Patent Publication Number: US-6984185-B2

Title: Device for gut stringing

Description:
This is a U.S. national phase application under 35 U.S.C. §371 of International Patent Application No. PCT/JP03/02004 filed Feb. 24, 2003, and claims the benefit of Japanese Patent Application No. 2002-48180 filed Feb. 25, 2002 which is incorporated by reference herein. The International Application was published in Japanese on Aug. 28, 2003 as WO 03/070330 A1 under PCT Article 21(2). 
   1. Technical Field 
   The present invention relates to a device for stringing a gut for a racket for badminton, tennis, or the like at a fixed tension. More specifically, the present invention relates to a compact and portable device for stringing a gut. 
   2. Background Technology 
   In badminton and tennis rackets, a gut is strung in a grid pattern on a frame to form the racket surface. This type of racket gut is generally strung in a roughly uniform manner with a fixed tension. The gut that forms the racket surface in this manner will inevitably break due to aggressive play or the lifespan of the gut. Restringing a gut also becomes necessary when the gut becomes loose or the user does not like the tension. Thus, although the frequency may vary, badminton and tennis rackets always involve restringing the gut. 
   Conventionally, restringing the gut has been a relatively difficult task to be performed by the player, who generally had to rely on specialists in sporting goods stores and the like to restring the gut. Restringing a gut is difficult because of the need to string the gut at a fixed tension, something which requires a relatively expensive and large machine. 
   The object of the present invention is to provide a device that allows gut restringing to be performed relatively easily while also providing a compact and portable device. 
   DISCLOSURE OF THE INVENTION 
   Resulting from various investigations made by the present inventor to overcome the problems described above, it was found that the problems could be solved with a device for stringing a gut for a racket including a plurality of gut holes formed along a ring-shaped frame. The device includes: a clamping mechanism clamping at least one position of the ring-shaped frame of the racket; and a tension head for holding a part of the gut loosely pre-tensed through a gut hole, the tension head applying tension to the gut. The clamping mechanism is attached to a frame base on which the racket is mounted. The tension head is disposed at an outer perimeter section of the ring-shaped frame so that the tension head can be abutted and moved away from an outer edge of the ring-shaped frame. When tension is applied to the gut, the tension head abuts the outer edge of the ring-shaped frame and supports at least one section of the ring-shaped frame. 
   In this type of device, the clamping mechanism is made pivotable around a position roughly at the center of the ring-shaped frame, and the tension head for applying tension is disposed slidably in the radial direction of the ring-shaped frame along a slide rail. As a result, the tension head acts as a slidable crimping clamp that clamps the frame. Thus, the frame can be clamped while the gut is pulled in a stable manner. Also, re-stringing of various types of rackets with different sizes of frames can be performed directly without requiring modifications to the device itself. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a side-view drawing showing an embodiment of the present invention. 
       FIG. 2  is a detail drawing of  FIG. 1 . 
       FIG. 3  is a perspective drawing showing an embodiment of the present invention. 
       FIG. 4  and  FIG. 5  are drawings illustrating the tension maintainer. 
       FIG. 6  is a drawing showing a device according to an embodiment of the present invention in a disassembled state and shows an example in which the parts are housed in a case or the like. 
       FIG. 7  and  FIG. 8  show how a device according to an embodiment of the present invention is used. 
       FIG. 9  is a perspective drawing showing an embodiment of the present invention being used. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
   The following is a description, with references to the drawings, of a gut-stringing device according to the present invention. 
   First, the structure of a gut-stringing device according to this embodiment will be described. 
     FIG. 1  is a side-view drawing showing an embodiment of a gut-stringing device according to the present invention.  FIG. 2  is a detail drawing of the same.  FIG. 3  is a perspective drawing of the same. 
   In  FIG. 1 , there is shown a pedestal C serving as the base of this device. A tension head H clamps a gut G and applies tension in the direction of the arrow a. The tension head H is mounted so that it can slide in the direction of arrow b along a slide rail R disposed on the pedestal C. Upper and lower clamp members  11 ,  12  clamp one side of a ring-shaped frame F and are supported on one end of an arm  9 , which is rotatably supported by a shaft  72  projecting from the pedestal C. The shaft  72  serves to rotatably support a bearing member  3  of a frame base T and is fitted in the bearing member  3  attached on the arm side. A disk  10  is made from a magnetic body and serves to magnetically secure a tension maintainer maintaining the tension of the gut when it has been strung using the tension head H. The central section of the disk  10  is secured on the bearing member  3 . The tension maintainer will be described later. The bearing member  3 , the arm  9 , the disk  10 , and the upper and lower clamp members  11 ,  12  are referred to as the frame base in this embodiment. The clamp members  11 ,  12  clamp a neck section N that serves as a connecting section between the frame F and a shaft S. The structure around the tension head H will be described using  FIG. 2 . 
     FIG. 2  is a detail drawing of  FIG. 1  and primarily shows the structure around the tension head H. 
   In  FIG. 2 , there is shown a main unit  14  of the tension head H. A sliding member  13  is inserted in the slide rail R and allows the tension head H to be slidably attached. The sliding member  13  is also a member for rotatably supporting the main unit  14 . The main unit  14  is fitted into a hole  17  formed on the upper portion of the sliding member  13 . A puller  15  applies tension to the gut and, in the main unit  14 , is rotatably supported around a rotation shaft  16 . A gut clamping plates  20  are disposed on the outer perimeter of the puller  15 . A projection  21  is used to come into contact with the gut and is disposed on a lower portion of the gut clamping plates  20 . A manual turning lever  18  is used to apply pulling tension and is attached to the puller  15  by way of a shaft  24 . When pulling the gut, rotational torque going from A to B is applied to the puller  15  by the manual turning lever. Threads are formed on part of the surface of the shaft  24 , the end of which is formed to reach the rotation shaft  16 . As a result, by turning the manual turning lever  18 , the end of the shaft  24  is brought into contact with the rotation shaft  16 , and the puller  15  can be temporarily secured at a desired rotation angle. Multiple gut holes  71  are formed in a regular pattern along the outer perimeter of the ring-shaped frame F for the racket. The structure for clamping the gut and the measuring of tension will be described using  FIG. 3 . 
     FIG. 3  is a perspective drawing of the device shown in  FIG. 1  and  FIG. 2 . The frame F of the racket is omitted. 
   A gut-tightening mechanism  23  secures the gut so that it is immobile by having the gut inserted between two clamping plates  20 . A cam operates to reduce the gap formed between the two gut clamping plates. 
   A return spring  19  serves to return the puller  15  to its initial position, one end thereof being engaged with the main unit  14  and the other end being engaged with the puller  15 . 
   A scale  22  indicates the tension applied to the gut. 
   Means for measuring the tension applied to the gut will be described. In  FIG. 3 , (1) first, the gut is interposed between the two gut clamping plates  20  and this is secured by squeezing from both sides using the tightening mechanism  23 . When doing this, slack in the gut between the frame F and the gut clamping plates is removed ahead of time. (2) The gut is stretched from this state. (3) The actual length of the stretched gut at this point corresponds to the tension applied to the gut, so this is used to measure the gut tension. In this embodiment, there is a pre-engraved scale  22  on the tension head H in which the pulled length is converted to tension (pounds). Thus, when the gut is pulled, the scale is read to measure the tension. 
   When using the device  1 , the tension maintainer that maintains the pulled gut is also used so this will be described.  FIG. 4  and  FIG. 5  show an example of the structure of a tension maintainer. 
     FIG. 4(   a ) is a side-view drawing of the tension maintainer  2 .  FIG. 4(   b ) is a front-view drawing of the tension maintainer  2 . 
   In  FIG. 4(   a ) and  FIG. 4(   b ), the tension maintainer  2  is formed from a middle plate  80 , two clamping plates  81  disposed on either side thereof, and a tightening mechanism  83 . These three plates are bonded toward the upper end section and form indentations  86  at the bottom end. At the bottom of the middle plate  80  are legs  85  to the ends of which are attached magnets. The structure of the tightening mechanism will be described using  FIG. 5(   a ) and  FIG. 5(   b ). 
     FIG. 5(   a ) is a detail drawing of  FIG. 4(   b ) and illustrates when the knob  84  is at point X in  FIG. 4(   a ).  FIG. 5(   b ) is a front-view drawing of the tension maintainer  2  when the knob  84  is at the point Y in  FIG. 4(   a ). The knob  84  is omitted from  FIG. 5(   a ) and  FIG. 5(   b ). 
   In  FIG. 5(   a ) and  FIG. 5(   b ), the tightening mechanism  83  is formed from a shaft  89  and two cams  87  attached thereto. The cams  87  are formed as short cylindrical shapes, and are engaged eccentrically to the shaft  89 . The outer perimeter surface of the cam  87  is equipped with the knob  84 . The shaft  89  passes through the middle plate  80  and the two clamping plates  81 . A contact surface  88  of the cam  87  is at an angle relative to the shaft  89 , and the contact surface  88  is in contact with the clamping plate  81 . The middle plate  80  is formed from resin, the clamping plates  81  are metal plates formed from spring steel, and the shaft  89  and the cams  87  are formed from brass. 
   In  FIG. 5(   a ) and  FIG. 5(   b ), the knob  84  is turned from X to Y in  FIG. 4(   a ). The cams  87  attached eccentrically to the shaft  89  rotate, and the rotational motion of the cams  87  is converted to linear motion that reduces the gap  82  between the clamping plates  81  and the middle plate  80 . The gut G disposed in the gap  82  is tightly secured in this manner. 
   The device  1  according to this embodiment as described above is set up as a ready-to-assemble structure that can be stored in a compact manner as shown in  FIG. 6 . 
   In  FIG. 6 , there is shown a gut-threading tool  4  for passing the gut through gut holes. A ring  5  is formed at the end thereof. The ring  5 , formed from piano wire with a diameter of approximately 0.2 mm, can hold its shape while being deformable into a desired shape. When inserting the gut in a gut hole: (1) The ring  5  of the gut-threading tool  4  is passed through the gut hole ahead of time. (2) The gut to be passed through the outer perimeter section and the inner perimeter section of the frame is inserted through the ring  5 . (3) Then, the gut-threading tool  4  is pulled out from the gut hole. This allows the gut to be strung without damaging the gut hole. 
   Next, the manner in which the gut-stringing device described above is used will be described. 
   FIRST EXAMPLE 
   In the example described below, the stringing of separate guts going vertically and horizontally in the racket will be described. Two guts are used. First, a gut is strung vertically and stretched to form vertical gut columns. Then, the horizontal gut is also stretched in the same way. This will be described using  FIG. 7  and  FIG. 8 . 
     FIG. 7  shows how the gut-stringing device according to this example is used. The racket is strung starting vertically. In this figure, the slide rail R is omitted. The center line along which the slide rail R moves is illustrated by the dashed dotted line, and the disk  10  and the upper and lower clamping members  11 ,  12  are illustrated by the dashed lines. 
   Before the gut-stringing operation is started, the vertical gut is extended as appropriate over the racket frame. 
   In  FIG. 7 , a gut  30  is loosely pre-tensed vertically on the racket. When mounting the gut, a knot  70  is formed ahead of time at one end of the gut. Then, the gut is passed through a gut hole. The vertical gut  30  is extended and passed through gut holes for a first column  31 , a second column  32 , a third column  33 , a fourth column  34 , and the like. 
   A loop L is formed between adjacent gut holes, and the loop L formed in this way is left loose. 
   After the extending of the vertical gut is completed, the neck section N of the racket is secured between the upper and lower clamping members  11 ,  12  of the frame base T. 
   Then, as shown in  FIG. 7 , the tension head H is positioned near a predetermined position of the frame F, i.e., the gut that is to be pulled in the beginning (the second row  32 ). The gut in the loop L is passed through the gap between the two gut clamping plates  20  and is secured from both sides. In this operation, the slack between the gut clamping plates  20  and the frame F is eliminated as much as possible. Then, the manual turning lever  18  is grasped and the gut is pulled. The tension applied to the gut can be read from the markings of the scale  22 . Once the desired tension, e.g., 20 pounds, is reached, the puller  15  is held in place so that it remains in that position. This is performed by twisting the turning lever  18  and pushing the end of the manual turning lever shaft  24  against the rotation shaft  16 . As a result, the puller  15  is held in place in opposition to the contraction of the return spring  19 . 
   After holding the puller  15  in place, the tension maintainer  2  is inserted between the pulled gut  32  (from the second column) and the adjacent first column gut  31 . While the tension maintainer  2  is inserted between the two adjacent guts (the first column  31  and the second column  32 ), the entire maintainer is magnetically secured to the disk  10  so that the tension applied by the puller  15  is maintained for this section of the gut. 
   With the tension being maintained with the tension maintainer  2 , the gut is removed from the gut clamping plate  20  and the puller  15  that was being held in place is released. Then, adjacent vertical guts are stretched one after the other using the same procedure. For example, the slack in the loop L between the fourth column  34  and the fifth column  35  is first increased by tugging the gut extended across the third column and the fourth column. The tension head H is moved close to the gut hole of the gut  34  of the vertical fourth column, and the gut  34  at the fourth column is stretched in the same way that the gut  32  at the second column was stretched. 
   The operation can be performed smoothly if multiple tension maintainers  2  are used, with the stretched guts being clamped one after the other. 
   Once the stringing of the gut  30  along the vertical direction of the racket is completed, a gut  50  for the horizontal direction of the racket is extended. 
     FIG. 8  shows the start of stringing the horizontal gut after the vertical gut has been tensed. In  FIG. 8 , the vertical gut  30  has been omitted. 
     FIG. 8  shows the horizontal gut  50 , which has been loosely pre-tensed starting from the frame neck section N so that it has been woven through the mounted vertical gut  30 . The horizontal gut can be stretched in the same manner as the vertical gut. 
   As  FIG. 8  shows, when stringing the horizontal gut, the racket is first turned, and the tension head H is pressed against a predetermined position on the outer perimeter of the frame (near a second row  52  of the gut). The stretching operation is then performed, and the stringing of the gut is completed. 
   SECOND EXAMPLE 
   In the example described above, the vertical or the horizontal gut has been loosely pre-tensed. In a different example descried below, the gut is mounted in the following manner: (1) a gut is extended across the racket; (2) the gut is stretched; (3) while maintaining tension, the gut for the next column is extended and steps (1) and (2) are repeated.  FIG. 9  illustrates how the device is used in this example. 
   As  FIG. 9  shows, in this example, the gut is pulled starting from the vertical center of the frame. The gut is formed with a knot  70  at one end and is passed through a gut hole ahead of time. The pulling of the gut begins after the gut has been extended for one round trip and is started from the gut at the second column. More specifically, the tension head H is set up near the gut hole through which the second column gut to be initially pulled passes. The second column gut is then secured by the gut clamping plates and pulled. The subsequent operations are similar to those of the first example. The puller  15  is held in place and the tension maintainer is placed between the first column gut and the second column gut to maintain tension. Then, the gut is extended across the third column and the fourth column and this time the fourth-column gut is pulled with the puller  15  to stretch the third-column gut and the fourth-column gut. The operation proceeds with the gut being extended across the sixth column, the eighth column . . . in the same way. Once the operation reaches the end of the frame, the rest of the vertical gut is mounted, and then the horizontal gut is mounted. 
   The structure and usage of the device  1  according to this embodiment was described. In the structure described above, the neck section N of the frame F is firmly clamped, so the frame can be adequately secured in a stable manner from just this one position. Since there is no need to clamp the outer perimeter of the frame F as in the conventional technology, the device does not need to be modified to secure various types of rackets with different frame sizes and shaft diameters. 
   In addition to the slide mechanism, the tension head H is equipped with a rotation mechanism so that when tension is to be applied to the gut, the tension head H can always be pressed against the outer perimeter surface of the frame F regardless of the rotation angle of the frame F. As shown in  FIG. 7  through  FIG. 9 , when the gut is stretched while the tension head H is pressed against the outer perimeter of the frame, the reaction to the pulling causes the tension head H to be pulled toward the frame, resulting in tighter contact. Thus, the gut can always be stretched in a stable manner. Since the tension head H clamps the frame at the same time, it also serves as a slidable crimping clamp. Because of this, the device can be used with no modification to re-gut various rackets having frames of different sizes. 
   In this embodiment, the neck section N of the frame F is clamped with the upper and lower clamp members  11 ,  12 , and the frame F is secured just from this position. However, the clamping mechanism is not restricted to this, and it would also be possible to have the outer perimeter of the frame F supported at two or more positions to secure the frame F. In this type of structure, deformation to the frame when the gut is pulled with a high tension can be prevented. An example of this structure could be multiple arms that are essentially level extending radially from the bearing member  3  with support poles formed at the ends thereof to support the outer perimeter of the frame. Adjustable tightening means can be set up at the sections of the support poles corresponding to the outer frame perimeter so that different types of frames can be supported. 
   Besides supporting the frame with clamping mechanisms and tension heads, it would also be possible to prevent frame deformation due to the gut being pulled at a high tension by using a well-known frame deformation preventing means in which the frame is tightly supported from its perimeter along a plane essentially perpendicular to the direction in which tension is applied to the gut. 
   The device according to this embodiment is used together with the tension maintainer  2 . Since the legs  85  are magnetically secured to the disk  10 , the tension maintainer is mounted so that it is secured to the frame base T while supporting the gut. Also, since the indentations  86  are formed on the lower section of the tension maintainer  2  according to the grid dimensions of the gut, the gut can be secured without any obstruction from the gut extending perpendicular thereto. 
   The present invention is not restricted to the structure of the embodiment described above. In the embodiment described above, the frame base T and the frame F secured thereto are rotated, but it would also be possible to provide similar advantages by having, conversely, the tension head H be rotatable around the frame F. also, the means for measuring the tension applied to the gut is not restructured to the example described above. It would also be possible to have a suitable signal sent to the user when the tension applied to the gut reaches a desired value. For example, when the tension applied to the gut reaches a desired value, a latch could be released so that a suitable signal is sent to the user. Alternatively, a lamp can be turned on when a desired tension is reached. 
   FIELDS OF USE IN INDUSTRY 
   By using the gut-stringing device according to the present invention described above, anyone can easily string a gut in a substantially uniform manner. Also, as shown in  FIG. 6 , the parts can be stored and carried in a compact manner, thus allowing the device to be easily carried while traveling. This contributes to an atmosphere where the player can concentrate on training. Also, since the tension head also serves as a slidable crimping clamp that clamps the frame, the gut can always be stretched in a stable manner while the frame is clamped. In addition, gut-stringing can be performed even if the environment does not allow a large gut-stringing machine to be used, making the device useful in emergency situations.