A bidirectional overload-resistant weighing and screening device based on micro-clearance nonlinear stiffness mutation and its design method

Abstract

This invention discloses a bidirectional overload resistant weighing and screening device and its design method based on micro-clearance nonlinear stiffness mutation. It solves the technical problems of existing weighing and screening devices, such as the susceptibility to single-point failure due to active locking mechanisms, system complexity, and secondary impact damage. The invention includes a screening bearing unit, an intermediate connecting flange, a support base, multiple vibration damping springs, multiple pressure sensors, and multiple limiting central shafts. The intermediate connecting flange is sleeved on the central cylinder and forms a downward overload clearance with the upper stepped surface of the bottom cylinder. The top cylinder has the smallest diameter and is connected to an anti-pull-out fastener, which forms a tensile overload clearance with the upper surface of the intermediate connecting flange. Through precise design of the clearance dimensions, the high-precision measurement path and the extreme load bypass path are decoupled at the physical level, simultaneously meeting the requirements for microgravity weighing and strong impact protection.

Description

Technical Field

[0001] This invention relates to a high-precision weighing and screening device and its design method, specifically to a bidirectional overload resistant weighing and screening device and its design method based on micro-clearance nonlinear stiffness mutation. Background Technology

[0002] In deep space exploration missions (such as lunar landing exploration), in-situ detection equipment, such as lunar regolith sieving, needs to perform high-precision weighing of collected materials (such as lunar regolith) under microgravity (approximately 1 / 6 g) conditions. To ensure measurement accuracy, miniature planar pressure sensors are typically selected. These sensors have extremely small full-scale deformation (usually on the order of 0.1 mm), and their ultimate overload threshold is typically 120% to 500%.

[0003] During launch and landing, lunar landers must endure extremely harsh, wide-band dynamic load environments, including sinusoidal vibrations of tens of g, random vibrations of 20-30 grms, and high-frequency shock spectrum responses of up to 6000 g at the moment of landing. Under these extreme dynamic loads, without protection, pressure sensors are highly susceptible to exceeding their ultimate overload threshold, leading to irreversible plastic yielding or even brittle fracture of the elastic body.

[0004] Existing weighing and screening devices often employ active locking mechanisms, such as pyrotechnic devices (e.g., explosive bolts) or motor-driven pin pullers, to lock under load during launch and unlock upon landing. This approach has the following drawbacks:

[0005] Single point of failure risk: Complex locking mechanisms are highly susceptible to cold welding or jamming after exposure to launch vibrations, deep space high vacuum, and extreme alternating temperature differences. If the mechanism fails to move and cannot unlock, the weighing function will completely fail, leading to the failure of the entire mission.

[0006] Secondary impact damage: When pyrotechnic devices are unlocked, they generate a high-frequency, high-volume impact response spectrum. This instantaneous energy release can easily cause secondary physical damage to nearby high-precision micro sensors, precision bearings, and other components.

[0007] Weight and resource costs: The active unlocking mechanism requires additional drive circuits, control cables and telemetry feedback sensors, which consumes the detector's extremely valuable mass resources and significantly increases the complexity of the control system. Summary of the Invention

[0008] The purpose of this invention is to solve the technical problems of existing weighing and screening devices, which often use pyrotechnic devices (such as explosive bolts) or motor-driven pin pullers for active locking mechanisms, which are prone to single-point failure, system complexity, and secondary impact damage. The invention provides a bidirectional overload resistant weighing and screening device and its design method based on micro-clearance nonlinear stiffness mutation.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0010] A bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation is characterized by the following: it includes a screening bearing unit, an intermediate connecting flange, and a support base arranged sequentially from top to bottom, as well as multiple vibration damping springs arranged between the screening bearing unit and the intermediate connecting flange, multiple pressure sensors connecting the intermediate connecting flange and the support base, and multiple limiting central shafts, wherein the number of multiple pressure sensors and multiple limiting central shafts is the same, and they are all evenly arranged along the circumference.

[0011] Each limiting center axis is a stepped columnar structure formed by a bottom cylinder, a middle cylinder, and a top cylinder arranged coaxially in sequence. The bottom cylinder has the largest diameter and a limiting block is provided at its bottom end. The support base is sleeved on the bottom cylinder and is limited by the limiting block. The intermediate connecting flange is sleeved on the middle cylinder and forms a downward pressure overload clearance with the upper surface of the bottom cylinder. The top cylinder has the smallest diameter and is connected to an anti-pull-out fastener, which forms a tensile overload clearance with the upper surface of the intermediate connecting flange.

[0012] The size of the under-pressure overload clearance satisfy: ;

[0013] The size of the tensile overload clearance satisfy: ;

[0014] in, This indicates the maximum normal underpressure deformation of the pressure sensor under full-scale rated load. This represents the compressive limit deformation of the elastic body inside the pressure sensor when it undergoes plastic yielding or irreversible physical failure. Indicates the margin for overload protection. This represents the limiting deformation at which the elastic body inside the pressure sensor undergoes tensile fracture. This indicates the allowance for tensile overload protection.

[0015] Furthermore, the screening support unit includes a material receiving device and a screening structure disposed in the material receiving device; the bottom of the material receiving device is fixedly connected to the upper ends of a plurality of vibration damping springs.

[0016] Furthermore, the damping spring is provided with a guide post. The lower end of the guide post is fixed to the intermediate connecting flange, and the upper end extends upward and is inserted into the guide hole opened at the bottom of the screening bearing unit with clearance fit, so as to prevent the damping spring from becoming unstable and tilting when it is compressed or subjected to lateral vibration.

[0017] Furthermore, the number of pressure sensors and limiting center shafts is at least three.

[0018] Furthermore, it also includes a micron-level precision adjustment mechanism;

[0019] The micron-level precision adjustment mechanism is located between the lower platform of the support base and the limiting block. It is used to adjust the overall height of the limiting center shaft, thereby eliminating machining errors and ensuring the absolute consistency of the downward overload clearance of each limiting center shaft.

[0020] Furthermore, the micron-level precision adjustment mechanism is a high-precision adjustment shim.

[0021] Furthermore, a radial clearance is formed between the intermediate connecting flange and the central cylinder, and a flexible guide sleeve with a low coefficient of friction is provided within the radial clearance;

[0022] A micro-damping contact layer is provided on each step surface of the limiting center shaft, and the material of the micro-damping contact layer is polyimide or hard rubber.

[0023] Furthermore, the flexible guide sleeve is made of polytetrafluoroethylene (PTFE).

[0024] This invention also provides a design method for a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation, characterized by the following steps:

[0025] Step 1: Determine the maximum normal downward pressure deformation of the pressure sensor under full-scale rated load using original manufacturer calibration data and mechanical testing. The compressive limit deformation of the internal elastic body when it undergoes plastic yielding or irreversible physical failure. and the limiting deformation of the internal elastomer during tensile fracture. ;

[0026] Step 2: Determine the overload protection margin of the pressure sensor. Tensile overload protection margin ;

[0027] Step 3: Design the limiting center shaft and assemble the limiting center shaft;

[0028] Step 4: Combine the parameters determined in Step 1 and Step 2 to adjust the tensile overload clearance and the compressive overload clearance, and obtain the bidirectional anti-overload weighing and screening device based on the nonlinear stiffness mutation of the micro-clearance.

[0029] Furthermore, step 4 also includes applying a MoS2 solid lubricant coating to the stepped surface of the limiting center shaft.

[0030] In step 4, the coefficient of linear expansion of the materials of the limiting center shaft and the anti-pull-out fastener is similar to that of the pressure sensor body material. Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] (1) Extremely high reliability: The design is a purely passive mechanical clearance structure, which does not require electrical control commands or pyrotechnic actions, and completely eliminates the risk of single-point failure such as cold welding and jamming in high vacuum environment.

[0032] (2) Compact and weight-reducing: The limiting center shaft, the intermediate connecting flange, and the anti-pull-out fastener form a limiting component and are integrated with the pressure sensor, eliminating the need for an independent locking mechanism and its drive control unit, which greatly reduces the volume and weight cost.

[0033] (3) No secondary impact: The gap closing process is smooth and there is no explosive energy release, avoiding impact damage to nearby precision components caused by active unlocking action.

[0034] (4) Measurement and protection are unified: Through the precise design of clearance size, the high-precision measurement path and the extreme load bypass path are decoupled at the physical level, while meeting the requirements of microgravity weighing and strong impact protection. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an embodiment of the bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation of the present invention;

[0036] Figure 2 This is a schematic diagram of the under-pressure overload clearance and the tensile overload clearance in an embodiment of a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to the present invention.

[0037] In the figure, 1-screening bearing unit; 2-vibration damping spring; 3-intermediate connecting flange; 4-pressure sensor; 5-limiting center shaft; 6-support base; 7-anti-pull-out fastener; 8-tensile overload clearance; 9-downward overload clearance. Detailed Implementation

[0038] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0039] like Figure 1 As shown, this embodiment provides a bidirectional overload-resistant weighing and screening device based on micro-clearance nonlinear stiffness mutation. It is a passive bidirectional overload protection and weighing and screening device with zero action and zero single-point failure. It includes a screening bearing unit 1, an intermediate connecting flange 3, and a support base 6 arranged sequentially from top to bottom. It also includes multiple damping springs 2 disposed between the screening bearing unit 1 and the intermediate connecting flange 3, at least three pressure sensors 4 connecting the intermediate connecting flange 3 and the support base 6, and at least three limiting central shafts 5. Through this parallel layout, the system can physically decouple the high-precision measurement path from the rigid bypass path of extreme environmental loads.

[0040] The screening support unit 1 includes a material receiving device and a screening structure disposed within the material receiving device; the bottom of the material receiving device is fixedly connected to the upper ends of multiple damping springs 2. To prevent the damping springs 2 from becoming unstable and tilting when subjected to pressure or lateral vibration, a guide post is also provided inside the damping spring 2 in this embodiment. The lower end of the guide post is fixed to the intermediate connecting flange 3, and the upper end extends upward and is inserted into the guide hole opened at the bottom of the screening support unit 1 with clearance fit. When subjected to pressure or lateral vibration, the damping spring 2 will not become unstable and tilted along its extension direction.

[0041] like Figure 2 As shown, each limiting center shaft 5 is a three-step column formed by the coaxial arrangement of a bottom cylinder, a middle cylinder, and a top cylinder. A micro-damping contact layer is provided on each step surface of the limiting center shaft 5. The material of the micro-damping contact layer is a thin layer of polyimide or hard rubber. This micro-damping contact layer can effectively absorb the high-frequency impact spectrum energy generated by hard collision at the moment the gap closes, preventing the delamination and damage of the small strain gauges inside the sensor caused by high-frequency vibration. The bottom cylinder has the largest diameter and a limit block at its bottom. The support base 6 is fitted onto the bottom cylinder and is limited by the limit block. A micron-level precision adjustment mechanism is set between the lower surface of the support base 6 and the limit block. During assembly, the overall height of the limiting center shaft 5 is adjusted by the micron-level precision adjustment mechanism to eliminate machining errors and ensure the absolute consistency of the downward overload clearance of each group above. The intermediate connecting flange 3 is fitted onto the middle cylinder. A flexible guide sleeve with a low friction coefficient is set in the radial clearance formed between the intermediate connecting flange 3 and the middle cylinder. The flexible guide sleeve is made of polytetrafluoroethylene (PTFE). The intermediate connecting flange 3 and the upper surface of the bottom cylinder form a downward overload clearance 9. The top cylinder has the smallest diameter and is connected to an anti-pull-out fastener 7. The anti-pull-out fastener 7 and the upper surface of the intermediate connecting flange 3 form a tensile overload clearance 8.

[0042] The dynamic stiffness mutation and bidirectional bypass working mechanism of the bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation during operation in this embodiment is as follows:

[0043] Lunar stable weighing mode (linear load-bearing): Under static or lunar microgravity operating conditions, the weight of the screening and bearing unit 1 carrying the material is completely pressed onto the pressure sensor 4 via the damping spring 2 and the intermediate connecting flange 3. The maximum normal downward deformation of the pressure sensor 4 under full-scale rated load is defined as... (For example, a miniature pressure sensor with a full-scale range of 5 kg is selected, its) (Approximately 0.1mm). To ensure no mechanical interference occurs during normal weighing, the dimension of the underload overload clearance 9 is [not specified]. It must be strictly greater than this value, that is In this state, the limiting center shaft 5 and the anti-pull-out fastener 7 are completely suspended. The overall rigidity of the measurement system composed of the intermediate connecting flange 3, pressure sensor 4, and support base 6 is equal to the rigidity of the pressure sensor 4, ensuring high-precision weight signal output.

[0044] This embodiment defines the physical failure boundary of a bidirectional overload-resistant weighing and screening device based on micro-clearance nonlinear stiffness mutation:

[0045] The complexity of the deep space environment requires the measurement system to have a well-defined impact resistance boundary. The limiting deformation under downward pressure that causes the internal elastic body of pressure sensor 4 to undergo plastic yielding or irreversible physical failure is defined as follows: (For example, when the ultimate compressive overload threshold of pressure sensor 4 is 200%, its physical deformation will cause damage.) (Approximately 0.2 mm); similarly, the limiting deformation at which tensile fracture occurs is defined as... (For example, when the pressure sensor 4 reaches its ultimate tensile overload threshold of 300%, its physical deformation will cause damage.) (Approximately 0.3 mm). In this embodiment, the design principle of the clearance core is to precisely position its closure point between the "normal weight deformation" and the "ultimate destructive deformation".

[0046] In this embodiment, a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation is in the launch-downward pressure overload protection mode (compression stiffness mutation):

[0047] When subjected to a strong downward transient overload such as a sinusoidal or random vibration, pressure sensor 4 undergoes elastic compression. The downward compression reaches the size of the downward overload clearance 9. At that moment, the bottom surface of the intermediate connecting flange 3 rigidly abuts against the upper stepped surface of the bottom cylinder of the limiting center shaft 5. Considering that structural yielding and dynamic overshoot are inevitable during a rigid collision, this embodiment introduces a downward overload protection margin. (That is, taking the deformation corresponding to a certain percentage of the ultimate failure value, for example, taking...) =0.05 mm). Therefore, the size of the underload overload clearance 9 is strictly defined as: (For example, take) (0.15mm). After the bottom surface of the intermediate connecting flange 3 comes into contact with the upper surface of the bottom cylinder of the limiting center shaft 5, the local stiffness increases instantaneously, and the subsequent destructive load is directly bypassed and unloaded to the support base 6, and the pressure sensor 4 is absolutely isolated in the safe area.

[0048] In this embodiment, a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation is in the launch pull-out overload protection mode (tensile stiffness mutation):

[0049] When the bidirectional overload-resistant weighing and screening device encounters reverse rebound or lateral coupling causing an upward tearing tendency, the tiny elastomer inside the pressure sensor 4 faces the risk of being broken. When the upward deformation reaches the size of the tensile overload clearance 8... At this time, the top surface of the intermediate connecting flange 3 and the bottom surface of the anti-pull-out fastener 7 are rigidly fitted together. Similarly, to absorb the overshoot during high-frequency rebound, this embodiment introduces a tensile overload protection margin. (That is, taking the deformation corresponding to a certain percentage of the ultimate failure value, for example, taking...) =0.25 mm). Therefore, the tensile overload clearance is strictly defined as (For example, take) (0.25 mm). After bonding, the anti-pull-out fastener 7 acts as an upward counter-pull force lever, completely cutting off the tension path of the pressure sensor 4 and effectively preventing it from breaking during high-speed impact.

[0050] In a preferred embodiment, to balance the compactness of the design with the absolute safety of the weighing, this comprehensive protection margin is typically set to the sensor's limit of physical damage deformation (…). or 15% to 30% of the limiting deformation. For example, when the limiting deformation... When the thickness is 0.2mm, the allowance is taken as a whole. The thickness is 0.03mm to 0.06mm (preferably 0.05mm), thus creating a perfect fault-tolerant closed loop between the theoretical model and engineering practice.

[0051] In this embodiment, to ensure highly reliable deployment in complex engineering environments, the following components are designed into the device:

[0052] 1. Axial Coplanarity Adjustment Design: To address the coplanarity errors that can easily occur when multiple sets of limiting components are installed in parallel, a micron-level precision adjustment mechanism (such as high-precision adjusting shims) is installed between the lower platform of the support base 6 and the limiting block. This mechanism eliminates machining and assembly tolerances, ensuring the absolute consistency of the underload clearance 9 of each set, and preventing the premature crushing of the pressure sensor on one side due to uneven force under transient impact.

[0053] 2. Radial Shear Resistance and Decoupling Design: To address the strong lateral vibration conditions during spacecraft launch, a flexible guide sleeve with a low coefficient of friction (such as PTFE) is installed within the radial clearance between the intermediate connecting flange (3) and the limiting center shaft (5). This design not only provides radial hard limiting during severe lateral oscillations, protecting the planar pressure sensor with extremely weak shear resistance, but also eliminates mechanical friction during axial movement, ensuring high-fidelity output and zero mechanical interference of the weighing signal under lunar microgravity conditions.

[0054] This embodiment also discloses a design method for a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation, including the following steps:

[0055] Step 1: Determine the maximum normal compressive deformation of pressure sensor 4 under full-scale rated load, the compressive limit deformation of the internal elastic body under plastic yielding or irreversible physical failure, and the limit deformation of the internal elastic body under tensile fracture through original factory calibration data and mechanical testing; or for customized pressure sensors, extract the elastic limit point and fracture point from the load-displacement curve through finite element analysis combined with static tensile-compression failure calibration tests of physical prototypes to determine them by actual measurement.

[0056] Step 2: Determine the downward overload protection margin and the tensile overload protection margin of pressure sensor 4; in this embodiment, the multi-physics coupling tolerance allocation is based on the service environment of the aerospace payload. Specifically, the margin values ​​comprehensively consider the boundary conditions in the following three dimensions:

[0057] Machining and assembly tolerances ( Considering the machining accuracy of the intermediate connecting flange 3 and the limiting center shaft 5 (such as IT6-IT7 grade tolerance) and the coplanarity error when multiple sets of limiting columns are assembled in parallel, a geometric allowance for the foundation needs to be allocated, usually in the micrometer range.

[0058] Thermal strain compensation under extreme temperature differences ( The lunar surface and deep space flight processes involve drastic alternating temperature differences. Due to the difference in the coefficients of linear expansion between the limiting center shaft 5, the anti-pull-out fastener 7 (such as aluminum alloy or titanium alloy), and the body of the pressure sensor 4 (such as stainless steel), a slight difference in axial thermal deformation will occur under extreme high and low temperatures. This difference is fully included in the protection margin to prevent thermal stress from encroaching on the clearance and causing the system to mis-contact or jam.

[0059] Dynamic overshoot under high transient impact ( When subjected to impact response spectra such as those experienced during spacecraft separation or landing, the rigid metal contact will result in structural yielding and transient elastic oscillations. Through structural dynamic transient response analysis, the peak value of this overshoot displacement is extracted and factored in.

[0060] Comprehensive margin calibration: The final overload protection margin is calculated using the root mean square or worst-case linear superposition method for the above error components. With tensile overload protection margin .

[0061] Step 3: Design the limiting center shaft 5 and assemble the limiting center shaft 5;

[0062] Step 4: Combine the parameters determined in Step 1 and Step 2 to adjust the tensile overload clearance 8 and the compressive overload clearance 9 to obtain a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation.

[0063] To meet the stringent deep-space environment adaptability requirements of spacecraft, this embodiment uses the following material matching:

[0064] The linear expansion coefficients of the materials of the limiting center shaft 5 and the anti-pull-out fastener 7 are similar to those of the body material of the pressure sensor 4, which offsets the thermal deformation difference under the extreme alternating temperature difference in deep space and eliminates the risk of mechanism jamming caused by thermal stress offsetting the micron-level protective clearance.

[0065] To prevent fretting wear and cold welding adhesion under long-term launch compression and deep space high vacuum environment, the stepped surface of the limiting center shaft 5 is treated with MoS2 solid lubricant coating.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation, characterized in that: It includes a screening bearing unit (1), an intermediate connecting flange (3), a support base (6) arranged from top to bottom, and multiple damping springs (2) arranged between the screening bearing unit (1) and the intermediate connecting flange (3), multiple pressure sensors (4) connecting the intermediate connecting flange (3) and the support base (6), and multiple limiting center shafts (5). The number of multiple pressure sensors (4) and multiple limiting center shafts (5) is the same, and they are all evenly arranged along the circumference. Each limiting center shaft (5) is a stepped columnar structure formed by the coaxial arrangement of a bottom cylinder, a middle cylinder, and a top cylinder. The bottom cylinder has the largest diameter and a limiting block is provided at its bottom end. The support base (6) is sleeved on the bottom cylinder and is limited by the limiting block. The intermediate connecting flange (3) is sleeved on the middle cylinder and forms a downward pressure overload clearance (9) with the upper surface of the bottom cylinder. The top cylinder has the smallest diameter and is connected to an anti-pull-out fastener (7). The anti-pull-out fastener (7) forms a tensile overload clearance (8) with the upper surface of the intermediate connecting flange (3). The size of the under-pressure overload clearance (9) satisfy: ; The size of the tensile overload clearance (8) satisfy: ; in, This indicates the maximum normal underpressure deformation of the pressure sensor (4) under full-scale rated load. This indicates the compressive limit deformation of the internal elastic body of the pressure sensor (4) when it undergoes plastic yielding or irreversible physical failure. Indicates the margin for overload protection. This indicates the limiting deformation of the internal elastic body of the pressure sensor (4) to undergo tensile fracture. This indicates the allowance for tensile overload protection.

2. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation as described in claim 1, characterized in that, The screening support unit (1) includes a material receiving device and a screening structure disposed in the material receiving device; the bottom of the material receiving device is fixedly connected to the upper end of a plurality of vibration damping springs (2).

3. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 1, characterized in that, The damping spring (2) is provided with a guide post. The lower end of the guide post is fixed on the intermediate connecting flange (3), and the upper end extends upward and is inserted into the guide hole opened at the bottom of the screening bearing unit (1) with clearance fit. This is to prevent the damping spring (2) from becoming unstable and tilting when it is compressed or subjected to lateral vibration.

4. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 1, characterized in that, The number of pressure sensors (4) and limiting center shafts (5) is at least three.

5. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 1, characterized in that, It also includes a micron-level precision adjustment mechanism; The micron-level precision adjustment mechanism is set between the lower platform of the support base (6) and the limiting block to adjust the overall height of the limiting center shaft (5), thereby eliminating machining errors and ensuring the absolute consistency of the downward overload clearance (9) of each limiting center shaft (5).

6. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 5, characterized in that, The micron-level precision adjustment mechanism is a high-precision adjustment shim.

7. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 1, characterized in that, A radial clearance is formed between the intermediate connecting flange (3) and the central cylinder, and a flexible guide sleeve with a low friction coefficient is provided in the radial clearance. A micro-damping contact layer is provided on each step surface of the limiting center shaft (5), and the material of the micro-damping contact layer is polyimide or hard rubber.

8. The bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 7, characterized in that, The flexible guide sleeve is made of polytetrafluoroethylene (PTFE).

9. A design method for a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Determine the maximum normal underpressure deformation of the pressure sensor (4) under full-scale rated load by using the original manufacturer's calibration data and mechanical testing. The compressive limit deformation of the internal elastic body when it undergoes plastic yielding or irreversible physical failure. and the limiting deformation of the internal elastomer during tensile fracture. ; Step 2: Determine the overload protection margin of the pressure sensor (4). Tensile overload protection margin ; Step 3: Design the limiting center shaft (5) and assemble the limiting center shaft (5); Step 4: Combine the parameters determined in Step 1 and Step 2 to adjust the tensile overload clearance (8) and the compressive overload clearance (9) to obtain a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation.

10. The design method of a bidirectional anti-overload weighing and screening device based on micro-clearance nonlinear stiffness mutation according to claim 9, characterized in that, Step 4 also includes applying a MoS2 solid lubricant coating to the stepped surface of the limiting center shaft (5); In step 4, the linear expansion coefficient of the materials of the limiting center shaft (5) and the anti-pull-out fastener (7) is similar to that of the body material of the pressure sensor (4).

Images