional racket, T and m are constant, but clapping line length has sizable difference, and therefore vibration frequency is also like this.Utilize rectangle face racket, the value of T, m and l (in each direction) can be constant, and therefore vibration frequency f can be constant.That is the simplest possibility scheme, and instruction is realized to the inventive approach of this possibility scheme below.Then we will consider more general possibility scheme.

Between side at tennis racket arsis line at frame of course not freely.Clap line along their length top-bottom cross mutually repeatedly, and therefore the performance of given racket must be determined by complicated calculations on computers, as in U.S. Patent No. 6,344, described in 006B1.That the racket (utilizing equation 1 to calculate) with the bat line of equal fundamental frequency provides optimal performance shown in this patent.

When we speak of the racket with rectangle face, be understood that and for the relative side of face, it is highly important that clapping line is attached to parallel.This leaves the freedom of our the bight cavetto in the part outside the position of placing through wires hole by face framework for.This cavetto bight makes racket have larger intensity and more good-looking.This racket shown in Figure 1.

Especially, Fig. 1 illustrates the tennis racket 20 with face or frame 22, and this face or frame form by being essentially straight side 24 and being essentially straight end 26.Frame 22 has cavetto bight 28 and neck 30, this neck extend to handle (look not shown).Main bat line 32 extends between side 24 at extension and shake-hands grip line 34 between end 26.

Constant-tension

The straightforward procedure of equating clap line frequency in each direction is to make the value of l, T and m constant.First we start with and temporarily suppose that face keeps substantially rectangular after threading from complete rectangular face before threading.When racket is during by threading, selected tension force T is applied to every and claps on line, but along with the carrying out of threading, and under tension force T, the increase of every new bat line has changed a little and gives the tension force of clapping line above.All bat lines attached good after, clap line tension and carry out equilibrium and be present in the tension force T ' producing clapping on line different from the tension force T applying.Qualified threading person, by the tension force of knowing that How to choose applies, makes produced tension force for expectation tension force.

Utilize the conventional thread-protected tube extending through on racket side and end for clapping line, balancing tension is incomplete.Friction on bat line in each thread-protected tube and in the face outer side edges between thread-protected tube hinders balancing tension.In addition, by the collision with ball, be applied to the power of clapping on line and will at least temporarily redistribute tension force.

The thread-protected tube and the side strip that use Teflon or have a teflon coatings can be avoided these difficulties.Teflon is extremely smooth, has coefficient of friction (being approximately 0.05 with respect to polished steel) minimum in real solid.Its use will guarantee that balancing tension is obtaining during threading and during the collision with ball fast and almost entirely.Also can provide and clap the equilibrium of line tension on whole face with other material with low-friction coefficient.

In fact, if face completely rectangular (except bight) before threading, being applied to the tension force of clapping in line will cause the side of face to curve inwardly.This will cause all bat line lengths to shorten, and the degree that shortens at the place, centre position of side is large and the degree that shortens on the position of the end near side is less.Result is clapped line length racket unequal and that reduce at the tension force of clapping on line by being.

In order to explain this effect, consider the beam that a length is l, this beam is supported and is subject to the power of the bat line that the attached tension force in the even interval of n root is T in each end.If Young's modulus and I that E is beam material are the area moments of beam cross section, the amount of deflection y (x) that beam is x place in the top distance apart from beam is provided by following equation:

y (x) = \frac{nT}{24 EIl} x (l - x) (l^{2} + x (l - x))

(equation 2)

Use l=13 inch, T=60 pound., n=19 root claps line, and for the E of carbon fiber pipe and the representative value of I, this function is drawn in Fig. 2.In curve map, run a curve 36 to illustrate that beam is along the amount of deflection of the length of frame beam.

With reference to Fig. 3, for the ease of watching, the aspect ratio with 4 to 1 draws the figure of sag curve 36 again.

Utilize the described value of relevant parameter, seen the long side 24 (in Fig. 1) that represents face beam deflection the ultimate range of about 0.5 inch.Yes for this maximum defluxion in the generation of the place, centre position (x=6.5 inch) of beam, and deflection distance value reduces continuously towards the direction away from centre position.Therefore the length that the level of locating in the centre position of face is clapped line 34 reduces about 1 inch (bending of every side 24 causes the amount of 0.5 inch).

The amount of deflection of the side 24 of actual face is more complicated than this, because these sides 24 are not rigid bracing beams and to clap the power that line applies be not uniform because serving as reasons.These amounts of deflection are not to provide by the simple analytical expression the equation 2 as above, but for any given racket geometry and material, they can easily estimate by computer, and they can directly record.The following fact is calculated the flexibility of real side and is become complicated: due to the geometry of the side of deflection, the power applying is discrete and claps on line position at each is different, or even to steady state value, is also like this clapping equilibrium of line tension.Equation to be separated be therefore highly coupling and be nonlinear because clap the amount that line tension is determined side camber, and the amount of side camber is determined bat line tension.Representative result will be provided below.

As the example of these results, consider 13 inches of long parallel sides of rectangle carbon fiber face 22, there are 19 and clap line hole, the distance in first count line hole and bight 28 is 2 inches, and all the other clap 0.5 inch of line span.Suppose the Young's modulus of fiber and the routine value of face cross section, if the every tension force of clapping 60 pounds of line carryings, the side of every face ultimate range of 0.21 inch that can curve inwardly at the place, centre position of beam.But if racket is by applying the tension force of 60 pounds to every bat line, by threading, so due to bending, the bat line tension producing will only be decreased to 51.7 pounds, and the maximum deflection of every side 24 distance will only have 0.18 inch.In order to make to clap the tension force of 60 pounds of line carrying expectation, the threading tension force applying will be had nothing for it but 69.6 pounds.These calculating are novelty and within the scope of the present invention involved.

Due to the bending of the side 24 of racket as described above, if we start with from rectangle face 22, racket is carried out to threading and will cause that constant-tension is (after equilibrium, preferably under Teflon thread-protected tube and side strip auxiliary), but can not produce bat line equal in length, and therefore can not produce the bat line that vibration frequency is equal.In order to obtain bat line equal in length, the present invention constructs face, and the side of face that makes it amount with suitably (depending on tension force) before threading is outwardly-bent.So, after threading, clap line tension and will side be become approach the configuration of rectangle.For a kind of preferred embodiment, provide the detailed content of this structure here below.These calculating are novelty and within the scope of the present invention involved.

In order to determine the aduncate amount cause, this amount enough greatly so that compensatory bandy use seem rationally, we make the changes delta f that claps line frequency be associated with the variation of bat line length Δ l with equation 1, this draws following equation:

Δ f/f=-Δ l/l (equation 3)

Use representative value l=10 inch, T=60 pound, mg=0.014oz/in (g=32ft/s ²), typical frequencies is f=670/s.Therefore typical case's collision time is t0=0.004s, and during colliding, clap line and vibrate about ft0=2.7 time, and the phase transformation standing is approximately 2 π ft0=17 radians.For the bat line of different length Δ l and the ball of collision are interacted in phase, we require phase variation to be less than π/4, namely 2 π Δ ft0 < π/4, or Δ f/f < 1/8ft0 ≈ 0.046.If (phase variation is greater than π/4, and so adjacent bat line is closing on when collision time finishes and will move in the opposite direction, thereby has reduced the bounce to ball.) so equation 3 provided 0.46 inch of Δ l <.This has implied as long as curve inwardly on every side 24 and be greater than 0.23 inch of Δ l/2 ≈, just should using compensation outwardly-bent.

Except above equating to clap line length with outwardly-bent foundation, also have other modes to obtain when the side of face curves inwardly and equate to clap line frequency.This idea is to use the bat line of variable-quality density m.If bending makes one to clap line length and be decreased to l1 and another root from l and clap line length and be decreased to l2 from l, if l1 claps proportionally m1/m2=l1 of the density m1 of line and density m2 that l2 claps line so ²/ l2 ²select, clap line or vibrate under same frequency for these two.

Describe the tennis racket with rectangle face above and how to have there is in the horizontal direction the bat line equal with frequency with in the vertical direction length.In addition, if will produce with the identical performance more uniformly of frequency of in the vertical direction in the horizontal direction.A kind of mode that realizes this point is that to make face be not only for rectangle, but be square.So, if level and vertically tension force are equal, level and vertical frequency also will equate.But most of sportsmen can have a preference for rectangle face, because it can give them larger batting region under current I TF (International Tennis Federation) rule of restriction racket size.

The actual mode of another kind that obtains in the horizontal and vertical directions equal frequencies is Th/Tv=(lv/lh) proportionally ²selection level is clapped line length lh and tension force Th, and vertically claps line length lv and tension force Tv.So, according to equation 1, level and vertically frequency will equate.Feasible for this is set to, level and vertically clap line length and can not differ and surpass 10% because clap line tension conventionally in the scope of 55 pounds to 65 pounds and according to

select.Suitable example is lh=11 inch and lv 12 inches.

Variable tension

In this joint, even if how we obtain instruction to have, clapping also identical bat line of the unequal situation lower frequency of line tension.This idea is structure rectangle racket, makes can set separately at the every tension force of clapping in line.This can be by realizing with locking thread-protected tube, and these locking thread-protected tubes are in place by their attached bat line locking.These thread-protected tubes allow to clap line and are pulled through along a direction (outside from face), and still (inwardly) can not be pulled through in opposite direction.So every (initially) tension force of clapping line can be set as desired like that, and claps on line and will balancing tension can not occur in difference, because clap line, can not slip over thread-protected tube.

Below how we construct this locking thread-protected tube by instruction.First we will explain how they are used to realize the target of equal frequencies.For this purpose, draw rectangle racket, make it face 22 on the left sides and it handle 38 on the right, as shown in FIG. 4.Allow the w be (long) upper side edge of face 22 and the initial constant distance between lower side 24, and allow the l be (short) limit, left side of face 22 and the distance between right edge or end 26.Allow x represent the distance measuring from the limit, left side of face, 0 < x < 1.Suppose that we start threading process from leftmost vertical bat line, apart from x=x1 place.This bat line is attached at lower side and is pulled through from upper locking thread-protected tube by the tension force t1 to choose, and it is in place to be then locked.This bat line pulls a distance, d 1 (x) downwards by upper racket side.Lower side will be pulled upward same distance, thereby the bat line length after locking will be w-2d1 (x1).When second (adjacent) bat line part is attached at x=x2 place, position with the tension force t2 being selected similarly, upper racket side is by another distance, d 2 (x) pulled down.This length by first count line part is decreased to w-2d1 (x1)-2d2 (x1), and therefore the tension force in this bat line part will be reduced to t1-2kd2 (x1), and wherein, k is the elastic constant of selected bat line.

By in order attached N clap line part and carry out by this way, at position xi, sentence initial tension ti and lock i bat line part, i=1,2, ..., N, side will be finally always to be curved inwardly apart from d (x)=∑ di (x), and will be finally Ti=ti-2kd (xi) at i the tension force of clapping in line part.Vertical clap line by similar attached good after, clap final lengths wi and final tension force Ti that line will obtain them, their value will depend on all initial tension t1 that choose ..., tN.

Target is to select the bat line tension t1 that applies ..., tN, making finally to clap line frequency f i is all (the fi=constant) equating according to following formula:

fi = \frac{1}{2 wi} \sqrt{\frac{Ti}{m}}

(equation 4)

For any given rectangle racket (geometry and material) and bat line, for N the bat line tension t1 applying ..., tN, can solve N equation (fi=constant) by computer.In chapters and sections below, we do this part thing for our preferred embodiment.

Use our locking thread-protected tube to also have other advantages.For example, locking thread-protected tube can be used to realize the Tension Difference of the expectation in the zones of different of face 22.Face is low performance region near the region of side, even be also like this for rectangle face.This can partly make up by the tension force that the bat line tension in these regions is chosen to be less than on the bat line near face center.This will provide strength more uniformly on whole face.

Another possible application of locking thread-protected tube is in thread-protected tube itself, to introduce some elasticity.This will be provided for controlling the additional selection of clapping line length, tension force and frequency.

Another significant advantage of locking thread-protected tube is that thread-protected tube provides owing to clashing into racket the ability that the bat line tension cause reduces to compensate.At ball with clap each collision between line to trend towards making clapping line elongated and die down and reduce their tension force.Simply bat line being pulled through to locking thread-protected tube can compensate this by making this bat line partly shorten and increase its tension force.Therefore, the necessity of threading will obviously be reduced again.(simple hand-held tensometer can connect with the bat line being drawn use, to inform the bat line tension that when obtains expectation).

Similarly, be installed with the bat line that can easily change disconnection on the independent independent racket of clapping line, and without whole threading again.This will save athletic time and cost greatly, and compensation is carried out to threading required extra time to racket.

A plurality of locking thread-protected tube embodiments are described now.These embodiments have been shown in Fig. 5 a to 5j.Each schematic diagram of locking thread-protected tube has illustrated the right side side bar 24 of face or 26 cross section, so face is the left side that is positioned at sections.Each sections comprise for

clap line

32 or 34 as the arrow towards right the single hole 40 passed through with being described.For this diagram, suppose to clap

line

32 or 34 and be attached on relative (left side) side of face, and the tension force of expectation is applied to and is clapped on line by the hole 40 shown in bat line is pulled through to the right along the direction of arrow.These diagrams provide under the tension force that uses locking thread-protected tube to choose at this and have been locked at the method in the hole 40 in beam by clapping line.

In Fig. 5 a, hole 40 be taper and clap line 32 or 34 in place by being locked during taper cork 42 (as shown in Fig. 5 b) is inserted into hole 40.This simple locking thread-protected tube structure utilize clap line 32 or 34 and stopper 42 and hole 40 between friction retrain bat line.In Fig. 5 c, the hole 40 of taper has screw thread, and as shown in thick line 44, and bat line 32 or 34 is passed in the medium pore 48 in the threaded cone screw 50 of compressible tool.The material of screw 50 can be compressed to reduce the diameter of medium pore 48 in tightening to the hole 40 of taper time.Screw 50 comprise for can by screw thread by screw-driving to hole 40 device, for example receive as the slit of screwdriver or narrow slotted recess.When screw 50 is screwed onto in hole 40, it is forced into claps on line 32 or 34 and will clap line and lock in place.In the cross section of the threaded screw 50 of taper and tool in Fig. 5 d, be shown as the bat line accepting state of medium pore 48 in opening.The outer surface 52 of cone screw 50 has the corresponding screw thread of screw thread 44 in the hole 40 with taper at Fig. 5 c.The two-part diagram that should understand Fig. 5 d shows the two halves of single cone screw.

In the example in hole 40 of another taper of locking thread-protected tube (as shown at Fig. 5 e),

clap line

32 or 34 be arranged in hole 40 cylindricality rod member 54 below by, this rod member is positioned at the left side (with reference to figure) of stop block 56 (being illustrated as black rectangle).Stop block 56, by being anchored in the hole 40 that is held in place in taper in hole wall 40, still also can be considered other

anchors.Clapping line

32 and 34 can, along with the rotation of cylinder 54 is freely drawn to the right, when still the pulling force on clapping line discharges, be held in place in the hole 40 of cylinder 54 wedged tapers and by bat line.

Figure in Fig. 5 f has described a kind of locking thread-protected tube with the hole 58 that is arranged in frame, and this hole has step configuration and comprises a pair of element 60 at the step place being arranged in hole 58 (toward each other tilt have hatched rod member).Element 60 is forced together by the spring assembly 62 shown in signal, and these spring assemblies are for example arranged between making body and each element 60 and are pressed against and clap on line to bear against on these elements and by them.In hole, 58 places can provide two or more this elements 60.Friction between element 60 and

bat line

32 or 34 prevents from clapping line and moves rearwards to the left side, but clapping line can easily be drawn to the right.Therefore, clap line is locked in place by locking thread-protected tube under the tension force of expectation.

The locking thread-protected tube of Fig. 5 g has been described with trip bolt 64

bat line

32 or 34 lockings is in place.Clap line through the medium pore 66 that is arranged in outside block 68 (as shown in black), this outside block is fixed on the frame of racket at 70 places, hole.Screw 64 is threaded in the matching thread in the hole 72 being located in block, and this matching thread extends transverse to clapping the hole 66 that line extends through.Screw 64 is screwed in downwards in hole 72, until it bears against, is clapping on

line

32 or 34, by clapping line pressure and leaning against, on the relative wall of medium pore 66, will clap line, locks in place.Outside block 68 is fixed on the frame of racket to can not fluff during use.

With reference to Fig. 5 h, similarly the threaded screw 64 of tool can be received by screw thread the hole 72 of the part being limited by recess 76 74 that is arranged in frame.By screw 64 is tightened in hole 72, screw 64 will be clapped

line

32 or 34 and be pressed against on the inwall in hole 70 so that under the tension force of expectation and will clap line and fix on the position of expectation.Recess 76 and/or screw 64 are configured to allow screw tighten and unscrew by user's finger or by instrument.Thereby this embodiment will be clapped line position by the locking thread-protected tube in embedding framework itself and lock.

A kind of locking thread-protected tube embodiment has been shown in Fig. 5 i, and this embodiment utilizes compressible flexible member 78, claps

line

32 or 34 through this flexible member, as indicated by dashed line.Compressible element 78 is arranged in the conical sleeve or cone 82 being formed in frame.Compressible element is by the threaded nut 80 of tool being screwed in the threaded cone 82 of tool and compressed.The threaded cone 82 of tool is arranged on the recess 84 that is arranged in frame.The nut 80 that turns left makes cone 82 that element 78 is pressed to and claps on line and so be held in place.In Fig. 5 i, element 78 can discharge and clap line to carry out tension adjustment by the threaded nut 80 of tool being screwed into the right in the threaded cone 82 of tool.The nut 80 that again turns left, locks bats line and be held in place under the tension force of expectation by flexible member 78 being pressed to clap on line.

Similar design has been shown in Fig. 5 j, and wherein, element 78 is by the threaded cone 86 of tool being screwed on the threaded cylinder 88 of tool and compressed.The cone that turns left 86 makes cone 86 that element 78 is pressed to and claps on line and so be held in place.

Operable locking thread-protected tube has many can realization and keeps other of each object of clapping line tension may embodiments within the scope of the invention, as will be clearly to those skilled in the art.

Frame embodiment

At this, consider the general Consideration of frame structure.In the previous section of this description, evaluated and described in detail the feature performance benefit of rectangle net racket face.In these chapters and sections, the structure of this racket be described.Conventional structure of racket technology is inadequate for rectangle racket, unless racket is too heavy, can not bat.Problem is that square corners (even if being rounded off) is the concentrated region of large stress after racket is by threading.In order to make racket bear these stress, relatively large reinforcement material must be covered in bight, this makes racket become heavy and uneven.

Two characteristics determining racket intensity are material and geometry.Be used to manufacture is that the main material of all modern racket is carbon fiber substantially.Reason is that carbon fiber has the maximum intensity weight ratio in any real material.The body tolerance of the strength of materials is its Young's modulus E.According to following equation, this modulus be defined as stress (power that per unit area applies, F/A) with the ratio of strain (the prolongation amount of per unit length or decrement δ l/l):

F/A=E δ l/l (equation 5)

According to following equation, the body of material weight tolerance is its density p, the ratio of weight W and volume V:

W=ρ V (equation 6)

Form has below been listed E and the ρ of aluminium, carbon fiber and titanium.

Young's modulus value has shown that carbon fiber is more solid but more shaky than titanium than aluminium, but these metals of its density ratio are much smaller, thereby the ratio of its intensity weight is much larger.Here it is, and carbon fiber is the reason of selected racket material.

In order to understand the effect of geometry in racket intensity, consider the uniform beam being supported 90 of the material with length L as shown in FIG. 6.Beam 90 be rectangle

racket face side

24 or 26 near each end, there is the naive model of support member 92.The bat line being attached on side applies the approximate uniform power of amplitude F=NT on the whole top of beam 90, and wherein, T is to be the quantity of clapping line at every tension force and the N clapping in line.This power has made beam 90 downward deflections ultimate range D, as shown in FIG. 6.

Due to deflection, the upper portion pressurized of beam, and the bottom tension of beam.Therefore, have one through the plane that is known as neutral axis 94 of beam 90, the length of this plane remains unchanged after deflection.This plane uses the dotted line 94 by Liang center to represent in Fig. 6.

As shown in FIG. 7, beam 90 deflection or bending under the effect of the power applying.Deflection distance D is determined according to following equation by the area inertia moment I of the cross section of the length L of the power F applying, beam, the Young's modulus E of material and beam:

D = \frac{5}{384} \frac{{FL}^{3}}{EI}

(equation 7)

I is limited according to following equation by the geometry of the cross-sectional slices of beam:

I=∫ dAy ²(equation 8)

This integration is about comprising the cross-sectional area of material, and y is the vertical range between neutral axis and cell area dA.

For example, if cross section is the annulus 96 (as shown in Figure 8) with inside radius r1 and outer radius r2, y is the vertical distance between horizontal neutral axle (dotting) and the cell area that (represents with shadow region) in the material between circle.In this case,

I = I_{A} = \frac{π}{4} ({r_{2}}^{4} - {r_{1}}^{r})

(equation 9)

The power that vertical arrow 98 representatives in Fig. 8 are applied by bat line tension.

The cross-sectional area of uniform beam is to be defined by following equation:

A=∫ dA (equation 10)

And weight is defined by following equation:

W=ρ AL (equation 11)

The target of structure of racket is to obtain sufficient intensity, thereby amount of deflection D is relatively little, and without requiring relatively large area A, thereby weight W is also relatively little.For given material (given E and ρ) and fixing weight (fixing A and L), so this target is to select the geometry of cross section, makes I large as far as possible.According to its definition (equation 8), when racket material is arranged to as far as possible the neutral axis away from the side (beam) of face, it is larger that I becomes.

This is the reason that conventional racket is formed by tube element structure.Most of material of light-wall pipe is positioned at neutral axis at a distance of relative position far away.This illustrates with annular cross section in Fig. 8.This tubular beams is more solid than the solid hopkinson bar of same material and equal weight, because the I of pipe (equation 9) is than the I of bar (I=π r ⁴/ 4) much bigger, wherein, r is the radius of bar.

This structure produces good effect for the oval racket of routine.But for rectangle racket, this structure is not desirable.The large stress of locating in the bight of face makes relatively thick pipe necessitate to obtain stability.In chapters and sections below, we are more suitable for instruction in racket of the present invention and have the alternative constructions design of more advantages.These designs will realize enough intensity, and do not require unacceptable weight.

Sandwich embodiment

Tubulose carbon fiber frame is solid, because many materials are away from neutral axis, as shown in the annulus for Fig. 8.As institute's record above us, but the solid degree of this structure is not enough to form preferred lightweight rectangle face embodiment.In this section, how we can construct more solid frame by carbon fiber sandwich by instruction.This sandwich comprises the carbon fiber board of two parallel relative thin that separated by light packing material.

The cross section of the beam 100 of being made by this sandwich is shown in Figure 9.Neutral axis 102 dots, and the power that vertically arrow 104 representatives are applied by bat line tension.Fig. 8 and Fig. 9 relatively show that part material in the material in tubular structure is away from neutral axis, but also have part material near neutral axis.On the other hand, sandwich makes all material (except light packing material) all away from neutral axis.

The size providing in Fig. 9 is total height d, the height h of the packing material l08 between two plate l06 and the width b of sandwich.The thickness of carbon fiber board 106 is respectively (d-h)/2.The area inertia moment of this sandwich cross section is defined by following equation: I _s=b (d ³-h ³)/12=b (d-h) (d ²+ dh+h ²)/12=A _s(d ²+ dh+h ²wherein, AS=b (d-h) is the carbon fibre material area in sandwich cross section in)/12 (equation 12).We are by proof in the situation that area is identical, and this moment of inertia is approximately the twice of annular the moment of inertia, I _a=π (r ₂ ⁴-r ₁ ⁴)/4=π (r ₂ ²-r ₁ ²) (r ₂ ²+ r ₁ ²)/4=A _a(r ₂ ²+ r ₁ ²)/4 (equation 13) wherein, A _a=π (r ₂ ²-r ₁ ²) be the carbon fibre material area in annular cross section.

If cross section has equal area (AS=AA), thereby beam has equal weight (equation 11), and the ratio of these the moment of inertias is defined by following equation:

\frac{I_{S}}{I_{A}} = \frac{1}{3} \frac{d^{2} + dh + h^{2}}{{r_{2}}^{2} + {r_{1}}^{2}}

(equation 14)

Utilize such fact, that is, carbon fibre material is thin, thus h ≈ d and r1 ≈ r2=d2/2, and from the diameter d 2 of cylindrical, this is reduced to

\frac{I_{S}}{I_{A}} = 2 \frac{d^{2}}{{d_{2}}^{2}}

(equation 15)

Therefore, if cross section has similar height, thereby d2 ≈ is d, and we are verified, and IS is approximately the twice of IA, thereby the intensity of sandwich beam is approximately the twice of the intensity of annular girder.

As can be seen here, by sandwich beam, replace pipe to construct rectangle frame, frame is by weight more solid and need to be lighter at place, bight.But this structure is not optimum.Problem or bight.Can combine the sandwich beam of the cross section having as shown in FIG. 9 and construct racket 110, as shown in Figure 10.Face bight 112 comprises the sandwich beam that is docking together and keeps together with suitable epoxy resin.But the solid degree of this simple structure is not enough to bear the stress being caused by bat line tension at place, bight.Reinforcement at place, bight is essential, and this has increased weight and the nose heave phenomenon of racket.

A kind of better building method is to make whole face 114 by single sandwich beam.Figure 11 illustrates this embodiment in the bight 116 with cavetto.Bight 116 is more solid, but not have to use relatively thick and wide and so the condition of quite heavy carbon fiber board under still solid not.

In order to understand, why bight must be strengthened, and considers in the bight 116 shown in Figure 12.This is the front view of face, and this face has as the parallel carbon fiber board 106 shown in shade element, and claps the vertical arrow of line 118 use and represent.The tension force across corner 116 of clapping in line 118 at these applies strong stress, because carbon fiber board 106 is long and thin.Below we will estimate these stress.

With reference to Figure 13, in order to estimate bight stress, we are modeled to top board at left end place, to be attached to rigidly the cantilever beam 120 on solid support part 122.If power F is being applied on the top of beam 120 apart from support member one segment distance L place, and beam 120 has width w and thickness t, and the stress producing in support member place is so provided by following equation:

σ_{\max} = \frac{6 FL}{w t^{2}}

(equation 16)

At 19, clap lines, clap under the condition of line under the tension force of 60 pounds for every, F=19 * 60 pound=1140 pounds.In side length, be 12 " condition under, we get L is average distance 6 ".We get w=0.75 ", the representative value of face width.If the weight of racket mostly is 14 ounces most, cantilever thickness maximum can be about t=0.1 so ".Utilize these values, equation 16 draws:

σ _max=5,500,000psi (equation 17)

This value is large, because t must be little to have acceptable racket weight.

The fracture strength of carbon fiber is approximately

σ _rupt=820,000psi (equation 18)

Because the stress ratio fracture strength applying is much bigger, so we infer that this sandwich embodiment of rectangle racket must be strengthened significantly, so that can not rupture in bight.This is difficult to accomplish under the condition that does not increase significantly racket weight.

Yes a kind of simplification of cantilever model, and it does not comprise the reinfocing effect of cavetto bight peace andante.Equally, can use stronger fiber and larger width, more complicated geometry and more excellent fiber placement pattern.But we have used practicable Fem Computer to calculate to evaluate relevant stress, and result has confirmed the conclusion drawing from model.Consider these large estimated values of bight stress, difficulty described here is obviously serious.

There is another problem in above-mentioned embodiment.Tension force in bat line on top board 124 in being attached to Figure 11 trends towards this plate to pull down, and the acarpous packing material 126 between plate is difficult to bear this power.Must prevent that with more solid and heavier filler this power from crush filler, be again to cause undesired extra frame weight.

In lower joint, we will describe a kind of preferred embodiment of rectangle racket of the present invention, and this embodiment is avoided all above-mentioned difficulties.Result will be a kind of solid but lightweight racket, and this racket has all properties advantage, is included in US Patent No. 6,344,006B1 and US7, those advantages described in 081,056B1.

Preferred embodiment

Although every pound of intensity of the material of above-mentioned sandwich embodiment is approximately the twice of every pound of intensity of conventional tubular material, we have confirmed that it has two key properties ignoring to a great extent this strength of materials.It causes acarpous bight, unless increased the rib of phase counterweight, and it makes the pressure of being damaged property of packing material, unless the resistive material that comprises phase counterweight.In this joint, how we construct a kind of improved sandwich by instruction, and this sandwich solves these problems, and has other advantages, and makes it possible to manufacture a kind of both solid and lightweight rectangle racket.

Idea is to use cross section to have the beam of " desk-top " structure rather than sandwich as shown in FIG. 9.Figure 14 illustrates this desk-top cross section.This cross section has three carbon fiber outside plates 130,132 and 134, rather than at two plates 106 shown in Fig. 9.Top (table top) plate 134 is similar to top structural panel sandwich 106, but bottom structural panel sandwich 106 is replaced by two sides (platform pin) plate 130 and 132.Neutral axis 136 dots, and the power that vertically arrow 138 representatives are applied by bat line tension.Volume 140 between platform pin 130 and 132 comprises and light packing material identical in sandwich.This desk-top cross section will have the every pound area inertia moment less than sandwich cross section, because it has more carbon fibre material to be arranged at more near on the position of neutral axis.Therefore, mesa structure beam 134 is more heavily necessary than sandwich beam, to have equal intensities, but this small additional weight is well made up by the following fact: the racket by these mesa structure beam constructions does not need across corner or filler to strengthen.Below we will prove these facts.

The size providing in Figure 14 is the width d, side (pin) plate 130 of top (table top) carbon fiber board 134 and 132 height b, the width h of the packing material between plate 140 and the thickness c of upper board 134.Side board 130 and 132 thickness are respectively (b-h)/2.

The gross area in the carbon fiber cross section in Figure 14 is A _t=2ab+cd, and the area inertia moment of this cross section is defined by following equation:

I _t=d (3b ²c+6bc ²+ 4c ³)/12+ab ³/ 6 (equatioies 19)

In equation 19 first is to be the contribution from platform pin from the contribution of table top and second.Because c will be always much smaller than b, so a kind of good being similar to is

I _t≈ db ²c/4+ab ³/ 6 (equatioies 20)

We continue to explain why this embodiment does not have the difficulty (acarpous bight, the filler exposing) of front a kind of embodiment, and a kind of solid and lightweight racket is provided.First we regard the intensity of beam as in the deflection distance (equation 7) at beam by quantitative.For identical power F, length L and modulus E, the moment of inertia is larger, and beam is more solid.As explained, for given cross-sectional area (and then weight of given beam), the moment of inertia I of mesa structure _t(equation 19) will be less than the moment of inertia I of sandwich _s(equation 12).But, can select size a, b, c, d, make I _tat least I _s90% (and then, consider equation 15, to surpass 80% degree, be greater than annular the moment of inertia I _a).As can be seen here, if we are chosen to just the cross-sectional area of mesa structure beam less times greater than the cross-sectional area of sandwich beam, the intensity of two kinds of beams will be identical.Below we will provide the example of the mesa structure beam size that can produce solid and lightweight rectangle racket.

Then we are more solid than those rectangle racket bights of the frame in use sandwich cross section by the rectangle racket bight of the frame in the desk-top cross section of proof use.Sandwich bight 116 has been shown in superincumbent Figure 12.Figure 15 illustrates corresponding mesa structure bight 142.First we make Slab by the cantilever with Figure 13, estimates by vertically clapping the stress that the tension force in line causes.For sandwich bight 116, plate is thin (t～0.1 inch) and wide (w～0.75 inch), and for mesa structure bight, and plate 134 is thick (t～0.75 inch) and narrow (w～0.1 ").The stress σ that this makes at support member place _maxdiffer greatly.

By the value of sandwich (F=1040 pound, L=6 inch, t=0.1 inch, w=0.75 inch) substitution in the expression formula (equation 16) of the stress at support member place, drawn very large stress 5,500,000psi, this stress ratio carbon fiber fracture strength 820,000psi is much bigger.On the other hand, by the value of sandwich (F=1040 pound, L=6 inch, t=0.75 inch, w=0.1 inch) this expression formula of substitution, draw much smaller stress:

σ _max=730,000psi (equation 21)

This is significantly less than fracture strength, has confirmed that mesa structure bight is much more solid than sandwich bight, and enough solid to bear the stress causing by clapping line tension.

Cantilever model is not considered the reinfocing effect of cavetto bight peace andante.We have used finite element analysis technology to calculate exactly the bight stress on the racket with the cavetto bight of being made by sandwich and mesa structure beam.Result is the little stress value of estimated value than above.The range of stress of calculating for sandwich bight is 1,700,000-2 for sandwich bight, 400,000psi, and be 530,000-650 for mesa structure bight, 000.The size of these scopes results from uses different size, lay pattern and epoxy resin.Utilize these any in may schemes, the superiority of bench-top configuration is obvious.

Therefore, use desk-top element make it possible to structure have enough solid to bear the rectangle racket in the bight of the power applying, and without any reinforcement.Therefore these elements have eliminated the problem in the shaky bight relevant with layer structured element.They have also eliminated the problem that the filler relevant with layer structured element crushes.From can clearly be seen that at the desk-top cross section shown in Figure 14, because table top carbon fiber board 134 is positioned on side board 130 and 132, the bat line tension 138 being applied on this table top carbon fiber board does not apply significant power to packing material 140.All power applying is substantially by side board 130 and 132 opposings.In chapters and sections below, this true laboratory proofing will be narrated.

By the rectangle racket of the desk-top element manufacture of carbon fiber of the present invention, therefore there is solid side, solid bight and shielded packing material.Here it is, and why they are preferred embodiments of rectangle racket.In addition, this manufacture also has another major advantage.By racket described in single carbon fiber sandwich construction, be to be easy to especially.Figure 16 illustrates this sandwich 148.It comprises top and bottom carbon fiber board 150 and 152, and these two plates are separated by light packing material 154.Packing material 154 can be the foamed material of fiber or non-fibrous material, expansion or other is by material natural or that synthetic material is made.These plates will become side (platform pin) plate 130 and 132 of the mesa structure in Figure 14.

Frame can be determined into single-piece 156 in this sandwich 148, shown at Figure 17.Then, attached upper length and thin carbon-fibre strips, the thickness of this carbon-fibre strips equals the size c in Figure 14, and width equals the thickness (the size d in Figure 14) of above-mentioned sandwich.Can use suitable epoxy resin that carbon-fibre strips is attached in the periphery of the face in Figure 17.In order to gain in strength, this carbon-fibre strips can have upper lip and lower lips, makes it become c shape.Epoxy resin bonding be installed and be used to this carbon-fibre strips can around the periphery of face.Lip or extension extend on top board 150 and base plate 152, have not only increased intensity but also have increased decorative appearance.Finally, can on the appropriate location around face periphery 158, get out through wires hole, thread-protected tube or thread-protected tube bar can be embedded in these holes, and can to carbon fiber handle bar 160, supplement and then be wrapped with tie with light material.Then, racket just can threading.

The shape of the shearogram in Figure 17 can generally be changed into comprises improvement previously discussed.Bight 162 can be rounded off, to improve racket intensity and outward appearance.The side 164 of face can be outwardly-bent, to obtain rectangular face completely after threading.Side strip can slotted or otherwise be changed to hold thread-protected tube and clap line.Easily structure is the major advantage of bench-top configuration of the present invention.

It is to calculate based on theory that the preferred rectangular ball of describing in this section is clapped embodiment.In lower joint, in fact how we will provide the details of the object lesson of these rackets being constructed and being tested.By intended size, by specified material, will the photo of the example constructing be shown and intensity and performance data will be provided.

The example of preferred embodiment and test

For the rectangle racket of manufacturing instructions preferred embodiment, we first select the feature of expectation.Most of modern rackets have 19 short bat lines and 16 long bat lines, and we will defer to this selection.According to the patent No.US6 at Brandt, the performance of recording in 344,006B1 is calculated, and the bat line interval of 0.5 inch approaches optimum, and therefore we also do this selection.We select the interior face size of 9.5 inches * 12 inches to adapt to this bat ray mode.At the face shown in Fig. 1, this pattern is shown.It is 1 inch and be 1.5 inches on aspect horizontal that first and last root are clapped gap in the vertical direction between line and inside casing side.

The weight of most of modern tennis rackets is between 10 to 14 ounces, and mass centre is positioned at Pai Hou district, and we also will add these constraintss.Therefore, we must select mesa structure size b, h, d and c (as defined in Figure 14), make these sizes enough large so that the side of racket and bight are enough solid to bear the bat line tension in common scope 55-65 pound, and make these sizes enough little to be no more than the weight boundary of 14 ounces.Once these mesa structure sizes all determine, just must calculate or measure the aduncate amount of the side of the face being caused by bat line tension.If maximum deflection distance, so must be by making the outwardly-bent racket of constructing of side, so that this is compensated over the boundary of (according to the equation 6) of deriving above 0.23 inch.

For the plate that forms mesa structure beam, we have selected the carbon fiber product that can buy on market.Platform pin 130 and 132 is made by the carbon fiber board with 45 ° of lay patterns.Table top 134 is made by the carbon fiber board with unidirectional lay pattern.The Young's modulus of this material is approximately E=2 * 10 ⁷psi, and density is ρ=0.96oz/in ³.

By these values, and in the value substitution the moment of inertia equation (equation 19) of optional mesa structure size b, h, d and c, we can estimate with equation 7 amount of deflection of racket side, we can estimate racket bight stress with equation 16, and we can calculate the weight of face.Then, we can confirm these results by carrying out finite element analysis.These calculating make us can select to produce enough mesa structure sizes of solid and lightweight racket.

These calculating have been implied for a kind of suitable selection of the mesa structure size of 12 inches of face sides as follows:

B=0.625 inch

H=0.55 inch (equation 22)

D=0.75 inch

C=0.0625 inch

Therefore, mesa thickness is that c=0.0625 inch and platform pin thickness are (d-h)/2=0.1 inch.By these values, the area inertia moment of the cross section of beam is I _t=0.0083in ⁴, and at tension force, be that under the condition of 60 pounds, the maximum defluxion of the side of 12 inches is 0.155 inch.For the face side of 9.5 inches, b can be decreased to 0.5 inch.

The side of 12 inches of face is designed to bear by 19 attached good power of 1140 pounds that respectively the bat line under the tension force of 60 pounds causes.The bat larynx of racket and handle needn't be solid like this.Power on these elements produces during the of short duration collision time (approximately 0.004 second) of racket batting.This power maximum is about 250 pounds, and continues one very short period, makes to clap larynx size and can be significantly less than those sizes in equation 22.

Racket is preferably independently clapped the mode of line part and is carried out threading to have for every main bat line and shake-hands grip line.Also will be understood that bat line can be single continuous bat line or can have several bat line segments.

All the other key elements of racquet design are unimportant and can be selected to consistent with current convention for performance.The design of final racket has been shown in Figure 18 a and 18b (face 166) and Figure 19 a, 19b and 19c (clapping larynx 168 and handle 170).Except the feature describing in detail above, these figure comprise some other characteristics.Because whole frame is determined in the carbon fiber sandwich of thickness d=0.75 inch, so all elements of racket (face 166, clap larynx 168, handle bar 170) all will have this thickness.Inner corner portion is with the radius cavetto of 1 inch, and external angle is with the radius cavetto of 1.625 inches.Clap larynx side and there is width b=0.625 inch.Clap larynx and narrow to form gradually the handle bar of 0.625 inch wide.Stipulated in the drawings every other size.Show in the drawings many holes.These holes alleviate racket for the region that is enough to hold them in intensity.For example, show in 176Chu hole, Shang bight, the position of attached bat larynx 168 174 (with reference to Figure 18 a).In the top view of Figure 19 a, hole 178 and the alignment of 180 centre positions along handle 170, and as visible in side view 19b, hole 182 is transverse to hole 180.These holes can be filled lightweight materials or be retained as the opening in frame.In handle part 170, provide handle forming element 184 so that comfortable grasping to be provided.

Figure 18 a and 18b show tennis 172 to obtain ratio sense with mirage.

The bat handle bar 170 of being determined by sandwich has the width of 0.625 inch and the height of 0.75 inch.Light material such as balsa is attached on this handle bar, as shown at Figure 19 a, 19b and 19c, as handle forming element, handle is zoomed into desired size (wide 1.25 inches and high 1.14 inches), and be shaped (octagon-shaped is standard and is here used).

At frame, from carbon fiber sandwich, determine and after peripheral attachment upper side edge (table top) plate, get out and clap line hole, as shown in Figure 18.Thread-protected tube and the locking thread-protected tube of preferably locking as described above thread-protected tube or other type to be inserted in these holes, and then can carry out threading to racket.Finally, end cap 186 and tie can be attached on handle.

Clapping line tension is preferably configured to for every main bat line and equates for every shake-hands grip line.In a kind of preferred embodiment, the bat line tension on main bat line and shake-hands grip line is equal to each other.The bat line vibration frequency of main bat line preferably equates and the bat line vibration frequency of shake-hands grip line is preferably equal to each other.In one embodiment, the vibration frequency of main bat line and shake-hands grip line equates.In some calculates, variable ti and li refer to respectively tension force and the length of every main bat line, and variable sj and kj refer to respectively tension force and the length of every shake-hands grip line.The line density of clapping line represents with mj for main bat line density and represents for shake-hands grip line density m ' j.

In the size described in above-mentioned figure, be to choose under the help of calculating in the theory of intensity and performance.Before manufacturing racket, by laboratory intensity measurements, confirm that these calculating are wise.We have designed the suitable strength test draft that we will instruct below.

In order to confirm to have selected size, the bench-top configuration (Figure 14) of (equation 22) is enough solid with the thread-protected tube that keep to embed and bear the power causing by clapping line tension, and we have designed at the equipment shown in Figure 20.A part for mesa structure beam 200 (illustrating by grey) is held in place by a pair of (illustrating with black) whole retainer 202.Clapping line 204 is passed in threadably the thread-protected tube 206 in two holes in beam 200 and is attached on load cell 208 (illustrating with the shade element on the right).It is upper that load cell 208 is attached to block 210 (illustrating with black), and the bolt 212 inserting by rotation, can make this block move backward.This moves backward and applies power F to clapping line, and the size of this power is indicated on by line and is connected in the display unit 214 (dash box that is used in lower middle position illustrates) on load cell.

The reading showing when display 214 is while being worth F, and the tension force in each root of two bat lines 204 is F/2.In order to make joist support be subject to the bat line tension of 60 pounds, it must bear the power that applies of 120 pounds.We have carried out test and we and have found that it has born the power that applies that surpasses 200 pounds have the mesa structure beam of the size providing in equation 22 by this way.This intensity that has confirmed beam is calculated.In Figure 21 and 22, shown the photo of testing equipment.

The testing length mesa structure beam that has confirmed by experiment to have given size is solid as estimated by our calculating, and we continue to describe and how similarly the intensity in our racket bight to be tested.We have designed the method for doing this part thing and have utilized the side of racket face and the small-sized duplicate 212 in bight, as shown in Figure 23.The mid portion 214 on the top of this duplicate 212 have with at the identical cross sectional dimensions of the desk-top cross section shown in Figure 14 (equation 22).The inner length of duplicate is 4.5 inches, and outer length is 5.75 inches.(inner length of the face of drawing in Figure 18 a is 12 inches).The bight flexibility of duplicate and actual racket is identical.

The power being caused on the long side of actual racket face by the every tension force of 60 pounds of clapping on line of clapping in line at 19 is 1140 pounds.Equivalent force F on duplicate 212 in the power of the identical stress of place, bight generation, when being applied to the centre position of duplicate, is 1390 pounds.(this power is larger, because effective lever arm is less.) in order to confirm that duplicate can bear this big or small power, we by duplicate 212 insert with to applying in the hydraulic press that load cell that power measures is connected.In Figure 24 and 25, provided the photo of this testing equipment.We increase the power F applying constantly, until the fracture at the beginning of the upper corner in duplicate.(it is thicker than another that bight is manufactured into, to guarantee that another bight first ruptures).When the power applying reaches 2250 pounds, we observe this fracture.Because this power is far longer than 1390 pounds, be equivalent to the power of 1140 pounds that applied by the bat line on our actual racket, we infer that the bight of this actual rectangle racket is not only enough solid to bear the stress facing.This has confirmed the correctness that we estimate the theory of our bight intensity and has continued structure of racket to our confidence.

Figure 26 illustrates according to the photo of the racket 230 of the generation that specification constructs above.The weight recording (W), barycenter (COM) and around perpendicular to handle and to be parallel to the weight moment of inertia (MOI) of axis (being positioned at 6 inches of places apart from handle end) of face as follows:

W＝14oz

COM=9.87 " (equation 3.18)

MOI＝2400oz.in ²

Racket of the present invention can have the band line weight that is less than 14 ounces.According to the present invention, also structure of racket one-tenth can be had and is less than 12 ounces, or even be less than the weight of 10 ounces.

By using on the tennis 234 that advanced by the big gun various positions under various impact velocities and on racket face, clash into racket, we have measured the performance of similar prototype racket 232, and this prototype racket has slightly different size and heavier and have different CF.Face 232 clips on the firm surface vertical with the direction of big gun 236 rigidly.The ball 234 of incident does not rotate and vertically clashes into racket 232.The ball speed of utilized grating Measurement accuracy incident and bounce-back.(racket does not move during these collisions.By providing these data, to racket, during colliding, be the conversion of the match situation of free body substantially subsequently.) for relatively, the oval racket of routine has been carried out to the measurement of same type.Figure 27 illustrates the photo of layout.

The parameter that characterizes the performance on the fixing arbitrfary point of racket on face is speed ratio at that point, the ratio of the speed that rebounds and incidence rate.Speed ratio between rectangle and oval racket relatively in, relatively at racket center, (the fixedly maximum performance point of racket) located and the difference between the speed ratio away from the given distance in center is important, because can clap line tension adjustment by change in the performance at racket center.Under identical incidence rate, relatively these differences are also important, because these speed ratios always reduce along with the increase of incidence rate.

Following table has been shown the speed ratio data of the measurement result that represents us.Impact velocity provides in first row.For rectangle and oval racket, below He center, center 3.5 " some place speed ratio relatively.As seen from the table, this speed ratio has reduced 0.52% and 0.75% for rectangle racket, and has reduced 10.48% and 8.55% for oval racket.As seen from the table, the eccentric performance of rectangle racket is better far away.

For these data transaction being become to be characterized in the data of the racket performance in the match situation that racket is free body substantially during colliding, we replace speed ratio with recovery coefficient (COR).COR between tennis and tennis racket is relativelythe ratio of bounce-back speed and relative incidence rate.This parameter (racket fixedly time this parameter be reduced to described speed ratio) be the amount of determining threading racket performance.The linear velocity of rebound is determined together with the details of racket batting (linear velocity and angular speed), racket kinematics characteristic (weight, COM, MOI) and incident ball characteristic (weight, linear velocity and angular speed) by the COR at point of impingement place completely with angular speed.

Following table is shown the COR data variation being caused by speed ratio data for 65.3mph collision above.We have supposed that rectangle and oval racket have equal weight, MOI and COM.The larger MOI of reality of rectangle racket will further improve their superiority with respect to oval racket.

For the fixing racket of frame, optimum performance is in face center.For free racket, maximum performance point shifts to handle direction, because that is the direction towards the COM of racket.For rectangle racket, this point affect Shi center downward 3.5 " locate, 0.75% performance reduces by 1.19% performance and improves and replace.For rectangle racket, this point affect Shi center downward 3.5 " locate, 8.55% performance reduces by 7.45% performance and reduces and replace.

The COR difference of showing in upper table causes being hit sizable track difference of tennis.The speed of being batted is determined together with all details of batting, incident ball and kinematics characteristic by ball-racket COR with rotation.For the representative value of these parameters, in the center of rectangle racket be only about 0.15mph at downward 3.5 inches of places by the difference of striking speed.Suppose the coefficient of friction of ball and the representative value of resistance coefficient, the difference by batting track producing is generally speaking less than 4 inches.For oval racket, corresponding difference is 6.5mph, and the difference by batting track producing is greater than 12.5 feet.The superiority of rectangle racket is apparent.

We provide the concrete preferred embodiment of rectangle racket design, but as one of ordinary skill will appreciate, the present invention has many other possible embodiments.

Although those of ordinary skills can advise other modification and change, being intended that of inventor in the scope of the claims authorized about this, be included in they in the scope of the contribution of prior art rationally and the institute suitably occurring change and revise.

Claims

1. a sport racket, comprising:

Making body, comprising:

The racket head substantially with rectangular face shape, described rectangular face shape substantially comprises cavetto bight, described racket head limits a plurality of bat lines installation site with the arrangement of being scheduled on four relative sides of described rectangular face shape;

Be fixed to the handle in described racket head; And

Clap line at least one, described bat line is arranged on described bat line installation site and sentences the main bat line part of restriction and shake-hands grip line part, described in each, main bat line part has substantially equal length and equal tension force substantially, and described in each, shake-hands grip line partly has substantially equal length and equal tension force substantially.

2. sport racket as claimed in claim 1, wherein, is less than 14 ounces with described at least one weight of clapping the described making body of line.

3. sport racket as claimed in claim 1, wherein, is less than 12 ounces with described at least one weight of clapping the described making body of line.

4. sport racket as claimed in claim 1, wherein, is less than 10 ounces with described at least one weight of clapping the described making body of line.

5. sport racket as claimed in claim 1, wherein, when putting on line in described racket head, described main bat line part and described shake-hands grip line partly have substantially equal bat line tension.

6. sport racket as claimed in claim 1, wherein, described rectangle racket head forms to have the shape of bandy side, makes when putting on line, and the side of described racket head is clapped line tension and is pulled into the side that is essentially straight.

7. a sport racket, comprising:

Making body, comprising:

Be fixed to the handle in described racket head; And

Clap line at least one, described bat line is arranged on described a plurality of bat lines installation site and sentences the main bat line part of restriction and shake-hands grip line part, described in each, main bat line part has main bat line fundamental vibration frequency, wherein, each main bat line frequency is substantially the same, described in each, shake-hands grip line part has shake-hands grip line fundamental vibration frequency, and wherein, each shake-hands grip line frequency is substantially the same.

8. sport racket as claimed in claim 7, wherein, described making body and the weight of clapping line are less than 14 ounces.

9. sport racket as claimed in claim 7, wherein, described making body and the weight of clapping line are less than 12 ounces.

10. sport racket as claimed in claim 7, wherein, described making body and the weight of clapping line are less than 10 ounces.

11. sport rackets as claimed in claim 7, wherein, clap the bat line line density that line has substantial constant for described at least one, and wherein

and

wherein, ti is the bat line tension of a main bat line part, and li is the bat line length of this main bat line part, and sj is the bat line tension of a shake-hands grip line part, and kj is the bat line length of this shake-hands grip line part.

12. sport rackets as claimed in claim 7, wherein, described at least one bat line has variable bat line line density, and wherein and

wherein, ti is the bat line tension of a main bat line part, and mi is the bat line density of this main bat line part, li is the bat line length of this main bat line part, sj is the bat line tension of a shake-hands grip line part, and m ' j is the bat line density of this shake-hands grip line part, and kj is the bat line length of this shake-hands grip line part.

13. sport rackets as claimed in claim 7, wherein,

(\sqrt{ti / mi}) / li = (\sqrt{sj / m^{,} j}) / kj .

14. sport rackets as claimed in claim 7, also comprise:

The expansion spool that can lock, described thread-protected tube is arranged at least some in described bat line installation site and claps line installation sites and sentence described bat line is partly held in place.

15. sport rackets as claimed in claim 7, also comprise:

The thread-protected tube that can lock, the end that described thread-protected tube is positioned at an end of main bat line part described in each and is positioned at shake-hands grip line part described in each is to be partly held in place described bat line.

16. sport rackets as claimed in claim 7, also comprise:

The thread-protected tube that can lock, each end that described thread-protected tube is positioned at each end of every described main bat line and is positioned at every described shake-hands grip line is to be held in place described bat line.

17. sport rackets as claimed in claim 14, wherein, described thread-protected tube of locking keeps described bat line part at described bat line installed position, to maintain the predetermined tension in the predetermined bat line part in described bat line part.

18. sport rackets as claimed in claim 17, wherein, the described thread-protected tube of locking in described shake-hands grip line part maintains the tension force in described shake-hands grip line part, makes

wherein, sj is that tension force and the kj in shake-hands grip line part is the length of shake-hands grip line part, and

Described thread-protected tube of locking in described main bat line part maintains the tension force in described main bat line part, makes

wherein, ti is that tension force and li in main bat line part are the length of main bat line part.

19. sport rackets as claimed in claim 17, wherein, the described thread-protected tube of locking in described shake-hands grip line part maintains the tension force in shake-hands grip line part, makes

wherein, sj is the tension force in shake-hands grip line part, and m ' j is the mass density of shake-hands grip line part, and kj is the length of shake-hands grip line part; And

Wherein, the described thread-protected tube of locking in described main bat line part maintains the tension force in main bat line part, makes

wherein, ti is the tension force in main bat line part, and mi is the mass density of main bat line part, and li is the length of main bat line part.

20. 1 kinds of sport rackets, comprising:

Racket head, comprises open frame, at the relative side place of the frame of described opening, limits the layout of clapping line hole, and described bat line hole comprises substantially tapered hole portion;

Be fixed to the handle in described racket head;

Clap line at least one, described bat line is configured to through described bat line hole and the frame that extends across described opening to limit face; And

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described thread-protected tube comprises substantially tapered thread-protected tube part, described in described thread-protected tube is partly inserted into substantially in tapered hole portion, by being frictionally engaged between described tapered hole portion substantially and described tapered thread-protected tube part substantially and described bat line, described thread-protected tube of locking is clapped line and is engaged and retrain described at least one bat line with described at least one under tension force.

21. 1 kinds of sport rackets, comprising:

Racket head, this racket head comprises open frame, at the relative side place of the frame of described opening, limits the layout of clapping line hole, and described bat line hole comprises substantially tapered hole portion, and described tapered hole portion substantially has screw thread;

Be fixed to the handle in described racket head;

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described thread-protected tube comprises the threaded tapered thread-protected tube part substantially of tool, described thread-protected tube is partly inserted in the threaded tapered hole portion substantially of described tool, by being threadedly engaged with between the threaded tapered hole portion substantially of described tool and the threaded tapered thread-protected tube part substantially of described tool and described bat line, described thread-protected tube of locking is clapped line and is engaged and retrain described at least one bat line with described at least one under tension force.

22. 1 kinds of sport rackets, comprising:

Racket head, this racket head comprises open frame, at the relative side place of the frame of described opening, limits the layout of clapping line hole, described bat line hole comprises substantially tapered hole portion;

Be fixed to the handle in described racket head;

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described in each, thread-protected tube comprises the rod member that is substantially cylindricality, described in described rod member is arranged on substantially in tapered hole portion, described in each thread-protected tube comprise be arranged in described in the scotch in tapered hole substantially, described in the described rod member wedging that is substantially cylindricality substantially in tapered hole to make described at least one to clap line and be held in place under tension force, but the described described at least one bat line of rod member permission that is substantially cylindricality is pulled through described thread-protected tube to be increased in the tension force of clapping on line stops bat line to move in opposite directions.

23. 1 kinds of sport rackets, comprising:

Racket head, this racket head comprises open frame, at the relative side place of the frame of described opening, limits the layout of clapping line hole;

Be fixed to the handle in described racket head;

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described thread-protected tube comprises the first lock portion and the second lock portion and biasing member, described biasing member setovers described the first lock portion and the second lock portion toward each other to engage to keep described at least one to clap line with described at least one bat line under tension force, the described at least one bat line of described the first locking member and the permission of the second locking member moves and to be increased in the tension force of clapping on line, still stops bat line to move in opposite directions through described lock portion along a direction.

24. 1 kinds of sport rackets, comprising:

Be fixed to the handle in described racket head;

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described thread-protected tube comprises to be clapped line passage and leads to the screwed hole of described bat line passage and can be threadably engaged the screw member in described screwed hole, and described screw member bears against and is arranged in described at least one of described bat line passage and claps line so that described at least one bat line is fixed on to described bat line passage.

25. sport rackets as claimed in claim 24, also comprise:

Outside block, this outside block limits described bat line passage and described screwed hole, and described screw member is bonded in this screwed hole.

26. sport rackets as claimed in claim 24, also comprise:

The part of the described screwed hole of restriction of described racket head, described screw member is bonded in described screwed hole.

27. 1 kinds of sport rackets, comprising:

Be fixed to the handle in described racket head;

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described in each, thread-protected tube comprises compressible flexible bat line clamping element, described bat line clamping element engages with described bat line, described in each, thread-protected tube comprises the threaded cone of tool, described cone engages with described clamping element, described in each, thread-protected tube comprises the threaded nut of tool, and described nut can be threadably engaged in the threaded cone of described tool to compress described clamping element and will clap line whereby in position.

28. 1 kinds of sport rackets, comprising:

Be fixed to the handle in described racket head;

Clap line at least one, described bat line is configured to limit, clap line through described bat line hole and the frame that extends across described opening; And

A plurality of thread-protected tubes of locking, described thread-protected tube is arranged in a plurality of bat lines hole in described bat line hole, described in each, thread-protected tube comprises compressible flexible bat line clamping element, described bat line clamping element engages with described bat line, described bat line clamping element is maintained in the threaded nut of tool, and be provided with the threaded part of tool at place, described bat line hole, the threaded nut of described tool can be threadably engaged in the threaded part of described tool, to described bat line is remained in described bat line hole under tension force.

29. 1 kinds of sport rackets, comprising:

Frame;

The handle being connected with described frame,

Described frame and described handle are formed by carbon fibre composite and have sandwich, and described sandwich comprises the first relative carbon fiber sheet and the second carbon fiber sheet, between described the first carbon fiber sheet and the second carbon fiber sheet, is provided with light core material.

30. sport rackets as claimed in claim 29, wherein, described frame and described handle are in a single-piece and have be characterized as the structure of determining from monolithic sandwich material.

31. sport rackets as claimed in claim 30, wherein, the moment of inertia of the face cross section of described sport racket is at least the twice of the moment of inertia with the annular cross section of equal area and similar size.

32. sport rackets as claimed in claim 29, also comprise:

Be fixed to the carbon-fibre strips on the outer peripheral face of at least a plurality of parts of described sport racket.

33. sport rackets as claimed in claim 32, wherein, described carbon-fibre strips is " C " shape and has first outer and the second outer field first and the second portion that covers respectively described sandwich.

34. sport rackets as claimed in claim 32, also comprise:

Be applied to a plurality of Kevlars material layer in described carbon-fibre strips.

35. sport rackets as claimed in claim 32, wherein, the area inertia moment of face cross section is at least 1.8 times of the moment of inertia with anchor ring of the same area.

36. sport rackets as claimed in claim 32, wherein, the weight of described racket is less than 14 ounces.

37. sport rackets as claimed in claim 32, wherein, the weight of described racket is less than 12 ounces.

38. sport rackets as claimed in claim 32, wherein, the weight of described racket is less than 10 ounces.

39. sport rackets as claimed in claim 32, wherein, the interior face length of described frame is between 11 inches to 15 inches, the interior face width of described frame is between 9 inches to 11 inches, the width of the side of the face of described frame is between 0.25 inch to 0.75 inch, the degree of depth of the side of the face of described frame is between 0.5 inch to 1 inch, and the thickness of the structural panel sandwich of described frame is between 0.025 inch to 0.15 inch.

40. sport rackets as claimed in claim 39, wherein, the stress being caused by the bat line tension that is less than 70 pounds in the lateral section of frame be less than frame face material disruptive force 80%.

41. sport rackets as claimed in claim 32, wherein, described frame has substantially rectangular face shape, described rectangular face shape substantially comprises cavetto bight, and described racket head limits a plurality of bat lines installation site with the arrangement of being scheduled on four relative sides of described rectangular face shape;

Be fixed to the handle in described racket head; And

Clap line at least one, described bat line is arranged on described a plurality of bat lines installation site and sentences the main bat line part of restriction and shake-hands grip line part, described in each, main bat line part has main bat line fundamental vibration frequency, described in each, shake-hands grip line part has shake-hands grip line fundamental vibration frequency, and described main bat line fundamental vibration frequency is substantially equal to described shake-hands grip line fundamental vibration frequency.

42. sport rackets as claimed in claim 39, also comprise:

In order to clap that line remains in described frame and the thread-protected tube of locking of installing by least one.

43. sport rackets as claimed in claim 42, wherein, described thread-protected tube of locking maintains at least one predetermined bat line tension of clapping on line being through in described frame.

44. sport rackets as claimed in claim 42, wherein, described thread-protected tube of locking maintains the described at least one predetermined tension of clapping on line, described predetermined tension makes the described at least one main bat line of clapping line partly have substantially equal fundamental vibration frequency, and described predetermined tension makes the described at least one shake-hands grip line of clapping line partly have substantially equal fundamental vibration frequency.

45. sport rackets as claimed in claim 44, wherein, the described fundamental vibration frequency of described main bat line part is substantially equal to the described fundamental vibration frequency of described shake-hands grip line part.

46. sport rackets as claimed in claim 29, wherein, the weight of described sport racket is less than 14 ounces.

47. sport rackets as claimed in claim 29, wherein, the weight of described sport racket is less than 12 ounces.

48. sport rackets as claimed in claim 29, wherein, the weight of described sport racket is less than 10 ounces.

49. 1 kinds for providing the method for sport racket, comprises the following steps:

Form frame, make described frame there is rectangular shape substantially;

With at least one bat line, give described frame threading, so that main bat line part and the shake-hands grip line part of extending to be provided between the relative side of described rectangular frame substantially;

Strain main bat line part, make each main bat line partly there is substantially equal length and equal tension force substantially; And

Tension shake-hands grip line part, makes each shake-hands grip line partly have substantially equal length and equal tension force substantially.

50. methods as claimed in claim 49, wherein, described formation step comprises formation rectangular frame substantially, this frame has bandy side, makes the step of the main bat line part of described tension and tension shake-hands grip line part on the side of described bending, apply enough power described side is pulled into the side that is essentially straight under bat line tension.

51. methods as claimed in claim 49, wherein, described threading step partly applies initial tension to main bat line part and shake-hands grip line; And

Wherein, described tension step is applied to final tension force in main bat line part and shake-hands grip line part.

52. methods as claimed in claim 49, wherein, described tension step is applied to substantially the same tension force in main bat line part and shake-hands grip line part.

53. methods as claimed in claim 49, wherein, described tension step comprises and being partly locked in the thread-protected tube that can lock to maintain the sub-step of clapping the tension force in line part clapping line.

54. methods as claimed in claim 53, wherein, the sub-step of described locking comprises by wedging power and being partly locked in the thread-protected tube that can lock clapping line.

55. methods as claimed in claim 53, wherein, the sub-step of described locking comprises the mode that the first screw member engages with the second screw member being partly locked in the thread-protected tube that can lock by clapping line by screw thread.