Grain friction coefficient measuring device

Abstract

The utility model provides a grain friction coefficient measuring device, which judges the falling of grains through a sensor and controls the inclination angle during static friction measurement through a sensor signal, is high in precision, is used for measuring a plurality of grains falling for multiple times, and is high in measuring efficiency and high in measuring accuracy. And the static and dynamic friction coefficients of the same sampling batch can be continuously measured. Comprising a static friction measuring table used for measuring the static friction coefficient, and a disc collecting bin mechanism used for receiving materials falling from the static friction measuring table at different inclination angles; the single-grain discharging mechanism is used for receiving the materials output by the discharging holes and discharging the materials in a single-grain mode. And the dynamic friction coefficient measuring mechanism is used for receiving the material falling from the single-particle discharging mechanism.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of grain friction coefficient measurement, especially to a kind of grain friction coefficient measuring device. BACKGROUND

[0002] In the cleaning, sowing, harvesting, processing and transportation process of grain seeds, the friction coefficient of the seeds and the contact surface is an important characteristic parameter to be considered.

[0003] In 2019, Li Zhaodong, Zhang Yi, etc. developed a friction coefficient automatic measurement system based on parallel four-bar mechanism [Li Zhaodong, Zhang Yi, Zhang Miaomiao, etc. Friction coefficient automatic measurement system based on parallel four-bar mechanism [J]. Hubei Agricultural Science, 2019, 58(2): 6. DOI: 10.14088 / j.cnki.issn0439-8114.2019.02.027.], based on the principle of measuring the slope, the four-bar mechanism is driven by the stepper motor to control the lifting of the slope, the panel is rotated through the mobile phone Bluetooth serial port software control panel, through the observation of human eyes, when most of the agricultural materials on the slope slide, use the mobile phone to control the motor to pause, the panel is kept at this position, the agricultural materials will slide into the collection box, through the pulse number emitted by the motor, the angle of the slope is converted, and the static friction coefficient value is further obtained. However, this measurement method measures the slope angle when most of the agricultural materials slide, so the angle of the agricultural materials that slide in turn before the measurement angle is determined is not considered, so this measurement is not accurate.

[0004] A Chinese utility model patent application discloses a kind of crop grain static friction coefficient automatic detection test device and method, disclosure number CN 114659976 A, disclosure date 2022.06.24, it is placed on the measured material by the measured crop grain, according to the installation position of the measured crop grain's shape size adjustment to laser sensor, guarantee the initial position of the measured crop grain and the laser sensor are placed in a straight line;When measured crop grain placement position is correct, that is, the laser sensor signal is blocked by the measured crop grain, control box green indicator light lights up, indicating that test preparation work is completed, test can be carried out, operator clicks start test button on touch screen, DC brushless motor starts, drive the test platform keeps low-speed steady rotation, when the test platform rotates to a certain angle, the measured crop grain begins to appear sliding, the laser sensor is turned from off to on state, the laser sensor immediately detects the change of the critical sliding state of the measured crop grain, controller makes logical judgment to the change of laser sensor signal, and sends stop signal to motor driver, when test platform stops rotating, the angle measured by single-turn absolute value encoder is the rotation angle of the test platform, that is, the static friction angle α of the measured crop grain, this measurement method can only measure one crop grain at a time, and when a batch or a certain type of crop grain needs to be measured, measuring only one grain cannot represent the friction angle of most crops, and if hundreds of grains are sampled and averaged, the static friction angle of the batch can be reflected to some extent, but the device measures one grain at a time, which is very inefficient.

[0005] In 2009, Cheng Hongsheng, Li Changyou, etc. conducted experimental research on the friction coefficient of litchi fruit shell [Cheng Hongsheng, Li Changyou, Bao Yanhua, etc. Measurement and experimental research on the friction coefficient of litchi fruit shell [J]. Journal of Yanbian University, 2009, 31(3): 5. DOI:10.3969 / j.issn.1004-7999.2009.03.012], designed an automatic measurement device for agricultural material friction coefficient according to Newton's second law, the static friction coefficient measurement process is to slowly lift the inclined plane by hand until the litchi shell slides off, and the angle of inclination of the inclined plane is recorded from the angle disc on the adjacent rack; The dynamic friction coefficient is detected by the sensor arranged on the inclined plane, and the acceleration of the litchi shell sliding down is calculated, and then the dynamic friction coefficient value of the litchi shell is calculated, and the experiment is carried out through the device. However, the static friction test is manually changed in angle, and the sliding is judged by naked eye, which has low precision.

[0006] From the above background technology, it can be known that the existing dynamic friction and static friction devices are mostly independent research or independent setting devices, and the test precision is low or one by one measurement to improve the test precision leads to low efficiency. Practical new type content

[0007] The utility model discloses a kind of grain friction coefficient measuring devices, it judges grain to descend by sensor and controls the inclination angle of static friction measurement by sensor signal, precision is higher, and it is measured according to multiple grains of multiple times falling, measurement efficiency is high, and the static, kinetic friction coefficient of the same sampling batch can be continuously measured.This measurement method calculates the average angle by weight of different falling angles and quantity of multiple grains of once sampling, more close to comprehensive static friction test of whole.

[0008] The technical scheme of the utility model is:

[0009] A kind of grain friction coefficient measuring device, including rack, further include,

[0010] Static friction measurement platform, the static friction measurement platform is formed by bearing slope, static friction measurement slope fixedly attached on bearing slope and the first photoelectric opposite emission switch of both sides of static friction measurement slope material end placement, the middle part bottom of bearing slope is connected with slope pivot by connecting piece, and slope pivot is rotatably connected on rack, and the first step motor fixed on rack is connected with slope pivot by first coupling;

[0011] Disc collecting bin mechanism, the funnel for receiving the material falling from bearing slope discharge lower end, the rotating disc collecting bin for receiving the material of funnel lower end, the collecting bin base at the bottom of rotating disc collecting bin, the collecting bin pivot rotatably connected on rack and the second step motor are formed, and rotating disc collecting bin is rotatably driven relative to collecting bin base by collecting bin pivot driven second step motor;

[0012] Single particle discharging mechanism, single particle discharging mechanism is used to receive the material output from discharging hole and discharges material with single particle;

[0013] Kinetic friction coefficient measurement mechanism, it is formed by the support plate of inclination arrangement, dynamic friction measurement slope fixedly attached on support plate and multiple groups of second photoelectric opposite emission switch arranged along the length direction of dynamic friction measurement slope, and each group of second photoelectric opposite emission switch is arranged on the support plate on both sides of dynamic friction measurement slope width direction, and the material falling down by single particle discharging mechanism is received by the upper end of dynamic friction measurement slope.

[0014] Preferably, the lower part of the static friction measurement slope of the first photoelectric opposite emission switch is provided with an indicating line.

[0015] Preferably, the funnel is fixed with a baffle for blocking material.

[0016] Preferably, the single-particle dosing mechanism is composed of a single-particle dosing bin, a single-particle dosing sleeve and a single-particle dosing rotor, the single-particle dosing bin is used to receive the material output by the dosing hole, the single-particle dosing rotor is rotationally connected in the single-particle dosing sleeve, a plurality of single-particle grooves are uniformly distributed on the outer circumferential surface of the single-particle dosing rotor, the single-particle dosing sleeve is provided with a passage at the upper end, which is communicated to the single-particle dosing rotor, the passage is used to receive the material of the single-particle dosing bin and deliver it to the single-particle dosing rotor, a scraping blade is fixed in the passage with one end abutting against the outer circumferential surface of the single-particle dosing rotor, and the single-particle dosing sleeve is provided with a dosing hole at the bottom.

[0017] Preferably, the support plate of the dynamic friction coefficient measuring mechanism is rotationally connected to the frame at the lower end, the support plate is connected with a support rod at the upper end, the frame is provided with arc-shaped adjusting holes at both sides of the support plate in the width direction, the support rod is provided with external threads at both ends and passes through the arc-shaped adjusting holes, and the external threads at both ends of the arc-shaped adjusting holes are screwed with locking nuts.

[0018] Preferably, the collecting bin rotating shaft is rotationally connected in the collecting bin bearing seat through the bearing at the lower end, the collecting bin bearing seat is fixed to the frame, and the upper end of the collecting bin rotating shaft is connected and fixed to the second stepping motor on the frame through the second coupling.

[0019] Preferably, the single-particle dosing rotor is connected to the third stepping motor through the dosing device rotating shaft and the third coupling.

[0020] A method for measuring the friction coefficient of grain particles by using the grain friction coefficient measuring device, characterized by comprising the following steps:

[0021] Firstly, the static friction measuring slope is placed in a horizontal state, and a plurality of grains are placed on the first laser transmission sensor side of the static friction measuring slope according to an interval;

[0022] Secondly, the first stepping motor is started, and the first stepping motor rotates with the static friction measuring slope under the control of the single-chip microcomputer. When the first photoelectric transmission switch detects that the material passes, the first stepping motor stops rotating. At this time, the falling material passes through the funnel along the static friction measuring slope and falls into the collecting bin. After the first collecting bin receives the material, the second stepping motor rotates to drive the rotating disc collecting bin to rotate one station, and the collecting bin with the material is moved away, and the next empty collecting bin is moved to the material receiving station. Then, the first stepping motor continues to rotate, and when the first photoelectric transmission switch detects that the material passes, the first stepping motor stops rotating. The falling material enters the collecting bin, and then the second stepping motor rotates to drive the rotating disc collecting bin to rotate one station, and the collecting bin with the material is moved away, and the next empty collecting bin is moved to the material receiving station. Then, the above steps are continued until all the grain materials on the static friction measuring slope are completely dropped.

[0023] Third, the number of material particles in the multiple collecting bins of the carousel collecting bin is calculated, and the calculation is recorded;

[0024] Fourth, the second stepper motor is opened, and the first collecting bin receiving the material is rotated to the position of the discharging hole, at which time the material in the collecting bin falls into the single-grain discharging mechanism from the discharging hole, and the single-grain discharging mechanism sequentially discharges the material particles to the dynamic friction measurement slope of the dynamic friction coefficient measurement mechanism;

[0025] Fifth, the distance between multiple groups of second photoelectric pairs of switches and the inclination angle of the dynamic friction measurement slope are measured in advance, the material particles fall on the dynamic friction measurement slope and are detected by multiple groups of second photoelectric pairs of switches, the time of passing through each group of second photoelectric pairs of switches is recorded, and the process is repeated until the material particles received by the single-grain discharging mechanism are discharged.

[0026] Sixth, the second stepper motor is rotated again, the second collecting bin receiving the material is positioned against the discharging hole for discharging, and then the single-grain discharging mechanism sequentially discharges the material particles to the dynamic friction measurement slope until the material received by the single-grain discharging mechanism is discharged. The above-mentioned actions of the second stepper motor and the single-grain discharging mechanism are repeated until all the materials in the collecting bins are emptied.

[0027] Preferably, for the calculation of the static friction coefficient, the pulses of the first stepper motor given by the single-chip microcomputer when the first stepper motor stops are read, the angle of the static friction measurement slope turned is calculated by the number of pulses to calculate the tan value, then the pulses at each time when the first stepper motor stops are continuously read, the tan value of each time when the first stepper motor stops after the object is detected by the first photoelectric pair of switches is calculated, that is, the static friction coefficient of each time of falling grain particles, the number of each time of falling grain particles and the static friction coefficient are determined, and then the number of each time of falling grain particles is multiplied by the corresponding friction coefficient to obtain a product, the products of multiple times of falling are added and then divided by the total number of all grain particles to obtain the average value of the static friction coefficient of the grain particles this time.

[0028] Preferably, for the calculation of the dynamic friction coefficient, at least two distances in multiple groups of sensors are calculated, the time of passing through the two distances is calculated according to the second photoelectric pair of switches, the acceleration is calculated by the distance and the passing time, and then the corresponding dynamic friction coefficient is calculated by the acceleration and the angle of the slope.

[0029] Preferably, the number of grains in the first step is 100-300.

[0030] The blanking hole is located at a position before the collecting bin material collecting station, the angle of the support plate is inclined to meet the requirement that the material can freely move on the dynamic friction measuring slope, the second photoelectric opposite switch has at least three groups, preferably four groups, the support plate lower end of the dynamic friction measuring mechanism is provided with a collecting hopper for receiving the falling material, the rotary disc collecting bin is exposed at the end away from the static friction measuring table, which is convenient for checking the number of particles in each collecting bin, and the edge guards are arranged on both sides of the static friction measuring slope in the width direction to prevent the wheat and other grain particles from falling outside.

[0031] The present application has the following advantages:

[0032] 1. The friction coefficient measuring device designed in this case combines the advantages of previous measuring mechanisms, innovates the structure on this basis, and realizes the measurement of dynamic and static friction coefficients on the same device through the upper and lower layout, realizes the automatic conversion from the simultaneous measurement of static friction coefficient of multiple particles to the measurement of dynamic friction coefficient of single particle through the rotary disc receiving the falling material and the accurate feeding of the feeder, which simplifies the measurement process, improves the continuity of the measurement system, and improves the measurement speed, the device connects the stepping motor and the slope shaft through the shaft coupling, without the need to calculate the transmission ratio, the slope angle value is calculated by reading the pulse number sent by the single-chip microcomputer to the stepping motor, and then the required static friction coefficient is calculated, and the falling of the detection material is replaced by the opposite type photoelectric switch, thereby improving the measurement accuracy.

[0033] 2. The present application realizes the automatic conversion from the simultaneous measurement of static friction coefficient of multiple particles to the measurement of dynamic friction coefficient of single particle by arranging the disc collecting bin structure and the single particle blanking mechanism between the static friction measurement and the dynamic friction measurement, improves the continuity and efficiency of the measurement, collects the multiple angle falling material particles through the disc collecting bin, calculates the average value of the overall friction coefficient according to the number of each falling and the value of the static friction coefficient, and greatly improves the measurement efficiency of the static friction coefficient, and the average value makes the overall friction of the grain particles more referential. The dynamic friction coefficient and the static friction coefficient of multiple materials in the single collecting bin of the disc collecting bin can be obtained, which provides beneficial data for the research on dynamic and static friction coefficients. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application, the drawings needed in the following embodiment description will be briefly introduced, and obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0035] Figure 1 It is a front view structure of the present application.Figure 2 is a perspective view of the utility model from a view angle one; Figure 3 is a perspective view of the utility model from a view angle two; Figure 4 is a perspective view of the utility model from a view angle three; Figure 5 is a perspective view of the utility model with the rack removed; Figure 6 is a perspective view of the utility model static friction measuring platform; Figure 1 ; Figure 7 is a perspective view of the utility model static friction measuring platform; Figure 2 ; Figure 8 is a perspective view of the utility model disc collecting bin mechanism; Figure 1 ; Figure 9 is a perspective view of the utility model disc collecting bin mechanism; Figure 2 ; Figure 10 is a perspective view of the utility model rotary disc collecting bin and collecting bin base connection; Figure 1 ; Figure 11 is a perspective view of the utility model rotary disc collecting bin and collecting bin base connection; Figure 2 ; Figure 12 is a perspective view of the utility model single particle discharging mechanism; Figure 1 ; Figure 13 is a perspective view of the utility model single particle discharging mechanism; Figure 2 ; Figure 14 is a sectional view of the utility model single particle discharging mechanism; Figure 15 is a perspective view of the utility model single particle discharging mechanism; Figure 16 is a perspective view of the utility model dynamic friction coefficient measuring mechanism; Figure 17 is a force analysis diagram of the measured material on the inclined plane; Figure 18 is a schematic diagram of the sensor along the inclined plane; Figure 19 is a serial port input interface display diagram; Figure 20 is a static friction coefficient measurement flow chart; Figure 21 is a dynamic friction coefficient measurement flow chart; Figure 22 is a control panel button naming diagram.

[0036] In the drawing, wherein: rack 1;

[0037] Static friction measuring platform 2, bearing inclined plane 201, static friction measuring inclined plane 202, first photoelectric opposite switch 203, inclined plane rotating shaft 204, first coupling 205, first stepper motor 206, indicating line 207, connecting piece 208;

[0038] Disc collecting bin mechanism 3, funnel 301, rotary disc collecting bin 302, collecting bin base 303, collecting bin rotating shaft 304, second stepper motor 305, collecting bin 306, discharging hole 307, collecting bin bearing seat 308, second coupling 309, baffle 310;

[0039] Single grain discharging mechanism 4, single grain discharging bin 401, single grain discharging fixed sleeve 402, single grain discharging rotor 403, single grain chute 404, channel 405, scraper 406, discharging hole 407, discharger rotating shaft 408, third coupling 409, third stepping motor 410;

[0040] Dynamic friction coefficient measuring mechanism 5, support plate 501, dynamic friction measuring slope 502, second photoelectric opposite switch 503, support rod 504, arc-shaped adjusting hole 505, locking nut 506, collecting hopper 507. Specific embodiments

[0041] The technical solutions in the embodiments of the present application will be described below with reference to the drawings of the embodiments of the present application. Figures 1-22 The technical solutions in the embodiments of the present application will be described below with reference to the drawings of the embodiments of the present application.

[0042] Static friction coefficient measurement formula derivation:

[0043] The measured material static on the slope will be affected by the gravity G, the support force N perpendicular to the normal direction of the slope, and the friction force F along the slope upward, as shown in the following figure: Figure 17 When the angle α is small, the component of gravity along the slope downward is smaller than the friction force, and the measured material remains static. As the slope angle α increases, when the gravity component is greater than the friction force, the measured material slides down the slope. At the moment of sliding of the measured material, the force condition can be derived as follows: (1.1)

[0045] N = mg cos α (1.2)

[0046] F is the same in value as the component f of gravity along the slope, and is opposite in direction, so F = μN,

[0047] Derivation of static friction coefficient:

[0048] μ s = F / N = mgsin α / mgcos α = tan α (1.3)

[0049] Dynamic friction coefficient measurement formula derivation:

[0050] According to Newton's second law of motion, it can be obtained that the measured material satisfies:

[0051] ma = mgsin α - μ k mgcos α (1.4)

[0052] Simplify as:

[0053] Analysis can be known: in the case of known angle of inclination, only need to obtain acceleration can be obtained measured material dynamic friction coefficient, in order to obtain acceleration, as shown in Figure 18 When the measured material slides along the slope A point above any position, we set the speed through the first sensor arrangement point A as v0, the speed through the second point B as v1, the time of sliding through AB segment distance as t1, the speed through C point as v2, and the time of sliding through CD point as t2, we derive the formula for calculating acceleration according to the kinematic equation:

[0054]

[0055] The three equations in (1.5) are solved simultaneously:

[0056]

[0057] The four sets of second photoelectric opposite switching switches are set along the distance between the slopes, which are 0.15m, 0.22m, 0.15m, and the values are substituted into formula 1.6:

[0058]

[0059] Analysis can obtain acceleration only by measuring the time of two segments of the four sensors, and the acceleration a is substituted into formula 1.4 to obtain:

[0060]

[0061] The formula derived in this way is conducive to direct single-chip microcomputer programming to realize automatic detection of the device.

[0062] All moving parts in the utility model reach a certain position accuracy in the device running process, therefore step motor control is adopted, the step motor has low cost, relies on pulse control to rotate the angle, has no cumulative error, and the rotation accuracy is high. The shaft and the driving motor are directly connected by a shaft coupling, the transmission accuracy of such a connection mode is high, but the torque of the transmission system cannot be increased, the torque of the system is equal to the torque of the motor, the static friction coefficient measuring part is relatively long, if the slope shaft 204 is fixed from the end of the slope, the motor needs to have very large torque, and the bearing slope 201 needs to have very strong rigidity to ensure the reliability of the shaft connection, which undoubtedly increases a lot of cost, therefore the transmission shaft is arranged in the middle, most of the torque required in the rotation process is balanced, and only a small force is needed to drive the slope to complete the rotation.

[0063] The design of the static friction slope lifting mechanism in the utility model:

[0064] According to the past research results, too much human intervention is involved in the process of measuring the static friction coefficient, such as the transmission through the gear or the soft rope pulling during the process of lifting the inclined plane. The gap of the gear will cause the vibration during the transmission process. The angle measurement in the past experiments is read by the scale. The scale is usually 1mm. The error of the human eye through the different angle degrees is about 1°. The grasping of the measured object in the falling moment is also observed by the human eye. The reaction time of the human is about 200-250ms. The error exists in all the key steps of the measurement process. The superposition of various errors will make the measurement result inaccurate. Reducing the human intervention in the measurement process is the key to the relatively accurate measurement result of the static friction coefficient. The accuracy of the measurement can be improved by replacing the human intervention with the machine. The falling observation can be realized by the sensing detection. The response time of the photoelectric counter switch is the shortest 0.5ms, which is 400-500 times higher than the human eye. The angle is read by the angle sensor in the conventional method, but this usually needs the host computer to realize, which undoubtedly increases the complexity of the control system and reduces the convenience of the equipment. If the step motor is used to control the rotation of the inclined plane, the gap or error will be generated in the conventional transmission method, which still cannot solve the problem encountered in the traditional measurement method. Only the direct connection of the shaft of the inclined plane through the shaft coupling can solve the problem. Such driving and transmission method can also solve the angle measurement problem. The number of pulses generated by the step motor during the process of reading and controlling the step motor by the single-chip microcomputer can be directly converted into the angle of the motor rotation. Therefore, the angle measurement is easier to solve.

[0065] But such design is not perfect, it will produce new problems, the inclined plane is composed of the bearing surface and the measurement surface, the design of the material of the measurement surface is expected to be able to directly measure the similar material as the white cast iron on the agricultural equipment, which has a large weight, and realizes the measurement of multiple measured materials. The number of measured materials is determined by the size of the measurement platform in the width direction (all the materials are arranged in a line to ensure that they will not be blocked by other measured materials with larger friction coefficient during the sliding process along the inclined plane). Therefore, the size of such sliding platform cannot be controlled to be very small. The result is that the motor needs a large enough torque, the shaft needs to bear a large torque, and the connecting piece 208 of the shaft and the inclined plane also needs enough strength, which increases the cost and the difficulty of the selection of the hardware of the system. Therefore, the problem can be solved by changing the position of the shaft. The position of the shaft is arranged at the geometric center of the inclined plane, which can balance the huge torque required during the rotation. This is similar to the design of the counterweight in the elevator. The strength requirement of the shaft is also reduced.

[0066] An indicating line 207 can be drawn on the static friction measuring slope 202 under the intersecting laser line of the first photoelectric intersecting switch 203, and the indicating line 207 is used to indicate the position of the laser line, and the placement of the row of wheat particles can be placed close to the indicating line 207.

[0067] The static friction measuring table 2 in the utility model is composed of a bearing slope 201, a static friction measuring slope 202 fixedly attached to the bearing slope 201, and a first photoelectric intersecting switch 203 on both sides of the material placement end of the static friction measuring slope 202.

[0068] The design of the turntable collecting bin 302 mechanism in the utility model is as follows:

[0069] In the previous research, there are few devices that can simultaneously measure multiple particles of the measured material, and only the friction coefficient automatic measurement system based on the parallelogram mechanism has appeared, but the measurement accuracy is difficult to guarantee, and it is mentioned that most of the falling wheat is observed to press the pause key, which is difficult to define, and if so, the wheat in the collecting bin must be in a relatively wide angle range to ensure that most of them fall, and such measurement results do not have reference value, but this research has brought inspiration to my design, and the extreme idea is adopted, assuming that there are as many collecting bins under the slope as the measured objects on the slope, and each bin collects only one measured object, so each collecting bin actually corresponds to an angle value, which can ensure the accuracy of the measurement results, but according to the pre-experiment, most of the wheat will slide at similar angles during the process of measuring the static friction coefficient at a time, that is, most of the friction coefficients of the wheat are similar, and if the change value of the angle is controlled within the effective range of the experimental results, the collecting bin 306 can simultaneously collect multiple measured objects with similar friction coefficients, and then a turntable type collecting bin is designed, which is connected with the stepping motor to facilitate the switching of the collecting bin.

[0070] In order to facilitate the subsequent dynamic friction coefficient measurement, the rotating disc collecting bin 302 is designed to be hollow, that is, the collecting bin 306 is made to be vertically permeable, and the rotating disc collecting bin 302 is rotatably connected with the collecting bin base 303, so that the material with the same static friction coefficient can be dropped into the single-particle discharging mechanism 4 (which will be described below) at a fixed position, thereby improving the continuity of the device measurement process. The rotating disc collecting bin 302 and the collecting bin base 303 are rotatably connected, and the rotating disc collecting bin 302 and the collecting bin base 303 can have a certain gap, but the gap cannot exceed the grain to be measured. Of course, the rotating disc collecting bin 302 and the collecting bin base 303 can also be in contact, and the contact surface is smooth to facilitate rotation.

[0071] The rotating disc collecting bin 302 mechanism has two support side plates fixed on the rack 1, and the funnel 301 is fixedly connected between the two support side plates. The rotating disc collecting bin 302 is arranged below the funnel 301. A plurality of vertically permeable collecting bins 306 are uniformly arranged on the rotating disc collecting bin 302. The collecting bin base 303 is sealed at the bottom of the rotating disc collecting bin 302, and the collecting bin base 303 is fixed on the rack 1. The discharging hole 307 vertically permeable is formed in the collecting bin base 303, and the discharging hole 307 is located at a position before the collecting bin 306. The funnel 301 is used to receive the grain falling from the static friction measuring slope 202. The collecting bin 306 on the rotating disc collecting bin 302 is used to receive the grain discharged from the funnel 301. The rotating direction of the rotating disc collecting bin 302 is away from the discharging hole 307. When the first collecting bin 306 rotates to the position of the discharging hole 307, the material is discharged from the discharging hole 307. The collecting bin shaft is fixed at the center of the rotating disc collecting bin 302. The lower end of the collecting bin shaft penetrates through the collecting bin base 303 and is rotatably connected in the collecting bin bearing seat 308 through a bearing. The collecting bin bearing seat 308 is fixed on the rack 1. The upper end of the collecting bin shaft 304 is connected and fixed to the second step motor 305 on the rack 1 through the second coupling 309.

[0072] The funnel 301 is fixed with a baffle 310 for blocking material. The baffle 310 can be in the shape of a U-shaped opening, and the opening of the U-shaped opening faces the static friction measuring slope 202. The purpose is to block the falling material so that it all falls into the funnel 301.

[0073] In the utility model, the single-particle discharging mechanism 4 is designed as follows:

[0074] According to the dynamic friction coefficient measurement formula, the acceleration of the material needs to be measured, and the process of measuring the acceleration cannot be interfered by other materials, so it is impossible to measure multiple particles at the same time. If the dynamic and static friction coefficients are measured on the same device, a single-particle discharging mechanism 4 needs to be developed to realize the conversion from static friction coefficient measurement to dynamic friction coefficient measurement, so as to complete the automatic measurement of the dynamic friction coefficient.

[0075] The single grain discharging mechanism 4 here and the seed metering device in the seeding machine are roughly the same in function and structure, so the structure design of the seeding machine seed metering device is referred to, and a single grain discharging mechanism for wheat is developed. Due to the huge difference in the properties of the measured grains, the single grain discharging mechanism 4 can only be developed for a specific measured object, and it is difficult to solve the poor universality problem through structural innovation alone. The discharging mechanism for other grains only needs to replace the single grain discharging rotor 403 with different groove (single grain groove 404) structure, and the installation is also very convenient. The single grain discharging sleeve 402 is provided with a hole on one side, and the rotating body can be removed by removing the axial fixation, and the installation is also the same. Special design is made on the shell part, and a scraper 406 is used to prevent two wheat grains from entering a seed groove.

[0076] The mechanism is still controlled by the third stepper motor 410, and the easy-to-program feature of the stepper motor will reduce the control difficulty of the system and make it easy to realize the automation of the whole system. The designed single grain discharging mechanism 4 for wheat has 8 grooves (single grain grooves 404) in the circumferential direction, that is, every 45 degrees of rotation of the motor will have a grain of wheat passing through the lower discharge hole by gravity and falling onto the dynamic friction coefficient measuring device.

[0077] The single-grain discharging mechanism 4 is composed of a single-grain discharging bin 401, a single-grain discharging fixed sleeve 402 and a single-grain discharging rotor 403, the single-grain discharging bin 401 is used to receive the material output by the discharging hole 307, the single-grain discharging rotor 403 is rotationally connected in the single-grain discharging fixed sleeve 402, a plurality of single-grain grooves 404 are uniformly distributed on the outer circumferential surface of the single-grain discharging rotor 403 at intervals, a passage 405 is formed in the upper end of the single-grain discharging fixed sleeve 402 and communicated to the single-grain discharging rotor 403, the passage 405 is used to receive the material of the single-grain discharging bin 401 and deliver it to the single-grain discharging rotor 403, a scraping blade 406 is fixed in the passage 405 and abuts against the outer circumferential surface of the single-grain discharging rotor 403, and a discharging hole 407 is formed in the bottom of the single-grain discharging fixed sleeve 402. The single-grain discharging fixed sleeve 402 has a circular cavity, the single-grain discharging rotor 403 is rotationally fitted in the cavity and slidably fitted with the cavity. The rotation direction of the single-grain discharging rotor 403 is towards the scraping blade 406, so that when there are two or more materials in a single-grain groove 404, the materials pressed on the upper part of the single-grain groove 404 can be hung off by the scraping blade 406, the single-grain groove 404 is designed to not simultaneously accommodate two material particles, if two material particles are placed in the groove, one of the material particles must protrude outward, which highlights the importance of the scraping blade 406, which can scrape off the material particle protruding outward and only keep the material particle completely placed in the single-grain groove 404. The opening of the passage 405 formed in the single-grain discharging fixed sleeve 402 is upward. The single-grain discharging rotor 403 is connected to the third stepping motor 410 through a discharger shaft 408 and a third coupling 409.

[0078] In the utility model, the dynamic friction coefficient measuring mechanism 5 is designed.

[0079] The dynamic friction coefficient measuring device cooperates with the single-grain discharging mechanism 4, the material to be measured dropped by the single-grain discharging mechanism 4 automatically slides along the measuring slope due to gravity, four pairs of sensors arranged along the slope, as shown in the figure, set S0 as 15 cm, set S1 as 22 cm, set S2 as 15 cm, when it is detected that the material passes, the time of passing the two distance S0 and S2 is automatically calculated, and then the acceleration is obtained, the angle of the slope is connected through the hinge joint and can move within a certain range, which is convenient for exploring the experimental angle suitable for different measurement objects in future experiments. Figure 18

[0080] ​The materials involved in the agricultural machine are various, and one of the innovation points of the device is that different experimental plates (static friction measurement slope 202 and dynamic friction measurement slope 502) can be replaced, and the experimental plates can be fixed on the bottom plate (bearing slope 201 or support plate 501) below by screws. It can be the material used for the agricultural machine in the field of grain production, so that the measurement can simulate different surface conditions in actual application, so that the experimental results are closer to the actual situation. The previous test cannot replace the test plate, and the material of the measurement platform is the material of the experimental plate, which increases the influence of accidental error and systematic error on the experimental results. The device is very convenient to replace the test plate, so that the advantages of wide application range of the device can be verified.

[0081] The dynamic friction coefficient measuring mechanism 5 is composed of a support plate 501 arranged obliquely, a dynamic friction measurement slope 502 fixed on the support plate 501, and a plurality of groups of second photoelectric opposite switches 503 arranged along the length direction of the dynamic friction measurement slope 502. Each group of second photoelectric opposite switches 503 is arranged on the support plate 501 on both sides of the width direction of the dynamic friction measurement slope 502, and the upper end of the dynamic friction measurement slope 502 is used to receive the material falling from the single-grain feeding mechanism 4. The second photoelectric opposite switch 503, because each group of photoelectric opposite switches has two photoelectric components, and four groups are arranged in the length direction of the support plate 501, so that the four photoelectric components on the same side of the four groups can be fixed on a photoelectric switch fixing plate, and the photoelectric switch fixing plate is fixed on the support plate 501, which facilitates installation and overall change of the distance between the two photoelectric switch components.

[0082] The lower end of the support plate 501 of the dynamic friction measurement mechanism is rotationally connected to the rack 1, the upper end of the support plate 501 is connected with a support rod 504, arc-shaped adjusting holes 505 are respectively formed in the rack 1 on both sides of the width direction of the support plate 501, external threads are respectively arranged at both ends of the support rod 504 and pass through the arc-shaped adjusting holes 505, and lock nuts 506 are respectively screwed on the external threads at both ends of the arc-shaped adjusting holes 505.

[0083] The lower end of the support plate 501 of the dynamic friction coefficient mechanism is arranged obliquely towards the direction of the static friction measurement mechanism, so that a v-shaped structure is formed between the static friction plate and the dynamic friction plate.

[0084] The whole device is described as follows:

[0085] The whole device adopts an interlaced upper and lower distribution layout, which minimizes the transportation of the measured material during the conversion from static friction coefficient measurement to dynamic friction coefficient measurement. In the rotation process of the rotary table collecting bin 302, the material will automatically enter the single-grain feeding bin 401 and wait for dynamic friction coefficient measurement.

[0086] The whole control steps of the device are as follows:

[0087] (1) Power on initialization, the ramp rotation until the limit switch (limit switch is set on the rack 1, so that the ramp to the horizontal plane when the limit switch is touched to stop), at this time the ramp is in the horizontal position, (hereinafter referred to as the motor number, the following mentioned are the abbreviation, drive static friction coefficient measurement ramp rotation is the first stepper motor 206 (motor 1 in the figure), drive the carousel collection bin 302 rotation is the second stepper motor 305 (motor 2 in the figure), drive single grain feeding mechanism 4 rotation is the third stepper motor 410 (motor 3 in the figure)) the second stepper motor 305 drive the carousel, the sensor detects the mark position is the initial position, the third stepper motor 410 drive the feeder to rotate to the mark position is the initial position (two mark positions are hardware above the protrusions, the protrusions cooperate with the corresponding position sensor to detect the position of the corresponding parts), start monitoring the sensor.

[0088] (2) Press the start button, the system starts, the first stepper motor 206 starts to run slowly and stably, when the photoelectric switch on the ramp detects that the material falls, the first stepper motor 206 stops rotating. The angle of the ramp turned (from the horizontal position to the moment when the photoelectric signal is detected) is calculated by the number of pulses sent to the first stepper motor 206 to calculate the required data tan value, and the measurement result is printed to the screen display.

[0089] (3) Press the second button, the second stepper motor 305 rotates 18 degrees (the result is calculated by the number of carousel collection bins 302 360° / 20=18°), and then the first stepper motor 206 rotates 1 degree (a delay is required here), and the tan value measured after each rotation is displayed in real time on the OLED display screen.

[0090] (4) Press the second button again, repeat the previous process, and the logic is repeated until all the materials are dropped. The static friction coefficient measurement process is shown in Figure 20 .

[0091] (5) Press the third button of the third stepper motor 410 control button, the third stepper motor 410 rotates 45 degrees (the calculation result is obtained from the 8 feeding holes 307 on the single grain feeding mechanism 4), and the third stepper motor 4103 control logic is simple and has no parallel movement with the other two motors.

[0092] (6) Until the material under the single particle discharging mechanism 4 falls, the sensor arranged in sequence along the slope detects the material, the controller automatically calculates the time of the material passing through the distance between two of the four sensors, and calculates the acceleration by the distance, and further calculates the required friction coefficient value by the acceleration and the slope angle (the angle of the slope here is input through the serial port after the system initialization), and finally the dynamic friction coefficient value is displayed on the OLED screen, and the dynamic friction coefficient measurement process is as shown in Figure 21

[0093] The following is a specific experimental process provided by the utility model:

[0094] In order to test the accuracy of the measurement data of the experimental device, the device takes wheat with different water contents as experimental objects, and carries out a plurality of comparative experimental analyses on white cast iron plates and stainless steel plates respectively. Through experiments, the relationship between the static and dynamic friction coefficients of grains, the water content of grains and the single factor of contact materials is studied, and the measured data in similar studies are compared to verify the accuracy and stability of the measurement data of the device.

[0095] 1.1 Experimental preparation

[0096] 1.1.1 Preparation of measurement samples

[0097] In order to obtain wheat with different water contents, we need to moisturize the wheat according to the agricultural industry standard, and the initial water content of the experimental wheat used is 8.66%. We want to prepare six kinds of wheat samples with different water contents of 10%, 11%, 14%, 16%, 18% and 20%, which are divided into two cases according to the standard:

[0098] (1) The target water content of the moisturized wheat increases by ≤4%, which can reach the moisturizing requirement by adding water once, and the moisturizing time is 16-24 hours, so that the water content of each part of the sample is balanced, thereby obtaining consistent experimental results. The 10% and 11% water content wheat to be prepared can be achieved by moisturizing once.

[0099] (2) The target water content of the moisturized wheat increases by >4%, which needs to be achieved by moisturizing twice. According to the initial water content of the wheat, the appropriate amount of water is added to make the first moisturizing to make the water content of the wheat reach 13.5%, and the moisturizing time needs to reach more than 48 hours. The second time, the water content reaches the target value, and the second moisturizing time reaches 18 hours for the experiment. The 14%, 16%, 18% and 20% water content wheat to be prepared needs to be achieved by moisturizing twice.

[0100] ​The amount of water for wheat tempering can be calculated according to the water adjustment table in the standard or according to the formula, and the amount of water in the water adjustment table is the amount of water for 1000g of wheat from the initial moisture to the target moisture. The corresponding water content can be calculated according to the actual weight of the tempered wheat multiplied by the corresponding percentage. The part of the water adjustment table is shown in Figure 5 .1, see the industry standard for details; the water injection amount calculation formula is as follows: x0 is the original moisture, x1 is the target moisture, the unit is percentage; m is the mass of the sample, the unit is gram:

[0101]

[0102] The actual water content of the tempered wheat is measured by using the moisture meter, which can better compare the data measured in similar studies. After tempering, the actual water content of the wheat is 9.97%, 10.95%, 13.92%, 16.04%, 18.07%, and 20.06%, respectively. The difference between the obtained value and the ideal value is less than ±0.1%. Based on this parameter, the experiment will be more accurate.

[0103] 1.1.2 Other matters should be done before the experiment

[0104] Before the experiment, a notebook is also needed to record the data, a notebook computer (the notebook computer is pre-installed with a serial port assistant), a USB to TTL module, a pair of tweezers, and a number of transparent plastic self-sealing bags. Before the experiment, sample the wheat in advance to determine the sample capacity. For wheat with different water contents, sample them respectively. After sampling, immediately pack them in self-sealing bags. At this point, the experiment is ready.

[0105] 1.2 Conduct measurement experiment

[0106] 1.2.1 Detailed description of the experiment

[0107] (1) Install the test experiment board: In the same group of experiments, the experimental board on the static friction coefficient measurement and dynamic friction coefficient measurement mechanism should be of the same material. The experimental board should be tightly attached to the bearing plate after installation. The experimental board (dynamic and static friction test slope) should not be bent. The lower end surface of the experimental board should be attached to the end of the bearing plate. The two limiting screws should be attached to prevent the experimental board from sliding during the experiment, which will affect the experimental results. The side end surface of the experimental board should be parallel to the side end surface of the bearing plate. After replacing the experimental board, the replaced experimental board should be placed horizontally on the lower layer of the device to prevent the measurement board from bending due to its own gravity for a long time.

[0108] (2) Photoelectric switch height adjustment: because different experimental board materials are different, the appropriate thickness is also different, and the photoelectric switch can only detect the object passing when the object blocks the infrared light. In the static friction coefficient measurement part, regardless of the material, the thickness is within 2mm due to the weight limit, and the photoelectric switch height does not need to be adjusted. In the dynamic friction coefficient measurement part, the height of the photoelectric switch fixing seat is adjustable (the freedom of the photoelectric switch in other directions is fixed), and the height of the photoelectric switch should be adjusted after replacing the experimental board of different thickness each time (the height can be adjusted by replacing the photoelectric switch fixing plate at the lower part of the photoelectric switch), so that it can sensitively detect the passing material. The sensitivity of the photoelectric switch can be detected in advance using the measured material, and the height of the photoelectric switch is fixed after the detection result is satisfactory.

[0109] (3) Serial port input: connect the notebook computer and the single-chip microcomputer through the USB to TTL module. After the system is powered on, press the reset button, and the system will automatically drive the three motors to rotate to the initial position. Then the screen will prompt to input the angle information of the current dynamic friction coefficient measurement mechanism. We send the current angle value to the single-chip microcomputer through the serial port assistant. First, select the serial port number, then select the baud rate (the baud rate is 115200), click to open the serial port, select the text mode as the sending mode, input the angle value in the sending area (the angle value must be input in English mode, and the decimal point must be kept to one decimal place), and finally click the send button to input the angle value to the single-chip microcomputer, as shown in Figure 19 .

[0110] (4) Experimental operation: place the wheat in front of the line on the experimental board (this line is the photoelectric switch's detection path, and the measured material will be detected by the photoelectric switch when passing through this line), use tweezers to place all the wheat with the abdominal groove facing downward in the same direction, press the start button K1 on the control panel (the button distribution and naming of the control panel are shown in Figure 22 ), the inclined plane will automatically and smoothly lift, stop at the moment when the wheat passes through the sensor, and then press the button K5. First, the disc collection bin will rotate one grid, and then the inclined plane will lift 1 degree (the angle of the inclined plane lifting at this point is adjustable between 0.5° and 1.5°). This can ensure that the wheat sliding at different angles falls into different collection bins. Record the static friction coefficient when the wheat slides and the number of wheat sliding at the same angle. After all the wheat slides, press the inclined plane reset button K2 to restore the inclined plane to the horizontal position. At this time, you can continue to place the wheat on the inclined plane and press the start button to continue the above process to realize continuous measurement.

[0111] After the disc collection warehouse turns a circle, the wheat will fall into the dynamic friction coefficient measurement storage warehouse. Press the button K6, and the single particle unloading mechanism will turn a grid. The mechanism inlet is directly above, and the outlet is directly below, so there is no material falling for the first four times. Starting from the fifth time, the material passes through the sensor arranged along the slope, and the single-chip microcomputer can automatically calculate the dynamic friction coefficient value of the passing material and print it to the screen. Press again to loop the above process, and the information on the screen will be updated in real time. Record the measured data each time with a notebook.

Claims

1. A cereal friction coefficient measuring device comprising a frame (1), characterized in that, Also include, The static friction measuring table (2) is composed of a bearing slope (201), a static friction measuring slope (202) fixedly attached on the bearing slope (201), and a first photoelectric counter switch (203) placed on both sides of the static friction measuring slope (202) at the material end. The middle part of the bearing slope (201) is connected to a slope shaft (204) through a connecting piece (208), and the slope shaft (204) is rotatably connected to the rack (1). The slope shaft (204) is connected to a first stepper motor (206) fixed on the rack (1) through a first coupling (205). An indicating line (207) is arranged on the static friction measuring slope (202) below the counter laser line of the first photoelectric counter switch (203); The disc collection bin mechanism (3) is composed of a funnel (301) placed at the lower end of the bearing slope (201) to receive the falling material, a rotating disc collection bin (302) placed at the lower end of the funnel (301) to receive the material of the funnel (301), a collection bin base (303) at the bottom of the rotating disc collection bin (302), a collection bin shaft (304) rotatably connected to the rack (1), and a second stepper motor (305). A plurality of upper and lower transparent collection bins (306) are uniformly arranged on the rotating disc collection bin (302) in a circular manner. The collection bin base (303) is used to block the collection bin (306) and has a discharge hole (307). The second stepper motor (305) drives the rotating disc collection bin (302) to rotate relative to the collection bin base (303) through the collection bin shaft (304). The funnel (301) is fixed with a baffle (310) for blocking material; Single grain discharging mechanism (4) is used to receive the material discharged from the discharge hole (307) and discharge the material in single grain; The dynamic friction coefficient measuring mechanism (5) is composed of a support plate (501) arranged obliquely, a dynamic friction measuring slope (502) fixedly attached on the support plate (501), and a plurality of groups of second photoelectric counter switches (503) arranged along the length direction of the dynamic friction measuring slope (502). Each group of second photoelectric counter switches (503) is arranged on the support plate (501) on both sides of the width direction of the dynamic friction measuring slope (502). The upper end of the dynamic friction measuring slope (502) is used to receive the material falling from the single grain discharging mechanism (4).

2. A cereal friction coefficient measuring device according to claim 1, characterised in that The single particle discharging mechanism (4) is composed of a single particle discharging bin (401), a single particle discharging fixed sleeve (402) and a single particle discharging rotor (403), the single particle discharging bin (401) is used to receive the material output by the discharging hole (307), the single particle discharging rotor (403) is rotatably connected in the single particle discharging fixed sleeve (402), a plurality of single particle grooves (404) are uniformly distributed on the outer circumferential surface of the single particle discharging rotor (403) at intervals, the single particle discharging fixed sleeve (402) is provided with a passage (405) at the upper end, which communicates with the single particle discharging rotor (403), the passage (405) is used to receive the material of the single particle discharging bin (401) and deliver it to the single particle discharging rotor (403), the passage (405) is fixed with a scraper (406) with one end abutting against the outer circumferential surface of the single particle discharging rotor (403), and the single particle discharging fixed sleeve (402) is provided with a discharging hole (407) at the bottom.

3. A grain friction coefficient measuring device according to claim 1, wherein The support plate (501) of the dynamic friction coefficient measuring mechanism (5) is rotatably connected to the rack (1) at the lower end, the support plate (501) is connected with a support rod (504) at the upper end, the rack (1) is provided with an arc-shaped adjusting hole (505) at each side of the width direction of the support plate (501), the support rod (504) is provided with external threads at both ends and passes through the arc-shaped adjusting hole (505), and the external threads at both ends of the arc-shaped adjusting hole (505) are screwed with locking nuts (506).

4. A grain friction coefficient measuring device according to claim 1, wherein The lower end of the collecting bin rotating shaft (304) passes through the collecting bin base (303) and is rotatably connected in the collecting bin bearing seat (308), the collecting bin bearing seat (308) is fixed on the rack (1), and the upper end of the collecting bin rotating shaft (304) is connected and fixed to the second step motor (305) on the rack (1) through the second coupling (309).

5. A grain friction coefficient measuring device according to claim 2, wherein The single particle discharging rotor (403) is connected to the third step motor (410) through the discharger rotating shaft (408) and the third coupling (409).

6. A grain friction coefficient measuring device according to claim 1, wherein The second photoelectric counter switch is provided with four groups.

7. A grain friction coefficient measuring device according to claim 1, wherein The rack (1) at the lower end of the support plate (501) of the dynamic friction measuring mechanism is provided with a collecting hopper (507) for receiving the falling material.

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