Assembly type magic cube structure gravity center measuring device and method for theoretical mechanics teaching

Abstract

The invention relates to the technical field of theoretical mechanics experiment teaching equipment, in particular to an assembly type magic cube structure gravity center measuring device and method for theoretical mechanics teaching. Comprising a testing mechanism and a plurality of supporting bases, and the supporting bases are located at the bottom end of the testing mechanism and used for supporting the testing mechanism; the testing mechanism comprises a separation frame and cover plates, and six surfaces of the separation frame are slidably connected with the cover plates. According to the assembled magic cube structure gravity center measuring device and method for theoretical mechanics teaching, through the concept of the structure, a two-dimensional plane device used in existing theoretical mechanics experiment teaching is transformed into a three-dimensional device, and meanwhile, a fixed structure of an original experiment device is transformed into a detachable assembled structure; the problems that in existing theoretical mechanics experiment teaching, experimental instruments are disjointed from actual engineering problems, and students are lack of interest are solved, the learning interest of the students is stimulated, and the operational ability and innovation ability of the students are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of theoretical mechanics experimental teaching equipment, and particularly to an assembled Rubik's cube structure centroid measurement device and method for theoretical mechanics teaching. Background Art

[0002] Centroid measurement plays a crucial role in the aerospace field. The precise centroid point helps ensure the accuracy of flight orbits, improve the performance of spacecraft, and guarantee flight safety. Centroid measurement technology is based on the principle of moment balance, and the relevant knowledge points are highly theoretical and abstract in theoretical mechanics teaching, making students feel bored when learning. Currently, the theoretical mechanics courses offered by many majors in higher engineering colleges have gradually increased the experimental class hours.

[0003] Currently, the models commonly used in theoretical mechanics experimental teaching are two-dimensional models, which can only measure the coordinates of the centroid in the x and y directions. The test content is relatively simple and has limitations, being disconnected from actual engineering. Because the centroid measurement technology in actual engineering applications is not limited to two-dimensional measurement, but three-dimensional or even multi-dimensional measurement. For example, in addition to measuring the centroid position of an object, it is also possible to measure the change trend and dynamic response of the centroid. Multi-dimensional measurement can provide more comprehensive information for the design and optimization of aerospace aircraft, improving the performance and safety of the aircraft. The currently used test models have a simple structure and fewer centroid design schemes, making it easy for students to obtain test results, lacking challenges and easily making students feel bored.

[0004] Therefore, an assembled Rubik's cube structure centroid measurement device and method for theoretical mechanics teaching are designed to provide another technical solution to the above technical problems. Summary of the Invention

[0005] Based on this, it is necessary to provide an assembled Rubik's cube structure centroid measurement device and method for theoretical mechanics teaching to solve the technical problems raised in the above background art.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An assembled Rubik's cube structure centroid measurement device for theoretical mechanics teaching, comprising a test mechanism and a plurality of support bases, and all the plurality of support bases are located at the bottom end of the test mechanism for supporting the test mechanism;

[0008] The test mechanism includes a partition frame and a cover plate, and cover plates are slidably connected to all six faces of the partition frame;

[0009] The partition frame is composed of a first component, a second component, a third component and a fourth component. The first component is located on top of the second component, the second component is located on top of the third component, and the third component is located on top of the fourth component.

[0010] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, it further includes a plurality of electronic scales. The top of the electronic scales is in contact with the bottom of the support base for centroid detection of the test mechanism.

[0011] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, positioning grooves are evenly distributed inside the cover plate. Assembly threaded holes are evenly distributed at positions staggered with the positioning grooves inside the cover plate. The cover plate and the partition frame are connected by the cooperation of the assembly threaded holes and screws.

[0012] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, the top of the support base is slidably connected to the positioning groove. The top of the support base and the positioning groove are both conical or cylindrical.

[0013] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, a first horizontal frame is fixed on the outside of the first component, and a second horizontal frame is fixed on the outside of the fourth component. Columns are fixed on the outside of the four end corners of the second component and the third component. Plug pins are fixed on the tops of the second horizontal frame and the columns. The plug pin at the top of the column is in interference fit with the bottom of the first horizontal frame. The plug pin at the top of the second horizontal frame is in interference fit with the bottom of the column. The plug pin at the top of the bottom column is in interference fit with the bottom of the top column.

[0014] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, the first component, the second component, the third component and the fourth component are all composed of a plurality of first partition plates, a horizontal bottom plate and a plurality of second partition plates. First partition plates are evenly fixed on the top of the second component, and second partition plates are evenly fixed on the top of the second component. The first partition plates and the second partition plates are fixed crosswise to form a plurality of placement cavities on the top of the horizontal bottom plate.

[0015] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, first connection threaded holes are evenly distributed around the first component and at the connection positions of the first partition board and the second partition board with the horizontal bottom board. Second threaded holes are provided at the top of the first component and the bottom of the fourth component and at the staggered positions of the first partition board and the second partition board. Third threaded holes are evenly distributed around the third component and at the connection positions of the first partition board and the second partition board with the horizontal bottom board. And the first connection threaded holes, the second threaded holes, and the third threaded holes respectively correspond to the positions of the assembly threaded holes in the corresponding cover plates.

[0016] As a preferred embodiment of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, it further includes a steel ball for being placed inside the placement cavity to provide different weight distribution methods.

[0017] The usage method of the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching, for any one of the above, the steps are as follows:

[0018] S1: Set the mass of the steel ball to m 1 grams, the total mass of n steel balls is nm 1 grams, set the total mass of the partition frame, the cover plate, and the screws fixing the two to m 2 grams, and make nm 1 > m 2 ;

[0019] S2: Assemble the first component, the second component, the third component, and the fourth component into a partition frame through pins. Randomly select any placement cavity in any layer of the partition frame to place n steel balls, and fix the cover plate on the six sides of the partition frame through the cooperation of screws and the assembly threaded holes to form a test mechanism;

[0020] S3: Place three electronic scales on the same horizontal plane, and place the three support bases at the central positions of the three electronic scales respectively, and then turn on the electronic scales and zero them;

[0021] S4: Place any side of the test mechanism downward at the vertices of the three support bases, and adjust the positions of the electronic scales and the support bases so that the vertices of the three support bases are inserted into the positioning grooves of the cover plate, and the test mechanism can remain stable.

[0022] S5: Select the lower left corner of the test mechanism as the coordinate origin to establish a space rectangular coordinate system, and respectively set up the x-axis, the y-axis, and the z-axis. For the x-y coordinate system, read the readings of the three electronic scales as M 1 、M 2 、M 3 , and the coordinates corresponding to the three positioning grooves are (x1 , y 1 ), (x 2 , y 2 ), (x 3 , y 3 );

[0023] S6: Rotate the test mechanism 90° about the x-axis, place the test mechanism at the vertices of the three support bases with the x-z coordinate system as the base, and adjust the positions of the electronic scales and the support bases so that the vertices of the three support bases are inserted into the positioning grooves of the cover plate and the test mechanism can remain stable;

[0024] S7: For the x-z coordinate system, read the readings of the three electronic scales as M 4 , M 5 , M 6 , and the coordinates corresponding to the three positioning grooves are (x 4 , z 1 ), (x 5 , z 2 ), (x 6 , z 3 );

[0025] S8: According to the theorem of resultant moment, obtain the two-dimensional centroid coordinates (x c1 , y c ) of the test mechanism in the x-y coordinate system and the two-dimensional centroid coordinates (x c2 , z c ) in the x-z coordinate system, and take the average of x c1 and x c2 as x c , then the three-dimensional centroid coordinates of the test mechanism are (x c , y c , z c );

[0026] S9: Place the assembled test mechanism on an electronic scale and weigh the total mass m 3 grams, and calculate the number of steel balls n:

[0027] S10: According to the three-dimensional centroid coordinates (x c , y c , z c ) of the test mechanism obtained in step S8 and the three-dimensional centroid coordinates (4, 4, 4) of the test mechanism without steel balls, according to the theorem of resultant moment, obtain the specific position coordinates (x 球 , y 球 , z 球 ) of the steel balls.

[0028] As a preferred embodiment of the method for using the assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention, the two-dimensional centroid coordinates (x c1 , y c ) of the x-y coordinate system are expressed as follows:

[0029]

[0030] The two-dimensional centroid coordinates (x c2 , z c ) of the x-z coordinate system are expressed as follows:

[0031]

[0032] The three-dimensional centroid coordinates of the test mechanism are (x c , y c , z c ),

[0033] The expression for the number of steel balls is as follows:

[0034]

[0035] where n is the largest integer not greater than its value;

[0036] The position coordinates (x 球 , y 球 , z 球 ) of the steel balls are expressed as follows:

[0037]

[0038] It can be seen without doubt that through the above technical solution of the present application, the technical problems to be solved by the present application can surely be solved.

[0039] Meanwhile, through the above technical solutions, the present invention has at least the following beneficial effects:

[0040] 1. The assembled Rubik's Cube structure centroid measurement device and method for theoretical mechanics teaching provided by the present invention transform the two-dimensional planar device used in the existing theoretical mechanics experimental teaching into a three-dimensional solid device through the concept of structure, and at the same time transform the fixed structure of the original experimental device into a detachable assembled structure; solve the problem that the experimental instruments in the existing theoretical mechanics experimental teaching are disconnected from the actual engineering problems and students lack interest, thereby stimulating students' learning interest and improving their hands-on ability and innovation ability.

[0041] 2. The gravity center measurement device of the assembled Rubik's Cube structure of the present invention has a simple structure and low cost. The assembled structure makes it easy to form during the 3D printing process. It can be printed layer by layer and then assembled, avoiding complex processes such as adding supports during integral forming. Moreover, ordinary plastics are used as materials, and together with an ordinary household electronic scale and steel balls, a complete set of devices can be formed, with extremely low cost, and can be used in large quantities for theoretical mechanics experimental teaching.

[0042] 3. The counterweight method of the gravity center measurement device of the assembled Rubik's Cube structure of the present invention can accurately give the gravity center position. Generally, the gravity center measurement device adjusts the gravity center position through a push rod or screws to change the test conditions. Although this method has high adjustment accuracy, its structure is complex, the manufacturing and maintenance costs are high, and it is not easy to accurately give the gravity center position after adjustment. The gravity center measurement device of the assembled Rubik's Cube structure adopts the Rubik's Cube structure, discretely distributes the counterweight steel balls into fixed compartments, and only needs to know the counterweight position to give the gravity center. Although the counterweight method of the Rubik's Cube structure cannot continuously adjust the gravity center position, the measurement accuracy is greatly improved.

[0043] 4. The gravity center measurement device of the assembled Rubik's Cube structure of the present invention is designed with a cover plate for blind measurement of the gravity center. At present, the aircraft gravity center test algorithm is optimized for a certain type of gravity center distribution, which leads to poor universality of the test. Adopting the Rubik's Cube structure can conveniently design the device cover plate to achieve blind measurement, and truly test the accuracy and ability of the test algorithm. Blind measurement means that when the number and distribution of the counterweight steel balls in the gravity center measurement device of the Rubik's Cube structure are unknown, their number and distribution are calculated through testing.

[0044] 5. The gravity center measurement device of the assembled Rubik's Cube structure of the present invention can carry out interactive game experiments. In addition to the teacher randomly placing steel balls and letting students test, the device can also divide students into two groups for a competition. One group places the steel balls, and the other group tests, and then they exchange. Finally, the one who gets the result fastest wins. Students can gradually increase the difficulty in multiple rounds of competition until the opponent cannot solve the result, and then all students and teachers discuss the solution together. The interactive teaching method can greatly improve students' learning interest and participation.

[0045] 6. There are few ready-made experimental instruments for theoretical mechanics experiments, and innovative experiments are currently in their infancy. This experimental device can provide certain equipment support for innovative experimental teaching of theoretical mechanics. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0047] Figure 1Schematic diagram of the overall application structure of the present invention;

[0048] Figure 2 Exploded view of the present invention;

[0049] Figure 3 Exploded view of the test mechanism of the present invention;

[0050] Figure 4 For the present invention Figure 3 Bottom view;

[0051] Figure 5 Schematic diagram of the structure of the cover plate of the present invention;

[0052] Figure 6 For the present invention Figure 5 Partial enlarged view at position A of the present invention;

[0053] Figure 7 Coordinate schematic diagram of the partition frame of the present invention.

[0054] In the figure: 1. Test mechanism; 2. Support base; 3. Electronic scale; 4. Partition frame; 5. Cover plate; 6. First component; 7. Second component; 8. Third component; 9. Fourth component; 10. First horizontal frame; 11. Second horizontal frame; 12. Column; 13. Plug; 14. Positioning groove; 15. Assembly threaded hole; 16. First partition board; 17. Horizontal bottom plate; 18. Second partition board. Detailed implementation manners

[0055] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0057] It should be noted that, without conflict, the embodiments in the present invention and the features and technical solutions in the embodiments can be combined with each other.

[0058] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0059] Embodiment 1

[0060] Refer to Figures 1-7, An assembled Rubik's Cube structure centroid measurement device for theoretical mechanics teaching, comprising a testing mechanism 1 and a plurality of support bases 2. The plurality of support bases 2 are all located at the bottom end of the testing mechanism 1 and are used to support the testing mechanism 1;

[0061] It further includes a plurality of electronic scales 3. The top of the electronic scale 3 is in contact with the bottom of the support base 2. Through the contact between the plurality of electronic scales 3 and the support base 2, the centroid of the testing mechanism 1 is detected;

[0062] In this embodiment, the electronic scale 3 is an ordinary household small electronic scale with a measuring range of 2 kilograms and an accuracy of 0.1 gram.

[0063] The testing mechanism 1 includes a partition frame 4 and a cover plate 5. The partition frame 4 is rectangular in shape and has six sides. The cover plate 5 is slidably connected to all six sides of the partition frame 4, so that the cover plate 5 can be assembled on the six sides of the partition frame 4 to close the six sides of the partition frame 4. Positioning grooves 14 are evenly distributed inside the cover plate 5. The positioning grooves 14 are arranged in four rows, with four in each row, so that the positioning grooves 14 can correspond to the placement cavities on the partition frame 4. Assembly threaded holes 15 are evenly distributed at positions staggered with the positioning grooves 14 inside the cover plate 5. The cover plate 5 and the partition frame 4 are connected by the cooperation of the assembly threaded holes 15 and screws. Furthermore, the cover plate 5 can be connected to the partition frame 4 by screwing the screws into the inside of the assembly threaded holes 15 to form a Rubik's Cube structure, and the screws inside the assembly threaded holes 15 can be removed as needed to separate the cover plate 5 from the partition frame 4;

[0064] In this embodiment, the top of the support base 2 and the positioning grooves 14 are both conical. The top of the support base 2 is slidably connected to the positioning grooves 14, so that the top of the support base 2 can directly enter the inside of the positioning grooves 14 to support the testing mechanism 1, thereby forming a stable connection structure through three support bases 2.

[0065] In other embodiments, the top of the support base 2 and the positioning grooves 14 are both cylindrical. The top of the support base 2 is slidably connected to the positioning grooves 14, and then the top of the support base 2 can enter the inside of the positioning grooves 14 to support the testing mechanism 1. It is also possible that the top of the support base 2 and the positioning grooves 14 are both trapezoidal, irregular, etc.

[0066] The partition frame 4 is composed of a first component 6, a second component 7, a third component 8, and a fourth component 9. The first component 6 is located on the top of the second component 7, the second component 7 is located on the top of the third component 8, and the third component 8 is located on the top of the fourth component 9, so that the first component 6, the second component 7, the third component 8, and the fourth component 9 can be assembled in sequence according to height to form the partition frame 4;

[0067] A first horizontal frame 10 is fixedly arranged on the outer side of the first component 6, and a second horizontal frame 11 is fixedly arranged on the outer side of the fourth component 9. When the first component 6 is located at the top in the partition frame 4 and the fourth component 9 is located at the bottom in the partition frame 4, the first horizontal frame 10 and the second horizontal frame 11 are symmetrically arranged. Columns 12 are fixedly arranged on the outer sides of the four end corners of the second component 7 and the third component 8. Thus, when the first component 6, the second component 7, the third component 8 and the fourth component 9 form the partition frame 4, the cover plate 5 can be assembled through the frame formed by the first horizontal frame 10, the columns 12 and the second horizontal frame 11. Bolts 13 are fixedly arranged on the tops of the second horizontal frame 11 and the columns 12. The bolt 13 at the top of the column 12 is in interference fit with the bottom of the first horizontal frame 10, the bolt 13 at the top of the second horizontal frame 11 is in interference fit with the bottom of the column 12, and the bolt 13 at the top of the bottom column 12 is in interference fit with the bottom of the top column 12. Therefore, the first horizontal frame 10 and the top column 12, the top column 12 and the bottom column 12, and the bottom column 12 and the second horizontal frame 11 can all be assembled through the sliding and interference fit of the bolts 13, thereby forming the partition frame 4;

[0068] The first component 6, the second component 7, the third component 8 and the fourth component 9 are all composed of a plurality of first partition plates 16, a horizontal bottom plate 17 and a plurality of second partition plates 18. The first partition plates 16 are uniformly fixedly arranged on the top of the second component 7, and the second partition plates 18 are uniformly fixedly arranged on the top of the second component 7. Thus, the first partition plates 16, the horizontal bottom plate 17 and the second partition plates 18 can be formed into one body, and the first partition plates 16 and the second partition plates 18 are fixedly arranged in a crosswise manner to form a plurality of placement cavities on the top of the horizontal bottom plate 17. Therefore, counterweight objects can be placed inside the placement cavities and supported by the horizontal bottom plate 17;

[0069] In this embodiment, the number of both the first partition plates 16 and the second partition plates 18 is three, so that the crosswise arrangement of the first partition plates 16 and the second partition plates 18 forms sixteen placement cavities on the top of the horizontal bottom plate 17, and the positions of the positioning grooves 14 correspond to the positions of the placement cavities.

[0070] In this embodiment, first connection threaded holes are evenly distributed around the first component 6 at the connection positions of the first partition plate 16 and the second partition plate 18 with the horizontal bottom plate 17. Second threaded holes are provided at the top of the first component 6 and the bottom of the fourth component 9 at the staggered positions of the first partition plate 16 and the second partition plate 18. Third threaded holes are evenly distributed around the third component 8 at the connection positions of the first partition plate 16 and the second partition plate 18 with the horizontal bottom plate 17. The first connection threaded holes, the second threaded holes, and the third threaded holes respectively correspond to the positions of the assembly threaded holes 15 in the corresponding cover plate 5. Thus, when the cover plate 5 is installed on the inner sides of the six faces of the partition frame 4, screws can enter the interior of the assembly threaded holes 15 and be connected to the corresponding first connection threaded holes or second threaded holes or third threaded holes, realizing the assembly of the cover plate 5 and the partition frame 4. And the cover plate 5 can be separated from the partition frame 4 by removing the screws.

[0071] In other embodiments, the threaded holes corresponding to the cover plate 5 can also be provided at other positions of the first component 6 or the second component 7 or the third component 8 or the fourth component 9.

[0072] It further includes a steel ball for being placed inside the placement cavity, and different weight distribution methods are provided according to being placed in different placement cavities.

[0073] In this embodiment, the support base 2, the partition frame 4, and the cover plate 5 are all formed by plastic 3D printing.

[0074] The using process of the assembled Rubik's cube structure centroid measurement device for theoretical mechanics teaching provided by the present invention is as follows: When in use, the first component 6, the second component 7, the third component 8, and the fourth component 9 formed by plastic 3D printing are stacked in sequence. And between the first component 6 and the second component 7, between the second component 7 and the third component 8, and between the third component 8 and the fourth component 9, they are all connected by the insertion of the dowel pins 13 and interference fit, combining the first component 6, the second component 7, the third component 8, and the fourth component 9 into one body to form the partition frame 4. Then, the steel balls providing weight are placed inside the corresponding placement cavities. Then, the cover plate 5 is assembled on the six faces of the partition frame 4 by sliding, and screws enter the interior of the assembly threaded holes 15 and the corresponding first connection threaded holes or second threaded holes or third threaded holes, realizing the assembly of the cover plate 5 and the partition frame 4. Then, the support base 2 is placed at the bottom of the bottom cover plate 5, and the top of the support base 2 enters the inner side of the corresponding positioning groove 14, realizing the support of the test mechanism 1 by the three support bases 2. Then, the support base 2 is placed on the top of the electronic scale 3 for centroid measurement.

[0075] Embodiment Two

[0076] Based on the above Embodiment One, its using method is disclosed, and the steps are as follows:

[0077] Step 1: Set the mass of the steel balls and other parts of the device;

[0078] There are n steel balls, made of stainless steel, each with a mass of m 1 grams, and the size is matched with the size of the placement cavity in the partition frame 4. Each placement cavity can just hold one steel ball and is tightly fixed.

[0079] The total mass of the partition frame 4, the cover plate 5 and the screws fixing the two is known, which is m 2 grams.

[0080] The total mass of n steel balls is nm 1 should be greater than the total mass m of the other parts of the device 2 to ensure the sensitivity of the device to the adjustment of the counterweight position.

[0081] Step 2: Randomly select any placement cavity in any layer of the partition frame 4 to place n steel balls, assemble the first component 6, the second component 7, the third component 8 and the fourth component 9 into the partition frame 4 through the pins 13, and fix the cover plate 5 on the six sides of the partition frame 4 through the cooperation of the screws and the assembly threaded holes 15 to form the test mechanism 1.

[0082] Step 3: Place three electronic scales 3 on the same horizontal plane, place the three support bases 2 at the center positions of the three electronic scales 3 respectively, and then turn on the electronic scales 3 and zero them.

[0083] Step 4: Place the assembled test mechanism 1 face down at the vertices of the three support bases 2, and adjust the positions of the electronic scales 3 and the support bases 2 so that the vertices of the three support bases 2 are inserted into the inner part of the positioning grooves 14 in the cover plate 5 and the test mechanism 1 can be kept stable.

[0084] Step 5: Select the lower left corner of the test mechanism 1 as the coordinate origin to establish a space rectangular coordinate system, set up the x-axis, y-axis and z-axis respectively. Assume that the side length of each placement cavity is 2, then the distance from each positioning groove 14 on each cover plate 5 to the coordinate axis is an odd multiple of 1.

[0085] Step 6: For the x-y coordinate system, read the readings of the three electronic scales 3 as M 1 , M 2 , M 3 , and the corresponding coordinates of the three positioning grooves 14 are (x 1 , y 1 ), (x 2 , y 2 ), (x 3 , y 3 ).

[0086] Step 7: Rotate the test mechanism 1 by 90° around the x-axis, and place the test mechanism 1 at the vertices of the three support bases 2 with the x-z coordinate system as the base. Then adjust the positions of the electronic scales 3 and the support bases 2 so that the vertices of the three support bases 2 are inserted into the positioning grooves 14 of the cover plate 5, and the test mechanism 1 can remain stable.

[0087] Step 8: For the x-z coordinate system, read the readings of the three electronic scales 3 as M 4 , M 5 , M 6 , and the coordinates corresponding to the three positioning grooves 14 are (x 4 , z 1 ), (x 5 , z 2 ), (x 6 , z 3 ).

[0088] Step 9: According to the theorem of resultant moment, the two-dimensional centroid coordinates (x c1 , y c ) of the test mechanism 1 in the x-y coordinate system can be obtained. The calculation formula is:

[0089]

[0090] The two-dimensional centroid coordinates (x c2 , z c ) in the x-z coordinate system, and the calculation formula is:

[0091]

[0092] Theoretically, the x c1 and x c2 calculated through the above two coordinate systems should be the same. However, due to measurement and calculation errors, there will be slight differences. Then take the average value of the two as the final x c .

[0093] Then the three-dimensional centroid coordinates of the test mechanism 1 are (x c , y c , z c ).

[0094] Step 10: Determine the number of steel balls. Place the assembled test mechanism 1 on an electronic scale 3 and weigh the total mass m 3 grams. Calculate the number of steel balls n through the formula:

[0095]

[0096] where n is the largest integer not greater than its value.

[0097] Step 11: Determine the specific position coordinates of the steel balls. Each part of the testing mechanism 1 has a uniform mass, and its center-of-gravity coordinates are at its center. Then, the center-of-gravity coordinates of the empty testing mechanism 1 are (4, 4, 4). Let the equivalent center-of-gravity coordinates of n steel balls be (x 球 , y 球 , z 球 ). Regarding the empty testing mechanism 1 and n steel balls as two separate entities, calculate the torques about the x, y, and z axes respectively. The algebraic sum of the torques of the two parts about one axis is equal to the torque of the testing mechanism 1 with the steel balls placed about the same axis, i.e., the principle of the resultant torque:

[0098] x 球 ·nm 1 + 4·m 2 = x c ·m 3

[0099] y 球 ·nm1 + 4·m 2 = yc·m 3

[0100] z 球 ·nm 1 + 4·m 2 = z c ·m 3

[0101] The equivalent center-of-gravity coordinates of n steel balls can be obtained as (x 球 , y 球 , z 球 ). If n = 1, then (x 球 , y 球 , z 球 ) are the coordinates of the center of gravity of the steel ball. If n > 1, since different distribution patterns of multiple steel balls can result in the same equivalent center-of-gravity coordinates, the mass distribution at different positions of the testing mechanism 1 needs to be measured multiple times. Since the partition frame 4 and the cover plate 5 are made of plastic and their mass is much smaller than that of the steel balls, when measuring the mass at different positions by moving the support base 2, comparing the positions with and without steel balls, the reading of the electronic scale 3 will change significantly. Thus, the distribution range of the steel balls can be gradually narrowed down, incorrect distribution patterns can be excluded, and finally, the position coordinates of multiple steel balls can be determined.

[0102] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An assembled Rubik's Cube structure gravity center measuring device for theoretical mechanics teaching, characterized in that: It comprises a testing mechanism (1) and a plurality of supporting bases (2), wherein the plurality of supporting bases (2) are all located at the bottom end of the testing mechanism (1) and are used to support the testing mechanism (1); The testing mechanism (1) comprises a partition frame (4) and a cover plate (5), and the six sides of the partition frame (4) are all slidably connected to the cover plate (5); The partition frame (4) is composed of a first component (6), a second component (7), a third component (8) and a fourth component (9), wherein the first component (6) is located on top of the second component (7), the second component (7) is located on top of the third component (8), and the third component (8) is located on top of the fourth component (9).

2. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 1 is characterized in that: It also comprises a plurality of electronic scales (3), the top of each of which is in contact with the bottom of the support base (2) and is used to detect the center of gravity of the test mechanism (1).

3. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 1 is characterized in that: Positioning grooves (14) are evenly distributed inside the cover plate (5), and assembly threaded holes (15) are evenly distributed inside the cover plate (5) and at positions staggered with the positioning grooves (14). The cover plate (5) and the partition frame (4) are connected by the assembly threaded holes (15) and screws.

4. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 3 is characterized in that: The top of the support base (2) is slidably connected to the positioning groove (14); the top of the support base (2) and the positioning groove (14) are both conical or cylindrical.

5. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 1 is characterized in that: A first horizontal frame (10) is fixed on the outer side of the first component (6), a second horizontal frame (11) is fixed on the outer side of the fourth component (9), columns (12) are fixed on the outer sides of the four end corners of the second component (7) and the third component (8), latches (13) are fixed on the tops of the second horizontal frame (11) and the columns (12), the top latches (13) of the columns (12) are interference fit with the bottom of the first horizontal frame (10), the top latches (13) of the second horizontal frame (11) are interference fit with the bottom of the columns (12), and the top latches (13) of the bottom columns (12) are interference fit with the bottom of the top columns (12).

6. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 1 is characterized in that: The first component (6), the second component (7), the third component (8) and the fourth component (9) are all composed of a plurality of first partition plates (16), a horizontal bottom plate (17) and a plurality of second partition plates (18); the first partition plates (16) are evenly fixed on the top of the second component (7); the second partition plates (18) are evenly fixed on the top of the second component (7); and the first partition plates (16) and the second partition plates (18) are cross-staggered and fixed to form a plurality of placement cavities on the top of the horizontal bottom plate (17).

7. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 6 is characterized in that: First connecting threaded holes are evenly distributed around the first component (6) and located at the connection position between the first partition plate (16) and the second partition plate (18) and the horizontal bottom plate (17); second threaded holes are evenly distributed around the first component (6) and the bottom of the fourth component (9) and located at the staggered position between the first partition plate (16) and the second partition plate (18); third threaded holes are evenly distributed around the third component (8) and located at the connection position between the first partition plate (16) and the second partition plate (18) and the horizontal bottom plate (17); and the first connecting threaded holes, the second threaded holes, and the third threaded holes correspond to the positions of the assembly threaded holes (15) in the corresponding cover plate (5), respectively.

8. The assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to any one of claims 1 to 7, characterized in that: The utility model also comprises a steel ball which is used for being placed in the placement cavity to provide different weight balancing modes.

9. A method for using a prefabricated Rubik's Cube structure gravity center measuring device for theoretical mechanics teaching, used for the prefabricated Rubik's Cube structure gravity center measuring device for theoretical mechanics teaching according to any one of claims 1 to 8, characterized in that: Here are the steps: S1: Set the mass of the steel ball to m1 grams, the total mass of n steel balls to nm1 grams, set the total mass of the partition frame (4) and the cover plate (5) and the screws fixing the two to m2 grams, and let nm1>m2; S2: Assemble the first component (6), the second component (7), the third component (8) and the fourth component (9) together by means of a latch (13) to form a partition frame (4), randomly select n steel balls and place them in any placement cavity of any layer in the partition frame (4), and fix the cover plate (5) on the six sides of the partition frame (4) by means of screws and assembly threaded holes (15), thereby forming a test mechanism (1); S3: placing three electronic scales (3) on the same horizontal plane, and placing three supporting bases (2) at the center of the three electronic scales (3), respectively, and then turning on the electronic scales (3) and clearing them to zero; S4: Place any one side of the test mechanism (1) facing downward on the vertices of the three support bases (2), and adjust the positions of the electronic scale (3) and the support base (2) so that the vertices of the three support bases (2) are inserted into the positioning grooves (14) of the cover plate (5), and the test mechanism (1) can remain stable. S5: Select the lower left corner of the test mechanism (1) as the coordinate origin to establish a spatial rectangular coordinate system, set up the x-axis, y-axis, and z-axis respectively, and read the readings of the three electronic scales (3) for the xy coordinate system, which are M1, M2, and M3 respectively, and the corresponding coordinates of the three positioning grooves (14) are (x1, y1), (x2, y2), and (x3, y3) respectively; S6: Rotate the test mechanism (1) 90° with the x-axis as the axis, place the test mechanism (1) on the vertices of the three support bases (2) with the xz coordinate system as the bottom surface, and adjust the positions of the electronic scale (3) and the support base (2) so that the vertices of the three support bases (2) are inserted into the positioning grooves (14) of the cover plate (5), and the test mechanism (1) can remain stable; S7: With respect to the xz coordinate system, the readings of the three electronic scales (3) are respectively M4, M5, and M6, and the corresponding coordinates of the three positioning grooves (14) are respectively (x4, z1), (x5, z2), and (x6, z3); S8: According to the resultant moment theorem, the two-dimensional center of gravity coordinates (x c1 ,y c ) and the two-dimensional centroid coordinates of the xz coordinate system (x c2 , z c ), and take x c1 and x c2 The mean value is x c , then the three-dimensional center of gravity coordinates of the test structure (1) are (x c ,y c , z c ); S9: Place the assembled test mechanism (1) on an electronic scale (3), weigh the total mass m3 grams, and calculate the number of steel balls n: S10: The three-dimensional center of gravity coordinates (x) of the test structure (1) obtained in step S8 c ,y c , z c ) and the three-dimensional center of gravity coordinates (4, 4, 4) of the test mechanism (1) when no steel ball is placed, and according to the resultant moment theorem, the specific position coordinates (x 球 ,y 球 , z 球 ).

10. The method for using the assembled Rubik's Cube structure center of gravity measuring device for theoretical mechanics teaching according to claim 9 is characterized in that: The two-dimensional centroid coordinates of the xy coordinate system (x c1 ,y c ), the expression is as follows: The two-dimensional centroid coordinates of the xz coordinate system (x c2 , z c ), the expression is as follows: The three-dimensional center of gravity coordinates of the test structure (1) are (x c ,y c , z c ), The expression of the number of steel balls is as follows: Where n is the largest integer not greater than its value; The position coordinates of the steel ball (x 球 ,y 球 , z 球 ), the expression is as follows:

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