Conveyor belt experiment demonstration instrument based on double-wheel emission

Abstract

The utility model provides a conveyor belt experiment demonstration instrument based on double-wheel emission, which comprises a bottom plate, and the bottom plate is provided with a double-wheel emission mechanism, a conveyor belt operation mechanism, a distance measurement mechanism, an experiment sliding block and an intelligent controller from right to left in sequence. According to the experiment demonstration instrument, the double-wheel launching mechanism is arranged to realize linear motion of the launched sliding block, the conveying belt running mechanism is arranged to realize clockwise and anticlockwise reciprocating motion of the conveying belt, and the distance measuring mechanism is arranged to accurately measure the instantaneous speed of the sliding block. The experiment demonstration instrument can truly restore and demonstrate various scenes when the transmission belt transmits the sliding block model, the running speed-time oscillogram can be linearly displayed on the display screen, a teacher can carry out demonstration experiments during teaching, the classroom teaching effect is improved, students can also explore and learn manually, and the learning interest of the students is stimulated.

Description

Technical Field

[0001] The utility model relates to an experimental demonstrator, in particular to a conveyor belt experimental demonstrator based on double-wheel launching. Background Art

[0002] In the kinematics course of compulsory physics 1 in senior high school, there is a class of classic exercises about conveyor belts transporting sliders, which are also hot exercises for college entrance examination preparation. This type of exercise involves complex physical scenarios: the conveyor belt is horizontal or inclined, the initial velocity direction of the slider is the same as or opposite to the running direction of the conveyor belt. After the slider slides onto the conveyor belt, the motion situation may be uniform motion all the time, accelerating all the time, decelerating all the time, decelerating first and then uniform motion, accelerating first and then uniform motion, decelerating forward first and then accelerating back, etc. A variety of motion states. Different combinations of the initial velocity of the slider and the running velocity of the conveyor belt result in complex and diverse motion properties of the slider. To solve such problems, in-depth analysis is required. In addition to being proficient in physical laws, a clear dynamic scenario graph needs to be constructed in the mind, and every motion stage of the slider on the conveyor belt needs to be described in detail, including how parameters such as the initial velocity, the velocity of the conveyor belt, friction, and acceleration affect the motion trajectory of the slider.

[0003] However, many students may have never seen a conveyor belt or have only seen the situation where the goods move at the same speed as the conveyor belt due to lack of life experience. This leads to incomplete and unclear analysis when they analyze such problems. At present, there is no relevant teaching aid on the market that can completely demonstrate this scenario. Teachers often can only describe it in words or use simulation animations in class, and students cannot understand and master this complex physical phenomenon through hands-on operation and experimental exploration. Content of the Utility Model

[0004] Aiming at the deficiencies of the existing technology, the utility model provides a conveyor belt experimental demonstrator based on double-wheel launching. By setting a double-wheel launching mechanism, the slider launched can perform linear motion. By setting a conveyor belt running mechanism, the conveyor belt can move back and forth clockwise and counterclockwise. By setting a ranging mechanism to accurately measure the instantaneous velocity of the slider, this experimental demonstrator can truly restore and demonstrate various scenarios when demonstrating the conveyor belt transmission module model, and the velocity-time waveform diagram of the operation is intuitively displayed on the display screen. Teachers can conduct demonstration experiments in teaching, improving the classroom teaching effect. Students can also conduct hands-on exploration and learning, stimulating students' learning interest.

[0005] To achieve the above purpose, the technical solution adopted by the utility model is:

[0006] Belt Experiment Demonstrator Based on Double-Wheel Launching, comprising a bottom plate, on which from right to left are successively arranged a double-wheel launching mechanism, a belt running mechanism, a ranging mechanism, an experimental slider and an intelligent controller; the double-wheel launching mechanism includes a launching mechanism support frame, inside which is provided a launching driving device, the launching driving device is connected to a rotating shaft, the rotating shaft penetrates the launching mechanism support frame from bottom to top and extends upwards to be connected to a first launching wheel, a rotating gear is sleeved on the rotating shaft, the rotating gear meshes with a transmission gear, the transmission gear is sleeved on a connecting shaft arranged parallel to the rotating shaft, the top end of the connecting shaft extends out of the launching mechanism support frame and is connected to a second launching wheel, and the bottom end of the connecting shaft is fixed on the launching mechanism support frame; the belt running mechanism includes a belt running support plate arranged parallel to the bottom plate up and down, both sides of the belt running support plate are connected to the bottom plate through a plurality of vertical support blocks, driving rollers and driven rollers are respectively arranged at both ends of the belt running support plate, a belt is sleeved between the driving roller and the driven roller, a synchronous wheel is arranged on the roller shaft of the driving roller, the synchronous wheel is connected to a forward and reverse motor located on the bottom plate through a synchronous belt, a motor controller for controlling the forward and reverse motor is arranged on one side of the belt running support plate, a display screen for displaying experimental parameters and running graphics is arranged on the other side of the belt running support plate, a photoelectric gate installation frame is arranged on the end side of the belt running support plate close to the double-wheel launching mechanism, the photoelectric gate installation frame straddles the belt running support plate from below and is located on both sides thereof, and a photoelectric gate is arranged on the photoelectric gate installation frame; the ranging mechanism includes a ranging support frame fixed on the bottom plate, and a laser ranging sensor is arranged on the ranging support frame; the experimental slider is a cylindrical slider, and the experimental slider can be placed between the first launching wheel and the second launching wheel and is tangent to both of them; the intelligent controller is arranged on the bottom plate, and the intelligent controller is electrically connected to the motor controller, the display screen, the photoelectric gate and the laser ranging sensor.

[0007] As a preferred technical solution, in order for this experiment demonstrator to also conduct a friction measurement experiment, on the one hand, to improve the utilization rate of resources, and on the other hand, to help students better understand and judge the conditions of static friction and dynamic friction, a friction measurement mechanism is arranged on the belt running support plate, the friction measurement mechanism includes clamping blocks clamped on both sides of the belt running support plate, a slide table support plate is arranged on the two clamping blocks, a lead screw slide table is arranged on the slide table support plate, a tension sensor is arranged on the front side of the lead screw slide table, the tension sensor is connected to a modulus AD conversion module located on the lead screw slide table, the modulus AD conversion module is electrically connected to the intelligent controller, a pull rope is connected to the tension sensor, and the pull rope is connected to an experimental object with a hook.

[0008] As a preferred technical solution, in order for this experimental demonstrator to also conduct experiments to verify the kinetic energy theorem, on the one hand, it further improves the utilization rate of resources, and on the other hand, it also facilitates students' understanding of the relationship between work done by force and kinetic energy change. An electronic scale support frame is provided on the bottom plate, and a weighing electronic scale is provided on the electronic scale support. The weighing electronic scale is electrically connected to the intelligent controller.

[0009] As a preferred technical solution, in order to facilitate lifting one end of the bottom plate to make the conveyor belt inclined at different angles, various scenario working conditions can be satisfied, and at the same time, it is also convenient to carry the bottom plate. This experimental demonstrator also includes a lifting frame support plate. A lifting frame is provided on the lifting frame support plate, and a hook that can move up and down along it is provided on the lifting frame. The hook can be hung on the pull rings provided on both ends of the bottom plate.

[0010] As a preferred technical solution, in order to lower the center of gravity of the experimental slider so that it can slide stably, a stainless steel gasket is provided at the bottom end of the experimental slider.

[0011] As a preferred technical solution, in order to reduce the friction coefficient between the experimental slider and the launching mechanism support frame and ensure that the relative sliding effect can be significantly demonstrated even when the initial velocity of the experimental slider is small in this experimental demonstrator, a layer of polytetrafluoroethylene film is provided below the stainless steel gasket.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] 1. By setting a double-wheel launching mechanism in this experimental demonstrator, the launched slider can move in a straight line. By setting a conveyor belt running mechanism, the conveyor belt can move back and forth clockwise and counterclockwise. By setting a ranging mechanism to accurately measure the instantaneous velocity of the slider, this experimental demonstrator can truly restore and demonstrate various scenarios when demonstrating the conveyor belt transmission module model, and the velocity-time waveform diagram of the operation is intuitively displayed on the display screen. Teachers can conduct demonstration experiments during teaching to improve the classroom teaching effect, and students can also conduct hands-on exploration and learning to stimulate students' learning interest.

[0014] 2. A friction force measuring mechanism is provided on the conveyor belt running support plate, enabling this experimental demonstrator to also conduct friction force measurement experiments. On the one hand, it improves the utilization rate of resources, and on the other hand, it is beneficial for students to better understand and judge the conditions of static friction and dynamic friction.

[0015] 3. An electronic scale is set on the bottom plate, enabling this experimental demonstrator to also conduct experiments to verify the kinetic energy theorem. On the one hand, it further improves the utilization rate of resources, and on the other hand, it also facilitates students' understanding of the relationship between work done by force and kinetic energy change.

[0016] 4. A lifting frame is set and pull rings are provided on the bottom plate, facilitating lifting one end of the bottom plate to make the conveyor belt inclined at different angles, which can meet various scenario working conditions, and at the same time, it is also convenient to carry the bottom plate.

[0017] 5. A stainless steel gasket is provided at the bottom end of the experimental slider to lower the center of gravity of the experimental slider, enabling it to slide stably and providing the accuracy of the experiment.

[0018] 6. A polytetrafluoroethylene film is provided on the surface of the support frame of the launching mechanism, effectively reducing the friction coefficient between the experimental slider and the support frame of the launching mechanism, ensuring that the experimental demonstrator can clearly demonstrate the relative sliding effect even when the initial velocity of the experimental slider is small. Description of the Drawings

[0019] The present utility model will be further described in detail below in conjunction with the drawings and specific embodiments.

[0020] Figure 1 is a structural schematic diagram of the present utility model;

[0021] Figure 2 is an axonometric view of the experimental demonstrator;

[0022] Reference numerals in the drawings: 1. Bottom plate, 2. Double-wheel launching mechanism, 2-1. Support frame of the launching mechanism, 2-2. Launch driving device, 2-3. First launching wheel, 2-4. Rotating gear, 2-5. Transmission gear, 2-6. Second launching wheel, 3. Conveyor belt running mechanism, 3-1. Conveyor belt running support plate, 3-2. Vertical support block, 3-3. Driving roller, 3-4. Driven roller, 3-5. Synchronous wheel, 3-6. Synchronous belt, 3-7. Forward and reverse motor, 3-8. Motor controller, 3-9. Display screen, 3-10. Photoelectric gate installation frame, 3-11. Photoelectric gate, 3-12. Conveyor belt, 4. Distance measuring mechanism, 4-1. Distance measuring support frame, 4-2. Laser distance sensor, 5. Experimental slider, 6. Friction force measuring mechanism, 6-1. Clamping block, 6-2. Slide table support plate, 6-3. Screw slide table, 6-4. Tensile force sensor, 6-5. Modular AD conversion module, 6-6. Pulling rope, 6-7. Experimental object, 7. Electronic scale support frame, 8. Weighing electronic scale, 9. Lifting frame support plate, 10. Lifting frame, 11. Hook, 12. Pulling ring. Detailed Embodiments

[0023] As Figure 1The following presents a specific embodiment of the present utility model, which is a conveyor belt experimental demonstrator based on dual-wheel launching, including a rectangular bottom plate 1. From right to left on the bottom plate 1, there are successively arranged a dual-wheel launching mechanism 2, a conveyor belt running mechanism 3, a ranging mechanism 4, an experimental slider 5, and an intelligent controller. The dual-wheel launching mechanism 2 includes a cubic launching mechanism support frame 2-1. Inside the launching mechanism support frame 2-1, there is a vertically placed launching driving device 2-2. In this embodiment, the launching driving device 2-2 is set as a DC motor, and the DC motor is connected to a PWM speed regulator, which can adjust the rotation speed of the DC motor to achieve the adjustment of the initial velocity of the experimental slider 5, so as to accurately launch it to move in a straight line. The launching driving device 2-2 is connected to a rotating shaft, and the rotating shaft penetrates through the launching mechanism support frame 2-1 from bottom to top and extends upward to be connected to a first launching wheel 2-3. A rotating gear 2-4 is sleeved on the rotating shaft, and the rotating gear 2-4 meshes with a transmission gear 2-5. The transmission gear 2-5 is sleeved on a connecting shaft arranged parallel to the rotating shaft. The top end of the connecting shaft extends out of the launching mechanism support frame 2-1 and is connected to a second launching wheel 2-6. The bottom end of the connecting shaft is fixed on the launching mechanism support frame 2-1. To ensure that the slider 5 moves in a straight line, in this embodiment, the first launching wheel 2-3 and the second launching wheel 2-6 are symmetrically arranged on the launching mechanism support frame 2-1. And to facilitate the heat dissipation of the motor, in this embodiment, the launching mechanism support frame 2-1 is provided with a hollow structure. The conveyor belt running mechanism 3 includes a rectangular conveyor belt running support plate 3-1 arranged parallel to the bottom plate 1 up and down. Both sides of the conveyor belt running support plate 3-1 are connected to the bottom plate 1 through a plurality of square vertical support blocks 3-2. In this embodiment, two vertical support blocks 3-2 are arranged on both sides of the conveyor belt running support plate 3-1. At both ends of the conveyor belt running support plate 3-1, there are respectively arranged a driving roller 3-3 and a driven roller 3-4. In this embodiment, the driving roller 3-3 is arranged on the right end side, and the driven roller 3-4 is arranged on the left end side. A conveyor belt 3-12 is sleeved between the driving roller 3-3 and the driven roller 3-4, so that the conveyor belt 3-12 can slide along the driving roller 3-3 and the driven roller 3-4. A synchronous wheel 3-5 is arranged on the roller shaft of the driving roller 3-3, and the synchronous wheel 3-5 is connected to a forward and reverse motor 3-7 located on the bottom plate 1 through a synchronous belt 3-6, as Figure 2As shown in the figure, in this embodiment, the forward and reverse motor 3-7 is set as a stepper motor. The stepper motor can drive the driving roller 3-3 to rotate forward or reverse, drive the driven roller 3-4 to rotate synchronously, and thus realize the clockwise or counterclockwise rotation of the conveyor belt 3-12. On one side of the conveyor belt running support plate 3-1, there is a motor controller 3-8 for controlling the forward and reverse motor 3-7. In this embodiment, acceleration, deceleration, left turn, right turn, start, and stop buttons are sequentially arranged on the motor controller 3-8 from left to right. On the other side of the conveyor belt running support plate 3-1, there is a display screen 3-9 that can display experimental parameters and operation graphics. Near the end side of the conveyor belt running support plate 3-1 close to the double-wheel launching mechanism 2, there is a photoelectric gate installation frame 3-10. The photoelectric gate installation frame 3-10 straddles the conveyor belt running support plate 3-1 from below and is located on both sides of it. A photoelectric gate 3-11 is arranged on the photoelectric gate installation frame 3-10. The photoelectric gate 3-11 measures the light blocking time, and the instantaneous speed is calculated by dividing the size of the light blocking object by the light blocking time. The ranging mechanism 4 includes a ranging support frame 4-1 fixed on the bottom plate 1. A laser ranging sensor 4-2 is arranged on the ranging support frame 4-1. In this embodiment, the BL-400NMW laser ranging sensor 4-2 with a repeatability accuracy of 1MM and a response time of 1.5MS is selected. The ranging range of this laser ranging sensor 4-2 is 20 to 60 cm, and it can measure the displacement of the slider throughout the process and without contact. The distance value of 20 to 60 CM is converted into a voltage value of 0 to 5V. In this embodiment, the laser ranging sensor 4-2 is fixed directly opposite the launch wheel at a distance of 60 cm to ensure that the laser ranging sensor 4-2 can completely capture the movement trajectory of the experimental slider 5. Every 0.02S, the laser ranging sensor 4-2 will collect a distance data, and these data are subsequently converted into an instantaneous speed through an algorithm. The experimental slider 5 is a cylindrical slider. The experimental slider 5 can be placed between the first launch wheel 2-3 and the second launch wheel 2-6 and is tangent to both of them. Then the horizontal distance between the first launch wheel 2-3 and the second launch wheel 2-6 is equal to the diameter of the experimental slider 5. In this embodiment, the experimental slider 5 is set as a cylindrical wooden block with a size of 2.8 cm × 2.8 cm. The intelligent controller is arranged on the bottom plate 1, and the intelligent controller is electrically connected to the motor controller 3-8, the display screen 3-9, the photoelectric gate 3-11, and the laser ranging sensor 4-2. In this embodiment, the data obtained from the experiment can be displayed in the form of a graph on the display screen 3-9 through programming. In order to visually judge the displacement of the experimental slider 5, scales are arranged on the sides of the bottom plate 1 and the conveyor belt running support plate 2-1.

[0024] A friction force measuring mechanism 6 is provided on the conveyor belt running support plate 2-1. The friction force measuring mechanism 6 includes clamping blocks 6-1 clamped on both sides of the conveyor belt running support plate 2-1. A sliding table support plate 6-2 is provided on the two clamping blocks 6-1. To ensure the firm connection between the sliding table support plate 6-2 and the two clamping blocks 6-1, in this embodiment, it is set that both the sliding table support plate 6-2 and the two clamping blocks 6-1 are made of magnetic materials. A screw rod sliding table 6-3 is provided on the sliding table support plate 6-2. The screw rod sliding table 6-3 is a mature existing structure, which includes a screw rod guide rail, a lead screw that can slide on the screw rod guide rail, and a hand wheel provided at the end of the screw rod to make it rotate and move. A tension sensor 6-4 is provided on the front side of the screw rod sliding table 6-3. The tension sensor 6-4 is connected to an analog-to-digital conversion module 6-5 located on the screw rod sliding table 6-3. In this embodiment, the analog-to-digital conversion module 6-5 is set as an HX711 pressure sensor. The analog-to-digital conversion module 6-5 is electrically connected to the intelligent controller. Then, the analog-to-digital conversion module 6-5 amplifies the signal received by the tension sensor 6-4 and transmits it to the intelligent controller, so that the experimental values are graphically displayed on the display screen 2-9. A pull rope 6-6 is connected to the tension sensor 6-4. The pull rope 6-6 is connected to an experimental object 6-7 with a hook, enabling this experimental demonstrator to also conduct a friction force experiment. On the one hand, it improves the utilization rate of resources, and on the other hand, it is beneficial for students to better understand and judge the conditions of static friction and dynamic friction.

[0025] An electronic scale support frame 7 is provided on the bottom plate 1. In this embodiment, the electronic scale support frame 7 is set on the left side of the distance measuring mechanism 4. A weighing electronic scale 8 is provided on the electronic scale support 7. The weighing electronic scale 8 is electrically connected to the intelligent controller. Then, the value obtained by the weighing electronic scale 8 can be numerically displayed on the display screen 2-9 through the intelligent controller, enabling this experimental demonstrator to also conduct a kinetic energy verification experiment. On the one hand, it further improves the utilization rate of resources, and on the other hand, it is also convenient for students to understand the relationship between force doing work and kinetic energy change.

[0026] This experimental demonstrator further includes a square-shaped lifting frame support plate 9. A lifting frame 10 is provided on the lifting frame support plate 9. A hook 11 that can move up and down along it is provided on the lifting frame 10. In this embodiment, through holes are evenly provided along the height direction of the lifting frame 10. The hook 11 is fixed on a penetration plate that can penetrate into the through holes. The penetration plate can horizontally penetrate through holes at different heights to realize the up and down movement of the hook. The hook 11 can be hung on the pull rings 12 provided at both ends of the bottom plate 1. In this embodiment, the pull rings 12 are fixed on the bottom plate 1 through hinge-type connectors, facilitating lifting of any end of the bottom plate 1 to make the conveyor belt inclined at different angles, which can meet various working conditions, and at the same time, it is also convenient to carry the bottom plate 1.

[0027] A stainless steel gasket is provided at the bottom of the experimental slider 5, which can effectively reduce the center of gravity of the experimental slider 5 and enable it to slide stably.

[0028] A layer of polytetrafluoroethylene film is provided under the stainless steel gasket. Then, from top to bottom, the bottom of the experimental slider 5 is successively provided with a stainless steel gasket and a polytetrafluoroethylene film layer, which can greatly reduce the friction coefficient between the experimental slider 5 and the support frame 2-1 of the launching mechanism, ensuring that the experimental demonstrator can clearly demonstrate the relative sliding effect even when the initial velocity of the experimental slider 5 is small.

[0029] When the present utility model is in use:

[0030] I. Conveyor belt-slider experiment

[0031] Place an experimental slider 5 between the two launching wheels. The experimental slider 5 is a cylindrical wooden block with dimensions of 2.8 cm * 2.8 cm. Fix a stainless steel gasket at the bottom of the experimental slider 5 to lower the center of gravity and improve the sliding stability. Stick a layer of polytetrafluoroethylene film on the bottom of the experimental slider 5 to reduce the friction coefficient. In this way, even when the initial velocity of the experimental slider 5 is small, the relative sliding effect can be clearly demonstrated. Utilize the frictional force between the two launching wheels and the experimental slider 5 to enable the experimental slider 5 to obtain the same linear velocity as the two launching wheels and start sliding onto the conveyor belt 3-12; when the experimental slider 5 passes through the photoelectric gate 3-11, it blocks the laser, causing the pin at the receiving end of the laser pair sensor to change from a high electrical frequency to a low electrical frequency. This pin is connected to the digital input pin of the single-chip microcomputer. Once the single-chip microcomputer detects that the level of this pin changes from high to low, it outputs a specific pulse through the program on another pin of the single-chip microcomputer. This pin is connected to the pin of a laser ranging sensor. The laser ranging sensor receives the specific pulse signal transmitted by the single-chip microcomputer, starts to emit laser every 2 ms, and automatically transmits back the pulse signal of the real-time distance between the experimental slider 5 and the laser ranging sensor to the single-chip microcomputer. The distance value is obtained through program decoding, the instantaneous velocity of the slider at each moment is obtained through an algorithm, and the data is sent to a serial port liquid crystal display through the serial port of the single-chip microcomputer. The display is pre-configured with a display file. There is a waveform control and a numerical control in the interface of this experiment. The numerical control prints the data transmitted through the serial port on the screen, and the waveform control displays the velocity-time image of the slider on the screen in real time. At the same time, the velocity waveform of the conveyor belt is also displayed for comparison. There are stop, left, and right buttons set at the lower right of the waveform diagram on the display.

[0032] (1) The conveyor belt 3-12 is kept in a horizontal state

[0033] ① When the conveyor belt 3-12 is stationary, press the stop button on the display screen 3-9, and then use the launching wheel to launch the experimental slider 5 at a certain speed. The speed value of the experimental slider 5 is displayed in real time on the display screen 3-9 and uniformly decreases to zero. The velocity-time graph is a straight line waveform with a negative slope, intuitively reflecting that the slider is doing uniformly decelerated motion on the conveyor belt 3-12;

[0034] ② Press the reverse button of the motor controller 3-8 to drive the conveyor belt 3-12 to run counterclockwise. Press the left button on the display screen 3-9. The speed waveform of the conveyor belt 3-12 displayed on the display screen 3-9 is a horizontal straight line with a negative ordinate, indicating that the conveyor belt is running at a constant negative speed;

[0035] Then use the first launching wheel 2-3 and the second launching wheel 2-6 to launch the experimental slider 5 at a certain speed. The initial velocity of the launched experimental slider 5 is opposite to the running direction of the conveyor belt 3-12. The instantaneous velocity value of the experimental slider 5 is displayed in real time on the display screen 3-9. It starts with a certain speed value, first uniformly decreases to zero speed and then uniformly increases in the reverse direction. When it reaches the same speed as the conveyor belt 3-12, it remains unchanged; the velocity-time graph is: first a straight line waveform with a negative slope, until the speed is zero, the waveform slope remains unchanged and grows along the negative y-axis direction, and finally it is consistent with the waveform of the conveyor belt 3-12, maintaining a horizontal waveform, intuitively reflecting that the experimental slider 5 first does uniformly decelerated motion on the conveyor belt until the speed is zero and then accelerates in the reverse direction, and does uniform motion after reaching the same speed as the conveyor belt;

[0036] ③ Press the forward button of the conveyor belt driver module to drive the conveyor belt 3-12 to run clockwise. Press the right button on the display screen 3-9. The speed waveform of the conveyor belt displayed on the display screen 3-9 is a horizontal straight line with a positive ordinate, indicating that the conveyor belt is running at a constant positive speed;

[0037] Then use the first launching wheel 2-3 and the second launching wheel 2-6 to launch the experimental slider 5 at a certain speed. The initial velocity of the experimental slider 5 is the same as the running direction of the conveyor belt 3-12;

[0038] (a) If the initial velocity value of the experimental slider 5 is greater than the running speed value of the conveyor belt, the speed value of the experimental slider 5 is displayed in real time on the display screen 3-9 and uniformly decreases to a certain stable value and then remains unchanged. The velocity-time graph is a straight line waveform with a negative slope and finally is consistent with the waveform of the conveyor belt 3-12, maintaining a horizontal waveform, intuitively reflecting that the experimental slider 5 is doing uniformly decelerated motion on the conveyor belt 3-12 until it has the same speed as the conveyor belt 3-12 and then does uniform motion.

[0039] (b) If the initial velocity value of the experimental slider 5 is less than the running speed value of the conveyor belt 3-12, the velocity value of the experimental slider 5 is displayed in real time on the display screen 3-9 and uniformly increases to a certain stable value and then remains unchanged. The velocity-time image starts as a straight-line waveform with a positive slope and finally the waveform remains horizontal, intuitively reflecting that the slider first undergoes uniform acceleration motion on the conveyor belt 3-12 until it has the same speed as the conveyor belt 3-12, and then undergoes uniform motion.

[0040] (2) Adjust the inclination of the conveyor belt 3-12

[0041] Hook one of the pull rings 12 to the hook 11 and lift one end of the conveyor belt 3-12 to make it in an inclined state. The inclination angle can be achieved by the up and down movement of the hook 11 on the lifting frame 10

[0042] , and the slider experiment on the inclined conveyor belt 3-12 can be carried out. Through the above methods of launching the experimental slider 5 and the speed measurement method, the speed values and waveform change diagrams of the slider in various situations are displayed on the display screen 3-9.

[0043] Second, friction measurement experiment

[0044] The conveyor belt 3-12 remains stationary, and the pulling rope 6-6 is connected to the experimental object 6-7. During the experiment, slowly rotate the handwheel to make the lead screw on the lead screw stage 6-3 move slowly, so that the pulling rope 6-6 is gradually tightened and the pulling force gradually increases. When the experimental object 6-7 on the conveyor belt 312 does not move, according to the two-force balance, the frictional force it receives from the conveyor belt 3-12 is equal in magnitude and opposite in direction to the pulling force. The pulling force sensor 6-4 measures the change in the pulling force, and the numerical value of the pulling force is transmitted to the intelligent controller through the analog-to-digital AD conversion module 6-5. Through the program of the analog-to-digital AD conversion module, the data is sent to the serial display screen 3-9. The display screen 3-9 is pre-set with an interface for the friction measurement experiment. There is a waveform control and a numerical control in this interface. The numerical control prints the data transmitted from the serial port on the screen, and the waveform control displays the change waveform of the frictional force received by the slider in real time on the screen. As the pulling force increases, the waveform first increases slowly. After reaching the maximum static frictional force, continue to rotate the handwheel to make the pulling force continue to increase. At this time, the experimental object 6-7 slides and is subject to sliding friction. At this time, start the conveyor belt to make the conveyor belt move relative to the experimental object 6-7, while the experimental object 6-7 is stationary relative to the ground under the pulling force of the pulling rope 6-6. At this time, the experimental object 6-7 is subject to sliding friction. According to the two-force balance, the sliding friction is equal to the pulling force, and it can be shown that the sliding friction is slightly smaller than the maximum static frictional force and the numerical value remains unchanged, and the waveform remains a horizontal line.

[0045] Third, experiment to verify the kinetic energy theorem

[0046] 1. Measure the mass of the object with a weighing electronic scale, transmit it to the intelligent controller, and measure the mass of the object through a program and display it on the screen;

[0047] 2. Use the method of the previous experiment to measure the sliding friction force on the object and display it on the screen;

[0048] 3. Keep the conveyor belt 3-12 stationary, launch the object at a certain speed with the launching wheel. When the object just slides onto the front end of the conveyor belt and passes through the photoelectric gate 3-11, measure the instantaneous speed, calculate the initial kinetic energy through the program and display it on the screen;

[0049] 4. When the object passes through the photoelectric gate 3-11, control the laser ranging sensor 4-2 to start measuring the distance and speed through the program. When the speed of the object is zero, calculate the distance it has slid and display it on the screen. Calculate the work done by the sliding block against the friction force through the program = sliding distance * friction force;

[0050] The work done by the sliding block against the friction force = sliding distance * friction force;

[0051] 5. By comparison, it is found that the decrease in the initial kinetic energy of the object block is approximately equal to the work done by it against the friction force within the allowable error range, thus verifying the kinetic energy theorem.

[0052] Of course, the above only describes in detail the preferred specific implementation manner of the present invention in combination with the attached drawings, and does not limit the implementation scope of the present invention accordingly. Any equivalent changes made according to the principles, structures and configurations of the present invention shall be covered within the protection scope of the present invention.

Claims

1. The conveyor belt experimental demonstrator based on dual-wheel launching is characterized in that: It includes a bottom plate (1), on which from right to left are successively arranged a double-wheel launching mechanism (2), a conveyor belt running mechanism (3), a ranging mechanism (4), an experimental slider (5) and an intelligent controller; the double-wheel launching mechanism (2) includes a launching mechanism support frame (2-1), inside which there is a launching driving device (2-2), the launching driving device (2-2) is connected to a rotating shaft, the rotating shaft penetrates the launching mechanism support frame (2-1) from bottom to top and extends upwards and is connected to a first launching wheel (2-3), a rotating gear (2-4) is sleeved on the rotating shaft, the rotating gear (2-4) meshes with a transmission gear (2-5), the transmission gear (2-5) is sleeved on a connecting shaft arranged parallel to the rotating shaft, the top end of the connecting shaft extends out of the launching mechanism support frame (2-1) and is connected to a second launching wheel (2-6), and the bottom end of the connecting shaft is fixed on the launching mechanism support frame (2-1); the conveyor belt running mechanism (3) includes a conveyor belt running support plate (3-1) arranged parallel to the bottom plate (1) up and down, both sides of the conveyor belt running support plate (3-1) are connected to the bottom plate (1) through a plurality of vertical support blocks (3-2), a driving roller (3-3) and a driven roller (3-4) are respectively arranged at both ends of the conveyor belt running support plate (3-1), a conveyor belt (3-12) is sleeved between the driving roller (3-3) and the driven roller (3-4), a synchronous pulley (3-5) is arranged on the roller shaft of the driving roller (3-3), the synchronous pulley (3-5) is connected to a forward and reverse motor (3-7) located on the bottom plate (1) through a synchronous belt (3-6), a motor controller (3-8) for controlling the forward and reverse motor (3-7) is arranged on one side of the conveyor belt running support plate (3-1), a display screen (3-9) for displaying experimental parameters and running graphs is arranged on the other side of the conveyor belt running support plate (3-1), a photoelectric door installation frame (3-10) is arranged at the end side of the conveyor belt running support plate (3-1) close to the double-wheel launching mechanism (2), the photoelectric door installation frame (3-10) straddles the conveyor belt running support plate (3-1) from below and is located on both sides of it, and a photoelectric door (3-11) is arranged on the photoelectric door installation frame (3-10); the ranging mechanism (4) includes a ranging support frame (4-1) fixed on the bottom plate (1), and a laser ranging sensor (4-2) is arranged on the ranging support frame (4-1); the experimental slider (5) is a cylindrical slider, and the experimental slider (5) can be placed between the first launching wheel (2-3) and the second launching wheel (2-6) and is tangent to both of them; the intelligent controller is arranged on the bottom plate (1), and the intelligent controller is electrically connected to the motor controller (3-8), the display screen (3-9), the photoelectric door (3-11) and the laser ranging sensor (4-2).

2. The conveyor belt experiment demonstration instrument based on double-wheel launching according to claim 1, characterized in that: A friction force measuring mechanism (6) is provided on the conveyor belt running support plate (3-1). The friction force measuring mechanism includes clamping blocks (6-1) clamped on both sides of the conveyor belt running support plate (3-1). The friction force measuring mechanism includes clamping blocks (6-1) clamped on both sides of the conveyor belt running support plate (3-1). A slide table support plate (6-2) is provided on the two clamping blocks (6-1). A lead screw slide table (6-3) is provided on the slide table support plate (6-2). A tension sensor (6-4) is provided on the front side of the lead screw slide table (6-3). The tension sensor (6-4) is connected to an analog-to-digital (AD) conversion module (6-5) located on the lead screw slide table (6-3). The analog-to-digital (AD) conversion module (6-5) is electrically connected to the intelligent controller. A pull rope (6-6) is connected to the tension sensor (6-4). The pull rope (6-6) is connected to an experimental object (6-7) with a hook.

3. The conveyor belt experiment demonstrator based on double-wheel launching according to claim 2, characterized in that: An electronic scale support frame (7) is provided on the bottom plate (1). A weighing electronic scale (8) is provided on the electronic scale support frame (7). The weighing electronic scale (8) is electrically connected to the intelligent controller.

4. The conveyor belt experimental demonstrator based on double-wheel launching according to any one of claims 1 to 3, characterized in that: This experimental demonstrator further includes a lifting frame support plate (9). A lifting frame (10) is provided on the lifting frame support plate (9). A hook (11) that can move up and down along it is provided on the lifting frame (10). The hook (11) can be hung on the pull rings (12) provided at both ends of the bottom plate (1).

5. The conveyor belt experimental demonstrator based on double-wheel launching according to claim 4, characterized in that: A stainless steel gasket is provided at the bottom end of the experimental slider (5).

6. The conveyor belt experimental demonstrator based on double-wheel launching according to claim 5, characterized in that: A layer of polytetrafluoroethylene film is provided below the stainless steel gasket.

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