Conveyor belt experiment demonstration instrument based on double-wheel emission

Abstract

The invention provides a conveyor belt experiment demonstration instrument based on double-wheel launching, and the instrument comprises a bottom plate, and the bottom plate is sequentially provided with a double-wheel launching mechanism, a conveyor belt operation mechanism, a distance measurement mechanism, an experiment sliding block, and an intelligent controller from right to left. 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 invention relates to an experimental demonstrator, in particular to a conveyor belt experimental demonstrator based on double-wheel emission. Background Art

[0002] In the kinematics course of the first compulsory high school physics course, there is a classic exercise about conveyor belts transporting sliders, which is also a hot exercise for college entrance examination preparation. This type of exercise involves complex physical situations: the conveyor belt is horizontal or inclined, the direction of the slider's initial velocity is the same as or opposite to the running direction of the conveyor belt, and after the slider slides onto the conveyor belt, the movement may be always uniform, always accelerating, always decelerating, first decelerating and then uniform, first accelerating and then uniform, first decelerating forward and then accelerating back, etc. The different combinations of the slider's initial velocity and the running speed of the conveyor belt lead to complex and diverse motion properties of the slider. To solve this type of problem, in-depth analysis is required. In addition to being proficient in the laws of physics, a clear dynamic scenario diagram must be constructed in the mind, and each stage of the slider's movement on the conveyor belt must be described in detail, including how parameters such as initial velocity, conveyor belt speed, friction, and acceleration affect the slider's motion trajectory.

[0003] However, due to lack of life experience, many students may have never seen a conveyor belt, or have only seen the goods and the conveyor belt moving at the same speed. This leads to their incomplete and unclear analysis of such problems. At present, there are no relevant teaching aids on the market that can fully demonstrate this situation. Teachers can only use language descriptions or simulation animations to explain the solution in class, and students cannot understand and master this complex physical phenomenon through hands-on operation and experimental exploration. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a conveyor belt experimental demonstrator based on double-wheel launch. The experimental demonstrator can realize the linear motion of the launched slider by arranging a double-wheel launch mechanism, and can realize the clockwise and counterclockwise reciprocating motion of the conveyor belt by arranging a conveyor belt running mechanism. The instantaneous speed of the slider is accurately measured by arranging a distance measuring mechanism. The experimental demonstrator can truly restore and demonstrate various situations when demonstrating the transmission belt transmission module model, and the running speed-time waveform diagram is intuitively displayed on the display screen. Teachers can conduct demonstration experiments when teaching to improve classroom teaching effects, and students can also conduct hands-on exploration and learning to stimulate students' interest in learning.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The conveyor belt experimental demonstrator based on double-wheel launch comprises a bottom plate, on which a double-wheel launch mechanism, a conveyor belt running mechanism, a distance measuring mechanism, an experimental slider and an intelligent controller are arranged in sequence from right to left; the double-wheel launch mechanism comprises a launch mechanism support frame, in which a launch drive device is arranged, and the launch drive device is connected with a rotating shaft, and the rotating shaft passes through the launch mechanism support frame from bottom to top and then extends upward and is connected with a first launch wheel, a rotating gear is sleeved on the rotating shaft, and the rotating gear is meshed with a transmission gear, and the transmission gear is sleeved on a connecting shaft arranged parallel to the rotating shaft, and the top end of the connecting shaft extends out of the launch mechanism support frame and is connected with the second launch wheel, and the bottom end of the connecting shaft is fixed on the launch mechanism support frame; the conveyor belt running mechanism comprises a conveyor belt running support plate arranged parallel to the bottom plate, both sides of the conveyor belt running support plate are connected to the bottom plate through a plurality of vertical support blocks, and the two end sides of the conveyor belt running support plate are respectively provided with a driving roller and a driven roller A conveyor belt is sleeved between the driving roller and the driven roller, a synchronous wheel is arranged on the roller shaft of the driving roller, and the synchronous wheel is connected to the forward and reverse motor located on the bottom plate through the synchronous belt, a motor controller for controlling the forward and reverse motor is arranged on one side of the conveyor belt running support plate, and a display screen for displaying experimental parameters and running graphics is arranged on the other side of the conveyor belt running support plate, a photoelectric gate installation frame is arranged on the end side of the conveyor belt running support plate close to the double-wheel launching mechanism, and the photoelectric gate installation frame is located on both sides of the conveyor belt running support plate after crossing the conveyor belt running support plate from below, and a photoelectric gate is arranged on the photoelectric gate installation frame; the distance measuring mechanism includes a distance measuring support frame fixed on the bottom plate, and a laser distance measuring sensor is arranged on the distance measuring 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 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 distance measuring sensor.

[0007] As an optimal technical solution, in order for this experimental demonstration instrument to also be able to conduct friction measurement experiments, on the one hand, it improves resource utilization, and on the other hand, it is helpful for students to better understand the conditions for judging static friction and dynamic friction. A friction measuring mechanism is provided on the conveyor belt running support plate, and the friction measuring mechanism includes card-embedded blocks embedded in both sides of the conveyor belt running support plate, and a slide support plate is provided on the two card-embedded blocks, and a screw slide is provided on the slide support plate. A tension sensor is provided on the front side of the screw slide, and the tension sensor is connected to an analog-to-digital AD conversion module located on the screw slide, and the analog-to-digital AD conversion module is electrically connected to the intelligent controller, and the tension sensor is connected to a pull rope, 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 be able to conduct experiments to verify the kinetic energy theorem, on the one hand, it can further improve resource utilization, and on the other hand, it can also facilitate students to understand the relationship between work done by force and kinetic energy changes. 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 base plate so that the conveyor belt can be tilted at different angles, it can meet various working conditions and is also convenient for carrying the base plate. The experimental demonstration instrument also includes a lifting frame support plate. A lifting frame is provided on the lifting frame support plate. The lifting frame is provided with a hook that can be lifted up and down, and the hook can be hung on the pull rings provided on the two end sides of the base 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 launch mechanism support frame and ensure that the experimental demonstrator can clearly demonstrate the relative sliding effect when the initial velocity of the experimental slider is relatively low, a layer of polytetrafluoroethylene film is provided under the stainless steel gasket.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. This experimental demonstrator can realize the linear motion of the launched slider by setting a double-wheel launching mechanism, and can realize the clockwise and counterclockwise reciprocating motion of the conveyor belt by setting a conveyor belt running mechanism. The instantaneous speed of the slider can be accurately measured by setting a distance measuring mechanism. This experimental demonstrator can truly restore and demonstrate various scenarios of the transmission belt transmission module model, and the speed-time waveform of the operation is intuitively displayed on the display screen. Teachers can conduct demonstration experiments to improve classroom teaching effects, and students can also explore and learn by hands-on to stimulate students' interest in learning.

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

[0015] 3. An electronic scale is set on the bottom plate, so that this experimental demonstrator can also be used to verify the kinetic energy theorem 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 the work done by force and the change of kinetic energy.

[0016] 4. A lifting frame and a pull ring are set on the bottom plate to facilitate lifting one end of the bottom plate so that the conveyor belt can be tilted at different angles, which can meet various working conditions and is also convenient for carrying the bottom plate.

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

[0018] 6. The surface of the launch mechanism support frame is provided with a polytetrafluoroethylene film, which effectively reduces the friction coefficient between the experimental slider and the launch mechanism support frame, ensuring that the experimental demonstrator can clearly demonstrate the relative sliding effect when the initial velocity of the experimental slider is small. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 This is the isometric view of the experimental demonstration instrument;

[0022] Figure numbers: 1, bottom plate, 2, double-wheel launching mechanism, 2-1, launching mechanism support frame, 2-2, launching drive 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 measuring sensor, 5, experimental slider, 6, friction measuring mechanism, 6-1, card embedment block, 6-2, slide support plate, 6-3, screw slide, 6-4, tension sensor, 6-5, analog-to-digital AD conversion module, 6-6, pull 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, pull ring. DETAILED DESCRIPTION

[0023] like Figure 1The figure shows a specific embodiment of the present invention, a conveyor belt experimental demonstrator based on double-wheel launch, comprising a rectangular bottom plate 1, on which a double-wheel launch mechanism 2, a conveyor belt running mechanism 3, a distance measuring mechanism 4, an experimental slider 5 and an intelligent controller are arranged in sequence from right to left; the double-wheel launch mechanism 2 comprises a cube-shaped launch mechanism support frame 2-1, and a vertically placed launch drive device 2-2 is arranged in the launch mechanism support frame 2-1. In this embodiment, the launch drive device 2-2 is arranged as a DC motor, and the DC motor is connected to a PWM speed regulator to adjust the speed of the DC motor. , to adjust the initial velocity of the experimental slider 5, so as to accurately launch it to make a linear motion, the launch drive device 2-2 is connected to a rotating shaft, the rotating shaft passes through the launch mechanism support frame 2-1 from bottom to top, then extends upward and is connected to the first launch wheel 2-3, a rotating gear 2-4 is sleeved on the rotating shaft, the rotating gear 2-4 is meshed with the 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 launch mechanism support frame 2-1 and is connected to the second launch wheel 2-6, the bottom end of the connecting shaft is fixed to the launch mechanism support frame 2-1, and the transmission gear 2-5 is sleeved on the connecting shaft arranged parallel to the rotating shaft. On the support frame 2-1, in order to ensure that the slider 5 makes a linear motion, the first launching wheel 2-3 and the second launching wheel 2-6 are symmetrically arranged on the launching mechanism support frame 2-1 in this embodiment, and in order to facilitate the heat dissipation of the motor, the launching mechanism support frame 2-1 is hollowed out in this embodiment; the conveyor belt running mechanism 3 includes a rectangular conveyor belt running support plate 3-1 arranged parallel to the bottom plate 1, and 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. A vertical support block 3-2 is provided, and a driving roller 3-3 and a driven roller 3-4 are respectively provided at both ends of the conveyor belt running support plate 3-1. 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, and 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 provided on the roller shaft of the driving roller 3-3, and the synchronous wheel 3-5 is connected to the forward and reverse motor 3-7 located on the bottom plate 1 through a synchronous belt 3-6. Figure 2As shown, in this embodiment, the forward and reverse motor 3-7 is set as a stepper motor, and the stepper motor can drive the driving roller 3-3 to rotate forward or reverse, and drive the driven roller 3-4 to rotate synchronously, thereby realizing the clockwise or counterclockwise rotation of the conveyor belt 3-12. A motor controller 3-8 for controlling the forward and reverse motor 3-7 is provided on one side of the conveyor belt running support plate 3-1. In this embodiment, acceleration, deceleration, left turn, right turn, start, and stop buttons are arranged on the motor controller 3-8 from left to right. A display screen 3-9 that can display experimental parameters and operation graphics is provided on the other side of the conveyor belt running support plate 3-1. The conveyor belt running support plate 3-1 is close to the conveyor belt running support plate 3-1. A photoelectric gate installation frame 3-10 is provided on the end side of the double-wheel transmitting mechanism 2. The photoelectric gate installation frame 3-10 is located on both sides of the support plate 3-1 after crossing the conveyor belt from below. A photoelectric gate 3-11 is provided on the photoelectric gate installation frame 3-10. The photoelectric gate 3-11 measures the light blocking time and converts the instantaneous speed by dividing the size of the light blocking object by the light blocking time. The distance measuring mechanism 4 includes a distance measuring support frame 4-1 fixed on the base plate 1. A laser distance measuring sensor 4-2 is provided on the distance measuring support frame 4-1. In this embodiment, a BL-400NMW laser distance measuring sensor 4-2 with a repeatability of 1MM and a response time of 1.5MS is selected. The laser distance sensor 4-2 has a distance measurement range of 20 to 60 cm, can measure the displacement of the slider in a full and zero-contact manner, and convert the 20 to 60 cm distance value into a 0 to 5 V voltage value. In this embodiment, the laser distance sensor 4-2 is fixed at a position 60 cm opposite to the launch wheel to ensure that the laser distance sensor 4-2 can completely capture the motion trajectory of the experimental slider 5. Every 0.02 seconds, the laser distance sensor 4-2 will collect distance data, which are then converted into instantaneous speed through an algorithm; the experimental slider 5 is a cylindrical slider, which can be placed between the first launch wheel 2-3 and the second launch wheel 2 -6 and are tangent to it, then the horizontal distance between the first launching wheel 2-3 and the second launching wheel 2-6 is equal to the diameter of the experimental slider 5. In this embodiment, the experimental slider 5 is set to be a cylindrical wooden block of 2.8cm×2.8cm; 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 on the display screen 3-9 through graphics through programming. In order to intuitively judge the displacement of the experimental slider 5, scales are provided on the sides of the bottom plate 1 and the conveyor belt running support plate 2-1 in this embodiment.

[0024] The conveyor belt running support plate 2-1 is provided with a friction measuring mechanism 6, and the friction measuring mechanism 6 includes an embedded block 6-1 embedded in both sides of the conveyor belt running support plate 2-1, and a slide support plate 6-2 is provided on the two embedded blocks 6-1. In order to ensure a firm connection between the slide support plate 6-2 and the two embedded blocks 6-1, the present embodiment arranges that the slide support plate 6-2 and the two embedded blocks 6-1 are made of magnetic materials, and a screw slide 6-3 is provided on the slide support plate 6-2. The screw slide 6-3 is an existing mature structure, which includes a screw guide rail, a screw that can slide on the screw guide rail, and a handwheel arranged at the end of the screw to rotate and move it. A tension sensor 6-4 is provided on the front side of the screw slide 6-3, and the tension sensor 6-4 is connected to the screw slide The analog-to-digital AD conversion module on the platform 6-3 is connected to the analog-to-digital AD conversion module 6-5. In this embodiment, the analog-to-digital AD conversion module 6-5 is set as an HX711 pressure sensor. The analog-to-digital AD conversion module 6-5 is electrically connected to the intelligent controller. Then the analog-to-digital AD 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 displayed in a graphic on the display screen 2-9. The tension sensor 6-4 is connected with a pull rope 6-6, and the pull rope 6-6 is connected to an experimental object 6-7 with a hook, so that this experimental demonstrator can also perform friction measurement experiments. On the one hand, it improves the utilization rate of resources, and on the other hand, it is helpful for students to better understand the conditions for judging 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 arranged 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. The value obtained by the weighing electronic scale 8 can be displayed on the display screen 2-9 through the intelligent controller, so that the experimental demonstrator can also perform kinetic energy verification experiments. 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 work done by force and kinetic energy changes.

[0026] The experimental demonstration instrument also includes a square lifting frame support plate 9, on which a lifting frame 10 is provided. The lifting frame 10 is provided with a hook 11 which can be lifted up and down. In this embodiment, the lifting frame 10 is provided with through holes evenly arranged up and down along its height direction. The hook 11 is fixed on a penetration plate that can penetrate the through hole. The penetration plate can cross through the through holes of different heights up and down to realize the up and down lifting of the hook. The hook 11 can be suspended on a pull ring 12 provided on the two end sides of the bottom plate 1. In this embodiment, the pull ring 12 is fixed to the bottom plate 1 through a hinge-type connecting piece, which is convenient for lifting any end of the bottom plate 1 to make the conveyor belt tilted at different angles, which can meet various situational conditions and is also convenient for carrying the bottom plate 1.

[0027] A stainless steel gasket is provided at the bottom end of the experimental slider 5, which can effectively lower the center of gravity of the experimental slider 5 so that it can slide stably.

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

[0029] When the present invention is used:

[0030] 1. Conveyor belt-slider experiment

[0031] An experimental slider 5 is placed between the two transmitting wheels. The experimental slider 5 is a cylindrical wooden block of 2.8cm*2.8cm. A stainless steel gasket is fixed at the bottom of the experimental slider 5 to lower the center of gravity and improve the sliding stability. A layer of polytetrafluoroethylene film is attached to 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. The friction between the two transmitting wheels and the experimental slider 5 is used to make the experimental slider 5 obtain a linear velocity consistent with the two transmitting wheels and begin to slide onto the conveyor belt 3-12; when the experimental slider 5 passes through the photoelectric gate 3-11, it blocks the laser, so that the pin of the receiving end of the laser beam sensor changes from high frequency to low frequency. The pin is connected to the digital input pin of the single-chip microcomputer. Once the single-chip microcomputer detects that the level of the pin changes from high to low, a specific pulse is output at another pin of the single-chip microcomputer through the program. The pin is connected to the pin of a laser ranging sensor. The laser ranging sensor receives the specific pulse signal from the single-chip microcomputer and starts The laser is emitted every 2ms, and the pulse signal of the real-time distance between the experimental slider 5 and the laser ranging sensor is automatically transmitted back to the single-chip microcomputer. The distance value is obtained through program decoding, and the instantaneous speed of the slider at each moment is obtained through the algorithm. The data is sent to a serial port LCD 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 the experiment. The numerical control prints the data transmitted from the serial port on the screen, and the waveform control displays the speed-time image of the slider in real time on the screen, and also displays the speed waveform of the conveyor belt for comparison. Stop, left, and right buttons are set at the bottom right of the waveform graph on the display.

[0032] (1) The conveyor belt 3-12 remains horizontal

[0033] ① When the conveyor belt 3-12 is stationary, press the stop button on the display screen 3-9, and then use the launch wheel to launch the experimental slider 5 at a certain speed. The speed value of the experimental slider 5 is evenly reduced to zero on the display screen 3-9 in real time, and the speed-time graph is a straight line waveform with a negative slope, which intuitively reflects that the slider is performing uniform deceleration 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, and press the left button on the display screen 3-9. The speed waveform of the conveyor belt 3-12 on the display screen 3-9 is a horizontal straight line with a negative vertical coordinate, indicating that the conveyor belt runs at a constant negative speed;

[0035] Then, the first launching wheel 2-3 and the second launching wheel 2-6 are used to launch the experimental slider 5 at a certain speed. The initial speed of the launched experimental slider 5 is opposite to the running direction of the conveyor belt 3-12. The instantaneous speed 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 opposite direction. When it reaches the same speed as the conveyor belt 3-12, it remains unchanged; the speed-time image is: first, it is a straight line waveform with a negative slope. After the speed reaches zero, the slope of the waveform remains unchanged and increases along the negative direction of the y-axis. Finally, it is consistent with the waveform of the conveyor belt 3-12, and the horizontal waveform remains unchanged, which intuitively reflects that the experimental slider 5 first performs uniform deceleration on the conveyor belt until the speed reaches zero, then accelerates in the reverse direction, and performs 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 in the clockwise direction. Press the right button on the display screen 3-9. The speed waveform of the conveyor belt on the display screen 3-9 is a horizontal straight line with a positive vertical coordinate, indicating that the conveyor belt is running at a constant positive speed.

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

[0038] (a) If the initial velocity of the experimental slider 5 is greater than the running speed of the conveyor belt, the display screen 3-9 will show in real time that the velocity of the experimental slider 5 decreases uniformly to a certain stable value and then remains unchanged. The velocity-time graph is a straight line waveform with a negative slope, and finally coincides with the waveform of the conveyor belt 3-12, keeping the horizontal waveform unchanged, which intuitively reflects that the experimental slider 5 performs uniform deceleration motion on the conveyor belt 3-12 until the speed is the same as that of the conveyor belt 3-12, and then moves at a uniform speed.

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

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

[0041] Hook one of the pull rings 12 onto the hook 11 to lift one end of the conveyor belt 3-12 to make it in an inclined state. The inclination angle can be achieved by lifting the hook 11 up and down on the lifting frame 10, and a slider experiment on the inclined conveyor belt 3-12 can be carried out. Through the above-mentioned launching experiment slider 5 method and speed measurement method, the speed value and waveform change diagram of the slider in various cases are displayed on the display screen 3-9.

[0042] Second friction test

[0043] The conveyor belt 3-12 remains stationary, the pull rope 6-6 is connected to the experimental object 6-7, and the hand wheel is slowly turned during the experiment to slowly move the screw on the screw slide 6-3, so that the pull rope 6-6 is gradually tightened and the tension gradually increases. When the experimental object 6-7 on the conveyor belt 312 does not move, according to the balance of two forces, the friction force given by the conveyor belt 3-12 is equal to the tension and opposite to the tension. The tension sensor 6-4 measures the change of its tension, and transmits the value of the tension to the intelligent controller through the analog-to-digital AD conversion module 6-5. The data is sent to the serial port display screen 3-9 through the program of the analog-to-digital AD conversion module. The display screen 3-9 is preset with an interface for measuring friction experiment. There is a waveform control and a numerical control in the 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 friction force of the slider in real time on the screen. As the tension increases, the waveform first increases slowly. After reaching the maximum static friction, the hand wheel is continued to be rotated to increase the tension. At this time, the experimental object 6-7 slides and is subjected to sliding friction. At this time, start the conveyor belt and let it move relative to the experimental object 6-7, while the experimental object 6-7 is stationary relative to the ground due to the pulling force of the rope 6-6. At this time, the experimental object 6-7 is subjected to sliding friction. According to the balance of two forces, the sliding friction is equal to the pulling force. It can be shown that the sliding friction is slightly smaller than the maximum static friction, the value remains unchanged, and the waveform remains a horizontal line.

[0044] Three experiments to verify the kinetic energy theorem

[0045] 1. Use a weighing electronic scale to measure the mass of the object, transmit it to the intelligent controller, measure the mass of the object through the program and display it on the screen;

[0046] 2. Use the method in the previous experiment to measure the sliding friction of the object and display it on the screen;

[0047] 3. The conveyor belt 3-12 remains stationary, and the object is launched at a certain speed by the launching wheel. When the object just slides onto the front end of the conveyor belt and passes through the photoelectric gate 3-11, the instantaneous speed is measured, and the initial kinetic energy is calculated by the program and displayed on the screen;

[0048] 4. When the object passes the photoelectric gate 3-11, the laser distance sensor 4-2 is controlled by the program to start measuring the distance and speed. When the speed of the object is zero, the distance it has traveled is calculated and displayed on the screen. The work done by the slider to overcome the friction force is calculated by the program = sliding distance * friction force;

[0049] 5. By comparison, it is found that the reduction in the initial kinetic energy of the object and the work done to overcome the friction can be considered to be approximately equal within the allowable error range, thus verifying the kinetic energy theorem.

[0050] Of course, the above is only a detailed description of the preferred specific implementation mode of the present invention in conjunction with the drawings, and is not intended to limit the scope of implementation of the invention. All equivalent changes made according to the principles, constructions and structures of the present invention should be included in the protection scope of the present invention.

Claims

1. A conveyor belt experimental demonstrator based on double-wheel launch, characterized in that: The invention comprises a bottom plate (1), wherein the bottom plate (1) is provided with a double-wheeled launching mechanism (2), a conveyor belt running mechanism (3), a distance measuring mechanism (4), an experimental slider (5) and an intelligent controller in sequence from right to left; the double-wheeled launching mechanism (2) comprises a launching mechanism support frame (2-1), wherein a launching driving device (2-2) is arranged inside the launching mechanism support frame (2-1), wherein the launching driving device (2-2) is connected to a rotating shaft, wherein the rotating shaft penetrates the launching mechanism support frame (2-1) from bottom to top, then extends upward and is connected to a first launching wheel (2-3), wherein a rotating gear (2-4) is sleeved on the rotating shaft, wherein the rotating gear (2-4) is meshed with a transmission gear (2-5), wherein the transmission gear (2-5) is connected to the transmission gear (2-6). 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 the 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) in the upper and lower directions, 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), and a driving roller (3-3) and a driven roller (3-1) are respectively arranged on both ends of the conveyor belt running support plate (3-1), and a conveyor belt is sleeved between the driving roller (3-3) and the driven roller (3-4). (3-12), a synchronous wheel (3-5) is provided on the roller shaft of the driving roller (3-3), and the synchronous wheel (3-5) is connected to the 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 provided on one side of the conveyor belt running support plate (3-1), and a display screen (3-9) for displaying experimental parameters and running graphics is provided on the other side of the conveyor belt running support plate (3-1), and a photoelectric door installation frame (3-10) is provided on the end side of the conveyor belt running support plate (3-1) close to the double-wheel launch mechanism (1), and the photoelectric door installation frame (3-10) crosses the conveyor belt running support from below. The board (3-1) is located on both sides thereof, and the photoelectric door installation frame (3-10) is provided with a photoelectric door (3-11); the distance measuring mechanism (4) comprises a distance measuring support frame (4-1) fixed on the bottom plate (1), and a laser distance measuring sensor (4-2) is provided on the distance measuring 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 them; the intelligent controller is arranged on the bottom plate (1), and the intelligent controller (1) is electrically connected to the motor controller (3-8), the display screen (3-9), the photoelectric door (3-11), and the laser distance measuring sensor (4-2).

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

3. The conveyor belt experimental demonstrator based on double-wheel launch according to claim 2 is 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), and the weighing electronic scale (8) is electrically connected to the intelligent controller.

4. The conveyor belt experimental demonstrator based on double-wheel launch according to any one of claims 1 to 3, characterized in that: The experimental demonstration device also includes a lifting frame support plate (9), on which a lifting frame (10) is arranged, and on which a hook (11) which can be lifted up and down is arranged, can be hung on pull rings (12) arranged at both ends of the bottom plate (1).

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

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

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