JP5638388B2 - ball - Google Patents

Description

  The technology disclosed herein relates to a ball that is used for various competitions, training, play, recreation, and the like that a person directly or indirectly throws, kicks, or strikes.

  Of the balls roughly divided into solid and hollow shapes, one of the hollow ball structures is a tube in which compressed air is sealed, and a nylon filament or the like is wound around the tube in any circumferential direction. There is known a structure comprising a reinforcing layer formed of a cover layer, a cover rubber layer formed on the reinforcing layer, and a skin layer composed of a plurality of leather panels bonded on the cover rubber layer. (For example, refer to Patent Document 1). The ball having this structure is called a pasted ball.

  Also, as a ball structure different from this, as disclosed in Patent Document 2, for example, the skin layers are formed by stitching the edges of a plurality of leather panels into a spherical shape, and within the skin layer. The structure which accommodated the tube in is known. A ball having this structure is called a sewing ball.

  As another ball structure, for example, in Patent Document 3, a tube is stored in a spherical woven fabric layer obtained by stitching a plurality of woven fabric pieces together, and a plurality of leather panels are provided on the surface of the woven fabric layer. A ball having a structure in which a skin layer is formed by bonding is disclosed.

US Pat. No. 4,333,648 Japanese Patent Laid-Open No. 9-19516 International Publication No. 2004/56424 Pamphlet

  By the way, in a competition using a ball, if the conditions when the ball is thrown, kicked or hit directly (hereinafter also referred to as a ball launch condition) are the same, the flight of the ball It is desirable that the trajectory is always the same trajectory. In other words, it is desirable that the ball reaches the desired position without the trajectory of the flying ball extending or falling, and without moving in the lateral direction perpendicular to the traveling direction of the ball. By doing so, the player will be able to control the ball as intended.

  In a game using a ball, the flight trajectory of the ball is changed to a predetermined change trajectory by forcibly rotating the ball. For example, when the ball is longitudinally rotated in the same direction as the traveling direction, the trajectory becomes a drop trajectory in which the ball falls greatly.

  Thus, when the ball trajectory is changed to a change trajectory, it is desirable that the ball trajectory always has the same change trajectory when the same rotation is given to the ball (when the rotation speed is the same). It is desirable that the amount of change in the ball trajectory is proportional to the amount of rotation given to the ball (the number of rotations) and the ball speed. By doing so, the player can obtain the desired ball trajectory and the controllability of the ball is enhanced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a ball with improved controllability.

The present invention relates to a ball in which a skin layer forming a spherical surface of a ball body is provided so that each of a plurality of three or more leather panels is adjacent to each other. The entire surface of each surface has continuous linear protrusions and discontinuous multiple recesses, and the continuous linear protrusions each have a hexagonal vertical projection plane. configured lattice shape that prevents the shape, the recess in the recess and the other of the leather panel in hand the leather panel is the large number of recesses are arranged equidistant from each other, in most of the mating portion of each leather panels adjacent to each other Doo is opened configured to be continuous with each other, in the remainder of the mating portions of the leather panels adjacent to each other Flynn the recess in the recess and the other of the leather panel in one of the leather panels to each other Become as a closed construction the convex portion of the convex portion or the other of the leather panel in one of the leather panel, further, adjacent the mating portion of each leather panels adjacent to the recess of the transverse cross section substantially V-shaped The leather panel is formed so as to be continuous in the extending direction of the mating portions of the leather panels, and the concave and convex portions are also present on the surface of the recess .

The present invention includes continuous linear convex portions and discontinuous multiple concave portions over the entire surface of each of a plurality of leather panels, and the continuous linear convex portions include a plurality of concave portions. configured to each lattice shape thwart a shape having a hexagonal vertical projection plane, and the plurality of recesses are arranged equidistantly from one another, of the hand in most of the mating portion of each leather panels and adjacent leather The concave portion in the panel and the concave portion in the other leather panel are open so as to be continuous with each other, and the concave portion in one leather panel and the concave portion in the other leather panel are the rest of the mating portions of the adjacent leather panels. Doo is configured such that a closed convex portion of the convex portion or the other of the leather panel in a discontinuous become as one of the leather panels to each other, further, if each leather panels adjacent to each other By the the back portion recess cross section substantially V-shaped is formed so as to be continuous in the direction of extension of the mating portions of the leather panels adjacent to each other, there is the recess and convex portions on the surface of the recess, When the ball is flying while rotating, the instability of the fluid force acting on the ball is suppressed, and the ball trajectory is stabilized to a predetermined trajectory.

FIG. 1 is a perspective view showing a volleyball according to the embodiment. FIG. 2 is an enlarged perspective view showing the surface of the volleyball. FIG. 3 is a partial cross-sectional view of a volleyball. 4 is a partial cross-sectional view of a volleyball having a structure different from that of FIG. FIG. 5 is a partial cross-sectional view of a volleyball having a structure different from those in FIGS. 3 and 4. FIG. 6 is a conceptual diagram showing another configuration of the convex portion. FIG. 7 is a conceptual diagram showing another configuration of the convex portion. FIG. 8 is a conceptual diagram showing another configuration of the convex portion. FIG. 9 is a conceptual diagram showing another configuration of the convex portion. FIG. 10 is a conceptual diagram showing another configuration of the convex portion. FIG. 11 is a conceptual diagram showing another configuration of the convex portion. FIG. 12 is a conceptual diagram showing another configuration of the convex portion. FIG. 13 is a conceptual diagram showing another configuration of the convex portion. FIG. 14 is a conceptual diagram showing another configuration of the convex portion. FIG. 15 is a conceptual diagram showing another configuration of the convex portion. FIG. 16 is a conceptual diagram showing another configuration of the convex portion. FIG. 17 is a conceptual diagram showing another configuration of the convex portion. FIG. 18 is a conceptual diagram showing another configuration of the convex portion. FIG. 19 is a conceptual diagram showing another configuration of the convex portion. FIG. 20 is a conceptual diagram showing another configuration of the convex portion. FIG. 21 is a conceptual diagram showing another configuration of the convex portion. FIG. 22 is a conceptual diagram showing another configuration of the convex portion. FIG. 23 is a conceptual diagram showing another configuration of the convex portion. 24 is a cross-sectional view taken along the line aa in FIG. FIG. 25 is a conceptual diagram showing another configuration of the convex portion. FIG. 26 is a conceptual diagram showing another configuration of the convex portion. FIG. 27 is a conceptual diagram showing another configuration of the convex portion. FIG. 28 is a conceptual diagram showing another configuration of the convex portion. 29 is a cross-sectional view taken along line bb of FIG. FIG. 30 is a conceptual diagram showing another configuration of the convex portion. FIG. 31 is an explanatory diagram showing a configuration of a ball according to a comparative example. FIG. 32A is a diagram showing the lift characteristics of the ball according to each example when the rotation speed is 300 rpm. FIG. 32B is a diagram showing the lift characteristics of the ball according to each example when the rotation speed is 480 rpm. FIG. 32C is a diagram illustrating the lift characteristics of the ball according to each example when the rotation speed is 600 rpm. FIG. 33A is a diagram showing lift characteristics of a ball according to a conventional example. FIG. 33B is a diagram illustrating lift characteristics of a ball according to a comparative example. FIG. 33C is a diagram illustrating a lift characteristic of the ball according to the example. FIG. 34A is a diagram showing a simulation result of the trajectory of the ball according to each example when the rotation speed is 300 rpm. FIG. 34B is a diagram showing a simulation result of the trajectory of the ball according to each example when the rotation speed is 480 rpm. FIG. 34C is a diagram showing a simulation result of the trajectory of the ball according to each example when the rotation speed is 600 rpm. FIG. 35 is a diagram illustrating an example of temporal variation of the lateral force acting on the ball according to the conventional example. FIG. 36 is a diagram illustrating an example of temporal variation of the lateral force acting on the ball according to the second embodiment. FIG. 37 is a diagram showing variations in the arrival position when a ball according to a conventional example is launched by a launching device. FIG. 38 is a diagram showing variations in the arrival position when a ball according to the second embodiment is launched by the launching device.

  The ball disclosed herein includes a ball body having a spherical surface and a convex portion raised from the surface of the ball body. The convex portion stabilizes the trajectory of the ball main body to a predetermined trajectory by suppressing instability of fluid force acting on the ball main body when the ball main body is flying while rotating. It rises like this.

  “Rotation” here is not limited to forcibly rotating the ball by applying a force in the rotation direction to the ball (that is, rotating at a relatively high rotation), but the force in the rotation direction against the ball. This is also included in “the ball body is flying while rotating”. That is, not only the case where the ball is rotating at a low rotation but also the case where the ball is rotating at an extremely low rotation and can be said to be non-rotating quasi-steadily can be included.

  The convex portion may be raised so as to reduce variations in arrival position when the ball body flies under the same conditions. The “arrival position” here includes both the flight distance (arrival position with respect to the flight direction) of the ball body and the arrival position in the lateral direction perpendicular to the flight direction. In other words, the convex portion suppresses the flight trajectory of the ball body from extending or falling, and also suppresses the lateral movement of the ball, thereby reducing variations in the arrival position.

  The convex portion may be raised so as to stabilize the trajectory to a predetermined drop trajectory when the ball body is flying while longitudinally rotating in the same direction as the traveling direction thereof. Here, “vertical rotation” means that the ball is forcibly rotated to rotate at a relatively high rotation.

  That is, when the ball is flying while rotating, the trajectory of the ball body is stabilized and variation in the arrival position is reduced, while when the ball is forcibly rotated, the trajectory of the ball drops to a predetermined drop. The present inventors have obtained the knowledge that the orbit is stabilized.

  The convex portion may be arranged on the entire surface of the ball main body in a predetermined pattern.

  The said convex part is good also as arrange | positioning equally on the whole surface of the said ball | bowl main body.

  The surface of the ball body may be formed by a plurality of panels.

  Hereinafter, embodiments of the ball will be described with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  FIG. 1 shows a ball according to this embodiment. Here, the ball will be described by taking a volleyball as an example. The ball is not limited to volleyball. For example, it may be a ball used for other competitions such as a soccer ball, a handball, and a basketball.

  As shown in an enlarged view in FIG. 2, the volleyball B includes a ball main body 1 and a convex portion 2 protruding from the surface of the ball main body 1.

  As shown in FIG. 3, FIG. 4, or FIG. 5, the ball body 1 has a so-called bonded ball structure in this embodiment. That is, the ball body 1 includes a spherical hollow tube 11, a reinforcing layer 12 that covers the surface of the tube 11, a cover rubber layer 13 made of, for example, natural rubber, and a cover rubber layer 13 that is coated on the reinforcing layer 12. It consists of a plurality of (18 in this volleyball B) leather panels 14 bonded to the surface via an adhesive, and includes a skin layer 15 that forms the spherical surface of the ball body 1.

  The tube 11 is made of an air impermeable elastic body such as butyl rubber. The tube 11 is filled with compressed air through a valve (not shown).

  The reinforcing layer 12 is made of a thread wound layer in which a nylon filament or the like having a length of several thousand meters is wound on the tube 11 in any circumferential direction, or a fabric layer in which a plurality of woven fabric pieces are sewn in a spherical shape. . This reinforcing layer 12 stabilizes the quality as a ball. That is, the reinforcing layer 12 improves the sphericity, durability, spherical maintainability, and strength against change with time of the ball body 1.

  The leather panel 14 is made of natural leather, artificial leather, or synthetic leather, and has a predetermined strip shape. The leather panel 14 has the surface of the ball body 1 in the respective directions of six axes that pass through the center of the ball body and are orthogonal to each other in the upper, lower, left, and right directions (hereinafter, each axis may be referred to as a central axis). Three pieces are arranged in each region formed in a substantially quadrangular shape when divided into six, and the peripheral portions thereof are in contact with each other. Thus, the skin layer 15 is formed by covering the surface of the ball body 1 with the leather panel 14. In addition, the shape of each leather panel and the number thereof are not particularly limited, and an appropriate shape and number can be adopted.

  In addition, although illustration is abbreviate | omitted, as for each leather panel 14, the peripheral part of the back surface is shaved diagonally in the thickness direction. As a result, a recess having a substantially V-shaped cross section is formed at a location where the peripheral portions of the leather panel 14 are joined to each other on the surface of the ball body 1. That is, predetermined irregularities are formed in advance on the surface of the volleyball B.

  3 to 5 schematically depict the cross section of the ball body 1 for easy understanding. In the illustrated example, the thickness of each layer is drawn substantially the same, but the thickness of each layer is actually different from each other.

  In the volleyball B of the present embodiment, the convex portions 2 are linear as shown in FIG. 2, and the linear convex portions 2 are equally spaced in two directions orthogonal to each other in each leather panel 14. Many are arranged in the space. Thus, a square lattice is formed by the convex portions 2 on the surface of the ball body 1. In other words, a large number of rectangular patterns are evenly arranged on the entire surface of the ball body 1.

  What is necessary is just to form each convex part 2 on the surface of the ball | bowl main body 1 as follows, for example. That is, for example, as shown in FIG. 3, a protrusion 13 a that protrudes outward in the radial direction is formed integrally with the cover rubber layer 13. Since the leather panel 14 adhered on the cover rubber layer 13 is bulged outward in the radial direction of the ball body 1 by the ridge 13a, the convex part 2 that is bulged from the surface of the ball body 1 is formed. Become.

  In addition, although the said protrusion 13a may be formed by integral molding with the cover rubber layer 13, formation of the protrusion 13a is not restricted to integral molding. For example, although not shown, the protrusion 13a can be formed by attaching a protrusion member having a predetermined height to the surface of the cover rubber layer 13 by adhesion or the like.

  Unlike this, for example, as shown in FIG. 4, the protruding portion 2 protruding from the surface of the ball body 1 is formed by forming the protrusion 14 a protruding from the surface integrally with the leather panel 14. May be.

  Further, instead of integrally molding the protrusion 14a with the leather panel 14, as shown in FIG. 5, for example, by attaching a protrusion member 14b to the surface of the leather panel 14 by, for example, bonding, the ball body 1 You may make it form the convex part 2 which protrudes from the surface of this.

  As will be described in detail later, each convex portion 2 protruding from the surface of the ball body 1 is uneasy about the fluid force acting on the ball body when the ball body 1 is flying (including extremely low rotation). It has a function of stabilizing the trajectory of the ball body to a predetermined trajectory while suppressing qualitative properties. That is, when the launch conditions of the ball body 1 are the same, variations in the arrival position (a lateral position perpendicular to the flight distance and the flight direction) are suppressed. Each convex portion 2 has a function of stabilizing the trajectory to a predetermined drop trajectory when the ball body 1 is flying while longitudinally rotating in the same direction as the traveling direction thereof. That is, when a similar rotation is given to the ball body 1, the ball trajectory is always the same drop trajectory. Further, the drop amount changes substantially in proportion to the rotation speed and the ball speed.

  Here, the height of each convex portion 2 is preferably about 0.05 to 0.4 mm, and more preferably about 0.1 to 0.2 mm. This makes it possible to achieve stabilization of the ball trajectory without impairing the handling performance of the ball body 1.

  Further, the ratio of the surface area (for example, see FIG. 3) of the convex portion 2 to the total surface area of the ball body 1 is preferably about 10 to 40%, and more preferably about 20 to 30%. As a result, the handleability of the ball body 1 and the stabilization of the ball trajectory are compatible. This ratio gives an index of how much the convex portion 2 should be provided with respect to the ball body 1.

  The arrangement and shape of the convex portions 2 are not limited to the arrangement and shape shown in FIG. Hereinafter, the arrangement | positioning of the convex part 2 and the variation of a shape are demonstrated, referring drawings.

  In FIG. 6, a hexagonal pattern is formed by the linear protrusions 2, and the hexagonal patterns are arranged side by side so as to contact each other. That is, a honeycomb lattice is formed by the convex portions 2.

  In FIG. 7, the convex portions 2 of the hexagonal pattern are arranged side by side at intervals. Adjacent hexagonal patterns are staggered.

  In FIG. 8, the convex portions 2 of the short line segments are arranged side by side at equal intervals in two oblique directions orthogonal to each other in FIG. Thus, a square lattice inclined obliquely is formed by the convex portion 2.

  In FIG. 9, the three convex portions 2 of the short line segments are arranged to form a triangle to form a triangular pattern, and the triangular patterns are arranged side by side at equal intervals in the vertical and horizontal directions in FIG. ing.

  In FIG. 10, the convex part 2 of a short line segment is further arrange | positioned in each lattice in the square lattice pattern shown in FIG. The directions of the convex portions 2 are different from each other in adjacent lattices.

  In FIG. 11, the three convex portions 2 of the short line segments are arranged to form a Y shape to form a Y shape, and the Y shape patterns are arranged at equal intervals on the top, bottom, left and right in FIG. It is arranged. Adjacent Y-shaped patterns are staggered. Further, the Y-shaped pattern is inverted in the vertical direction with a predetermined regularity. Thus, a hexagonal lattice is formed by the six Y-shaped patterns, and the Y-shaped pattern is arranged in each lattice.

  In FIG. 12, a triangular lattice is formed by arranging the linear convex portions 2 at equal intervals in the vertical and diagonal directions. In other words, a large number of equilateral triangle patterns are arranged side by side so as to contact each other.

  In FIG. 13, a rhombus pattern is formed by the linear protrusions 2, and the rhombus patterns are arranged side by side so as to contact each other.

  In FIG. 14, a circular pattern is formed by the linear protrusions 2, and the circular patterns are arranged side by side so as to contact each other vertically and horizontally in FIG. 14.

  In FIG. 15, while forming a circular pattern by the convex part 2 of a short line segment, the circular pattern is arrange | positioned side by side at intervals up and down and right and left in FIG.

  In FIG. 16, the circular patterns in FIG. 15 are arranged in a staggered pattern.

  In FIG. 17, the circular patterns in FIG. 14 are arranged side by side so as to partially overlap each other vertically and horizontally in FIG.

  In FIG. 18, the convex portions 2 of the short line segments are arranged in a # shape, and the # patterns are arranged in a staggered manner in each of two directions orthogonal to each other. The arrangement is not limited to the staggered arrangement.

  In FIG. 19, the convex portions 2 of the short line segments are arranged side by side in each of two directions orthogonal to each other. As a result, a square lattice in which the convex portion 2 does not exist at the lattice point is formed.

  In FIG. 20, the convex portions 2 of the short line segments are arranged in a cross shape, and the cross pattern is arranged side by side in each of two directions orthogonal to each other.

  In FIG. 21, the convex portions 2 of relatively long line segments are arranged in one direction. Here, the interval between the convex portions 2 may be periodically changed as shown in FIG.

  In FIG. 22, the convex portions 2 of the short line segments are arranged in a V shape, and the V patterns are arranged side by side in two directions orthogonal to each other.

  In FIG. 23 and FIG. 24, the convex portions 2 protruding in a spike shape from the surface are arranged so as to form a hexagonal pattern, and the hexagonal patterns are arranged side by side vertically and horizontally in FIG.

  In FIG. 25, the hexagonal pattern of FIG. 23 is arranged in a staggered pattern.

  In FIG. 26, the convex portions 2 protruding in a spike shape from the surface are arranged so as to form a square pattern, and the square patterns are arranged side by side at intervals in the vertical and horizontal directions in FIG.

  In FIG. 27, the convex portions 2 protruding in a spike shape from the surface are arranged so as to form a triangular pattern and an inverted triangular pattern, and the triangular pattern and the inverted triangular pattern are partially shared with each other vertically and horizontally in FIG. Are arranged side by side so that they overlap.

  In FIG. 28 and FIG. 29, the protrusions 2 that protrude from the surface in the form of dots are arranged side by side at equal intervals in the vertical and horizontal directions in FIG. An annular concave groove 21 is formed around each convex portion 2. The concave groove 21 can be omitted.

  In FIG. 30, the dot-like convex portions 2 in FIG. 28 are arranged in a staggered manner.

  In addition, the arrangement | positioning and shape of the convex part 2 shown in FIG. 2, FIG. 6-30 can also combine 2 or 3 or more.

  Next, specific examples will be described. First, a commercially available volleyball (diameter 209 mm) having 18 leather panels 14 pasted on its surface was prepared as a conventional example.

  On the other hand, as shown in FIG. 2, a volleyball in which convex portions 2 are formed in a square lattice shape was prepared as an example.

  As a comparative example, as shown in FIG. 31, a linear member 3 having a circular cross section with a diameter of 0.45 mm is formed on the surface of a commercially available volleyball B with a predetermined diameter (centered on the central axis). A volleyball pasted so as to have a circular shape as shown in FIG. Specifically, the ball of the comparative example has six linear members 3 on the surface so that each of the six axes passing through the center of the ball main body and perpendicular to each other in the vertical and horizontal directions and the front and rear is circular with a diameter of 187 mm. It is the ball pasted on. In FIG. 31, five line members 3 are illustrated, and one line member disposed on the back side of the ball body 1 is not illustrated in the drawing.

  A wind tunnel experiment was conducted on each of the above examples to examine the aerodynamic characteristics of the balls of each example. The results are shown in FIGS. 32 and 33 as changes in the lift coefficient CL with respect to the Reynolds number Re. Further, the behavior of the ball was considered with respect to these values (see FIG. 34). Here, FIG. 32A shows a case where the ball is vertically rotated at 300 rpm in the same direction as the traveling direction, FIG. 32B shows a case where the ball is vertically rotated at 480 rpm in the same direction as the traveling direction, and FIG. Is a comparison of the lift coefficient of each ball when it is rotated longitudinally at 600 rpm in the same direction as the traveling direction. FIG. 33A is a comparison of lift coefficients when the number of rotations is changed for each of the balls of the conventional example, FIG. 33B is the ball of the comparative example, and FIG. 33C is the ball of the example. Here, the vertical lines in FIGS. 32 and 33 indicate the Reynolds number Re corresponding to the ball speed of 50 km / h, and the region where the Reynolds number Re is higher than this is, for example, the practical speed region in volleyball. Become. Therefore, in the following, attention is focused on a region on the right side of the vertical thin line.

  First, referring to FIG. 32A, the lift coefficient of the comparative example ball and the example ball is larger on the minus side (the absolute value is larger) than the conventional example ball. A larger force acts downward on the ball than on the conventional ball. Therefore, the drop amount of the ball of the comparative example and the ball of the example is larger than that of the conventional ball.

  32B and 32C, the ball of the comparative example has a higher lift coefficient than the ball of the conventional example, but the ball of the example has a higher lift coefficient on the minus side than the ball of the conventional example. Become. Therefore, even when the rotational speed is relatively high, the drop amount of the ball of the example is larger than that of the ball of the conventional example.

  Further, referring to FIG. 33A, the ball of the conventional example has a large change in the lift coefficient CL at the rotation speeds of 480 rpm and 600 rpm with respect to the lift coefficient CL at the rotation speed of 300 rpm. On the other hand, the lift coefficient CL changes suddenly. At the same time, in the conventional ball, the lift coefficient CL may not change monotonously with respect to the change in the Reynolds number Re. For example, when the rotational speed is 300 rpm, the lift coefficient CL decreases monotonously as the Reynolds number Re increases. On the other hand, when the rotational speed is 600 rpm, the lift coefficient CL hardly increases as the Reynolds number Re increases. It does not change (or increases slightly) and its characteristics are completely different. For example, when the rotational speed is 480 rpm, there is a Reynolds number at which the lift coefficient CL falls, and the lift coefficient CL does not change monotonously with an increase in the Reynolds number Re.

  Further, the ball of the comparative example has a difference between the lift coefficient CL at the rotation speed of 300 rpm and the lift coefficient CL at the rotation speed of 480 rpm, the lift coefficient CL at the rotation speed of 480 rpm, and the lift force at the rotation speed of 600 rpm. Unlike the difference from the coefficient CL, the change in the lift coefficient CL is not constant with respect to the change in the rotational speed. In the ball of the comparative example, the lift coefficient CL may not change monotonously with respect to the change in the Reynolds number Re when the rotation speed is constant. For example, when the rotational speed is 300 rpm, the lift coefficient CL hardly changes as the Reynolds number Re increases. At the rotational speeds of 480 rpm and 600 rpm, the lift coefficient CL increases as the Reynolds number Re increases. It increases monotonously and has different characteristics.

  On the other hand, in the ball of the example, the lift coefficient CL does not change suddenly with respect to the change in the rotation speed, and the lift coefficient CL is substantially proportional to the change in the rotation speed. Further, when the rotational speed is constant, the lift coefficient CL increases relatively monotonously as the Reynolds number Re increases. From this, the ball of the example has a larger drop amount than the balls of the conventional example and the comparative example, and the drop amount is proportional to changes in the rotation speed and the ball speed. Therefore, the ball of the embodiment can obtain a stable drop trajectory during vertical rotation.

  The above description is based on the lift coefficient CL, but the actual drop amount must also take into account the effect of speed reduction due to the drag coefficient CD. 34A to 34C show the results of simulating the trajectory at the time of service for each of the volleyballs of the conventional example, the comparative example, and the example, based on the experimental results described above and also taking into consideration the influence of the speed reduction. 34A, the rotation speed of the ball is set to 300 rpm, FIG. 34B, the rotation speed of the ball is set to 480 rpm, and FIG. 34C, the rotation speed of the ball is set to 600 rpm.

  Here, in the above simulation, the trajectory of the ball is simulated when the ball is launched at a speed of 50 km / h from a height of 2.2 m, 2 m behind the end line. The ball launch angle is set to be the same in the conventional example, the comparative example, and the example. That is, at each rotational speed, the launch angle of the conventional example and the comparative example is set to the same angle as the launch angle at which the ball of the example exceeds the net at the center of the court.

  According to this, when the rotational speed is 300 rpm (see FIG. 34A), the balls of the conventional example and the comparative example have substantially the same trajectory, whereas the balls of the example have a ball trajectory after the vicinity of the highest point. And it turns out that it has fallen a little rather than the comparative example. In other words, the trajectory of the ball of the example changes more than the conventional example, and thus the ball of the example has a slightly shorter flight distance than the conventional example and the comparative example.

  When the rotation speed is 480 rpm (see FIG. 34B), the ball of the comparative example has a longer flight distance than the conventional example, whereas the ball of the example has a shorter flight distance than the conventional example. This tendency is the same when the rotational speed is 600 rpm. Further, as the number of rotations of the balls of the example increases, the difference in the trajectory from the balls of the conventional example becomes conspicuous.

  Next, as another example, a conventional example of a commercially available volleyball (this conventional example is the same as the above-described conventional example) and a volleyball in which convex portions 2 are formed in a honeycomb lattice shape as shown in FIG. The second embodiment) was prepared, and the ball trajectory stability was compared between the conventional example and the second embodiment.

  FIG. 35 is a graph showing the time variation of the force in the direction orthogonal to the flying direction of the ball (hereinafter, the force acting on the ball is also referred to as lateral force) obtained by conducting a wind tunnel experiment on the conventional example. FIG. 36 is a diagram of the temporal variation of the lateral force L obtained by conducting the wind tunnel experiment on the second embodiment. Here, each ball is kept stationary without rotating. The wind speed is 14 m / s. Referring to FIG. 35, the amplitude of the lateral force L is about ± 0.5N in the conventional example, whereas the amplitude of the lateral force L is reduced to about ± 0.25N in the second embodiment. . That is, in the second embodiment, the fluctuation of the lateral force is small compared to the conventional example. Therefore, when the ball according to the second embodiment actually flies, the flight trajectory of the ball is orthogonal to the traveling direction. It will be suppressed that it shakes in the horizontal direction.

  Next, the variation in the arrival position when each ball of the conventional example and the second example was actually launched by the launching device was evaluated. Although the illustration of the launching device is omitted, in order to simulate hitting a volleyball by a person's palm, a rotating arm that is pivotally supported on the base end side and rotates around the pivoting shaft, and a distal end of the rotating arm The ball is set in the vicinity of the lowest position in the rotation of the rotary arm. The hitting device hits the ball when the hitting plate hits the approximate center of the ball as the rotary arm rotates. With this configuration, the launching device does not apply a force in the rotational direction to the ball at the time of launching, so that each example ball flies while rotating at a low or very low speed. Become. The launching device changes the initial speed of the ball by adjusting the rotation speed of the rotating arm, and also changes the angle at which the striking plate hits the ball by adjusting the setting position of the ball. The ball launch angle is changed. In this embodiment, the launching conditions of the launching device are an initial speed of 14 m / s and a launching angle of about 20 °. FIG. 37 is a diagram showing variation in the arrival position of the ball according to the conventional example, and FIG. 38 is a diagram showing variation in the arrival position of the ball according to the second embodiment. In the direction of flight, the horizontal axis (X-axis) is the flight distance of the ball, and the vertical axis (Y-axis) is the amount of lateral displacement of the ball. Therefore, in each of FIGS. 37 and 38, the position of the floor surface reached by the ball is plotted on the XY plane. Here, 90 trials are made for each example.

  First, referring to FIG. 37 (conventional example), the arrival position of the ball is within the range of 1200 to 1700 cm (X axis) and −250 to 250 cm (Y axis). As shown, it can be seen that there are cases where the flight distance becomes longer or shorter, or where the amount of lateral displacement increases. In order to evaluate the variation in the arrival position, the average value in the X direction and the average value in the Y direction are calculated from the above data, and are defined as the average arrival position. The average arrival position and the arrival in each trial The standard deviation of the distance between the positions was calculated. The standard deviation calculated based on the data in FIG. 37 was 54.66.

  On the other hand, referring to FIG. 38 (second embodiment), the ball reaching position is within the range of 1200 to 1700 cm (X axis) and −250 to 250 cm (Y axis), as in the conventional example. Thus, unlike the conventional example, there are almost no cases where the flight distance becomes longer or shorter, or the lateral shift amount becomes larger. The standard deviation calculated based on the data of FIG. 38 is 41.29, and it can be seen that the variation is smaller than that of the conventional example. Therefore, in the second embodiment, the trajectory of the ball is prevented from extending or falling with respect to the flight distance of the ball, and the trajectory is shaken in the lateral direction perpendicular to the traveling direction of the ball. It can be seen that this is also suppressed. This indicates that it is advantageous for the player to reach the desired position, that is, to control the ball as intended.

  As described above, the ball to which the technology disclosed herein is applicable is not limited to the volleyball B. In addition, this technique can be applied to various balls for competition, training, play, recreation, and the like. In addition, as a game ball, a soccer ball, a handball, etc. can be mentioned as a specific example.

  Further, the structure of the ball is not limited to the stuck ball. This technique can be applied to balls having various structures. For example, the present technology can be applied not only to a hollow ball but also to a solid ball.

  In addition, as a structure of a hollow ball other than the bonded ball, for example, a so-called structure having a spherical skin layer by stitching edges of a plurality of leather panels and a tube housed in the skin layer, so-called A sewing ball can be given as a specific example. When the present technology is applied to the sewing ball, the protrusion may be provided by forming the protrusion integrally with the leather panel, or the protrusion may be provided by attaching a protrusion member to the surface of the leather panel by bonding or the like. A part may be provided.

  In addition, as a hollow ball structure, for example, a plurality of woven fabric pieces are stitched together to store a tube in a spherical woven fabric layer, and a plurality of leather panels are bonded to the surface of the woven fabric layer. The structure can also be given as another specific example. When the present technology is applied to a ball having this structure, a ridge portion may be integrally formed on the leather panel, or a ridge member may be attached to the leather panel by bonding or the like, as in the case of the sewing ball. Further, for example, a protruding member that protrudes from the surface of the ball may be provided by sticking a protrusion member to the woven fabric layer and adhering a leather panel thereon.

  As described above, the technique disclosed herein is useful for various balls because the ball trajectory during rotation is stabilized and the ball controllability is improved.

1 Ball body 14 Leather panel 2 Convex B Volleyball

Claims (1)

The ball body is a ball formed by providing a skin layer forming a spherical surface of a ball body so that each of a plurality of three or more leather panels is adjacent to each other. A lattice having continuous linear convex portions and a large number of discontinuous concave portions in the entire area, and the continuous linear convex portions block each of the multiple concave portions as a shape having a hexagonal vertical projection plane. is configured in the shape, and the plurality of recesses are disposed equidistantly from each other, continuous and concave in the recess and the other of the leather panel in the leather panels hand in most of the mating portion of each leather panels where adjacent an opened configured to, in the remainder of the mating portions of the leather panels to each other said adjacent the recess in the recess and the other of the leather panel in one of the leather panel is discontinuous to each other One is a closed construction the convex portion of the convex portion or the other of the leather panel in the leather panels, furthermore, the mating portions of the leather panels adjacent to each leather adjacent a recess cross section substantially V-shape A ball characterized in that it is formed so as to be continuous in the direction in which the mating portions of the panels extend, and the concave and convex portions are also present on the surface of the depression .

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