JP7625787B2 - racket - Google Patents

Description

The present invention relates to a racket used in tennis and other sports.

Tennis rackets have a frame and strings. In the past, natural gut was mainly used as strings. Natural gut is made from sheep intestines. In recent years, strings are mainly made of synthetic resin. Strings made of synthetic resin have excellent durability. Strings made of resin compositions with polyester or nylon as the base material are widely used. A string made of polyester is disclosed in JP 2009-226107 A.

JP 2009-226107 A

Natural gut has excellent shot feel and resilience. However, natural gut is inferior in spin and control.

Nylon strings offer excellent feel and resilience. However, they are inferior in terms of spin and control.

Polyester strings have excellent spin and control performance. However, they are inferior in feel and resilience.

A tennis racket may use main strings and cross strings made of a material different from that of the main strings. With this tennis racket, the advantages of both the main string material and the cross string material may be realized. However, the main strings make a large contribution to performance, while the cross strings make a small contribution to performance. Therefore, the advantages of the cross string material are not fully realized.

By adjusting the way the strings are strung on the frame, high tension and low tension regions can be formed in the strings. With this tennis racket, the advantages of both the high tension region and the low tension region can be achieved. However, when this tennis racket is used repeatedly, the tension in the high tension region gradually decreases and the tension in the low tension region gradually increases. With a tennis racket after a change in tension has occurred, it is no longer possible to achieve both the advantages of the high tension region and the low tension region.

The objective of this invention is to provide a racket with an excellent balance of performance features.

A racket according to the present invention has a head and a face contoured by the head. The face has a plurality of first longitudinal threads, a plurality of second longitudinal threads, and a plurality of transverse threads. The first longitudinal threads have a specification different from the specification of the second longitudinal threads.

Preferably, the first longitudinal thread has a material different from the material of the second longitudinal thread.

The material of the first vertical thread may be a resin composition having a polyester base material, and the material of the second vertical thread may be a resin composition having a nylon base material.

The material of the first vertical thread may be a resin composition having a polyester base material, and the material of the second vertical thread may be natural gut.

The first vertical thread may be made of a resin composition based on nylon, and the second vertical thread may be made of natural gut.

The first longitudinal thread may have an elongation rate different from the elongation rate of the second longitudinal thread. Preferably, the ratio of the elongation rate E1 of the first longitudinal thread to the elongation rate E2 of the second longitudinal thread (E1/E2) is less than or equal to 48/52 or greater than or equal to 52/48.

The first vertical thread may have a tension different from the tension of the second vertical thread. Preferably, the ratio of the tension T1 of the first vertical thread to the tension T2 of the second vertical thread (T1/T2) is less than or equal to 48/52 or greater than or equal to 52/48.

Preferably, the ratio (N1/N2) of the number of first vertical threads N1 to the number of second vertical threads N2 is greater than or equal to 2/8 and less than or equal to 8/2.

Preferably, a first vertical thread is adjacent to one or two second vertical threads, and a second vertical thread is adjacent to one or two first vertical threads.

Preferably, the first and second vertical threads are arranged alternately from the center of the face toward the outside in the width direction.

The racket of the present invention has advantages resulting from the first longitudinal thread and advantages resulting from the second longitudinal thread.

FIG. 1 is a front view showing a racket according to an embodiment of the present invention. FIG. 2 is an enlarged exploded view of a portion of the racket of FIG. FIG. 3 is an enlarged view of a portion of the face of the racket of FIG. FIG. 4 is a schematic diagram showing a first main string of the racket of FIG. FIG. 5 is a schematic diagram showing the second main string of the racket of FIG. FIG. 6 is a schematic diagram showing the cross strings of the racket of FIG. FIG. 7 is a schematic diagram showing the first main string and the second main string of the racket of FIG.

The present invention will now be described in detail based on a preferred embodiment, with reference to the drawings as appropriate.

Figure 1 shows a tennis racket 2. This tennis racket 2 has a frame 4, a grip 6, an end cap 8, a grommet 10, and a face 12. This tennis racket 2 can be used for hard tennis. In Figure 1, the arrow X indicates the width direction of the tennis racket 2, and the arrow Y indicates the axial direction of the tennis racket 2.

The frame 4 has a head 14, two throats 16, and a shaft 18. The head 14 forms the outline of the face 12. The front shape of the head 14 is approximately elliptical. The long axis direction of the ellipse coincides with the axial direction Y of the tennis racket 2. The short axis direction of the ellipse coincides with the width direction X of the tennis racket 2. One end of each throat 16 is continuous with the head 14. This throat 16 merges with the other throat 16 near the other end. The throat 16 extends from the head 14 to the shaft 18. The shaft 18 extends from the point where the two throats 16 merge. The shaft 18 is formed continuously and integrally with the throat 16. The portion of the head 14 sandwiched between the two throats 16 is the yoke 20.

The frame 4 is hollow. The material of the frame 4 is fiber-reinforced resin. In this embodiment, the matrix resin of the fiber-reinforced resin is a thermosetting resin. A typical thermosetting resin is an epoxy resin. A typical fiber of the fiber-reinforced resin is a carbon fiber. The fiber is a long fiber.

As shown in FIG. 2, the head 14 has a grommet groove 22. This grommet groove 22 is recessed from the outer peripheral surface of the head 14. As shown in FIG. 1, the grommet groove 22 is formed around almost the entire circumference of the head 14, except for the yoke 20.

The head 14 further has a number of holes 24. Each hole 24 penetrates the head 14. The number of holes 24 is arranged around almost the entire circumference of the head 14.

The grip 6 is formed by a tape wound around the shaft 18. The grip 6 prevents the player's hand from slipping against the tennis racket 2 when the tennis racket 2 is swung. An end cap 8 is attached to the end of the grip 6.

As shown in FIG. 2, the grommet 10 has a base 26 and a number of pipes 28. The base 26 has a belt shape. Each pipe 28 is formed integrally with the base 26. The pipes 28 stand upright from the base 26.

The grommet 10 is typically made of a synthetic resin that is softer than the frame 4. The racket 2 may have multiple grommets 10. The grommets 10 may be spaced apart from each other. The number of pipes 28 in each grommet 10 may be one.

The grommet 10 is attached to the head 14. When the grommet 10 is attached to the head 14, the base 26 is housed in the grommet groove 22. A portion of the base 26 may protrude from the grommet groove 22. When the grommet 10 is attached to the head 14, the pipes 28 pass through the holes 24. One pipe 28 is passed through each hole 24.

Figure 3 is an enlarged view of a portion of the face 12 of the tennis racket 2 of Figure 1. As shown in Figure 3, the face 12 has a plurality of first longitudinal threads 30a, a plurality of second longitudinal threads 30b, and a plurality of transverse threads 32. Each of the first longitudinal threads 30a is stretched on the head 14 along the axial direction (Y direction). The first longitudinal threads 30a intersect with the transverse threads 32. Each of the second longitudinal threads 30b is stretched on the head 14 along the axial direction (Y direction). The first longitudinal threads 30a intersect with the transverse threads 32. Each of the transverse threads 32 is stretched on the head 14 along the width direction (X direction). The transverse threads 32 intersect with the vertical threads. The face 12 is generally aligned along the X-Y plane.

[string]
The tennis racket 2 has a first main string. The first main string 34 is shown in FIG. 4. The first main string 34 is strung in a zigzag pattern on the head 14. The first main string 34 passes through a plurality of holes 24 (see FIG. 2). In other words, the first main string 34 passes through a plurality of pipes 28. One end 36 of the first main string 34 forms a knot. The other end 38 of the first main string 34 also forms a knot. A plurality of first longitudinal threads 30a are formed by the first main string 34. In this embodiment, eight first longitudinal threads 30a are formed from one first main string 34. These first longitudinal threads 30a are arranged symmetrically with respect to the center of the head 14 in the width direction. The tennis racket 2 may have a plurality of first main strings 34.

This tennis racket 2 has a second main string. This second main string 40 is shown in FIG. 5. In FIG. 5, the second main string 40 is shown by a dotted line for convenience. The second main string 40 is strung in a zigzag pattern on the head 14. The second main string 40 passes through a plurality of holes 24 (see FIG. 2). In other words, the second main string 40 passes through a plurality of pipes 28. One end 42 of the second main string 40 forms a knot. The other end 44 of the second main string 40 also forms a knot. A plurality of second longitudinal threads 30b are formed by this second main string 40. In this embodiment, eight second longitudinal threads 30b are formed from one second main string 40. These second longitudinal threads 30b are arranged symmetrically with respect to the center of the width direction of the head 14. The tennis racket 2 may have a plurality of second main strings 40.

This tennis racket 2 has a cross string. This cross string 46 is shown in FIG. 6. The cross string 46 is strung in a zigzag pattern on the head 14. The cross string 46 passes through a plurality of holes 24 (see FIG. 2). In other words, the cross string 46 passes through a plurality of pipes 28. One end 48 of the cross string 46 forms a knot. The other end 50 of the cross string 46 also forms a knot. A plurality of horizontal threads 32 are formed by this cross string 46. In this embodiment, 19 horizontal threads 32 are formed from one cross string 46. The tennis racket 2 may have a plurality of cross strings 46. The cross string 46 may be integral with the first main string 34 (see FIG. 4). The cross string 46 may be integral with the second main string 40 (see FIG. 5).

Figure 7 shows the first main string 34 and the second main string 40. As described above, in this embodiment, eight first longitudinal threads 30a are formed from the first main string 34, and eight second longitudinal threads 30b are formed from the second main string 40. Therefore, the number of longitudinal threads is 16. Since the hole 24 through which the first main string 34 passes is selected, and the hole 24 through which the second main string 40 passes is selected, the second longitudinal thread 30b does not overlap the first longitudinal thread 30a on the face 12. The first longitudinal threads 30a and the second longitudinal threads 30b are alternately arranged from the center of the width of the face 12 toward the outside.

[Vertical thread specifications]
The specifications of the first longitudinal thread 30a are different from the specifications of the second longitudinal thread 30b, so that the tennis racket 2 can satisfy both the advantages of the first longitudinal thread 30a and the advantages of the second longitudinal thread 30b.

[1. Differences in materials]
A typical difference in specifications is a difference in material. When the first longitudinal thread 30a is molded from a resin composition and the second longitudinal thread 30b is molded from another resin composition, this corresponds to a difference in material. Differences in base polymer, additives, and amounts of additives correspond to differences in resin compositions. When one longitudinal thread is molded from a resin composition and the other longitudinal thread is made of natural gut, this also corresponds to a difference in material.

[1.1 Polyester and nylon]
The first longitudinal thread 30a may be made of a resin composition based on polyester, and the second longitudinal thread 30b may be made of a resin composition based on nylon. The first longitudinal thread 30a has a small deformation amount upon impact with a ball. The first longitudinal thread 30a may contribute to spin performance and control performance. The second longitudinal thread 30b has a large deformation amount upon impact with a ball. The second longitudinal thread 30b may contribute to resilience performance and hitting feeling. In this tennis racket 2, spin performance, control performance, resilience performance, and hitting feeling are balanced. The second longitudinal thread 30b may be made of a resin composition based on polyester, and the first longitudinal thread 30a may be made of a resin composition based on nylon.

[1.2 Polyester and natural gut]
The first longitudinal thread 30a may be made of a resin composition based on polyester, and the second longitudinal thread 30b may be made of natural gut. The first longitudinal thread 30a has a small deformation amount upon impact with a ball. The first longitudinal thread 30a may contribute to spin performance and control performance. The second longitudinal thread 30b has a large deformation amount upon impact with a ball. The second longitudinal thread 30b may contribute to resilience performance and hitting feeling. In this tennis racket 2, spin performance, control performance, resilience performance, and hitting feeling are balanced. The second longitudinal thread 30b may be made of a resin composition based on polyester, and the first longitudinal thread 30a may be made of natural gut.

[1.3 Nylon and natural gut]
The first longitudinal thread 30a may be made of a resin composition based on nylon, and the second longitudinal thread 30b may be made of natural gut. The first longitudinal thread 30a has a relatively small deformation amount upon impact with a ball. The first longitudinal thread 30a may contribute to spin performance and control performance. The second longitudinal thread 30b has a relatively large deformation amount upon impact with a ball. The second longitudinal thread 30b may contribute to resilience performance and hitting feeling. In this tennis racket 2, spin performance, control performance, resilience performance, and hitting feeling are balanced. The second longitudinal thread 30b may be made of a resin composition based on nylon, and the first longitudinal thread 30a may be made of natural gut.

[1.4 Grade]
The grade of the substrate of the first longitudinal thread 30a may be different from the grade of the substrate of the second longitudinal thread 30b. For example, the material of the first longitudinal thread 30a may be a resin composition in which polyester is the substrate, and the material of the second longitudinal thread 30b may be a resin composition in which another polyester is the substrate. The polyester of the first longitudinal thread 30a and the polyester of the second longitudinal thread 30b may differ in raw materials, components, molecular weight, crystallinity, thermal history, processing history, etc. The material of the first longitudinal thread 30a may be a resin composition in which nylon is the substrate, and the material of the second longitudinal thread 30b may be a resin composition in which another nylon is the substrate. The nylon of the first longitudinal thread 30a and the nylon of the second longitudinal thread 30b may differ in raw materials, components, molecular weight, crystallinity, thermal history, processing history, etc.

[2 Elongation rate]
The difference in material can be embodied as a difference in elongation. The elongation E1 of the first longitudinal thread 30a and the elongation E2 of the second longitudinal thread 30b are the elongation when each thread is pulled with a stress of 200 MPa. The elongation is measured by a tensile tester. This tester has a pair of chucks. A string is wound around each chuck. The test conditions are as follows:
Testing machine: SHIMADZU AG-Xplus 5kN
Chuck: SHIMADZU 5kN air capstan type
343-23325-30
Chuck distance: 210 mm
Gauge distance: 150mm
Pull speed: 1 mm/sec
Plot interval: 100 msec
Ambient temperature: 25°C
Three measurements are taken for each string, and the median value is used as the representative value.

[2.1 E1<E2]
The elongation percentage E1 of the first longitudinal thread 30a may be smaller than the elongation percentage E2 of the second longitudinal thread 30b. The first longitudinal thread 30a has a small deformation amount upon impact with a ball. This second longitudinal thread 30b has a large deformation amount upon impact with the ball. This second longitudinal thread 30b can contribute to the repulsion performance and the shot feeling. In No. 2, the spin performance, control performance, repulsion performance, and shot feeling are balanced. From this viewpoint, the ratio (E1/E2) is preferably equal to or less than 48/52, more preferably equal to or less than 45/55, and particularly preferably equal to or less than 43/57. Particularly preferred.

[2.2 E1>E2]
The elongation percentage E1 of the first longitudinal thread 30a may be greater than the elongation percentage E2 of the second longitudinal thread 30b. The first longitudinal thread 30a has a large deformation amount upon impact with a ball. The second longitudinal threads 30b contribute to the resilience performance and the shot feeling. The second longitudinal threads 30b are small in deformation upon impact with the ball. The second longitudinal threads 30b contribute to the spin performance and the control performance. In the racket 2, spin performance, control performance, repulsion performance, and shot feeling are balanced. From this viewpoint, the ratio (E1/E2) is preferably equal to or greater than 52/48, more preferably equal to or greater than 55/45, and particularly preferably equal to or greater than 57/43. is particularly preferred.

[3. Differences in tension]
Another example of the difference in specifications is the difference in tension. The string is strung on the head 14 under tension. An operator can adjust the tension T1 of the first longitudinal thread 30a and the tension T2 of the second longitudinal thread 30b. The first main string 34 is not integral with the second main string 40. Therefore, the tension of the second longitudinal thread 30b does not increase due to a decrease in the tension of the first longitudinal thread 30a. Furthermore, the tension of the first longitudinal thread 30a does not increase due to a decrease in the tension of the second longitudinal thread 30b. Even if the tennis racket 2 is used repeatedly, the tension difference between the first longitudinal thread 30a and the second longitudinal thread 30b can be maintained.

[3.1 T1>T2]
The tension T1 of the first vertical thread 30a when it is strung on the head 14 may be greater than the tension T2 of the second vertical thread 30b when it is strung on the head 14. The first vertical thread 30a is The first longitudinal thread 30a has a small deformation amount upon impact. This can contribute to spin performance and control performance. The second longitudinal thread 30b has a large deformation amount upon impact with the ball. The second longitudinal thread 30b has This can contribute to the repulsion performance and the shot feeling. In the tennis racket 2, the spin performance, the control performance, the repulsion performance and the shot feeling are balanced. From this viewpoint, the ratio (T1/T2) is preferably 52/48 or more. , 55/45 or more is more preferable, and 57/43 or more is particularly preferable.

[3.2 T1<T2]
The tension T1 of the first vertical thread 30a when it is stretched on the head 14 may be smaller than the tension T2 of the second vertical thread 30b when it is stretched on the head 14. The first vertical thread 30a is connected to the ball. The first longitudinal thread 30a has a large deformation amount upon impact with the ball. The first longitudinal thread 30a can contribute to the resilience performance and the shot feeling. The second longitudinal thread 30b has a small deformation amount upon impact with the ball. This can contribute to spin performance and control performance. In the tennis racket 2, the spin performance, control performance, repulsion performance, and shot feeling are balanced. From this viewpoint, the ratio (T1/T2) is preferably 48/52 or less. It is preferably 45/55 or less, more preferably 43/57 or less.

The material of the first vertical thread 30a may be different from the material of the second vertical thread 30b, and the tension T1 of the first vertical thread 30a may be different from the tension T2 of the second vertical thread 30b.

[Other specification differences]
The thickness of the first longitudinal thread 30a may be different from the thickness of the second longitudinal thread 30b. The cross-sectional shape of the first longitudinal thread 30a may be different from the cross-sectional shape of the second longitudinal thread 30b. The surface roughness of the first longitudinal thread 30a may be different from the surface roughness of the second longitudinal thread 30b.

[N1/N2]
The ratio (N1/N2) of the number N1 of the first longitudinal threads 30a to the number N2 of the second longitudinal threads 30b in the face 12 is preferably 2/8 or more and 8/2 or less. In a tennis racket 2 in which the ratio (N1/N2) is 2/8 or more, the advantages derived from the first longitudinal threads 30a are fully exhibited. From this point of view, the ratio (N1/N2) is more preferably 3/7 or more, and particularly preferably 4/6 or more. In a tennis racket 2 in which the ratio (N1/N2) is 8/2 or less, the advantages derived from the second longitudinal threads 30b are fully exhibited. From this point of view, the ratio (N1/N2) is more preferably 7/3 or less, and particularly preferably 6/4 or less. In the embodiment shown in FIG. 7, the number N1 is 8, and the number N2 is 8. Therefore, the ratio (N1/N2) is 1.0.

[Placement]
Each first longitudinal thread 30a is preferably adjacent to one or two second longitudinal threads 30b. Each second longitudinal thread 30b is preferably adjacent to one or two first longitudinal threads 30a. In this tennis racket 2, both the advantages of the first longitudinal thread 30a and the advantages of the second longitudinal thread 30b can be satisfied. When a first longitudinal thread and a second longitudinal thread are adjacent to each other, no other longitudinal thread exists between these longitudinal threads.

As mentioned above, in the embodiment shown in FIG. 7, the first longitudinal threads 30a and the second longitudinal threads 30b are arranged alternately from the center of the width of the face 12 toward the outside. Therefore, in this tennis racket 2, the advantages of both the first longitudinal threads 30a and the second longitudinal threads 30b can be fully achieved.

In the embodiment shown in FIG. 7, one or two vertical threads with a large amount of deformation at impact are present between two vertical threads with a small amount of deformation at impact. In other words, the distance between the two vertical threads with a small amount of deformation at impact is sufficiently large. Therefore, the vertical thread with a small amount of deformation at impact can sufficiently bite into the ball. This tennis racket 2 has excellent spin performance.

[Horizontal thread specifications]
The horizontal thread 32 may have the same specifications as the first vertical thread 30a. The horizontal thread 32 may have the same specifications as the second vertical thread 30b. The horizontal thread 32 may have specifications different from the first vertical thread 30a and different from the second vertical thread 30b. The tennis racket 2 may have two types of horizontal threads 32 with different specifications.

The effects of the present invention will be explained below by way of examples, but the present invention should not be interpreted in a restrictive manner based on the description of these examples.

[Example 1]
A tennis racquet having the structure shown in Figures 1-7 was manufactured. The first longitudinal thread was made of a polyester based resin composition. The second longitudinal thread was made of a nylon based resin composition. The cross thread was made of a polyester based resin composition. The first longitudinal thread had a tension of 50 pounds-force (lbf), the second longitudinal thread had a tension of 50 pounds-force, and the cross thread had a tension of 50 pounds-force.

[Examples 2 to 8 and Comparative Examples 1 to 6]
Tennis rackets of Examples 2-8 and Comparative Examples 1-6 were obtained in the same manner as in Example 1, except that the threads were used as shown in Tables 1-3 below.

[evaluation]
A player was asked to play a rally using each tennis racket. The player was asked to evaluate the repulsion performance (flight), spin performance, shot feeling, and control performance. The results are shown in Table 1-3 below. The higher the value, the more favorable the evaluation.

As is clear from Tables 1-3, the tennis rackets of each embodiment have well-balanced performance. The superiority of the present invention is clear from these evaluation results.

The racket of the present invention can be used in a variety of sports, including soft tennis, squash, and badminton.

Reference Signs List 2: Tennis racket 4: Frame 10: Grommet 12: Face 14: Head 22: Grommet groove 30a: First vertical thread 30b: Second vertical thread 32: Horizontal thread 34: First main string 40: Second main string 46: Cross string

Claims (11)

Head and
and a face contoured by the head,
the face having a plurality of first longitudinal threads, a plurality of second longitudinal threads, and a plurality of transverse threads;
the first longitudinal thread has a specification different from that of the second longitudinal thread;
The first longitudinal thread is adjacent to one or two second longitudinal threads, and the second longitudinal thread is adjacent to one or two first longitudinal threads,
the cross-sectional shape of the first longitudinal thread is different from the cross-sectional shape of the second longitudinal thread ;
The first longitudinal threads have a different surface roughness than the second longitudinal threads . The racket of claim 1, wherein one of the specifications is material, and the first longitudinal thread is made of a material different from that of the second longitudinal thread. The material of the first vertical thread is a resin composition having a polyester base material,
3. The racket of claim 2, wherein the second longitudinal threads are made of a resin composition based on nylon. The material of the first vertical thread is a resin composition having a polyester base material,
3. The racket of claim 2, wherein the second longitudinal threads are made of natural gut. The material of the first longitudinal thread is a resin composition having nylon as a base material,
3. The racket of claim 2, wherein the second longitudinal threads are made of natural gut. A racket according to any one of claims 1 to 5, wherein the first longitudinal thread has an elongation percentage E1 different from the elongation percentage E2 of the second longitudinal thread. The racket of claim 6, wherein the ratio (E1/E2) of the elongation percentage E1 of the first vertical thread to the elongation percentage E2 of the second vertical thread is 48/52 or less or 52/48 or more. A racket according to any one of claims 1 to 7, wherein the first longitudinal thread has a tension T1 different from the tension T2 of the second longitudinal thread. The racket according to claim 8, wherein the ratio (T1/T2) of the tension T1 of the first vertical thread to the tension T2 of the second vertical thread is 48/52 or less or 52/48 or more. A racket according to any one of claims 1 to 9, in which the ratio (N1/N2) of the number of the first vertical threads N1 to the number of the second vertical threads N2 is 2/8 or more and 8/2 or less. The racket according to any one of claims 1 to 10, wherein the first vertical threads and the second vertical threads are arranged alternately from the center of the face toward the outside in the width direction.

Images