A kind of kilogram weight automation verification device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YUNNAN INST OF MEASUREMENT TEST TECH RES
- Filing Date
- 2025-08-29
- Publication Date
- 2026-06-23
Smart Images

Figure CN224398794U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to an automated kilogram weight calibration device, belonging to the field of weight calibration technology. Background Technology
[0002] Weights are tools used to measure the weight of objects, and their accuracy is a crucial aspect of quality control. Over time, the weight of weights may change, affecting their accuracy. Regular calibration of weights ensures their mass and weight accuracy, thereby guaranteeing reliability in various measurement and inspection processes. Therefore, weight calibration is necessary to guarantee their precise mass. Weight mass calibration involves comparing the weight to be tested with a standard weight on a mass comparator to determine the mass error of the weight under test.
[0003] Traditional weight calibration typically employs manual methods, which are inefficient and prone to significant errors. To improve the efficiency and accuracy of weight calibration, an increasing number of metrology and testing institutions are adopting automated methods. Current automated weight calibration mechanisms generally consist of an integrated testing platform equipped with a multi-station comb-shaped fork-tooth structure manipulator capable of 360° rotation at its end, a built-in mass comparator, and an intelligent control system that receives, calculates, and outputs data from the mass comparator in real time.
[0004] Chinese invention patent application No. 202010661541.4 discloses a device for dual-weight transfer and alternating loading, comprising: a device body including a base and a cover, the cover being mounted on the base, the cover and base surrounding each other to form a loading space; a worktable mounted on the base for placing the weight to be measured and / or the balancing weights; a mass comparator mounted on the base for measuring the mass of the weight to be measured; and a weight transfer mechanism including a drive assembly and a transfer arm, the drive assembly being mounted on the base, the transfer arm being mounted on the drive assembly, the drive assembly driving the transfer arm to transfer the weight to be measured and / or the balancing weights between the worktable and the mass comparator; wherein the width of the weight placement portion of the transfer arm is sufficient to allow two weights of different weights to be placed side by side along the width direction of the weight placement portion, and the groove enables automatic centering of the weights, improving the measurement accuracy and the efficiency of transfer and detection. However, using this patented device for weight verification is still not simple and fast enough, resulting in the need for further improvement in the overall efficiency of weight detection. Utility Model Content
[0005] In order to overcome the shortcomings of the prior art, this utility model provides an automated kilogram weight verification device.
[0006] The technical solution adopted in this utility model is as follows: an automated kilogram weight verification device is designed, including a frame, a mass comparator, and a carrying mechanism. The frame is equipped with an openable cover, and the mass comparator and the carrying mechanism are both housed inside the cover. The cover provides protection and reduces detection interference. The mass comparator is equipped with a toothed disk, and the carrying mechanism is equipped with a weight fork for placing the weight. The carrying mechanism can drive the weight fork through the toothed disk, so that the weight on the weight fork falls onto the toothed disk for detection. After the detection is completed, the weight fork reverses and passes through the toothed disk to remove the weight.
[0007] The bearing mechanism includes a transverse component, a support frame, and a lifting component. The transverse component is mounted on the frame, and the support frame is mounted on the transverse component, which drives the transverse component to reciprocate laterally. The lifting component is mounted on the support frame. The weight fork includes a tested weight fork and a standard weight fork. The tested weight fork and the standard weight fork are slidably mounted on opposite sides of the support frame. The tested weight fork and the standard weight fork are respectively connected to the lifting component, which drives the tested weight fork and the standard weight fork to reciprocate up and down.
[0008] In use, after placing the weight to be tested and the standard weight on the tested weight fork (B) and the standard weight fork (A) respectively, the tested weight and the standard weight are loaded onto the toothed disk of the mass comparator according to the weight verification procedure (ABBA, ABA) for comparison. The readings on the comparator are read, recorded, and calculated to determine whether the tested weight is qualified. Specifically, the horizontal movement component drives the support frame to move laterally back and forth so that the tested weight fork (B) or the standard weight fork is facing the toothed disk. The lifting component drives the tested weight fork and the standard weight fork to move up and down back and forth, so that the tested weight or the standard weight on the tested weight fork or the standard weight fork is loaded onto the toothed disk of the mass comparator for comparison, or the lifting component removes the weighed weight from the toothed disk of the mass comparator.
[0009] Furthermore, the support frame includes a support plate and support legs respectively installed on opposite sides of the support plate. The lifting assembly includes a lifting nut seat that can move up and down. The support plate is provided with a lifting guide rail. The lifting nut seat is provided with a lifting slider that is slidably connected to the lifting guide rail. The lifting nut seat is slidably connected to the support plate through the lifting slider and the lifting guide rail. The support plate is provided with a clearance opening. The lifting nut seat is provided transversely through the clearance opening and can move down within the clearance opening. The tested weight fork and the standard weight fork are respectively provided on the lifting nut seats located on both sides of the clearance opening.
[0010] Furthermore, the lifting assembly also includes a lifting screw assembly, a lifting motor, and a reducer. A base plate is provided on the support plate, and the reducer is mounted on the base plate. The lifting motor is provided at the input end of the reducer, and the lifting screw assembly is provided at the output end. The lifting screw assembly is driven to work by the lifting motor. The screw nut of the lifting screw assembly is connected to the lifting nut seat. The lifting nut of the lifting screw assembly moves up and down, thereby driving the lifting nut seat to move.
[0011] Furthermore, pull plates are provided on both sides of the lifting nut seat. The tested weight fork and the standard weight fork are respectively installed on the lifting nut seat through the pull plates. The pull plates make the installation and connection of the tested weight fork and the standard weight fork more stable and reliable.
[0012] Furthermore, a clamping plate is provided at one end of the lifting nut seat that passes through the clearance opening. The clamping plate is located between the lifting nut seat and the pull plate, and serves to balance the weight, limit the position, and increase the installation connection area. Both the tested weight fork and the standard weight fork are designed with an L-shaped structure, and their vertical walls are fixedly connected to the pull plate, making the connection more reliable.
[0013] Furthermore, the lateral movement assembly includes a lateral sliding mechanism and a lateral driving mechanism. A set of lateral sliding mechanisms is respectively installed under the two support legs of the support frame. Each lateral sliding mechanism includes a base, a lateral slide rail, and a lateral slider. The base is fixed to the frame, and the lateral slide rail is installed on the base. The lateral slider is slidably installed on the lateral slide rail and connected to the support legs. The support frame slides laterally via the lateral sliding mechanism. The lateral driving mechanism is installed on one set of lateral sliding mechanisms. The lateral driving mechanism drives the lateral slider to slide, thereby causing the support frame to slide.
[0014] Furthermore, protective shells are provided on both sides of the base in the width direction to prevent debris from entering. The two protective shells form a strip-shaped opening above the base. A pad is provided at the lower end of the support leg. The pad is set in an I-shaped structure and is locked at the strip-shaped opening to increase sliding stability. A pad plate is provided on the lower side of the pad, and the pad plate is connected to the transverse slider.
[0015] Furthermore, the lateral movement drive mechanism includes a lateral movement nut seat, a lateral movement motor, and a lateral movement lead screw assembly installed at the output end of the lateral movement motor. The lead screw nut of the lateral movement lead screw assembly is connected to the lateral movement nut seat, and the lateral movement nut seat is disposed between the pad block and the pad plate. The lateral movement slider is driven to slide through the above mechanism.
[0016] Furthermore, the transverse nut seat includes an extension block and a mounting base installed at one end of the extension block. The screw nut of the transverse screw assembly is installed on the mounting base. The extension block is disposed between the pad and the pad block, which facilitates installation.
[0017] Furthermore, a placement frame is provided under the mass comparator, with feet at each of the four corners of the placement frame. A marble platform is provided on the placement frame, and the mass comparator is placed on the marble platform. Blocks are provided on the placement frame on each of the four sides of the marble platform. The above mechanism ensures the stable placement of the mass comparator and guarantees accurate test results.
[0018] Compared with the prior art, the beneficial effects of this utility model are as follows: After placing the weight to be tested and the standard weight on the weight fork (B) and the standard weight fork (A) respectively, the weight to be tested and the standard weight are loaded onto the toothed disk of the mass comparator for comparison according to the weight verification process (ABBA, ABA). The readings on the comparator are read, recorded and calculated to determine whether the weight to be tested is qualified. This improves the automation level of weight verification, thereby improving verification efficiency. The weight verification process is simple and fast. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the isometric view of this utility model.
[0021] Figure 2 This is a schematic diagram showing the concealed frame and other structures of this utility model.
[0022] Figure 3 for Figure 2 A diagram showing the structure after further concealment.
[0023] Figure 4 for Figure 2 A diagram from another perspective.
[0024] Figure 5 for Figure 2 Schematic diagram of cross-section.
[0025] Figure 6 This is a schematic diagram of the mass comparator of this utility model and its assembly with some components.
[0026] Figure 7 This is a schematic diagram of the support plate of this utility model.
[0027] In the diagram: 1. Frame; 2. Mass comparator; 3. Cover; 4. Toothed disk; 5. Transverse movement assembly; 6. Support frame; 7. Lifting assembly; 8. Test weight fork; 9. Standard weight fork; 10. Support plate; 11. Support leg; 12. Photoelectric switch; 13. Lifting nut seat; 14. Lifting guide rail; 15. Lifting slider; 16. Clearance port; 17. Lifting screw assembly; 18. Lifting motor; 19. Reducer; 2 0. Pull plate; 21. Clamping plate; 22. Base; 23. Horizontal slide rail; 24. Horizontal slider; 25. Protective shell; 26. Pad block; 27. Pad plate; 28. Horizontal nut seat; 29. Horizontal motor; 30. Horizontal lead screw assembly; 31. Extension block; 32. Mounting base; 33. Placement rack; 34. Foot; 35. Marble table; 36. Stop block; 37. Adjusting block; 38. Display device; 39. Electrical control module. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0030] Example 1
[0031] like Figure 1-5As shown: An automated kilogram weight verification device includes a frame 1, a mass comparator 2, and a support mechanism. The frame 1 is equipped with an openable transparent cover 3, such as an electric sliding door. The mass comparator 2 and the support mechanism are both located inside the cover 3. The mass comparator 2 is equipped with a toothed disk 4, and the support mechanism is equipped with a weight fork for placing weights. The weight fork and the toothed disk 4 are respectively provided with staggered teeth. The support mechanism can drive the weight fork through the toothed disk 4, so that the weight on the weight fork falls onto the toothed disk 4 for testing. More specifically, a placement frame 33 is provided under the mass comparator 2. The placement frame 33 has feet 34 at each of its four corners (which can be used to adjust the height of the four corners to ensure stable placement of the mass comparator 2). A marble platform 35 is provided on the placement frame 33, and the mass comparator 2 is placed on the marble platform 35. Stops 36 are provided on the four sides of the placement frame 33 on the marble platform 35. Adjustment blocks 37 are also provided on the stops 36. The adjustment blocks 37 have oblong holes, and are fixed to the stops 36 with bolts through the oblong holes. The position of the adjustment pads can be adjusted through the oblong holes, thereby adjusting the clamping force on the mass comparator 2. Figure 6 As shown, the mass comparator 2 has a separate support structure placed on the mounting ground, reducing the impact of the frame 1 on it.
[0032] For example, the supporting mechanism includes a transverse component 5, a support frame 6, and a lifting component 7. The transverse component 5 is mounted on the frame 1, the support frame 6 is mounted on the transverse component 5, and the lifting component 7 is mounted on the support frame 6. The weight fork includes a tested weight fork 8 and a standard weight fork 9. The tested weight fork 8 and the standard weight fork 9 are slidably mounted on opposite sides of the support frame 6, and the tested weight fork 8 and the standard weight fork 9 are respectively connected to the lifting component 7.
[0033] To further improve the automation level of this embodiment, photoelectric switches 12 can be installed at the mounting locations of the tested weight fork 8 and the standard weight fork 9. For example, photoelectric switches 12 can be installed on opposite sides of the support frame 6 where the tested weight fork 8 and the standard weight fork 9 are mounted, with the photoelectric switches 12 facing the tested weight and the standard weight on the tested weight fork 8 and the standard weight fork 9, to determine whether weights have been placed before proceeding with the calibration work. Alternatively, photoelectric switches 12 can be installed on the transverse component 5 (slightly different from the photoelectric switches 12 on the support frame 6) to control or determine its position after transverse movement, ensuring it is in a centered position, with the tested weight fork 8 facing the toothed disk 4 or the standard weight fork 9 facing the toothed disk 4.
[0034] Example 2
[0035] This embodiment is a further refinement of the components of the bearing mechanism based on Embodiment 1. In this embodiment, the support frame 6 includes a support plate 10 and support legs 11 respectively installed on opposite sides of the support plate 10. Specifically, slots are provided on the support legs 11, and the support plate 10 is inserted into the slots and bolted in. The lifting assembly 7 includes a lifting nut seat 13 that can move up and down. The support plate 10 is provided with a lifting guide rail 14, which is usually arranged in pairs. The lifting nut seat 13 is provided with a lifting slider 15 that is slidably connected to the lifting guide rail 14. The support plate 10 is provided with a clearance opening 16, such as... Figure 7 As shown, the lifting nut seat 13 is arranged transversely through the clearance opening 16, and the tested weight fork 8 and the standard weight fork 9 are respectively arranged on the lifting nut seat 13 on both sides of the clearance opening 16. The clearance opening 16 can be a rectangular opening or a C-shaped opening.
[0036] In this embodiment, the lifting assembly 7 further includes a lifting screw assembly 17, a lifting motor 18, and a reducer 19. A seat plate is provided on the support plate 10, and the reducer 19 is mounted on the seat plate. The lifting motor 18 is located at the input end of the reducer 19, and the lifting screw assembly 17 is located at the output end. The two are generally connected by a coupling. The lifting screw assembly 17 typically includes a screw, a screw nut, a transmission seat, and a support seat. The transmission seat and the support seat are respectively located on the support plate 10 at the upper and lower ends of the clearance opening 16. The two ends of the screw are respectively located on the transmission seat and the support seat. The screw and the output end of the reducer 19 are connected by a coupling. The screw nut of the lifting screw assembly 17 is connected to the lifting nut seat 13.
[0037] Pull plates 20 are respectively provided on both sides of the lifting nut seat 13. The tested weight fork 8 and the standard weight fork 9 are respectively installed on the lifting nut seat 13 through the pull plates 20. More specifically, a clamping plate 21 is also provided at one end of the lifting nut seat 13 that passes through the relief opening 16. The clamping plate 21 is located between the lifting nut seat 13 and the pull plate 20. The tested weight fork 8 and the standard weight fork 9 are both designed with an L-shaped structure, and their vertical walls are connected and fixed to the pull plate 20, while their horizontal walls are provided with insert teeth.
[0038] Example 3
[0039] This embodiment is a further refinement of the transverse component 5 based on embodiment 2. In this embodiment, the transverse component 5 includes a transverse sliding mechanism and a transverse driving mechanism. A set of transverse sliding mechanisms is respectively provided under the two support legs 11 of the support frame 6. The transverse sliding mechanism includes a base 22, a transverse slide rail 23, and a transverse slider 24. The base 22 is fixed to the frame 1. The transverse slide rail 23 is provided on the base 22. The transverse slider 24 is slidably provided on the transverse slide rail 23. The transverse slider 24 is connected to the support leg 11. The transverse driving mechanism is provided on one of the transverse sliding mechanisms, and the transverse driving mechanism drives the transverse slider 24 to slide. More specifically, protective shells 25 are respectively provided on both sides of the base 22 in the width direction, and the two protective shells 25 form a strip-shaped opening above the base 22. A pad 26 is provided at the lower end of the support leg 11. The pad 26 is set in an I-shape and is locked at the strip-shaped opening. A pad plate 27 is provided on the lower side of the pad 26, and the pad plate 27 is connected to the transverse slider 24. At this time, the photoelectric switch 12 provided on the transverse component 5 can be provided on the protective shell 25 on the outside of the base 22 on the side where the transverse drive mechanism is located. Specifically, photoelectric switches 12 can be provided at both ends and the middle part of the protective shell 25 on the outside of the base 22 (corresponding to the centering of the support frame 6 of the bearing mechanism, the centering of the tested weight fork 8 to align with the mass comparator 2, or the centering of the standard weight fork 9 to align with the mass comparator 2, respectively). Then, a moving contact is provided on the pad 26 of the support leg 11. As the support frame 6 moves, when the moving contact covers the photoelectric switch 12 at a certain position on the transverse component 5, it is used to judge and control the position of the support frame 6. The above control process can be achieved using existing technologies.
[0040] For example, the lateral drive mechanism includes a lateral nut seat 28, a lateral motor 29, and a lateral lead screw assembly 30 mounted on the output end of the lateral motor 29. Typically, the lateral lead screw assembly 30 also includes a transmission seat, a mounting seat 32, a lead screw, and a lead screw nut. The lead screw is connected to the output end of the lateral motor 29 via a coupling. The lead screw nut of the lateral lead screw assembly 30 is connected to the lateral nut seat 28, which is disposed between a pad 26 and a pad 27. More specifically, the lateral nut seat 28 includes an extension block 31 and a mounting seat 32 mounted on one end of the extension block 31. The lead screw nut of the lateral lead screw assembly 30 is mounted on the mounting seat 32. The extension block 31 is disposed between the pad 27 and the pad 26. The lead screw of the lateral lead screw assembly 30 passes through the extension block 31 and is threadedly connected to the lead screw nut.
[0041] It should be noted that the mass comparator 2 is usually equipped with a display device 38 to display the detection results of the weight mass. This application is also usually equipped with an electronic control module 39 to control the entire verification process. For example, a controller is used. When it is detected that the tested weight and the standard weight are placed on the tested weight fork 8 and the standard weight fork 9 respectively (for example, through detection by photoelectric switch 12), the verification process is started. The above-mentioned controller and its control process can be implemented using existing technical means, and will not be described in detail here. In addition, this application can be used with a robotic arm with a weight fork-like robotic arm to complete the process of loading the tested weight and the standard weight onto the tested weight fork 8 and the standard weight fork 9, and the process of removing the tested weight and the standard weight from the tested weight fork 8 and the standard weight fork 9 after verification.
[0042] In use, place the weights to be tested (usually multiple) and the standard weights near this application. Then, place one weight to be tested and one standard weight on the weight fork 8 and the standard weight fork 9 respectively. After placing the weight to be tested and the standard weight on the weight fork 8 (B) and the standard weight fork 9 (A) respectively, load the weight to be tested and the standard weight onto the toothed disk 4 of the mass comparator 2 for comparison according to the weight testing procedure (ABBA, ABA). Read the values on the comparator, record and calculate (usually done automatically by the controller, but can also be done manually) to determine whether the weight to be tested is qualified.
[0043] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. An automated kilogram weight verification device, comprising a frame (1), a mass comparator (2), and a support mechanism, wherein the frame (1) is provided with an openable cover (3), the mass comparator (2) and the support mechanism are both disposed within the cover (3), the mass comparator (2) is provided with a toothed disk (4), and the support mechanism is provided with a weight fork for placing weights, the support mechanism being able to drive the weight fork through the toothed disk (4), so that the weight on the weight fork falls onto the toothed disk (4) for detection; characterized in that: The bearing mechanism includes a transverse component (5), a support frame (6), and a lifting component (7). The transverse component (5) is mounted on the frame (1), the support frame (6) is mounted on the transverse component (5), and the lifting component (7) is mounted on the support frame (6). The weight fork includes a tested weight fork (8) and a standard weight fork (9). The tested weight fork (8) and the standard weight fork (9) are slidably mounted on opposite sides of the support frame (6). The tested weight fork (8) and the standard weight fork (9) are respectively connected to the lifting component (7).
2. The automated kilogram weight verification device according to claim 1, characterized in that: The support frame (6) includes a support plate (10) and support legs (11) respectively installed on opposite sides of the support plate (10). The lifting assembly (7) includes a lifting nut seat (13) that can move up and down. The support plate (10) is provided with a lifting guide rail (14). The lifting nut seat (13) is provided with a lifting slider (15) that is slidably connected to the lifting guide rail (14). The support plate (10) is provided with a clearance opening (16). The lifting nut seat (13) is arranged across the clearance opening (16). The weight fork to be tested (8) and the standard weight fork (9) are respectively provided on the lifting nut seats (13) on both sides of the clearance opening (16).
3. The automated kilogram weight verification device according to claim 2, characterized in that: The lifting assembly (7) also includes a lifting screw assembly (17), a lifting motor (18), and a reducer (19). A seat plate is provided on the support plate (10), and the reducer (19) is installed on the seat plate. The lifting motor (18) is provided at the input end of the reducer (19), and the lifting screw assembly (17) is provided at the output end. The screw nut of the lifting screw assembly (17) is connected to the lifting nut seat (13).
4. The automated kilogram weight verification device according to claim 3, characterized in that: Pull plates (20) are provided on both sides of the lifting nut seat (13), and the tested weight fork (8) and the standard weight fork (9) are respectively installed on the lifting nut seat (13) through the pull plates (20).
5. The automated kilogram weight verification device according to claim 4, characterized in that: The lifting nut seat (13) is provided with a clamp (21) at one end through the relief opening (16). The clamp (21) is located between the lifting nut seat (13) and the pull plate (20). The tested weight fork (8) and the standard weight fork (9) are both set as L-shaped structures, and their vertical walls are connected and fixed to the pull plate (20).
6. The automated kilogram weight verification device according to any one of claims 2-5, characterized in that: The transverse component (5) includes a transverse sliding mechanism and a transverse driving mechanism. A set of transverse sliding mechanisms is respectively provided under the two support legs (11) of the support frame (6). The transverse sliding mechanism includes a base (22), a transverse slide rail (23) and a transverse slider (24). The base (22) is fixed on the frame (1). The transverse slide rail (23) is provided on the base (22). The transverse slider (24) is slidably provided on the transverse slide rail (23). The transverse slider (24) is connected to the support leg (11). The transverse driving mechanism is provided on one of the transverse sliding mechanisms. The transverse driving mechanism drives the transverse slider (24) to slide.
7. The automated kilogram weight verification device according to claim 6, characterized in that: The base (22) is provided with protective shells (25) on both sides in the width direction. The two protective shells (25) form a strip opening above the base (22). The lower end of the support leg (11) is provided with a pad (26). The pad (26) is set with an I-shaped structure and is locked in the strip opening. The pad (26) is provided with a pad plate (27) on the lower side. The pad plate (27) is connected to the horizontal sliding slider (24).
8. The automated kilogram weight verification device according to claim 7, characterized in that: The lateral drive mechanism includes a lateral nut seat (28), a lateral motor (29), and a lateral lead screw assembly (30) installed at the output end of the lateral motor (29). The lead screw nut of the lateral lead screw assembly (30) is connected to the lateral nut seat (28), and the lateral nut seat (28) is disposed between the pad block (26) and the pad plate (27).
9. The automated kilogram weight verification device according to claim 8, characterized in that: The transverse nut seat (28) includes an extension block (31) and a mounting seat (32) installed at one end of the extension block (31). The screw nut of the transverse screw assembly (30) is installed on the mounting seat (32). The extension block (31) is disposed between the pad (27) and the pad (26).
10. The automated kilogram weight verification device according to claim 1, characterized in that: The mass comparator (2) is provided with a placement rack (33), and the four corners of the placement rack (33) are respectively provided with feet (34). A marble platform (35) is provided on the placement rack (33), and the mass comparator (2) is placed on the marble platform (35). Blocks (36) are respectively provided on the placement rack (33) located on the four sides of the marble platform (35).