Ball serving machine for tennis training

Abstract

The utility model discloses a pitching machine for tennis training, which relates to the technical field of tennis training appliances and comprises a machine body mechanism and a base, a pull rod is fixedly connected onto the base, and a ball frame is mounted on the surface of the pull rod; the ball discharging mechanism is fixedly connected to the surface of the pull rod and comprises a first motor fixedly connected to the pull rod, an output shaft of the first motor is fixedly connected with a rotating disc, the top of the rotating disc is fixedly connected with a ball distributing rotating wheel, and a first motor support is fixedly connected with a baffle; and the ball serving mechanism is installed on the surface of the base and comprises a horizontal rotating piece movably connected to the base, and a vertical rotating piece is installed on the horizontal rotating piece. According to the tennis ball serving machine, through the cooperation of the ball feeding mechanism and the ball serving mechanism, when the tennis ball serving machine is used, internal tennis balls cannot be clamped due to friction, the balls can be normally served, the ball serving modes are diversified, and multi-dimensional training of trainees is facilitated.

Description

Technical Field

[0001] This utility model relates to the technical field of tennis training equipment, and in particular to a tennis training ball-serving machine. Background Technology

[0002] Tennis is a graceful and intense sport, known as the world's second most popular ball sport. Tennis is usually played between two singles players or two pairs. Players hit the ball with tennis rackets across a net on a tennis court. With the development of tennis in China, more and more people are starting to play the sport. Tennis skills require a lot of practice, and the ball machine used for tennis training is an important piece of equipment.

[0003] However, in practical applications, there are still some unresolved problems. The following are some common problems with tennis ball machines used for training: When using a tennis ball machine, multiple tennis balls accumulate inside the machine. Most of the time, the balls fall into the launcher on their own. Because the tennis balls may generate a lot of friction with each other, this may cause the tennis balls to get stuck, affecting the normal serve. In addition, the serve method is relatively simple, which is not conducive to the multi-dimensional training of students. Utility Model Content

[0004] In view of the problems existing in the current tennis training ball-serving machines, this utility model is proposed.

[0005] Therefore, the problem to be solved by this utility model is how to solve the problem that when multiple tennis balls accumulate inside the tennis ball machine during use, they mostly fall into the launcher by themselves. However, due to the large friction between the tennis balls, the balls may get stuck, affecting the normal launch of the ball. Furthermore, the launch method is relatively simple, which is not conducive to the multi-dimensional training of students.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a tennis training ball-serving machine, comprising,

[0007] The body structure includes a base, on which a pull rod is fixedly connected, and a ball frame is mounted on the surface of the pull rod.

[0008] A ball-distributing mechanism, fixedly connected to the surface of a pull rod, includes a first motor fixedly connected to the pull rod, a turntable fixedly connected to the output shaft of the first motor, a ball-distributing wheel fixedly connected to the top of the turntable, and a baffle fixedly connected to the support of the first motor; and...

[0009] The ball-serving mechanism, mounted on the base surface, includes a horizontal rotating component movably connected to the base, a vertical rotating component mounted on the horizontal rotating component, a fixed plate rotatably connected to the vertical rotating component, a second motor and a third motor fixedly connected to the fixed plate, an upper ball wheel fixedly connected to the output shaft of the second motor, a lower ball wheel fixedly connected to the output shaft of the third motor, and a guide frame fixedly connected to one side of the fixed plate.

[0010] As a preferred embodiment of the tennis training ball-serving machine of this utility model, the horizontal rotating component includes a first shoulder screw fixedly connected to the base, a rotating base and a thrust ball bearing are sleeved on the first shoulder screw, a fixing nut is threaded to the upper end of the first shoulder screw, and the thrust ball bearing is located between the base and the rotating base and between the fixing nut and the rotating base.

[0011] In a preferred embodiment of the tennis training ball-serving machine of this utility model, a fourth motor is fixedly connected to the top of the rotating base, the output shaft of the fourth motor passes through the rotating base and is fixedly connected to a first connecting rod, one end of the first connecting rod is rotatably connected to an external threaded bearing, and a guide hole that mates with the external threaded bearing is opened at the bottom of the base, and the external threaded bearing is slidably connected therein.

[0012] In a preferred embodiment of the tennis training ball-serving machine of this utility model, a limit switch is fixedly connected to the bottom of the rotating chassis, a first power converter is installed on the fourth motor, and a support wheel is fixedly connected to the top of the base, and the support wheel is in contact with the bottom of the rotating chassis.

[0013] In a preferred embodiment of the tennis training ball-serving machine of this utility model, the vertical rotating component includes a fifth motor fixedly connected to the top of the rotating base, the fixed plate is rotatably connected to the fifth motor support, the output shaft of the fifth motor is fixedly connected to a second connecting rod, one end of the second connecting rod is rotatably connected to a third connecting rod, and one end of the third connecting rod is rotatably connected to the fixed plate.

[0014] In a preferred embodiment of the tennis training ball-serving machine of this utility model, the third connecting rod is provided with pins at both ends, one pin passing through the third connecting rod and the second connecting rod, and the other pin passing through the third connecting rod and the fixing plate. Both ends of the pins are fitted with retaining rings. The second connecting rod, the third connecting rod, and the fixing plate are all provided with needle roller bearings, which are fitted on the outer surface of the pins.

[0015] In a preferred embodiment of the tennis training ball-serving machine of this utility model, a second power converter is installed on the fifth motor, a circular flange bearing seat is fixedly connected to the fifth motor support, a second shoulder screw is fixedly connected to one side of the fixing plate, one end of the second shoulder screw passes through the circular flange bearing seat and is threaded with a nylon anti-loosening nut, an adjustment mounting plate is fixedly connected to the rotating chassis, and a limit switch mounting plate is fixedly connected to the adjustment mounting plate.

[0016] In a preferred embodiment of the tennis training ball-serving machine of this utility model, a mounting component is fixedly connected to the rotating base, a housing is fixedly connected to the mounting component, a three-pin socket is fixedly connected to the housing, and a power switch is installed on the three-pin socket.

[0017] In a preferred embodiment of the tennis training ball-serving machine of this utility model, a foot cup is fixedly connected to the bottom of the base, a connecting shaft is fixedly connected to the pull rod, wheels are rotatably connected to both ends of the connecting shaft, and an anti-static chain is fixedly connected to the bottom of the base.

[0018] In a preferred embodiment of the tennis training ball-serving machine of this utility model, an adjustment pad is fixedly connected to the top of the rotating base, a PCB board is fixedly connected to the rotating base, a photoelectric switch is fixedly connected to the fixed plate, and a friction pad is fixedly connected inside the guide frame.

[0019] The beneficial effects of this utility model are as follows: Through the cooperation of the ball-feeding mechanism and the ball-serving mechanism, the tennis balls inside the tennis ball serving machine will not get stuck due to friction when the machine is in use, allowing the ball to be served normally. Furthermore, the serving methods are more diverse, which is beneficial for multi-dimensional training of students. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A three-dimensional structural diagram of a ball-serving machine used for tennis training.

[0022] Figure 2 A three-dimensional structural diagram of the ball-dropping mechanism of a ball-serving machine used for tennis training.

[0023] Figure 3 Partial three-dimensional structure of a tennis training ball machine Figure 1 .

[0024] Figure 4 A three-dimensional structural diagram of a portion of the vertical rotating component of a tennis training ball machine.

[0025] Figure 5 A three-dimensional structural diagram of a portion of the horizontal rotating component of a tennis training ball machine.

[0026] Figure 6 Partial three-dimensional structure of a tennis training ball machine Figure 2 .

[0027] In the diagram: 100. Body mechanism; 101. Base; 102. Pull rod; 103. Ball frame; 104. Mounting component; 105. Outer shell; 106. Power switch; 107. Three-pin socket; 108. Foot cup; 109. Connecting shaft; 110. Wheel; 111. Anti-static chain; 200. Ball lowering mechanism; 201. Turntable; 202. First motor; 203. Ball splitting wheel; 204. Baffle; 300. Ball serving mechanism; 301. Horizontal rotating component; 302. Vertical rotating component; 303. Fixing plate; 304. Second motor; 305. Upper ball wheel; 306. Third motor; 307. Lower ball wheel; 308. Guide frame; 309. Adjustment pad; 310. PCB board; 311. Photoelectric switch; 312, friction pad; 301a, first shoulder screw; 301b, rotating chassis; 301c, thrust ball bearing; 301d, fourth motor; 301e, first connecting rod; 301f, external thread bearing; 301g, limit switch; 301h, first power converter; 301i, support wheel; 302a, fifth motor; 302b, second connecting rod; 302c, third connecting rod; 302d, pin; 302e, snap ring; 302f, needle roller bearing; 302g, second power converter; 302h, circular flange bearing housing; 302i, second shoulder screw; 302j, nylon anti-loosening nut; 302k, debugging mounting plate; 302L, limit switch mounting plate. Detailed Implementation

[0028] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0031] Example 1

[0032] Reference Figures 1-4 This is the first embodiment of the present invention. This embodiment provides a tennis training ball serving machine. The tennis training ball serving machine includes a body mechanism 100, a ball dropping mechanism 200 and a ball serving mechanism 300. The ball dropping mechanism 200 prevents the tennis balls from getting stuck due to friction between them, and enables the ball to be served normally. The ball serving mechanism 300 enables a variety of serving methods, which is beneficial for multi-dimensional training of students.

[0033] Specifically, the machine body 100 includes a base 101, on which components can be easily installed. A pull rod 102 is fixedly connected to the base 101. The pull rod 102 is telescopic, which facilitates the pulling, moving and carrying of the ball-launching machine. A ball frame 103 is fixedly connected to the pull rod 102 by bolts. The ball frame 103 is installed on the surface of the pull rod 102. The ball frame 103 places and limits the collected balls, which is convenient for the subsequent ball dropping by the ball dropping mechanism 200.

[0034] Specifically, the ball-dropping mechanism 200 is fixedly connected to the surface of the pull rod 102, including a first motor 202 fixedly connected to the pull rod 102. The output shaft of the first motor 202 is fixedly connected to a turntable 201, which is a plastic tennis ball turntable. A ball-separating wheel 203 is fixedly connected to the top of the turntable 201. Through the arrangement of the turntable 201 and the ball-separating wheel 203, when the turntable rotates counterclockwise, the ball-separating wheel 203 separates the overlapping tennis balls one by one into the feed hopper of the turntable 201. A baffle 204 is fixedly connected to the support of the first motor 202. Through the arrangement of the baffle 204, the turntable 201 rotates to the position of the ball-dropping baffle 204, and the baffle 204 blocks the remaining balls from falling into the ball guide groove at the same time.

[0035] Specifically, the serving mechanism 300 is mounted on the surface of the base 101 and includes a horizontal rotating component 301 movably connected to the base 101. The horizontal rotating component 301 can adjust the horizontal orientation of the serve. A vertical rotating component 302 is mounted on the horizontal rotating component 301, which can adjust the vertical orientation of the serve. A fixing plate 303 is rotatably connected to the vertical rotating component 302. The fixing plate 303 provides a position for the installation of the second motor 304 and the third motor 306. The second motor 304 and the third motor 306 are fixedly connected to the fixing plate 303 respectively.

[0036] The output shaft of the second motor 304 is fixedly connected to the upper ball wheel 305, and the output shaft of the third motor 306 is fixedly connected to the lower ball wheel 307. With the upper ball wheel 305 and the lower ball wheel 307 set up, under the drive of the second motor 304 and the third motor 306, the upper ball wheel 305 and the lower ball wheel 307 rotate in opposite directions, giving the tennis ball a forward squeezing force. The tennis ball is launched along the angle of the upper ball wheel 305 and the lower ball wheel 307 at this time and reaches the designated position. A guide frame 308 is fixedly connected to one side of the fixed plate 303. The guide frame 308 catches and guides the tennis ball falling from the turntable 201 and guides it to enter between the rotating upper ball wheel 305 and the lower ball wheel 307 for launch.

[0037] Example 2

[0038] Reference Figures 2-6 This is the second embodiment of the present invention, which is based on the previous embodiment.

[0039] Specifically, the horizontal rotating component 301 includes a first shoulder screw 301a fixedly connected to the base 101. The first shoulder screw 301a limits the rotation of the rotating base 301b, allowing the rotating base 301b to rotate only along it. The rotating base 301b and the thrust ball bearing 301c are fitted on the first shoulder screw 301a. A fixing nut is threaded onto the upper end of the first shoulder screw 301a. The fixing nut fixes the rotating base 301b and the thrust ball bearing 301c to the first shoulder screw 301a, preventing them from moving upwards and detaching.

[0040] The thrust ball bearing 301c is located between the base 101 and the rotating chassis 301b, and between the fixed nut and the rotating chassis 301b. The thrust ball bearing 301c supports the rotating chassis 301b and separates the fixed nut from the rotating chassis 301b, so that the rotating chassis 301b can rotate smoothly when driven, thereby adjusting the horizontal orientation of the upper ball wheel 305 and the lower ball wheel 307.

[0041] A fourth motor 301d is fixedly connected to the top of the rotating chassis 301b. The output shaft of the fourth motor 301d passes through the rotating chassis 301b and is fixedly connected to the first connecting rod 301e. One end of the first connecting rod 301e is rotatably connected to an external thread bearing 301f. The bottom of the base 101 has a guide hole that mates with the external thread bearing 301f, and the external thread bearing 301f is slidably connected inside it.

[0042] With the first connecting rod 301e in place, it rotates under the drive of the fourth motor 301d, which in turn causes the external thread bearing 301f to move within the guide hole on the base 101. At this time, the base 101 is relatively fixed, while the rotating chassis 301b is movable. When the fourth motor 301d is running, the first connecting rod 301e pushes the fourth motor 301d and the rotating chassis 301b to rotate, which in turn drives the vertical rotating component 302 and its fixed plate 303, the second motor 304, the third motor 306, the upper ball wheel 305, and the lower ball wheel 307 to rotate horizontally, thus changing the direction of the horizontal serve.

[0043] A limit switch 301g is fixedly connected to the bottom of the rotating chassis 301b. The limit switch 301g controls the angle travel of the rotating chassis 301b. A first power converter 301h is installed on the fourth motor 301d. The first power converter 301h is set to adjust and switch the forward and reverse rotation of the output shaft of the fourth motor 301d, thereby realizing the forward and reverse control of the rotating chassis 301b and completing the reciprocating adjustment of multiple angles. A support wheel 301i is fixedly connected to the top of the base 101 and contacts the bottom of the rotating chassis 301b. There are several support wheels 301i. The support wheels 301i support the rotating chassis 301b without affecting its normal rotation and reducing the force on the thrust ball bearing 301c.

[0044] The vertical rotating component 302 includes a fifth motor 302a fixedly connected to the top of the rotating chassis 301b. The fixed plate 303 is rotatably connected to the support of the fifth motor 302a. The output shaft of the fifth motor 302a is fixedly connected to a second connecting rod 302b. One end of the second connecting rod 302b is rotatably connected to a third connecting rod 302c. One end of the third connecting rod 302c is rotatably connected to the fixed plate 303. Through the arrangement of the second connecting rod 302b and the third connecting rod 302c, the fixed plate 303 can be adjusted vertically under the drive of the output shaft of the fifth motor 302a, thereby adjusting the vertical orientation of the upper ball wheel 305 and the lower ball wheel 307 to meet the adjustment of different vertical serving angles.

[0045] The third connecting rod 302c has pins 302d passing through both ends. One pin 302d passes through the third connecting rod 302c and the second connecting rod 302b, while the other pin 302d passes through the third connecting rod 302c and the fixing plate 303. Both ends of the pins 302d are fitted with retaining rings 302e. The pins 302d and retaining rings 302e fix the third connecting rod 302c to the second connecting rod 302b and the fixing plate 303 respectively. At the same time, the third connecting rod 302c can rotate relative to the second connecting rod 302b and the fixing plate 303, thereby driving the fixing plate 303 to rotate vertically in the form of a crank.

[0046] Needle roller bearings 302f are provided on the second link 302b, the third link 302c, and the fixed plate 303, and are sleeved on the outer surface of the pin 302d. By providing needle roller bearings 302f, the resistance between the pin 302d and the second link 302b, the third link 302c, and the fixed plate 303 is reduced, making it rotate more smoothly.

[0047] A second power converter 302g is installed on the fifth motor 302a. The second power converter 302g enables the forward and reverse rotation adjustment of the output shaft of the fifth motor 302a, thereby controlling the forward and reverse rotation of the vertical rotation of the fixed plate 303. A circular flange bearing seat 302h is fixedly connected to the support of the fifth motor 302a. A second shoulder screw 302i is fixedly connected to one side of the fixed plate 303. One end of the second shoulder screw 302i passes through the circular flange bearing seat 302h and is threaded with a nylon anti-loosening nut 302j. Through the arrangement of the circular flange bearing seat 302h, the second shoulder screw 302i and the nylon anti-loosening nut 302j, the fixed plate 303 and the support of the fifth motor 302a can be connected, so that the fixed plate 303 can rotate vertically relative to the support of the fifth motor 302a.

[0048] An adjustment mounting plate 302k is fixedly connected to the rotating chassis 301b. The adjustment mounting plate 302k is fixedly connected to the rotating chassis 301b by screws. A limit switch mounting plate 302L is fixedly connected to the adjustment mounting plate 302k. The limit switch mounting plate 302L is fixedly connected to the adjustment mounting plate 302k by screws. With the setting of the adjustment mounting plate 302k and the limit switch mounting plate 302L, the stroke control component used to adjust the rotation angle of the fixed plate 303 and the lower ball wheel 307 on it can be installed.

[0049] A mounting bracket 104 is fixedly connected to the rotating chassis 301b. The housing 105 is fixedly connected to the rotating chassis 301b via the mounting bracket 104. The housing 105 is fixedly connected to the mounting bracket 104 and protects the internal components. A three-pin socket 107 is fixedly connected to the housing 105. A power switch 106 is installed on the three-pin socket 107. The three-pin socket 107 and the power switch 106 enable normal power connection and switching of the ball machine.

[0050] The base 101 has multiple feet 108 fixedly connected to its bottom. These feet 108 provide support and leveling for the base 101. This is existing technology and will not be described in detail here. A connecting shaft 109 is fixedly connected to the pull rod 102. The connecting shaft 109 provides a position for the installation of the wheels 110. The wheels 110 are rotatably connected to both ends of the connecting shaft 109. The wheels 110 facilitate the movement of the ball machine. An anti-static chain 111 is fixedly connected to the bottom of the base 101. The anti-static chain 111 can transfer static electricity from the ball machine to the ground, reducing the impact of static electricity on the operation of the ball machine.

[0051] An adjusting pad 309 is fixedly connected to the top of the rotating chassis 301b. The adjusting pad 309 can provide buffer support for the fifth motor 302a. A PCB board 310 is fixedly connected to the rotating chassis 301b. A photoelectric switch 311 is fixedly connected to the fixing plate 303. The photoelectric switch 311 can control the opening, closing and speed adjustment of the fourth motor 301d and the fifth motor 302a. A friction pad 312 is fixedly connected inside the guide frame 308. The friction pad 312 increases the friction between the guide frame 308 and the tennis ball inside, making the serve more stable. The surfaces of the fourth motor 301d and the fifth motor 302a are covered with shielding covers.

[0052] When in use, after the equipment is powered on and running for 2 minutes, the bagged tennis balls are poured in, and the operation of the first motor 202, as well as the opening and closing of the second motor 304 and the third motor 306, are controlled. The rotation of the output shaft of the first motor 202 causes the turntable 201 and the ball-separating wheel 203 to rotate counterclockwise. During the rotation process, the ball-separating wheel 203 separates the overlapping tennis balls one by one into the turntable 201 hopper.

[0053] The turntable 201 rotates to the ball drop gate baffle 204, which blocks the remaining balls from falling into the ball guide groove in the guide frame 308. The tennis ball falls into the ball guide groove by gravity and rolls along the ball guide groove to the space between the upper ball wheel 305 and the lower ball wheel 307, where it is subjected to a forward squeezing force. The tennis ball is then launched along the angle between the upper ball wheel 305 and the lower ball wheel 307 at this time and reaches the designated position.

[0054] The second motor 304 and the third motor 306 are controlled to open or close, thereby enabling various ball release methods, such as topspin or backspin. Each of these requires the operation of a motor. When horizontal and vertical rotation angle adjustments are needed, or when the ball release angle and direction need to be changed, the operation of the fourth motor 301d and the fifth motor 302a is controlled, thereby enabling the upper ball wheel 305 and the lower ball wheel 307 to rotate horizontally and vertically.

[0055] In summary, through the cooperation of the ball-dropping mechanism 200 and the ball-serving mechanism 300, compared with existing technologies, the tennis balls inside the ball-serving machine will not get stuck due to friction when in use, allowing the ball to be served normally. Furthermore, the serving methods are more diverse, which is beneficial for students' multi-dimensional training.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A tennis ball training machine, characterized by: include, The body mechanism (100) includes a base (101), on which a pull rod (102) is fixedly connected, and a ball frame (103) is mounted on the surface of the pull rod (102); A ball-dropping mechanism (200), fixedly connected to the surface of a pull rod (102), includes a first motor (202) fixedly connected to the pull rod (102), a turntable (201) fixedly connected to the output shaft of the first motor (202), a ball-distributing wheel (203) fixedly connected to the top of the turntable (201), and a baffle (204) fixedly connected to the support of the first motor (202); and, The ball-serving mechanism (300) is mounted on the surface of the base (101) and includes a horizontal rotating component (301) movably connected to the base (101). A vertical rotating component (302) is mounted on the horizontal rotating component (301). A fixed plate (303) is rotatably connected to the vertical rotating component (302). A second motor (304) and a third motor (306) are fixedly connected to the fixed plate (303). An upper ball wheel (305) is fixedly connected to the output shaft of the second motor (304). A lower ball wheel (307) is fixedly connected to the output shaft of the third motor (306). A guide frame (308) is fixedly connected to one side of the fixed plate (303).

2. The tennis training ball-serving machine as described in claim 1, characterized in that: The horizontal rotating component (301) includes a first shoulder screw (301a) fixedly connected to the base (101). A rotating base (301b) and a thrust ball bearing (301c) are sleeved on the first shoulder screw (301a). A fixing nut is threaded to the upper end of the first shoulder screw (301a). The thrust ball bearing (301c) is located between the base (101) and the rotating base (301b) and between the fixing nut and the rotating base (301b).

3. The tennis ball serving machine according to claim 2, wherein: A fourth motor (301d) is fixedly connected to the top of the rotating chassis (301b). The output shaft of the fourth motor (301d) passes through the rotating chassis (301b) and is fixedly connected to a first connecting rod (301e). One end of the first connecting rod (301e) is rotatably connected to an external thread bearing (301f). The bottom of the base (101) is provided with a guide hole that cooperates with the external thread bearing (301f), and the external thread bearing (301f) is slidably connected therein.

4. The tennis ball serving machine of claim 3, wherein: A limit switch (301g) is fixedly connected to the bottom of the rotating chassis (301b), a first power converter (301h) is installed on the fourth motor (301d), and a support wheel (301i) is fixedly connected to the top of the base (101), and it is in contact with the bottom of the rotating chassis (301b).

5. The tennis ball serving machine of claim 2, wherein: The vertical rotating component (302) includes a fifth motor (302a) fixedly connected to the top of the rotating chassis (301b). The fixed plate (303) is rotatably connected to the support of the fifth motor (302a). The output shaft of the fifth motor (302a) is fixedly connected to a second connecting rod (302b). One end of the second connecting rod (302b) is rotatably connected to a third connecting rod (302c). One end of the third connecting rod (302c) is rotatably connected to the fixed plate (303).

6. The tennis ball serving machine of claim 5, wherein: The third connecting rod (302c) has pins (302d) passing through both ends. One pin (302d) passes through the third connecting rod (302c) and the second connecting rod (302b), and the other pin (302d) passes through the third connecting rod (302c) and the fixing plate (303). Both ends of the pin (302d) are fitted with snap rings (302e). The second connecting rod (302b), the third connecting rod (302c), and the fixing plate (303) are all equipped with needle roller bearings (302f), which are fitted onto the outer surface of the pin (302d).

7. The tennis ball serving machine according to claim 6, wherein: A second power converter (302g) is installed on the fifth motor (302a). A circular flange bearing seat (302h) is fixedly connected to the support of the fifth motor (302a). A second shoulder screw (302i) is fixedly connected to one side of the fixing plate (303). One end of the second shoulder screw (302i) passes through the circular flange bearing seat (302h) and is threaded with a nylon anti-loosening nut (302j). An adjustment mounting plate (302k) is fixedly connected to the rotating chassis (301b). A limit switch mounting plate (302L) is fixedly connected to the adjustment mounting plate (302k).

8. The tennis ball serving machine of claim 5, wherein: A mounting component (104) is fixedly connected to the rotating chassis (301b), a housing (105) is fixedly connected to the mounting component (104), a three-core socket (107) is fixedly connected to the housing (105), and a power switch (106) is installed on the three-core socket (107).

9. The tennis ball serving machine of claim 8, wherein: A foot cup (108) is fixedly connected to the bottom of the base (101), a connecting shaft (109) is fixedly connected to the pull rod (102), wheels (110) are rotatably connected to both ends of the connecting shaft (109), and an antistatic chain (111) is fixedly connected to the bottom of the base (101).

10. The tennis serving machine as claimed in claim 2, wherein: An adjustment pad (309) is fixedly connected to the top of the rotating chassis (301b), a PCB board (310) is fixedly connected to the rotating chassis (301b), a photoelectric switch (311) is fixedly connected to the fixing plate (303), and a friction pad (312) is fixedly connected inside the guide frame (308).

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