FR2484265A1 - Machine for stringing sports racquets - has strings held taught by lever system supporting counterweight to move upper arm - Google Patents

Abstract

The machine for stringing tennis or other rackets has a frame supporting a cradle which hold the racket frame horizontally and can pivot through 360 degrees. Each string (4) is tightened after it has been put through the frame by a lever system. A vertical lever has an arm on its lower extremity on which another arm pivots, supporting a counterweight and resting on a roller fixed on the end of a second vertical sliding on a bar. The lever moves an arm joined to an upper arm which moves from a position near the frame to one further away.

Description

MACHINE FOR STRINGING TENNIS RACKETS OR THE LIKE
The present invention relates to an improved machine for stringing all models of tennis rackets, squash, balmington or any other similar item.

 It relates more particularly to a machine which allows both the stringing of rackets and other similar articles whose frames may have different dimensions, the tensioning of the different strands of the stringing being carried out automatically and with very high precision.

When you want to string a tennis racket or any other similar item, different probe'mes arise and wear essentially
- maintaining the racket preferably in a horizontal position, without causing deformation of the frame,
- the passage of the rope in the holes provided on the periphery of the frame
- tensioning, as regular as possible of the strand in place,
- maintaining the voltage communicated to the strand during the establishment of the next strand.

 Thus, the patent of the United States of America No. 2,043,813 describes a machine in which the frame of the racket is held horizontally by means of a cradle pivotally mounted on a support for holding the frame, on this cradle the racket is held by means of adjustable internal billiards allowing to use the same installation for rackets having different dimensions. These billiards are made in such a way that they immobilize the racket without blocking the orifices for the passage of the strings, but have the major disadvantage of a deformation of the frame either when laying the uprights or the spans, the billiards only serving as racket support.

Furthermore, the tensioning of each strand is obtained by means of a spring system which is associated with means making it possible to communicate a tension more or less equal to all the strands of the rope. In Réndral, we can say that these tension adjustment means are constituted by a system with stops limiting the tensile force of the spring which transmits the tension to the strands.

 In this type of embodiment, the tension after setting up strand is obtained by introducing a blocking wedge into the outlet.

 If such a type of equipment is simple, easy to implement, it nevertheless has a number of drawbacks.

Indeed, if it makes it possible to control the action of the spring system making it possible to tension the strand, the resulting tension will not however be constant from one strand to another, taking into account the fact, that the establishment from the end of the strand on the tensioning system, and as a result of the pre-tension which is communicated to this strand cannot be produced very precisely. Finally, maintaining tension by means of a blocking wedge is not very effective and can damage the rope under tension.

 US Patent No. 2,309,849 also describes a machine for stringing rackets which solves the problems posed by this operation.

However, it should be noted that the system for tensioning the rope is very complex. Maintaining the tension communicated to the strands in place and obtained by means of a clamp, placed under the frame of the racket, which is movable. longitudinally on a slider so as to be able to pinch the crumb strand in place near said frame.

However, this clamp system becomes difficult to use, especially in the last uprights and through as a result of the clamping angle.

 Finally, the patent of the United States of America 3,511,502 describes the improvement to machines of the aforementioned type in which a mobile clamp system is used which allows the tension of the strands put in place to be maintained, this clamp being movable in height and in orientation, mounted for rotation- and sliding in the central part of the cradle, keeps the tension of the strands in place. However, such a system does not make it possible to obtain with certainty an equivalent tension for all the strands in place. In addition, it has the major drawback of having to tighten the clamp holder increasingly stronger as one moves away from the central part of the clamping axis.

Now we have found, and this is what is the subject of the present invention, a racket stringing machine, improved, simple2 easy to implement, which overcomes the drawbacks of previous machines and thus ensures a constant tension, precise to all strands of the rope.

The invention therefore relates to an improved machine for stringing tennis rackets or the like of the type comprising
a frame supporting in its upper part a horizontal cradle mounted on said frame so as to be able to pivot 3602 during the stringing operation and which is provided with means (pushers) making it possible to horizontally hold the frame of the racket,
means for tensioning each strand of the rope after passing through the orifices provided on the periphery of the frame,
- means for maintaining the tension of the strand thus in place1
and it is characterized by the fact that the tensioning means are constituted by a rocking system essentially comprising a vertical lever fixed on a horizontal axis pivotally mounted on the upper part of the frame, and whose
- The upper arm has, at its free end, means for hooking the strand to be stretched, this end being able to move from a position close to the periphery of the frame to a distant position when the strand of the string is tensioned
the lower arm is subjected on the one hand to the action of return means making it possible to bring the upper arm close to the frame and on the other hand to the action of a force exerted by a counterweight system and which tends to move the upper arm away from the periphery of the racket frame, the said lower arm connected to a lever system having at its end part a counterweight which produces on this arm a constant tensile force at the end of the upper arm and whatever the angular position of this upper arm.

In one embodiment of the invention, the return means making it possible to bring the upper arm close to the racket frame are constituted by a lever system and the force exerted by the counterweight system is transmitted to the lower arm via a linkage system which rests on a roller. In this embodiment the lower arm attached to the rod system and calculated from my niece such that the force exerted by the counterweight system on the lower arm produces, at the end of the upper arm, a constant pulling force, and this , at all stages of the tensioning operations and whatever the angular position of said upper arm.

 Furthermore, maintaining the tension after the strand has been put in place can be achieved by all known devices, such as; for example by means of a double clamp, known as a flying clamp, which can be placed both below and above, as well as by means of a clamp system, such as that described in the patent of the United States of America 2,309,849.

The invention and the advantages which it brings, will however be better understood thanks to the embodiment given below for information but not limitation and which is illustrated by the annexed diagrams in which
FIGS. 1 and 2 are respectively front and side views of a machine according to the invention,
FIG. 3 illustrates, diagrammatically in perspective, the tensioning system, according to the invention,
FIG. 4 is a front view,
FIG. 5 is a top view,
FIG. 6 is a side view of a cradle allowing rackets of different dimensions to be held,
FIG. 7 represents a section of a system which allows the frame of the racket to be maintained,
- lsstigures 8,9,10,11,12,13,14 and 15 represent the parts inside the support of the frame,
FIGS. 16 and 17 show a section through the blocking block of the base of the plate of the racket frame support,
- Figures 18, 19,20,21,22,23,24 show the section of the di, different parts which make up the brake cited in Figures 16 and 17.

If reference is made to the appended figures, the machine according to the invention comprises a frame 1 produced in a conventional manner and which carries in its upper part a cradle 2 intended to hold the frame of the racket horizontally. This cradle is mounted on part 3 of the frame 1 so as to be able to receive a rotation of 3602. It is provided with means for holding the frame, an exemplary embodiment of which, illustrated by FIGS. 4, 5 * 6, will be described in more detail detail later.

This machine includes means for tensioning each strand of the rope, maintaining the tension after the strand has been put in place can be done by means already known (see flying pliers or double pliers).

In accordance with the invention and as is shown in more detail in FIG. 3, the means for tensioning each strand 4 of the rope, are constituted by a rocking system b comprising essentially a vertical lever fixed on a horizontal axis 6 montd pivoting on the bats.

 The upper arm 7 of the lever comprises at its free end hooking means 9 for the strand 4 to be stretched. These attachment means 9 can be constituted in a simple manner, by two rollers, one of which is fixed to the upper part of the arm 7, the other free bears against the fixed roller.

 The free end 8 of the upper arm 7 can move from a position A close to the frame 10 of the racket to a position 3 away from said frame when the power is turned on.

The lower arm 11 of the lever 5 is subjected, on the one hand to the action of a return means 12 making it possible to bring the upper arm 7 near the frame 10 and, on the other hand to the action of a force exerted by a counterweight system t3. This counterweight system t3 tends to move the upper arm 7 away from the frame 10, in order to obtain a constant tensile force T at the end of the upper arm 7, regardless of its position.

The lower arm 11 is integral with the arm 7 fixed on a horizontal axis 6 pivotally mounted on the frame.

 In the exemplary embodiment illustrated by FIG. 3, the return means making it possible to bring the upper arm 7 near the frame 10 to position A are formed, killed by a system such as a lever t2 acting on the arm 1 by virtue of an articulation 60, this lever 12 being controlled by means of a cam 15 actuated by a motor not shown, this cam acting on a lever 16 pivotally mounted at 17 on the frame 1 of the machine.

Furthermore, the counterweight system 13 which transmits the tensile force to the upper end 8 of the arm 7 is constituted by an assembly comprising an arm 18 connected by means of a clevis 61 to the arm 11.

 The roller 22 fixed to the end of the axis on an arm 23 is fixed perpendicular to the horizontal bar which slides by means of four supports 25 on a bar 26 fixed to the frame by two uprights 27.

 The arm 18 has at its end a pin 19 which is connected to two arms which pivot on its end; the arm 20 pivots on one end 62 on the axis 19 and its other end on the frame 1. The arm 21 pivots at its end 63 on the axis 19 while its other end supports the counterweight 13.

The arm 21 is supported on the roller 22 described above.

 The operation of such an installation is as follows when placing a rope, under the action of the cam 15 (or by any other equivalent means such as for example by means of a pedal), the lowering of the lever 12 which is integral with the arm 11 and consequently, causes the pivoting of the upper arm 7 to bring its end 8 close to the frame in position A.

 During this movement, the arm 18 also causes the arms 20 and 21 to descend; The arm 21 being supported on the roller 22, follows the movement and causes the counterweight 13 to tip over and is at its upper point D.

After the end 4 of the strand has been placed in the holding means 9, the action of the return means is eliminated, in this case, the cam 15 is under the action of the counterweight system 13 and causes the reverse movement; that is to say, the counterweight 13 descends to position C forcing the arm 18 to rise. The arm 18 raises the arm 1t tilting the arm 7 to an equilibrium position ensuring the desired tension. We can therefore see that, thanks to this method of installation, it is possible to communicate constant tension. Indeed, depending on the pre-tension given, the end 8 of the suparieur7 arm will tend to move away more or less from the frame 10 maie whatever the position of this end8 the force transmitted by the counterweight system will be well always constant.

 moreover, thanks to such an embodiment it is possible to adjust the tension as desired. For example, as this is shown in more detail in FIGS. 3, by the diary intern of a screw system 28, controlled by a crank 29 in a simple manner, the bar 24 is made to slide along the bar 26 which causes the displacement of the arm 23 which at its end the roller 22 on which the arm 21 is supported having at its end the counterweight 13. It will be noted that according to the displacement of the fulcrum 22 the desired tension force is obtained . It then suffices to calibrate the rule 30 as a function of the force exerted by the counterweight 13.We are thus sure to always have identical successive tensions.

 Compared to previous systems, such a tensioning device has great advantages in that it is practically wear-resistant, foolproof, and that it avoids any precaution when setting up the strand.

 After passage and tensioning of a strand, the tension is blocked by any suitable means, such as by means of a clamp system, the end of the strand is then released and the cradle is pivoted. support to set up the next strand.

 Figures 4 to 15 illustrate a particular embodiment of a cradle holding the frame of the racket allowing the maintenance of any type of racket and also facilitates the establishment of the strands. In fact this cradle has the particularity of having only one branch this. which facilitates the manipulations of the operator and the possible passage of the reverser of the existing type.

As can be seen in FIG. 4, the racket support 31 is of a single branch fixed to a plate 32 pivoting at 3602, during the stringing operation, at its axis 33 on the upper part of the frame 1 The branch 31 carries at its upper part the whole racket support intended to handle the frame horizontally. This cradle can receive all kinds of rackets consists of two plates 35 each attached to a piece 36 sliding in a tube 37, rectangular, square or cylindrical.

 The sliding of the two parts 36 is affected by the intermediary of a screw 38 half left, half right so that when the knurled button 39 is operated the two parts 36 move apart or approach according to the dimension of the racket to string.

The screw 38 is held in the tube 37 by means of the pie 'ce 40 and the clamp 41. The screw 38 right-left can be replaced by two straight screws or two independent left screws but still held by the part 40 to each end of the tube, so that, depending on the operation of the calf button 39 placed at each end, the pieces 36 approach or move apart depending on the size of the racket to be strung.

The frame of the racket or any other similar artiols, is held in place on the cradle by the billiards 40 and the traditional pushers 41. The pushers 41 can be placed at the appropriate hole 42 according to the racket model.

The brake for locking the plate 32, shown in Figure 16-17, is made up of the parts in Figures 18 to 24.

 The brake operates as follows; the screw 43, fixed to the table 3, passing through the hole in the piece 44, is screwed onto the piece 45. By screwing the screw 43 held on the frame 1, the piece 45 which advances in contact with the piece 44 is advanced at point 47 on a slope, rises as the screw 43 is tightened. The part 45 then comes to hang on its upper part 48 at the plate 32. The plate 32 is thus blo that from the desired position, it suffices slightly unscrew the screw 43, the part 45 slightly moves away from its fulcrum 47, the point 48 no longer being in contact with the plate, this one / Pptutter again for the next maneuver.

 Such a type of machine that is simple to make, foolproof, has many advantages compared to previous machines by the fact that it allows the maintenance of any type of racket without causing the slightest deformation of the frame, the passage of the strands of the rope in a simple way, the regular tensioning of each strand, and leaving a free space for handling the different passages of the strands of rope.

Claims (4)

Claims 1) Stringing machine for tennis rackets or the like of the type comprising A b & i supporting in its upper part a horizontal cradle 2 mounted on said frame 1 so as to be able to pivot 360 during the stringing operation and which is provided with billiards 40 and pusher 41 making it possible to horizontally maintain the racket frame. Means for tensioning each strand 4 of the string after passing through the orifices provided on the periphery of the frame 10 of the racket. Means for tensioning the strand thus put in place. And this machine is characterized by the fact that the tensioning means are constituted by a lever system essentially comprising a vertical lever 18 having at its lower end an arm 19 on which pivots an arm 20 and an arm 21 which carries & its extracts the counterweight 13 and which rests on a roller 22 fixed to the end of the arm 23 which, itself, can be placed by sliding on the bar 26. The lever 18 driving in its movement the arm 11 secured to the upper arm 7 which thus moves from a position A close to the periphery of the frame 10 to a forced position B thus producing the tensioning. The lever 18 is subjected, on the one hand to the action of return means making it possible to bring the upper arm 7 close to the frame 10, and on the other hand, to the action of a force exerted by a sys head & counterweight 13 and which tends to move the upper arm 8 away from the frame. The force exerted by the counterweight system 13 on the lever 18 produces a constant pulling force P at the end 8 of the upper arm as soon as the desired tension is chosen, entered and calibrated in rule 30. 2) A machine for stringing tennis rackets according to claim 1, characterized in that the return means making it possible to bring the upper arm 7 near the frame 10 of the racket will be constituted by a lever system 18/21 , the force T exerted by the counterweight system 13 being transmitted by means of the counterweight 13 bearing on the valet 22. The force T exerted by the counterweight system 13 on the lower arm 11 produced at the end 8 of the upper arm 7 a tensile force T and this as long as the position of @@@@@ 22 remains invariable. 3) Stringing machine according to one of claims 1 and 2 charac sad by the fact that the cradle 2 for holding the frame of the racket is a single branch facilitating the work of the stringer leaving greater ease to perform the different string passing operations in the appropriate positions of the racket holes. 4) Stringing machine having a blocking brake characterized by the fact that it consists of a screw allowing the part 45 to come into contact with the part 44 provided with a slope 47. Part 45 coming under the effect of the screw 22 and of the slope 47 bear 48 under the plate 32, blocks it as described in FIG. 17.