WO2007138541A2

WO2007138541A2 - Racquet stringing apparatus

Info

Publication number: WO2007138541A2
Application number: PCT/IB2007/051987
Authority: WO
Inventors: Graeme Edward Hulme-Jones
Original assignee: Graeme Edward Hulme-Jones
Priority date: 2006-05-25
Filing date: 2007-05-25
Publication date: 2007-12-06
Also published as: WO2007138541A3

Abstract

This invention relates to racquet stringing apparatus and includes a portable string tensioner and a portable string anchor. The tensioner operatively engages a frame (14) of a racquet (12), grips a length of a string (21) with which the frame is being strung, and, via displacement means thereof, tensions a length of the string. The string anchor (26) operatively anchors to the frame a length of string that has been tensioned by the tensioner (24). Each of the string anchor and the string tensioner is thus a self-contained device that interacts between a racquet frame and a string only. The devices are used to sequentially tension string spans in a head part of a racquet frame during stringing of the frame. The devices are easily portable, for instance in a sports kit bag, which clearly may be convenient to a user.

Description

RACQUET STRINGING APPARATUS

THIS INVENTION relates to racquet stringing apparatus.

A racquet, as referred to herein, includes a frame and at least one string. The frame includes a head part and a handle part and, optionally, a throat part. The head part has a plurality of spaced apart holes defined through it. The string is threaded through the holes and defines a plurality of spans defining a grid pattern on the inside of the head part. Insofar as the features of such racquets are known to those skilled in the art, they will not be elaborated on herein.

Although various methods of stringing a racquet are known to those skilled in the art, an example of such a method will now be described, albeit partially and not in detail. The method employs the use of a stringing machine which includes a mounting formation for a head part of a racquet frame, at least two string clamps, and a string tensioner. A head part of a racquet frame to be strung is mounted on the mounting formation. A knot is tied in a first end of a string which has a first and a second end. From the inside of the frame, the string is threaded from its second end out of the frame via a suitably selected first hole defined through the frame until the knot lodges against the inside of the frame. The string is threaded into the frame via a second hole, adjacent to the first, and out of the frame via a suitably selected third hole, opposite to the second, so that a first span of the string is defined from the second hole to the third, although the span may have some slack in it. The first span now defines a trailing end at the second hole and a leading end at the third hole. Using the tensioner, the string is gripped where it protrudes from the outside of the frame via the third hole and a length of the string is pulled out of the frame to tension the first span to a required tensile force. The leading end of the first span is gripped via a first string clamp for maintaining the tension in the span after release of the string from the tensioner. The string is released from the tensioner. The string is threaded from its second end into the frame via a fourth hole defined through the frame, adjacent to the third hole, and out of the frame via a fifth hole, adjacent to the second and opposite the fourth, until the string lodges around the portion of the outside of the frame between the third and fourth holes and a second span of the string is defined from the fourth hole to the fifth, although the span may have some slack in it. The second span now defines a trailing end at the fourth hole and a leading end at the fifth hole. The tensioner is moved relative to the mounting formation and the racquet to where the string protrudes from the outside of the frame via the fifth hole. The string is gripped here via the string grip means of the tensioner and a length of the string is pulled out of the frame to tension the second span to a required tensile force. The leading end of the second span is gripped via a second string clamp for maintaining the tension in the second span after release of the string from the tensioner. The string is released from the tensioner. The first string clamp is released and the above steps are repeated until all the spans required to be defined by the string have been defined and tensioned. The string is tied in a knot inside the frame at the leading end of its last span, after being threaded out of the frame via the hole at the leading end of this span and back into the frame via an adjacent hole.

The method described above is merely an example and many variations exist. In many cases, more than one string will be used to string a racquet.

Any reference herein to a string, a first end of a string, a second end of a string, a span, a leading end of a span, and a trailing end of a span must be interpreted in analogy to the above example of stringing a racquet.

According to the invention there is provided racquet stringing apparatus for tensioning spans of a string as they are sequentially defined within a head part of a racquet frame, the apparatus including

a portable string tensioner including

a structure including frame engagement means defining two frame engagement formations, for engaging the frame on opposite sides of a hole in the frame through which a length of string to be tensioned passes and for holding the structure secure with respect to the frame during tensioning;

string grip means, carried by the structure, for gripping the length of string on the outside of the frame; and displacement means, carried by the structure, for displacing the string grip means with respect to the structure for tensioning the length of string; and

a portable string anchor including string grip means for gripping the length of string that has been tensioned and frame engagement means for simultaneously engaging the frame, thereby anchoring the length of string to the frame.

Each of the string anchor and the string tensioner is thus a self-contained device that interacts between the head part of a racquet frame and an associated string only. The apparatus of the invention thus obviates the requirement of a stringing machine providing for a racquet frame to be mounted on it. The apparatus of the invention is easily portable, for instance in a sports kit bag, which clearly may be convenient to a user.

A typical mode of use of the apparatus during stringing of the head part of a racquet frame will now be briefly described:

A first span of the string is tensioned using the string tensioner.

The string anchor is used to anchor the leading end of the first span to the frame.

The string tensioner is removed from the string and the frame.

The string is threaded through two further holes through the frame to define a second span.

The second span is tensioned using the string tensioner.

The string anchor is removed from the string and the frame and used to anchor the leading end of the second span to the frame. Alternatively, the apparatus may include another string anchor, as defined, and this one may be used to anchor the leading end of the second span to the frame before removing the other one from the first span. Subsequent spans of the string are similarly defined and then tensioned using the string tensioner and string anchor.

In a particular embodiment of the apparatus of the invention

the frame engagement means of the string anchor includes a pair of hook formations, for engaging a racquet frame by hooking onto the outer periphery of the head part of the frame;

a clearance that exceeds the spacing between two adjacent holes in a head part of a racquet frame is defined between the hook formations; and

the configuration of the string anchor is such that, with the hook formations hooked onto the outer periphery of a head part of a racquet frame, the string grip means of the string anchor is disposed on the inside of the head part.

In a more particular embodiment of the above particular embodiment

the string anchor includes a bridge formation interconnecting the hook formations and a link formation interconnecting the bridge formation and the string grip means;

the configuration of the string anchor is such that, whilst operatively anchoring a leading end of a span of a string to a racquet frame, both the hole through which the string extends at the leading end and the adjacent hole through which the string must next be threaded into the head part of the frame are exposed so as to permit such threading; and

the link formation is pivotally connected to the bridge formation to pivot about an axis which, in use of the anchor on a head part of a racquet frame, will be disposed perpendicularly to the general plane of the head part.

In the apparatus of the invention, each frame engagement formation of the string tensioner may be a clamp for operatively engaging a racquet frame by clamping onto the frame. In this case, the frame engagement means of the string anchor may fit in between the clamps. The clamps may be manually operable via knurled nuts.

In the apparatus of the invention, the displacement means of the string tensioner may include electromechanical displacement means. The electromechanical displacement means may include a display providing for operative display of a tensile force exerted by the string tensioner on a string gripped by the string grip means of the string tensioner.

The electromechanical displacement means may include control means, including input means for entering a magnitude of tensile force into it, operable to control the displacement means to tension a string operatively gripped by the string grip means of the string tensioner to a magnitude of tensile force entered via the input means.

The invention extends also to a string tensioner, per se, of the apparatus of the invention, as defined herein.

The invention extends also to a string anchor, per se, of the apparatus of the invention, as defined herein.

The invention is described below by way of an example of racquet stringing apparatus, in accordance with the invention, with reference to and as illustrated in the accompanying diagrammatic drawings. In the drawings:

Figure 1 shows a diagrammatic perspective view of an arrangement including a tennis racquet, a string with which the racquet is being strung, and an embodiment of racquet stringing apparatus, in accordance with the invention;

Figure 2 shows a diagrammatic perspective view of certain parts of a string tensioner of the apparatus of Figure 1 ; and

Figure 3 shows a diagrammatic perspective view of a string anchor of the apparatus of Figure 1 .

In Figure 1 , an embodiment of racquet stringing apparatus, in accordance with the invention, is designated generally by the reference numeral 10. The apparatus 10 is shown in an operative configuration with respect to a racquet 12, which includes a frame 14 including a handle part 16 and a head part 18. The head part 18 defines therethrough a plurality of spaced apart holes, of which five are designated by the reference numerals 20.1 to 20.5.

As will be described in more detail hereinafter, the head part 18 is being strung with a string 21 . Ten spans of the string 21 have already been defined, three of which are designated by the reference numerals 22.1 , 22.9, and 22.10, respectively. A length 23 of the string 21 projects from the head part 18 via the hole 20.4.

The apparatus 10 includes a string tensioner 24 and a string anchor 26.

The string tensioner 24 includes a housing 28, a structure 30, string grip means in the form of a string clamp 32, and electromechanical displacement means which is housed in the housing 28 and which will be described below with reference to Figure 2. The string clamp 32 projects through and is displaceable along a slot 33 defined in the housing 28. The string clamp 32 will be described in more detail below, with reference to Figure 2. The displacement means includes an LCD display 34 and switches 35 carried on the outside of the housing 28.

The structure 30 includes frame engagement means in the form of two frame engagement formations, particularly clamps 36, for releasably engaging a head part of a racquet frame by clamping onto those opposite faces of the head part 18 that are disposed substantially parallel to the general plane of the head part. The clamps 36 are spaced apart and each is operable via a knurled nut 38.

One operative position of the string tensioner 24 with respect to the head part 18 of the racquet is shown in Figure 1 . The two clamps 36 are clamped onto the said opposite faces of the head part 18. As will be described in more detail hereinafter, the spans 22.1 to 22.10 have already been tensioned by the tensioner 24.

With reference particularly to Figure 2, the string clamp 32 includes a pair of clamp formations 40 defining between them complementary convex and concave surfaces, respectively, that abut in the view shown. Although not clear from the drawings, these surfaces are friction grip surfaces. The clamp 32 includes an internal spring (not shown) that biases the said surfaces of the clamp formations 40 towards abutment. Via two wings 42, the clamp formations are manually displaceable apart so as to permit a short length of a string to be inserted between them. Upon release of the wings 42, the string is then clamped fixed between the clamp formations 40 under bias of the spring. This is the case shown in Figure 1 .

The displacement means of the string tensioner 24 includes, amongst other components, an electric motor 48, a gear arrangement 49, a lead screw 50, control means in the form of an electronic circuit (partially shown, as will be described below), a first shuttle member 52, a second shuttle member 54, two identical S-type load cells 56 (of which only one is clearly shown), each secured on opposite ends thereof to the members 52 and 54, respectively, and two rechargeable batteries 57 for powering the displacement means. The tensioner 24 may, alternatively or additionally, include a power socket providing for an external power source, e.g. a transformer powered by a mains power supply, to be connected to it for powering the displacement means.

The lead screw 50 is driven by the motor 48 via the gear arrangement 49. The lead screw 50 is translationally fixed with respect to the structure 30. Via manual operation of the switches 35 (see Figure 1 ), the motor 48 may be caused to rotate in either a forward or a reverse direction, the direction particularly being selectable via the switches.

The shuttle member 52 defines therethrough a smooth passage through which the lead screw 50 extends. The string clamp 32 is mounted on the shuttle member 52.

The shuttle member 54 also defines therethrough a passage through which the lead screw 50 extends, but this passage defines an internal screw thread complementary to a screw thread defined around the lead screw 50. Through rotation of the lead screw 50 by the motor 48, linear displacement of the shuttle member 54 along the length of the lead screw is effected.

The electronic circuit includes a pc board (not shown), including a processor, the batteries 57, the display 34 (see Figure 1 ), the switches 35 (see Figure 1 ), a suitable arrangement of strain gauges mounted on the load cells 56, and wiring (partially shown). Insofar as such suitable location of strain gauges on S-type load cells is either known to, or can be ascertained by trial by, those skilled in the art, this is not elaborated on herein.

By pressing and holding down the switch 35.1 or the switch 35.2 (see Figure 1 ), the motor 48 is operated to rotate in a forward or a reverse direction, respectively. Forward rotation will cause a corresponding rotation of the lead screw 50 in a direction (hereinafter referred to also as forward rotation) that will cause it to displace the shuttle member 54 in the direction of the motor. Through such displacement, the shuttle member 54 will act on the load cells 56 which, in turn, will tend to drag the shuttle member 52 along.

With reference to both Figures 1 and 2, with the string 21 gripped by the string clamp 32 in the configuration shown in Figure 1 , forward rotation of the lead screw 50 caused by holding down the switch 35.1 will cause displacement of the shuttle member 52 which, after taking up of slack in the string, will induce a tensile force in the string equal to the sum of the tensile forces in the load cells 56. Via the strain gauges, the processor determines the tensile forces in the load cells 56 and determines their sum, which is displayed on the display 34. This sum is equal to the resultant tensile force in the length 23 of the string 21 and, accordingly, at least substantially equal to the tensile force in the span 22.10. The force displayed on the display 34 will clearly increase as tensioning of the string portion 23 progresses. The tensioning may be halted by releasing the switch 35.1 , particularly when a required tensile force is displayed.

The processor of the control circuit of the string tensioner 24 may alternatively be programmable, e.g. via input means such as the switches 35, with a required tensile force to be displayed on the display 34. The control circuit may then be configured to control the motor 48 to automatically tension a string gripped by the clamp 32 to the programmed force.

The switch 35.2 may clearly be pressed to displace the string clamp 32 towards the frame clamps 36. With reference now particularly to Figure 3, the string anchor 26 includes a bridge formation 66 defining two hook formations 68 that are spaced apart. The clear distance between the formations 68 particularly exceeds double the spacing between two adjacent holes 20 in the head part 18. The anchor 26 includes also a link formation 70, which is pivotally connected at one end thereof to the bridge formation 66 to pivot about an axis 72, and string grip means in the form of a string clamp 74.

The string clamp 74 includes two jaws 76.1 and 76.2, a lever 78, a rod 80, and a pin 82. The rod 80 is slidably received in a passage (not shown) defined through the jaw 76.2 and the jaw 76.1 is secured to one end thereof. The pin 82 extends through the opposite end of the rod 80 and the lever 78 is mounted on the pin 82 to pivot with respect to the rod 80. The lever 78 defines two cam formations 84, each including a flat portion 86. The hook formations 68 have high friction material pads 88 defining faces of the hook formations facing in the direction of the string clamp 74. The purpose of these pads is to operatively frictionally engage the outer surface of the head part of a racquet frame to prevent slipping, as will be apparent from the remainder of this description.

The lever 78 is shown in a first position thereof, in which the jaws 76.1 and 76.2 are apart to permit a string to be inserted between them. By pivotally displacing the lever 78 upwards, in the view shown, the cam formation 84 acts on the jaw 76.2 and the rod 80 draws the jaw 76.1 towards the jaw 76.2. As such, a string operatively received between the jaws will be gripped by them.

Stringing of the racquet 12 of Figure 1 will now be briefly described with reference particularly to Figure 1 and the tensioning of the string 21 via the apparatus 10 will be highlighted in this description.

The string 21 defines opposite first and second ends 90 and 92, the latter of which is not shown. A knot was tied in the end 90. The string 21 was then threaded from its end 92 from the inside of the head part to its outside and via a hole adjacent to the hole 20.1 , then into the frame via the hole 20.1 , and then out of the frame via the hole 20.2 until the knot in the end 90 lodged against the inside of the frame and a first span 22.1 of the string was defined, although the span had some slack in it. The span 22.1 then defined a leading end 94 and a trailing end 96. The string 21 was threaded zigzag fashion through suitably selected holes 20 to define the spans 22.1 to 22.10. Each span was tensioned, using the apparatus 10, prior to defining the next span. Such tensioning was done in essentially the same manner for each of the spans 22.1 to 22.10 and, as such, such tensioning will be described hereinafter with reference to the span 22.10 only.

The span 22.10 is shown already tensioned. The string clamp 74 of the string anchor 26 grips the leading end of the span 22.10 and the pads 88 on the respective hook formations 68 (see Figure 3) abut against the outside surface of the head part under the tension in the span 22.10. As such, the string anchor 26 anchors the leading end 96 of the span 22.10 to the head part. Before the span 22.10 had been defined, the string anchor 26 had been disposed on the opposite side of the head part where it anchored the leading end 96 of the span 22.9 to the head part. The string 21 was threaded from its end 92 into the head part via the hole 20.3 and out of the head part via the hole 20.4 to define the span 22.10. Due to the anchor 26 anchoring the leading end 96 of the span 22.9 to the head part and the fact that the span was in tension, the span 22.10 defined a trailing end 94 that was effectively held stationary with respect to the head part. The portion 23 of the string 21 projecting from the hole 20.4 was gripped by the clamp 32 of the tensioner 24. The switch 35 on the tensioner 24 was held depressed to cause the displacement means to exert a tensile force on the span 22.10 until the tensile force displayed on the display 34, corresponding to the tensile force in the span 22.10, reached a predetermined value, upon which tensioning was halted by releasing the switch. The anchor 26 was removed from the leading end 96 of the span 22.9 and positioned as currently shown with its bridge formation 66 (see Figure 3) between the clamps 36 of the string tensioner 24. With the hook formations 68 (see Figure 3) manually held against the frame in this position, the string clamp 74 was clamped onto the leading end 96 of the span 22.10. As such, the span was anchored to the head part.

With the string anchor 26 in the position shown, its pivotal axis 72 (see Figure 3) is disposed perpendicularly with respect to the general plane of the head part 18. Pivoting of the combination of the link formation 70 and the clamp 74 with respect to the bridge formation 66 (see Figure 3) can thus accommodate the string 21 and head part in positions where a leading end of a span of the string meets the frame at an acute angle. The string tensioner 24 may now be removed from the head part by releasing the clamps 36 and moved to a new position on the opposite side of the frame and engaged with the frame with its clamps 36 disposed on opposite sides of the hole 20.5, particularly with the hole midway between the clamps. A next span of the string 21 may be defined by threading the string 21 from its end 92 into the frame via the hole (not shown) adjacent to the hole 20.4 and, in the drawing, to the right of the hole 20.4 and out of the frame via the hole 20.5. This span may then be tensioned via the tensioner 24 in its new position (not shown). Clearly, the clear spacing between the hook formations 68 (see Figure 3) of the anchor 26 is sufficient to permit the string 21 to be threaded out of the head part via the hole 20.4 and into the frame via the said adjacent hole whilst the anchor remains in the position shown.

The apparatus 10 may similarly be used for tensioning the required longitudinal string spans of the racquet 18.

The Applicant envisages that the apparatus 10 may also include an additional string anchor identical to the string anchor 26 for performing a slight variation of the method described above, in which one of the string clamps anchors to the head part a leading end of a particular span of the string 21 during tensioning of the next span, the other string clamp anchors to the frame the leading end of the latter span after the span has been tensioned, and the former string anchor is removed only thereafter.

The string tensioner 24 and the string anchor 26 are both small and easily portable items, which can be conveniently carried by a player along with spare string, e.g. in a sports bag. As such, the player may have the stringing apparatus 10 and the spare string available whenever using the racquet to be available for stringing the racquet when required.

The Applicant envisages that the racquet stringing apparatus of the invention may provide a convenient and economical means for stringing a racquet. It is further envisaged that the apparatus may be suitable for stringing different types of racquets, e.g. tennis racquets, squash racquets, and racquetball racquets. Clearly, due to the fact that each of the tensioner 24 and the anchor 26 acts between the string 21 and the head part, in the apparatus there is no requirement, as is often associated with racquet stringing machines, for a bed on which to mount the head part.

In an alternative embodiment of racquet stringing apparatus (not illustrated), in accordance with the invention, the displacement means of its string tensioner may include manual displacement means in lieu of the motor 48 (see Figure 2) of the apparatus 10 of the drawings. Such displacement means may include a crank handle.

Claims

1 . Racquet stringing apparatus for tensioning spans of a string as they are sequentially defined within a head part of a racquet frame, the apparatus including

a portable string tensioner including

string grip means, carried by the structure, for gripping the length of string on the outside of the frame; and

displacement means, carried by the structure, for displacing the string grip means with respect to the structure for tensioning the length of string; and

2. Apparatus as claimed in claim 1 , in which

3. Apparatus as claimed in claim 2, in which

the configuration of the string anchor is such that, whilst operatively anchoring an end of a span of a string to a racquet frame, both the hole through which the string extends at the end and the adjacent hole through which the string must next be threaded into the head part of the frame are exposed so as to permit such threading; and

4. Apparatus as claimed in any one of the preceding claims, in which each frame engagement formation of the string tensioner is a clamp for operatively engaging a racquet frame by clamping onto the frame.

5. Apparatus as claimed in claim 4, in which the frame engagement means of the string anchor can fit in between the clamps.

6. Apparatus as claimed in claim 4 or in claim 5, in which the clamps are manually operable via knurled nuts.

7. Apparatus as claimed in any one of the preceding claims, in which the displacement means of the string tensioner includes electromechanical displacement means.

8. Apparatus as claimed in claim 7, in which the electromechanical displacement means includes a display providing for operative display of a tensile force exerted by the string tensioner on a string gripped by the string grip means of the string tensioner.

9. Apparatus as claimed in claim 7 or in claim 8, in which the electromechanical displacement means includes control means, including input means for entering a magnitude of tensile force into it, operable to control the displacement means to tension a string operatively gripped by the string grip means of the string tensioner to a magnitude of tensile force entered via the input means.

10. Apparatus as claimed in any one of the preceding claims, in which the string anchor is one of a pair of such string anchors.

1 1 . A string tensioner of apparatus as claimed in any one of claims 1 to 9.

12. A string anchor of apparatus as claimed in any one of claims 1 to 9.

13. Apparatus as claimed in claim 1 , substantially as herein described with reference to the accompanying diagrammatic drawings.

14. A string tensioner as claimed in claim 1 1 , substantially as herein described with reference to the accompanying diagrammatic drawings.

15. A string anchor as claimed in claim 12, substantially as herein described with reference to the accompanying diagrammatic drawings.