JP2000342737A - Ball shooting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize speed and directional property of ball which is shot from a shooting pipe. SOLUTION: There are provided a shooting pipe 13 which is composed of a straight cylindrical tube of which an opening of one end is a pressure air intake and an opening of the other end is a ball shooting opening, a closed-end cylindrical cup 20 which is engaged with the inside of the shooting pipe movably and a side of the shooting opening is opened and a side of the pressure air intake is closed and a ball is installed in it and a stopper 22 which stops movement of the cup at a position of at least the shooting opening and can be jumped only the ball out from the shooting opening. The ball is installed in the cup and moved then the cup is stopped by the stopper at the shooting opening then the ball is jumped out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball launcher, and more particularly to a ball launcher which is suitably used as a launcher for a tennis ball and which can launch a ball having a stable directionality at a speed.

[0002]

2. Description of the Related Art Conventionally, a large number of ball launchers for automatically launching sports balls such as tennis balls and game balls have been provided and used for repetitive training. For example, in a tennis ball launcher disclosed in Japanese Utility Model Laid-Open No. 57-10877 and Japanese Patent Laid-Open No. 48-42827,
A spring system that operates an arm (hammer, striker) for hitting a ball by using a spring force is disclosed. In the ball launcher disclosed in JP-A-63-318969,
A drum system in which a ball is forcibly fed by a drum rotated by an electric drive motor is disclosed. Further, in the ball launcher disclosed in Japanese Utility Model Laid-Open Publication No. 57-90175, as shown in FIG.
And a ball is dropped from a hopper 4 to a firing tube 3 provided in the blower 2, and the air is blown (air pressure) to control the firing of the ball.

[0003]

In the above-mentioned spring system, only a low-speed ball having a spring force of 10 m / sec or less can be fired, and the deformation of the spring is unstable. However, there is a problem that the ball is not stable and cannot be fired with high accuracy. Further, there is a problem that the spring is fatigued quickly and durability is poor.

[0004] Compared with the above-mentioned spring system, the above-mentioned drum system allows high-speed firing and uses a motor to rotate the drum, so that speed control can be performed easily and stably. Instead of firing from a straight line,
Since the ball is fired from the rotating drum, the ball is rotated or deformed, and there is a problem that the accuracy of the speed and directionality is reduced.

In the above-mentioned air system, the air pressure can be set and adjusted by a pressure gauge, so that the ball speed is stabilized and the speed can be easily adjusted. In addition, since the directionality is stabilized by passing the ball through a linear guide tube having an appropriate length, it is recognized that this is a preferable method as compared with the spring method and the drum method.

In the case of the air system, the ball is a cylinder (firing tube)
Since the ball is fired through, the relationship between the ball diameter and the inner diameter of the cylinder has a great influence on the speed and directionality. That is, if the difference between the inner diameter of the cylinder and the outer diameter of the ball (ball diameter) is too small, the ball cannot move inside the cylinder and cannot be fired, whereas if the difference is too large, the air flow will be biased or uneven, and the speed will increase. And the accuracy of directionality deteriorates.

In particular, in the case of a tennis ball, the surface of the ball is covered with two materials called a melton, which are generally made of a blended fiber of wool and nylon, so that the ball surface is not a true sphere and two meltons are used. During the pasting,
Since there is a gap called a seam, the flow of air in the cylinder is difficult to be constant, and the air flow tends to be uneven or slightly uneven. Therefore, even in the air system, for example, when a cylinder having an inner diameter of 67.54 mm is used and balls having a ball diameter (outer diameter) of 66.82 mm and 66.08 mm are used, the ball diameter differs by 0.74 mm. However, the drop point of the ball differs by 1 m or more, or the ball speed is 3 m
/ S or more, and the position at which the ball hits the gut surface varies.

Recently, ball launchers have been used not only for practice but also for evaluation tests of sports equipment such as tennis rackets and golf clubs.
Therefore, the accuracy of the speed and direction of the shot ball is also important. Therefore, in an air-type ball launcher, there is a demand for improving the correlation between the ball diameter and the cylindrical diameter to improve the accuracy of the speed and directionality of the shot ball.

The present invention has been made in view of the above-mentioned demands, and has as its object to provide a ball launcher having a stable speed and directionality. In particular, an object of the present invention is to increase the accuracy of the speed and direction of a ball in a ball launcher for a tennis ball in which the speed and direction are difficult to stabilize.

[0010]

According to the present invention, there is provided a firing tube comprising a straight cylindrical tube having one end opening serving as a pressure air inlet and the other end opening serving as a ball outlet, A cup having a bottomed cylindrical shape that is movably fitted inside the firing tube, has an opening on the firing port side, and is closed on the side of the pressure air intake, and a ball into which a ball is inserted, and at least one of the firing tubes There is provided a ball launcher comprising: a stopper that stops movement of the cup at the position of the launch port and allows only the ball to fly out of the launch port.

As described above, if a configuration is adopted in which the ball is inserted into the cup and the ball is moved together with the cup without moving only the ball in the launch tube, the speed of the ball depends on the speed of the cup moving in the launch tube. I do. Since the outer diameter of the cup is a perfect circle and moves along the inner peripheral surface of the launch tube having the perfect circle, the flow of air is stable, and thus the speed and directionality of the shot ball are stable.

The difference between the inner diameter of the cylinder in which the cup moves and the outer diameter of the cup is 0.05 mm or more and 0.2 mm or less.
The reason why the length is set to 0.05 mm or more is that if the thickness is less than 0.05 mm, the cup cannot move in the cylinder. 0.
The reason why the diameter is set to 2 mm or less is that if the diameter is larger than 0.2 mm, the air flow in the cylinder is deviated, or the cup inclines and vibrates in the cylinder, causing variations in speed and directionality, resulting in poor accuracy. It is due to becoming.

The inner diameter of the cup is +0.25 of the outer diameter of the ball.
mm + 3.00 mm. + 0.25m
The reason for setting the distance to m or more is that if the distance is smaller than +0.25 mm, the ball will not fly out of the cup.
In addition, the reason why the distance is +3.00 mm or less is that +3.00 mm.
If the diameter is larger than mm, the ball rolls and vibrates in the cup, so that the speed and the directionality vary and the accuracy is deteriorated.

The ball launcher of the present invention is suitably used for launching a rigid tennis ball. That is, as described above, since the tennis ball is covered with melton, the surface is not a true sphere, and since there is a seam on the surface, it can be inserted into the cup and moved in the firing tube. preferable. In addition, it can be used not only for tennis balls but also for launchers such as baseball balls.

The firing tube is connected to a pressure air supply tube via an on-off valve, and an intermediate portion in the length direction of the firing tube is rotatably supported at the shaft. An elevating mechanism is connected between the connecting position to the supply pipe and the firing pipe is inclined to adjust the elevation angle of the firing port. further,
The above-described elevating mechanism including a launch tube, an air tank, and an air shack is mounted on a base, and wheels are attached to the base so that the base can be self-propelled, thereby improving usability.

In addition, a rubber O-ring is fitted to the end face of the stopper where the cup collides with the firing tube so as to be fitted therein, so as to absorb the impact at the time of the cup collision. With this configuration, the durability of the cup can be increased.

[0017]

Embodiments of the present invention will be described below in detail with reference to the embodiments shown in the drawings. 1 to 5 show a rigid tennis ball launcher. The launcher has a pair of front and rear support frames 12 erected on a base 11, and a launch tube 13 is supported between upper surfaces of the support frames 12. 14 support rotatably. Wheels 15 are attached to the four corners of the base 11 so that the base 11 can run on its own. In the firing position, the screws 17 attached to the brackets 16 protruding downward at the four corners of the base 11 are tightened, so that the fixtures 18 connected to the lower ends of the screws 17 are fixed to the roadbed and fixed. I have.

As shown in FIG. 4, the firing tube 13 is a straight circular cylinder having a straight line with both ends open. In this embodiment, the firing tube 13 is made of stainless steel and has a length L1 of 1200 mm and an inner diameter D1 of 80 mm. 03 mm. The opening at the distal end of the firing tube 13 is a ball firing port 13a, and the opening at the base end is a pressure air inlet 13b communicating with a pressure air supply pipe 21 via an electromagnetic on-off valve 19. The electromagnetic on-off valve 19 is provided with a switch 19a provided on the upper surface of the casing.
Is opened and closed.

A cup 20 is movably fitted inside the firing tube 13. One end of the cup 20 is an opening 20a for inserting a ball, and the other end is a closed-end cylindrical shape having a closed bottom wall 20b and made of stainless steel. In the present embodiment, the outer diameter D2 is 79.95 mm, and the inner diameter D3 is 67.96.
mm, the length L2 is 60 mm, and the thickness W of the bottom wall 20a is 10 mm.
mm. A tennis ball B is inserted into the cup 20, the bottom wall 20b is directed inside the firing tube 13 toward the pressure air inlet 13b, and the opening 20a is inserted into the ball firing port 13a.
Facing.

The pressure air inlets 13b at both ends of the firing tube 13
The stoppers 22 and 23 for stopping the movement of the cup 20 are attached to the and the ball discharge port 13a, respectively.
These stoppers 22, 23 are provided with annular plate portions 22a, 23.
The bosses 22b, 23b are inserted into the firing tube 13 and are closely fitted to the inner peripheral surface in a shape in which the bosses 22b, 23b are protruded from the inner periphery of a. Abuts on the end face of Note that these stoppers 22 and 23 may be provided integrally with the firing tube 13.

Rubber O-rings 24 and 25 are attached to the tips of the bosses 22b and 23b to absorb the impact when the cup 20 collides. In the present embodiment, the inner diameter of the stoppers 22 and 23 is 75 mm, and is smaller than the outer diameter of the cup 20 of 79.95 mm. The O-rings 24 and 25 are formed by NBR, and the outer diameter D4 is set to 80 m.
m, and the thickness W2 is 2.7 mm.

At the base end of the firing tube 13, an opening 13c for charging a ball is provided, a lid 26 for opening and closing the opening 13c is hinged, and a lock claw 26a for locking when closing is provided. Lock frame 1 provided on outer surface of pipe 13
3d. Also, a silicone rubber sheet 27 is attached to the periphery of the opening 13c for sealing.

The ball B is inserted into the firing tube 13 through the opening 13c and inserted into the cup 20 through the opening 20a.
As will be described later, the cup 20 is driven by compressed air into the firing tube 13.
It moves to the firing port 13a side and is stopped by the stopper 22. The operation of returning the cup 20 to the base end side from this position is performed by inserting an operating rod (not shown) from the firing port 13a and pushing it back. In addition, the ball is inserted from the firing port 13a side into the cup 20 located on the firing port 13a side without providing the ball insertion opening in the firing tube 13,
The cup 20 loaded with the ball may be moved from the firing port 13a to the proximal end side by an operating rod.

An air tank 30 is connected to a supply pipe 21 for supplying pressurized air to the firing pipe 13, and the air tank 30 is connected to a compressor (not shown) via a pipe. An air gauge 31 is attached to the air tank 30. In addition, the feed pipe 21 has a luplicator (Euler) 3
2 is connected to spray oil, so that the launch tube 1
3 is supplied with pressurized air containing mist oil.

By including oil in the pressurized air, the oil improves the slip between the firing tube 13 and the cup 20, so that a good ball can be fired and the firing tube 1
3 and the cup 20 have improved durability. Further, since the cup 20 exists between the pressurized air inlet and the ball, the ball is not contaminated by the sprayed oil. In the conventional cupless apparatus, there is no viewpoint of improving the slipperiness and durability of the cup, and the oil is not added to the pressurized air because the ball is contaminated by the sprayed oil. Was.

A support plate 33 is connected to a lower portion of the launch tube 13 between a fulcrum position by the support shaft 14 and a base end, and an air jack 35 is attached between the support plate 33 and the base 11. ing. A pressurized air source 36 is connected to the air jack 35, and pressurized air is supplied to the air jack 35 by operating a lever 36 attached to the pressurized air source 36. Further, a lock lever 38 is connected to the support plate 33 so as to be slidable in a groove 37 a of a lock plate 37 erected from the base 11. When adjusting the elevation angle of the firing tube 13, the air jack 35 is moved up and down to
3 is tilted with the support shaft 14 as a fulcrum, and the lock lever 38 is operated at a required position to fix the position of the firing tube 13. When changing the elevation angle, the lock is released by operating the lock lever 38 and the air jack 35 is used to move up and down.

In the ball launcher having the above configuration, FIG.
As shown in (A), after inserting the tennis ball B into the cup 20 at the base position inside the firing tube 13 and then supplying compressed air to the firing tube 13, the cup 20 and the ball B in the cup 20 move. Energy is given, and it moves to the firing opening 13a at high speed. As shown in FIG. 4B, the cup 20 comes into contact with a stopper 22 attached to the firing port 13a and stops, but the ball B jumps out of the firing port 13a due to the applied kinetic energy.

When the cup 20 moves in the firing tube 13,
The inner peripheral surface of the firing tube 13 and the outer peripheral surface of the cup 20 have a perfect circular shape, and the distance between the outer peripheral surface of the cup 20 and the inner peripheral surface of the firing tube 13 is 0.04 mm ((80.03-79. 9
Since the gap of 5) / 2) is provided, the cup 20 is moved to the firing port 13a without generating a tilt in the firing tube 13.

The ball B inserted in the cup 20
Is 0, 1 between the inner peripheral surface of the cup 20 and the outer peripheral surface of the ball.
25 mm to 1.5 mm (0.25 mm / 2 to 3.00 m
Since the gap of (m / 2) is provided, the cup 20 can be held without rolling in the cup 20 and moved to the firing port 13a, and can jump out of the cup 20 when the cup 20 is stopped at the firing port 13a.

[0030]

[Experimental Example] In order to test the performance (speed and directionality) of the ball launcher of the embodiment of the present invention, the ball launcher of the embodiment (hereinafter referred to as the ball launcher of the example) and the comparative example were tested. A tennis ball was fired with a ball launcher. The ball launcher of the comparative example has a length of 1200 mm and an inner diameter of 67 mm.
The 54 mm launch tube was mounted in place of the launch tube of the example. A ball was directly inserted without fitting a cup into the inside of this firing tube, and the ball was fired by moving the ball inside the firing tube with pressurized air. Other configurations are the same as those of the launcher of the embodiment except that the launch tube is replaced.

In the firing test, as shown in FIG. 6, the ball launcher 10 is installed toward the wall 50, and the tip (ball launch port 13a) of the ball launcher 10 is 2.0 mm away from the wall 50.
m apart. The elevation angle θ toward the wall 50 of the launch tube 13 was 5 degrees.

The speed of the ball B was measured by installing a photoelectric sensor 51 immediately before the wall D. As the photoelectric sensor 51, a transmission-type sensor unit with a lens manufactured by OMRON Corporation (model E)
32-T17L) and an amplifier (E3X-F21). The four sensor parts 51A to 51D were arranged with a width of 10 cm in the direction in which the ball B passed and a distance of 1 m in the height direction. The ball speed was obtained from the following equation. Ball speed (m / sec) = 0.1 m / Time for ball to pass between sensors (sec)

The position of the collision of the ball B with the wall D was measured by sticking a pressure-sensitive paper to the vicinity of the collision position of the ball D with the wall D. The pressure-sensitive paper used was a pressure measurement film Fuji Prescale (LLLLW) manufactured by Fuji Photo Film Co., Ltd. The coordinates of the collision position were read from the center of the circular trace of the ball on the pressure-sensitive paper. In the coordinates, the height to the collision position is read with the floor being 0 in the Y direction, the center line is drawn on the wall which is the front center of the launcher 10 in the X direction, the center line is set to 0, and the left The length was read as minus and the right as plus.

The tennis ball B used in the experiment was a tennis ball FOPT made by Dunlop. These balls were used by opening the container case immediately before the test. Ball B
The outer diameter of the dial gauge is as shown in Fig. 7 (1) (2) (3)
Were measured at three points in the orthogonal direction shown in FIG.

Table 1 below shows the measured values of the above three points and the average value of the used balls. As described in Table 1, the maximum value of the diameter of the ball used was No. 7 of 66.
No. 83 mm, minimum ball size. 8, 65.73 mm
And the difference was 1.1 mm.

With the launchers of the examples and comparative examples, 10
Each ball was fired three times each, and the speed and the collision position were measured by the above method. At that time, the speed of the balls fired by the launchers of the example and the comparative example was about 15 m / sec.
c, the supply air pressure to the firing tube of the embodiment is 1.
The supply air pressure to the firing tube of the comparative example was adjusted to 0.88 kgf / cm3.

The outer diameter (diameter), speed, and collision position of the tennis ball measured above are shown in Tables 1 and 2 below.

[0038]

[Table 1]

[0039]

[Table 2]

As shown in Table 1, the range of the maximum value-minimum value of the speed of the ball fired by the ball shooting machine of the embodiment was 1.53 m / sec, and the standard deviation was 0.39. On the other hand, as shown in Table 2, the range of the maximum value-minimum value of the ball speed shot by the ball shooter of the comparative example was 3.12 m / sec, and the standard deviation was 0.77. .

As described above, when the ball launcher of the embodiment was used, the range between the maximum value and the minimum value of the ball speed was small and the standard deviation was small as compared with the comparative example. From this result, it was confirmed that the tennis ball fired by the ball launcher of the example had a stable ball speed and good accuracy.

Regarding the collision position, the width of the collision position in the X direction of the ball fired by the ball launcher of the embodiment is 36.
The width of the collision position in the Y direction was 74.2 mm, the standard deviation was 13.54, and the standard deviation was 13.54. On the other hand, the width of the collision position in the X direction of the ball fired by the ball launcher of the comparative example is 53.1 mm, and the standard deviation is 1
1.79, the width of the collision position in the Y direction was 92.1 mm, and the standard deviation was 19.32.

As described above, when the ball launcher of the embodiment was used, the width and the standard deviation of the ball impact position were smaller in both the X and Y directions than in the comparative example. From these results, it was confirmed that the tennis ball fired by the ball launcher of the present invention has a stable directionality of the ball and has good accuracy.

As described above, the ball launcher of the comparative example
Compared to the ball launcher of the embodiment, the ball speed and direction of the launched ball are not stable and the accuracy is poor for the following reasons.

That is, the inner diameter of the firing tube of the comparative example is 67,54.
+0.71 mm to +1.81 mm
mm, the ball can be moved smoothly to the launch port within the launch tube, but the gap between the inner peripheral surface of the launch tube and the outer peripheral surface of the ball differs depending on the ball because there is a difference in the individual diameter of the ball. However, since the flow of the compressed air varies, the ball speed is not stable. For example, no. Since the ball No. 7 has a large diameter, the speed is lower than that of the other balls. In addition, since the ball is not a true sphere, the gap between the outer peripheral surface of the ball and the inner peripheral surface of the firing tube is not evenly formed in all circumferential directions, so that the direction of the shot ball is not stable, and the collision position varies. Has occurred.

On the other hand, when the ball launcher of the embodiment is used, the speed and directionality of the shot ball can be stabilized, and the accuracy can be improved for the following reasons. That is, since the ball is put in the cup and moved in the firing tube, the difference between the outer diameter of the cup and the inner diameter of the firing tube can always be maintained at a constant value of 0.08 mm even if there is a difference in the ball diameter. Therefore, the ball speed can be stabilized without being affected by the diameter of the ball. Therefore, when the ball launcher of the embodiment is used, The ball with the maximum value of 7 showed almost the same speed as the other balls. In addition, since the difference between the cup outer diameter and the firing tube inner diameter is set to an appropriate value of 0.08 mm, it is possible to prevent the cup from being caught on the firing tube and unable to move when the difference is too small, and the difference is large. It is also possible to prevent the launch tube from tilting and vibrating when it is too long.
Therefore, the ball can be accurately fired. Further, since the inside diameter of the cup into which the ball is placed is 67.96 mm, which is +1.13 mm to +2.23 mm than the diameter of the ball, the ball can be fired without being caught on the cup or rolling in the ball.

[0047]

As is apparent from the above description, according to the ball launcher of the present invention, the cup is movably fitted into the launch tube, the ball is loaded into the cup, and the ball is loaded. The compressed cup is moved to the launch port of the launch tube with pressurized air, and only the cup is stopped by the stopper at the launch port so that the ball jumps out of the launch port. Even if the ball is not a true sphere, if the pressure air is kept constant, the cup moves at a constant speed in the firing tube, and the ball can be fired at a constant speed.

Further, since the cup moves in the firing tube while the ball is held in the cup without rolling, and the ball jumps out of the firing port, the directionality of the ball can be stabilized.

Therefore, in particular, the conventional ball launcher can be suitably used as a launcher for a hard tennis ball in which it is difficult to stabilize the ball speed and directionality.

Further, since the ball is fired by the compressed air, the ball speed can be increased and the speed can be easily adjusted. In addition, the elevation angle of the launcher can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a front view of a ball launcher according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a side view of FIG. 1;

FIGS. 4A and 4B are enlarged sectional views showing a firing tube and a cup.

FIG. 5 is an enlarged sectional view of a cup.

FIG. 6 is a schematic diagram showing a test apparatus.

FIGS. 7A, 7B, and 7C are diagrams showing a method of measuring the diameter of a tennis ball.

FIG. 8 is a drawing showing a conventional example.

[Explanation of symbols]

 Reference Signs List 11 base 13 launch tube 13a launch port 13b pressure air inlet 14 support shaft 20 cup 22, 23 stopper 24 25 O-ring 30 air tank 35 air jack B ball

Claims (6)

[Claims] A firing tube comprising a linear cylindrical tube having an opening at one end serving as a pressure air inlet and a ball opening at the other end; a discharge tube movably fitted inside the firing tube; A cup having a bottomed cylindrical shape that is open and closed on the side of the pressure air intake, into which a ball is inserted, and stopping the movement of the cup at least at the position of the firing port of the firing tube, A ball launcher characterized by having a stopper that allows only the ball to fly out of the vehicle. 2. The ball launcher according to claim 1, wherein a difference between an inner diameter of the launch tube and an outer diameter of the cup is 0.05 mm or more and 0.2 mm or less. 3. The inner diameter of the cup is + (the outer diameter of the ball).
The ball launcher according to claim 1, wherein the ball launcher has a length of 0.25 mm or more and 3.00 mm or less. 4. The ball launcher according to claim 1, which is used for launching a rigid tennis ball. 5. The launching tube is connected to a pressurized air supply tube via an on-off valve, and an intermediate portion in the longitudinal direction of the launching tube is rotatably supported at a pivotal position. An elevation mechanism is connected between the connection position to the air supply pipe and the elevation pipe, and the elevation angle of the discharge port can be adjusted by inclining the discharge pipe.
The ball launcher according to claim 4. 6. The impact of the cup collision is absorbed by fitting a rubber O-ring into the firing tube at an end face position of the stopper where the cup collides with the launch tube. 2. The ball launcher according to claim 1.