Macro-micro cross-scale analysis method for tribological performance of elevator safety gear

Abstract

The application discloses a kind of macro-microscopic cross-scale analysis method of elevator safety gear tribology, the application relates to safety gear tribology analysis technical field, comprising the following steps: constructing the three-dimensional finite element model of the contact surface of elevator safety gear to be detected and guide rail, and obtaining operating braking condition parameters as input, the pressure time series data of safety gear and guide rail contact surface are analyzed by model.Based on pressure time series data, construct macro transient temperature model, simulate contact surface time-varying temperature data, and dynamically correct local friction coefficient.The corrected friction coefficient is fed back to the model, and the time-varying temperature field is updated.Temperature field and pressure data are analyzed using Archard's law, and the micro-wear depth is calculated and the failure risk area is selected.Finally, by braking decay coefficient, the wear depth of failure risk area is comprehensively judged to detect the friction performance of elevator safety gear, realize the accurate evaluation and prediction of elevator safety gear performance.

Description

Technical Field

[0001] This invention relates to the field of tribological analysis technology for elevator safety clamps, specifically a macro-micro cross-scale analysis method for the tribological performance of elevator safety clamps. Background Technology

[0002] In modern elevator systems, the safety brake is a critical safety component. Its main function is to quickly brake and stabilize the elevator in the event of an accident, ensuring passenger safety. However, with increased use, the friction and wear between the safety brake and the guide rails gradually intensifies. This not only affects the elevator's braking performance but may also lead to potential safety hazards.

[0003] Traditional tribological analysis methods often assess friction coefficients and wear through static experiments or simple dynamic tests. However, these methods fail to fully understand the complex mechanical and thermal environments experienced by the contact surface between the safety gear and the guide rail under actual operating conditions. Especially during braking, the impact of high pressure generated at the contact surface and transient temperature changes caused by friction on the friction coefficient is not adequately considered. Furthermore, existing wear assessment methods largely rely on static or historical data, lacking real-time and dynamic feedback mechanisms, making it difficult to accurately assess the failure risk of the safety gear. In addition, traditional wear models typically assume a constant friction coefficient, failing to make real-time corrections, leading to significant errors in assessing wear depth and failure risk. Therefore, there is an urgent need for an analytical method that comprehensively considers the multiphysics interactions between the elevator safety gear and the guide rail contact surface during dynamic operation, enabling comprehensive monitoring and accurate assessment of elevator safety gears.

[0004] In the prior art, CN119397847A discloses a macro-micro cross-scale analysis method for the tribological performance of wind turbine main shaft sliding bearings. Specifically, the macro-model is established based on the actual structure of the wind turbine main shaft sliding bearing, equivalent to a three-layer structure of rigid bearing base—elastic surface support layer—main shaft. The micro-model focuses on the lubrication state at the friction pair boundary, establishing a three-layer micro-molecular model characterizing "main shaft-lubricating oil-elastic support layer". The macro-model changes the thickness of the support layer, while the micro-model changes the composition of the support layer material. The macro-micro cross-scale analysis model analyzes the friction coefficient of the tribological interface under different support layer thicknesses and material compositions to obtain the optimal thickness and optimal material composition ratio suitable for the service conditions of wind turbine main shaft sliding bearings. This scheme determines the optimal parameters for the service conditions of wind turbine main shaft sliding bearings through comprehensive analysis of macro and micro models. However, this scheme only builds models based on static data and does not involve a dynamic feedback mechanism. Furthermore, the tribological performance of wind turbine main shaft sliding bearings is inconsistent with the tribological performance requirements of elevator safety clamps; therefore, the tribological performance of elevator safety clamps cannot be determined using the same analysis method.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a macro-micro cross-scale analysis method for the tribological properties of elevator safety clamps, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A macro- and micro-scale cross-scale analysis method for the tribological properties of elevator safety clamps, comprising the following steps:

[0009] A three-dimensional finite element model of the contact surface between the elevator safety gear and the guide rail is constructed. At the same time, the operating braking condition parameters of the elevator safety gear are obtained. The operating braking condition parameters are used as input to the three-dimensional finite element model. The pressure time series data of the contact surface between the safety gear and the guide rail during operation are analyzed through the three-dimensional finite element model.

[0010] Based on pressure time series data and operating braking condition parameters, a macroscopic transient temperature model is constructed. The macroscopic transient temperature model is used to simulate the time-varying temperature data of the contact surface between the safety clamp and the guide rail during elevator braking, and the local friction coefficient of the contact surface between the safety clamp and the guide rail is dynamically corrected based on the time-varying temperature data.

[0011] The corrected local friction coefficient is fed back and evolved to replace the initial dynamic friction coefficient in the macroscopic transient temperature model, and the time-varying temperature data of the contact surface between the safety clamp and the guide rail is updated to form a time-varying temperature field.

[0012] Based on the analysis of time-varying temperature field and pressure time series data using Arcard's law, the micro wear depth was calculated, the micro critical failure threshold was set, and the wear depth of each area of ​​the contact surface between the safety clamp and the guide rail was traversed to screen out the failure risk area.

[0013] The vibration characteristics of the elevator under test during the current braking process are obtained. The braking fade coefficient is characterized by the vibration characteristics. The friction performance of the elevator safety gear is judged by combining the braking fade coefficient with the wear depth of the failure risk zone. Based on the judgment results, corresponding usage opinions are issued.

[0014] Furthermore, the specific steps for constructing the three-dimensional finite element model of the contact surface between the elevator safety gear and the guide rail are as follows: obtaining the current feature information of the elevator safety gear and the guide rail, including size, shape and material properties; establishing a three-dimensional geometric model based on the size, shape and material properties of the elevator safety gear and the guide rail; selecting finite element analysis software; importing the three-dimensional geometric model into the finite element analysis software; meshing the contact surface between the safety gear and the guide rail in the three-dimensional finite element model; and applying corresponding operating braking parameters to the three-dimensional finite element model according to the elevator's working conditions.

[0015] The specific operating and braking parameters mentioned above include the elevator's operating gravity load, the elevator's initial braking speed, the density of the safety clamp material, the specific heat capacity of the safety clamp material, and the thermal conductivity of the safety clamp material.

[0016] The method of simulating the operation process through finite element analysis and collecting pressure time-series data of each grid on the contact surface between the safety clamp and the guide rail specifically includes: applying boundary conditions to the three-dimensional finite element model, determining the fixed end or support point, defining the force and its direction applied to the safety clamp according to the gravity load of the elevator operation, setting the acquisition time step, collecting the pressure time-series data of each grid on the contact surface between the safety clamp and the guide rail during the simulated braking process through the set acquisition time step, and recording the corresponding timestamp.

[0017] Furthermore, based on pressure time-series data and operating braking condition parameters, a macroscopic transient temperature model is constructed. The specific expression used by the macroscopic transient temperature model to calculate time-varying temperature data is as follows:

[0018] ;

[0019] In the formula, For the material density of the safety clamp, For the specific heat capacity of the safety clamp material, At the i-th grid point on the contact surface between the safety clamp and the guide rail, Time-varying temperature data at any given moment. For divergence operators, for The thermal conductivity of the safety clamp material at all times. The temperature gradient between the contact surface of the safety clamp and the guide rail. For the i-th grid, in The time-varying frictional heat source generated by constant friction, where t is the time variable during the simulated braking process of the elevator. For time intervals;

[0020] Wherein, the i-th grid, in Time-varying frictional heat source generated by constant friction Specifically, this is characterized by the elevator braking speed and the coefficient of friction between the safety clamp and the guide rail contact surface. The specific formula used for calculation is as follows:

[0021] ;

[0022] In the formula, Let be the corrected local friction coefficient of the i-th mesh at time t. For the i-th grid, the normal pressure at time t is specifically represented by the pressure time-series data at the corresponding timestamp. Let i be the area of ​​the i-th grid. Let be the elevator braking speed at time t, where i is the index of the grid on the contact surface between the safety clamp and the guide rail. , This represents the total number of grid cells.

[0023] In the formula, Let be the corrected local friction coefficient of the i-th mesh at time t. For the i-th grid, the normal pressure at time t is specifically represented by the pressure time-series data at the corresponding timestamp. Let i be the contact area of ​​the i-th grid. Let be the elevator braking speed at time t, where i is the index of the grid on the contact surface between the safety clamp and the guide rail. , This represents the total number of grid cells.

[0024] Furthermore, the time-varying temperature data is mapped to the contact surface to dynamically correct the local friction coefficient of the contact surface between the safety clamp and the guide rail. The formula used for the dynamic correction calculation is as follows:

[0025] ;

[0026] In the formula, For the i-th grid, in The local friction coefficient at time t. For time t, the time-varying temperature data at the i-th grid is... Indicates in At time i, the corrected local friction coefficient of the i-th mesh is... For reference to ambient temperature, The melting point temperature of the safety clamp material. This represents the initial moment during the simulated braking process of the elevator. The softening coefficient of the material is obtained specifically through temperature gradient data of the contact surface between the safety clamp and the guide rail.

[0027] Furthermore, the time-varying temperature data of the contact surface between the safety clamp and the guide rail is updated to form a time-varying temperature field. Specifically, the corrected local friction coefficient is applied to each grid of the contact surface between the safety clamp and the guide rail, generating a new friction coefficient field. The macroscopic transient temperature model is dynamically run using the local friction coefficients recorded in the friction coefficient field to calculate heat conduction and frictional heat, obtaining new time-varying temperature data. This new time-varying temperature data is recorded and stored, generating the time-varying temperature field. The local friction coefficient is dynamically corrected using the temperature data in the time-varying temperature field. This process is repeated until the entire elevator braking simulation process is completed, at which point the entire elevator braking simulation process is terminated. The time-varying temperature field includes the time-varying temperature data of each grid within the contact surface between the safety clamp and the guide rail at different times during the entire elevator braking simulation process; and the time when the entire elevator braking simulation process is terminated is recorded as the termination time. .

[0028] Furthermore, the time-varying temperature field and pressure time-series data are embedded with the modified Arcard law to calculate the micro-wear depth. The specific formula used to calculate the micro-wear depth is as follows:

[0029] ;

[0030] In the formula, In order to be in At time i, the microscopic wear depth of the i-th grid. The wear coefficient of the safety clamp base. For temperature sensitivity coefficient, for Braking speed at any moment From the initial moment of the elevator braking simulation to The time variable within a given moment, This is the wear reference temperature. The temperature-dependent hardness of the safety clamp material at time t;

[0031] The temperature-dependent hardness of the safety clamp material The specific formula used for the calculation is as follows:

[0032] ;

[0033] In the formula, The room temperature hardness of the safety clamp material. For the softening slope of the safety clamp material, This refers to the glass transition temperature of the safety clamp material.

[0034] Furthermore, the specific logic used to identify the failure risk zone is as follows:

[0035] After terminating the entire elevator braking simulation process, the micro-wear depth If the mesh is found to be severely worn, it is marked as a failure risk zone.

[0036] After terminating the entire elevator braking simulation process, the micro-wear depth If the wear of the mesh is deemed to meet the requirements, the mesh will be excluded from further analysis. This is the microscopic critical failure threshold.

[0037] Furthermore, the vibration characteristic information includes vibration amplitude and vibration frequency. The braking fade coefficient is characterized by this vibration characteristic information, and the specific formula used to calculate the braking fade coefficient is as follows:

[0038] ;

[0039] In the formula, This is the braking fade coefficient. This refers to the amplitude of elevator vibration. This is the reference amplitude for elevator vibration. The frequency of elevator vibration. The elevator vibration reference frequency, and These are the weighting coefficients for vibration amplitude and vibration frequency, respectively. and and All are greater than 0;

[0040] The friction performance of the elevator safety gear under test is comprehensively judged by combining the braking fade coefficient with the wear depth of the failure risk zone, and corresponding usage opinions are issued based on the judgment results. The specific logic is as follows:

[0041] when and If the friction performance of the safety brake of the elevator under test is poor and the brake fade is at level one, the elevator under test should be taken out of service and the safety brake should be replaced.

[0042] when and If the friction performance of the elevator safety brake is good, and the brake fade is at level one, further investigation into the cause of the elevator vibration should be conducted.

[0043] when and When the condition is as described, it indicates that the friction performance of the elevator safety gear under test is good, and the braking fade condition is level two. The safety gear should be repaired in a timely manner.

[0044] when and When the value is 0, it indicates that the friction performance of the elevator safety brake under test is excellent, the braking fade is level three, and the braking performance of the elevator under test meets the requirements.

[0045] in, and These represent the braking fade threshold and the wear risk threshold, respectively. In order to be in At any given moment, the average micro-wear depth of the failure risk zone.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] First, by applying a three-dimensional finite element model, the pressure changes on the contact surface during elevator operation can be captured in real time, thereby accurately simulating the corresponding transient temperature changes, providing a more reliable basis for assessing wear depth.

[0048] Secondly, the introduction of the dynamic feedback mechanism makes the correction of the local friction coefficient no longer static, but reflects the changes in friction conditions during elevator operation in real time. By feeding the corrected local friction coefficient back to the macroscopic transient temperature model to replace the initial dynamic friction coefficient, this feedback evolution mechanism makes the update of the friction coefficient interact with the changes in the temperature field, forming a cyclic adjustment, which improves the accuracy and reliability of the model.

[0049] Finally, based on the combination of modified Arcard's law and time-varying temperature field, the calculation of micro wear depth is made more precise, and different wear stages can be fed back in a timely manner according to the friction coefficient, providing a scientific basis for the safe operation of elevators. Furthermore, by monitoring vibration characteristic information, the braking fade coefficient of elevators can be effectively characterized, and the accurate prediction of braking performance can be achieved by combining micro wear depth, thus providing strong support for maintenance decisions. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall method flow of the present invention;

[0051] Figure 2 This is a temperature distribution diagram of each grid on the contact surface between the safety clamp and the guide rail;

[0052] Figure 3 A map showing the mapping between grid temperature and wear depth;

[0053] Figure 4 This is a curve showing the relationship between grid temperature and wear depth. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0055] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0056] Example:

[0057] Please see Figures 1-4 The present invention provides a technical solution:

[0058] A macro- and micro-scale cross-scale analysis method for the tribological properties of elevator safety clamps, comprising the following steps:

[0059] Step 1: Construct a three-dimensional finite element model of the contact surface between the elevator safety gear and the guide rail, and simultaneously obtain the operating braking parameters of the elevator safety gear. Use the operating braking parameters as input to the three-dimensional finite element model, and analyze the pressure time series data of the contact surface between the safety gear and the guide rail during operation through the three-dimensional finite element model.

[0060] The specific steps for constructing a 3D finite element model of the contact surface between the elevator safety clamp and the guide rail are as follows: Obtain the current feature information of the elevator safety clamp and guide rail, including size, shape, and material properties. Based on this information, establish a 3D geometric model. The specific steps for establishing the 3D geometric model include: selecting suitable CAD software, such as SolidWorks, AutoCAD, CATIA, or Fusion 360, and drawing sketches in the software using the obtained dimensional information. For both the safety clamp and the guide rail, draw their cross-sectional sketches. Based on the sketches, use the Extrude or Revolve functions to generate the 3D shape. For complex shapes, functions such as cutting, chamfering, and filleting can be used for modification.

[0061] Choose a finite element analysis software and import the 3D geometric model into it. For example, ANSYS is a widely used finite element analysis software in the industry, which provides powerful simulation functions and is suitable for various analyses such as thermal, structural, and fluid analysis. It supports the modeling and analysis of complex geometries and has a rich material database and advanced solvers. Alternatively, Abaqus is particularly suitable for nonlinear analysis and simulation of complex material behavior, and provides powerful modeling and post-processing tools, making it suitable for complex engineering problems.

[0062] Mesh the contact surface between the safety clamp and the guide rail in the three-dimensional finite element model, and apply the corresponding running braking parameters to the three-dimensional finite element model according to the elevator's working conditions.

[0063] The specific operating and braking parameters mentioned above include the elevator's operating gravity load, the elevator's initial braking speed, the density of the safety clamp material, the specific heat capacity of the safety clamp material, and the thermal conductivity of the safety clamp material.

[0064] The gravity load of the elevator refers to the weight generated by the elevator and its load, which can be directly measured by weighing equipment when the elevator is fully loaded and unloaded; the initial braking speed of the elevator is monitored in real time by a speed sensor during actual elevator operation.

[0065] The specific methods for obtaining the material density, specific heat capacity, and thermal conductivity of safety clamps are as follows: Consult material data sheets to determine the density of materials such as steel and aluminum alloys. Commonly used material data sheets or databases, such as ASM Handbook and MatWeb, provide relevant information. Find the specific heat capacity data for the relevant materials. Common engineering material data books or online databases, such as CRC and MatWeb, provide reference values. Similar to specific heat capacity, the thermal conductivity of the relevant materials can be found in engineering material data sheets or databases. The relationship between the thermal conductivity of a specific material and temperature usually needs to be determined experimentally. The thermal conductivity of many materials can be found in relevant material data sheets or literature, providing specific thermal conductivity data at different temperatures.

[0066] The method for simulating the operation process through finite element analysis and collecting pressure time-series data of each grid on the contact surface between the safety gear and the guide rail specifically includes: applying boundary conditions to the three-dimensional finite element model, determining the fixed end or support point, defining the force applied to the safety gear and its direction based on the gravity load of the elevator operation, setting the acquisition time step, and collecting the pressure time-series data of each grid on the contact surface between the safety gear and the guide rail during the simulated braking process through the set acquisition time step, and recording the corresponding timestamps. In general, for finite element analysis of elevator braking, the time step can be set between 0.001 seconds and 0.01 seconds, depending on the elevator's operating speed and braking characteristics.

[0067] Step 2: Based on pressure time series data and operating braking condition parameters, construct a macroscopic transient temperature model. Simulate the time-varying temperature data of the contact surface between the safety clamp and the guide rail during elevator braking using the macroscopic transient temperature model, and dynamically correct the local friction coefficient of the contact surface between the safety clamp and the guide rail based on the time-varying temperature data.

[0068] ;

[0069] In the formula, For the material density of the safety clamp, For the specific heat capacity of the safety clamp material, At the i-th grid point on the contact surface between the safety clamp and the guide rail, Time-varying temperature data at any given moment. For divergence operators, for The thermal conductivity of the safety clamp material at all times. The temperature gradient between the contact surface of the safety clamp and the guide rail. For the i-th grid, in The time-varying frictional heat source generated by constant friction, where t is the time variable during the simulated braking process of the elevator. The time interval can be set to 1 second; the initial time-varying temperature data of the contact surface between the safety clamp and the guide rail is taken from the ambient temperature of the elevator location.

[0070] Based on the fundamental theory of heat conduction, this equation describes the propagation of heat in materials and the energy transfer caused by temperature changes. It reflects that during elevator braking, the heat generated by friction is absorbed by the material, resulting in temperature changes. It takes into account both the input of energy through frictional heat and the output through heat conduction. Since the temperature change during elevator braking is transient, partial differential equations are used to describe the temperature changes in time and space, which can more accurately simulate the actual situation.

[0071] The left side This section represents the temperature change of a material per unit time due to the absorption or release of heat. This reflects the principle of energy conservation; the temperature change of a system is related to its density, specific heat capacity, and rate of change of heat.

[0072] Among them, the divergence operator Used to describe the distribution and transfer of heat in space. It describes the diffusion of heat in space, reflects the ability of a material to transfer heat, and is related to the material's thermal conductivity and temperature gradient. It represents the thermal conduction effect in a temperature field, which varies with time and space.

[0073] Time-varying frictional heat sources depend on contact pressure, coefficient of friction, and relative velocity. The frictional heat source term represents the heat generated during elevator braking due to the friction between the safety clamp and the guide rail. This term is the main driver of transient temperature changes, reflecting the high-temperature region caused by friction.

[0074] Wherein, the i-th grid, in Time-varying frictional heat source generated by constant friction Specifically, it is characterized by the initial braking velocity of the elevator and the coefficient of friction between the safety clamp and the guide rail contact surface. The specific formula used for calculation is as follows:

[0075] In the formula, Let be the corrected local friction coefficient of the i-th mesh at time t. For the i-th grid, the normal pressure at time t is specifically represented by the pressure time-series data at the corresponding timestamp. Let i be the contact area of ​​the i-th grid. Let be the elevator braking speed at time t, where i is the index of the grid on the contact surface between the safety clamp and the guide rail. , This represents the total number of grid cells.

[0076] This formula calculates the frictional heat of each grid by combining the product of frictional force, friction coefficient, and normal pressure with contact area and velocity. Based on the fundamental principles of tribology, the generation of frictional heat is directly related to the friction coefficient, normal pressure, and relative velocity of the contact surfaces. These three factors effectively quantify the heat generated by friction. During elevator braking, the heat generated by friction affects temperature changes. The formula dynamically expresses the contribution of frictional heat to temperature changes, conforming to the principle of energy conservation. By summing the frictional heat of all grids, the overall frictional heat is obtained, ensuring the comprehensiveness of the model and considering the details and complexity of the contact surfaces.

[0077] The time-varying temperature data is mapped to the contact surface to dynamically correct the local friction coefficient of the contact surface between the safety clamp and the guide rail. The formula used for the dynamic correction calculation is as follows:

[0078] ;

[0079] In the formula, For the i-th grid, in The local friction coefficient at time t. For time t, the time-varying temperature data at the i-th grid is... Indicates in At time i, the corrected local friction coefficient of the i-th mesh is... For reference to ambient temperature, The melting point temperature of the safety clamp material. This represents the initial moment during the simulated braking process of the elevator. The softening coefficient of the material is obtained specifically through temperature gradient data of the contact surface between the safety clamp and the guide rail.

[0080] It should be noted that the local friction coefficient of the i-th mesh at the initial moment... Specifically, based on material properties and the baseline value of friction performance under contact conditions, friction performance generally decreases with increasing temperature. High temperatures cause material softening, thereby reducing the coefficient of friction. Therefore, the formula reflects the negative impact of temperature on the coefficient of friction through exponential decay. With time-varying temperature data Inversely proportional, exponential form The decay function makes the friction coefficient exhibit nonlinear characteristics as a function of temperature, which can more realistically simulate the behavior of materials at high temperatures.

[0081] Temperature difference Used to calculate the degree to which the material's operating temperature exceeds the reference ambient temperature. The higher the temperature, the more significant the correction to the coefficient of friction; material softening coefficient. This parameter is used to quantify the degree of softening of a material as temperature changes, affecting the rate of decrease in the coefficient of friction. Different materials have different softening characteristics, so this parameter will vary from material to material, and its value is generally between 0.001 and 0.5.

[0082] Meanwhile, the ambient temperature is generally 25 degrees Celsius. .

[0083] Step 3: Feedback evolution of the corrected local friction coefficient to replace the initial dynamic friction coefficient in the macroscopic transient temperature model, update the time-varying temperature data of the contact surface between the safety clamp and the guide rail, and form a time-varying temperature field.

[0084] The time-varying temperature data of the contact surface between the safety clamp and the guide rail is updated to form a time-varying temperature field. Specifically, the corrected local friction coefficient is applied to each grid of the contact surface between the safety clamp and the guide rail, generating a new friction coefficient field. The macroscopic transient temperature model is dynamically run using the local friction coefficients recorded in the friction coefficient field to calculate heat conduction and frictional heat, obtaining new time-varying temperature data. This new time-varying temperature data is recorded and stored, generating the time-varying temperature field. The local friction coefficient is dynamically corrected using the temperature data in the time-varying temperature field. This process is repeated until the entire elevator braking simulation is completed, at which point the entire elevator braking simulation is terminated. The time-varying temperature field includes the time-varying temperature data of each grid within the contact surface between the safety clamp and the guide rail at different times during the entire elevator braking simulation. The time at which the entire elevator braking simulation is terminated is recorded as the termination time. .

[0085] Existing technologies typically use fixed friction coefficient values, which may not accurately reflect friction under actual working conditions, leading to inaccurate temperature predictions. Many traditional models do not consider the impact of temperature on the friction coefficient and fail to achieve dynamic updates. This means that under high-temperature conditions, changes in material properties, such as the friction coefficient, cannot be adjusted in a timely manner. Dynamically updating the local friction coefficient can more accurately reflect the true friction between the safety clamp and the guide rail, thereby improving the accuracy of temperature predictions. As the temperature changes during braking, the friction coefficient is also adjusted accordingly, allowing the model to adapt to different working environments in real time, enhancing the robustness and reliability of the system.

[0086] Step 4: Based on Arcard's law, analyze the time-varying temperature field and pressure time series data, calculate the micro wear depth, set the micro critical failure threshold, traverse the wear depth of each area of ​​the contact surface between the safety clamp and the guide rail, and screen out the failure risk area.

[0087] By embedding time-varying temperature field and pressure time-series data into the modified Arcard law, the micro-wear depth is calculated. The specific formula used to calculate the micro-wear depth is as follows:

[0088] ;

[0089] In the formula, In order to be in At time i, the microscopic wear depth of the i-th grid. The wear coefficient of the safety clamp base. For temperature sensitivity coefficient, for Braking speed at any moment From the initial moment of the elevator braking simulation to The time variable within a given moment, This is the wear reference temperature. The temperature-dependent hardness of the safety clamp material at time t;

[0090] It should be noted that, in At time i, the microscopic wear depth of the i-th grid Used to characterize the wear level of safety clamps. The larger the value, the greater the wear depth of the i-th grid, and the more severe the wear of the safety clamp. Meanwhile... Specifically, it refers to the predicted wear depth of the safety gear in a subsequent time period, obtained by simulating the braking of the elevator under test based on the operating braking condition parameters of the safety gear. The subsequent time period specifically refers to the time range from the start to the completion of the braking simulation.

[0091] Many materials soften at high temperatures, resulting in a decrease in hardness. This decrease in hardness means the material is more susceptible to damage during friction, thus increasing the wear rate. At high temperatures, the material surface may undergo oxidation or other chemical reactions, which also contribute to an increased wear rate, further exacerbating wear. Therefore... With micro wear depth Proportional, specifically through This indicates the degree of influence of temperature, where a temperature sensitivity coefficient is introduced when the temperature exceeds the reference value. Adjusting the wear depth reflects the actual impact of temperature on wear; temperature sensitivity coefficient. Specifically, the setup should be done by referring to the safety clamp technical manual and combining it with expert experience.

[0092] Increased contact pressure means increased force per unit contact area. Under high pressure, the contact between material particles becomes tighter, resulting in stronger interaction forces. This makes the material surface more susceptible to plastic deformation or wear. Under high pressure, the material may reach its fatigue limit more quickly, leading to the formation and propagation of microcracks, thus accelerating wear. Therefore, increased contact pressure directly leads to an increased wear rate, which is why pressure is proportional to wear depth in the formula.

[0093] Braking speed The integral reflects the relative distance traveled over a certain time period. The more the objects slide, the greater the wear. The greater the sliding speed, the more intense the relative motion between the objects, and the greater the friction on the contact surfaces. This increase in friction leads to a higher wear rate.

[0094] This formula incorporates the basic idea of ​​Arcard's Law and extends it by introducing temperature and time variables, enabling the model to more accurately reflect the wear process under dynamic conditions. By considering changes in temperature and pressure, the model can better adapt to actual operating conditions, especially during the braking process of equipment such as elevators, where wear is a time-varying process closely related to environmental conditions.

[0095] The temperature-dependent hardness of the safety clamp material The specific formula used for the calculation is as follows:

[0096] ;

[0097] In the formula, The room temperature hardness of the safety clamp material. For the softening slope of the safety clamp material, This refers to the glass transition temperature of the safety clamp material.

[0098] It should be noted that when Exceed At that time, the hardness decreases as the temperature increases. This change is due to... The function describes the nonlinear characteristics of the material softening rate. The function provides a smooth transition when the temperature changes, avoiding abrupt changes in hardness, thus making the model more consistent with reality.

[0099] Safety clamp material softening slope The sensitivity of hardness to temperature changes is affected. A higher value indicates a faster decrease in hardness as temperature rises, thus increasing the risk of wear. (Safety clamp material softening slope) It can be obtained through hardness testing.

[0100] This formula is designed based on the principles of materials science and thermodynamics, taking into account the actual impact of temperature on material properties. Many materials undergo structural and property changes upon heating, especially polymers and composites, whose hardness and strength are affected by temperature. This effect is particularly critical in applications such as safety clamps, where the working environment experiences drastic temperature changes. The glass transition temperature is an important characteristic of many polymers and composites, marking the transition of the material from a hard and brittle state to a soft state. This transition significantly affects the mechanical properties of the material, especially hardness and wear resistance.

[0101] The specific logic used to select the failure risk zone is as follows:

[0102] After terminating the entire elevator braking simulation process, the micro-wear depth If the mesh is found to be severely worn, it is marked as a failure risk zone.

[0103] After terminating the entire elevator braking simulation process, the micro-wear depth If the wear of the mesh is deemed to meet the requirements, the mesh will be excluded from further analysis. The microscopic critical failure threshold is set according to the actual use of the elevator, and is generally set between 5μm and 20μm.

[0104] Step 5: Obtain vibration characteristic information of the current braking process of the elevator under test, characterize the braking fade coefficient through the vibration characteristic information, and comprehensively judge the friction performance of the safety gear of the elevator under test by combining the braking fade coefficient with the wear depth of the failure risk zone, and issue corresponding usage opinions based on the judgment results.

[0105] The vibration characteristic information includes vibration amplitude and vibration frequency, which can be specifically measured by an accelerometer. The accelerometer is used to measure the amplitude and frequency of the vibration. The accelerometer can provide high-precision vibration signals, which are suitable for monitoring the elevator braking process.

[0106] The braking fade coefficient is characterized by vibration characteristics, and the specific formula used to calculate the braking fade coefficient is as follows:

[0107] ;

[0108] In the formula, This is the braking fade coefficient. This refers to the amplitude of elevator vibration. This is the reference amplitude for elevator vibration. The frequency of elevator vibration. The elevator vibration reference frequency, and These are the weighting coefficients for vibration amplitude and vibration frequency, respectively. and and All are greater than 0;

[0109] It should be noted that the braking fade coefficient Used to characterize the decline in elevator braking capacity, indicating the degree of performance degradation of the braking system, with values ​​between 0 and 1, where 1 indicates no decline and 0 indicates complete failure.

[0110] The vibration amplitude of the elevator This reflects the vibration that occurs during elevator braking. Wear reduces braking efficiency, and typically, the vibration amplitude increases after wear. (The formula contains...) This part represents the proportion of the change in vibration amplitude after wear relative to the reference amplitude. If the vibration amplitude after wear... If it increases, this part will be a positive value, representing the braking fade coefficient. The decrease indicates a decline in the performance of the braking system.

[0111] Through the natural logarithm function This technology handles frequency variations and smoothly reflects deviations from the reference value. Larger variations in vibration frequency, and a greater difference between the vibration frequency and the reference frequency, indicate more severe degradation in the elevator's braking performance.

[0112] In elevator braking systems, vibration amplitude Vibration frequency is usually directly related to the friction state and energy loss of the brake. When the brake wears, the decreased friction performance leads to a significant increase in vibration amplitude. Therefore, vibration amplitude is of significant intuitive importance in judging the braking performance of an elevator; vibration frequency... While related to wear, its variation is influenced by various factors, including the system's natural frequency, material properties, and load changes. Frequency variations may reflect nonlinear or complex dynamic characteristics, and their impact on braking performance may be less pronounced than that of amplitude. Therefore, setting... and and All are greater than 0.

[0113] The friction performance of the elevator safety gear under test is comprehensively judged by combining the braking fade coefficient with the wear depth of the failure risk zone, and corresponding usage opinions are issued based on the judgment results. The specific logic is as follows:

[0114] when and When the condition is indicated, it means that the friction performance of the safety brake of the elevator under test is poor and the braking fade is at level one. The elevator under test should be taken out of service and the safety brake should be replaced. Specifically, it means that the current elevator braking vibration is serious, and the safety brake will wear out severely in subsequent use, posing a significant safety hazard and is no longer suitable for continued use.

[0115] when and If the reading is "good", it indicates that the friction performance of the elevator safety brake under test is good, and the brake fade is at level one. Further testing is needed to determine the cause of the elevator's vibration. Specifically, it indicates that the current elevator brake vibration is severe, but the wear of the safety brake is within a controllable range. Further testing is needed to determine whether the vibration is caused by the degradation of friction performance.

[0116] when and When the condition is as described, it indicates that the friction performance of the elevator safety gear under test is good, and the braking fade condition is level two. Specifically, this means that the current elevator braking vibration condition is good, but continued use will cause serious wear of the safety gear, leading to safety hazards. Therefore, the safety gear should be repaired in a timely manner.

[0117] when and When the value is 0, it indicates that the friction performance of the elevator safety brake under test is excellent, the braking fade is level three, and the braking performance of the elevator under test meets the requirements.

[0118] in, and These represent the braking fade threshold and the wear risk threshold, respectively. In order to be in At any given moment, the average micro-wear depth of the failure risk zone. and It can be configured based on expert experience.

[0119] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0120] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0121] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0122] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A macro-microscale cross-scale analysis method for the tribological properties of elevator safety clamps, characterized in that, The specific steps include: A three-dimensional finite element model of the contact surface between the elevator safety gear and the guide rail is constructed. At the same time, the operating braking condition parameters of the elevator safety gear are obtained. The operating braking condition parameters are used as input to the three-dimensional finite element model. The pressure time series data of the contact surface between the safety gear and the guide rail during operation are analyzed through the three-dimensional finite element model. Based on pressure time series data and operating braking condition parameters, a macroscopic transient temperature model is constructed. The macroscopic transient temperature model is used to simulate the time-varying temperature data of the contact surface between the safety clamp and the guide rail during elevator braking, and the local friction coefficient of the contact surface between the safety clamp and the guide rail is dynamically corrected based on the time-varying temperature data. The corrected local friction coefficient is fed back and evolved to replace the initial dynamic friction coefficient in the macroscopic transient temperature model, and the time-varying temperature data of the contact surface between the safety clamp and the guide rail is updated to form a time-varying temperature field. Based on the analysis of time-varying temperature field and pressure time series data using Arcard's law, the micro wear depth was calculated, the micro critical failure threshold was set, and the wear depth of each area of ​​the contact surface between the safety clamp and the guide rail was traversed to screen out the failure risk area. The vibration characteristics of the elevator under test during the current braking process are obtained. The braking fade coefficient is characterized by the vibration characteristics. The friction performance of the elevator safety gear is judged by combining the braking fade coefficient with the wear depth of the failure risk zone. Based on the judgment results, corresponding usage opinions are issued.

2. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 1, characterized in that: The specific steps for constructing a three-dimensional finite element model of the contact surface between the elevator safety gear and the guide rail are as follows: obtaining the current feature information of the elevator safety gear and the guide rail, including size, shape and material properties; establishing a three-dimensional geometric model based on the size, shape and material properties of the elevator safety gear and the guide rail; selecting finite element analysis software; importing the three-dimensional geometric model into the finite element analysis software; meshing the contact surface between the safety gear and the guide rail in the three-dimensional finite element model; and applying corresponding operating braking parameters to the three-dimensional finite element model according to the elevator's working conditions. The specific operating and braking parameters mentioned above include the elevator's operating gravity load, the elevator's initial braking speed, the density of the safety clamp material, the specific heat capacity of the safety clamp material, and the thermal conductivity of the safety clamp material. The method of simulating the operation process through finite element analysis and collecting pressure time-series data of each grid on the contact surface between the safety clamp and the guide rail specifically includes: applying boundary conditions to the three-dimensional finite element model, determining the fixed end or support point, defining the force and its direction applied to the safety clamp according to the gravity load of the elevator operation, setting the acquisition time step, collecting the pressure time-series data of each grid on the contact surface between the safety clamp and the guide rail during the simulated braking process through the set acquisition time step, and recording the corresponding timestamp.

3. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 2, characterized in that: Based on pressure time-series data and operating braking condition parameters, a macroscopic transient temperature model is constructed. The specific expression used by the macroscopic transient temperature model to calculate time-varying temperature data is as follows: ； In the formula, For the material density of the safety clamp, For the specific heat capacity of the safety clamp material, At the i-th grid point on the contact surface between the safety clamp and the guide rail, Time-varying temperature data at any given moment. For divergence operators, for The thermal conductivity of the safety clamp material at all times. The temperature gradient between the contact surface of the safety clamp and the guide rail. For the i-th grid, in The time-varying frictional heat source generated by constant friction, where t is the time variable during the simulated braking process of the elevator. For time intervals; Wherein, the i-th grid, in Time-varying frictional heat source generated by constant friction Specifically, this is characterized by the elevator braking speed and the coefficient of friction between the safety clamp and the guide rail contact surface. The specific formula used for calculation is as follows: ； In the formula, Let be the corrected local friction coefficient of the i-th mesh at time t. For the i-th grid, the normal pressure at time t is specifically represented by the pressure time-series data at the corresponding timestamp. Let i be the area of ​​the i-th grid. Let be the elevator braking speed at time t, where i is the index of the grid on the contact surface between the safety clamp and the guide rail. , This represents the total number of grid cells.

4. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 3, characterized in that: The time-varying temperature data is mapped to the contact surface to dynamically correct the local friction coefficient of the contact surface between the safety clamp and the guide rail. The formula used for the dynamic correction calculation is as follows: ； In the formula, For the i-th grid, in The local friction coefficient at time t. For time t, the time-varying temperature data at the i-th grid is... Indicates in At time i, the corrected local friction coefficient of the i-th mesh is... For reference to ambient temperature, The melting point temperature of the safety clamp material. This represents the initial moment during the simulated braking process of the elevator. The softening coefficient of the material is obtained specifically through temperature gradient data of the contact surface between the safety clamp and the guide rail.

5. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 4, characterized in that: The time-varying temperature data of the contact surface between the safety clamp and the guide rail is updated to form a time-varying temperature field. Specifically, the corrected local friction coefficient is applied to each grid of the contact surface between the safety clamp and the guide rail, generating a new friction coefficient field. The macroscopic transient temperature model is dynamically run using the local friction coefficients recorded in the friction coefficient field to calculate heat conduction and frictional heat, obtaining new time-varying temperature data. This new time-varying temperature data is recorded and stored, generating the time-varying temperature field. The local friction coefficient is dynamically corrected using the temperature data in the time-varying temperature field. This process is repeated until the entire elevator braking simulation is completed, at which point the entire elevator braking simulation is terminated. The time-varying temperature field includes the time-varying temperature data of each grid within the contact surface between the safety clamp and the guide rail at different times during the entire elevator braking simulation. The time at which the entire elevator braking simulation is terminated is recorded as the termination time. .

6. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 5, characterized in that: By embedding time-varying temperature field and pressure time-series data into the modified Arcard law, the micro-wear depth is calculated. The specific formula used to calculate the micro-wear depth is as follows: ； In the formula, In order to be in At time i, the microscopic wear depth of the i-th grid. The wear coefficient of the safety clamp base. For temperature sensitivity coefficient, for Braking speed at any moment From the initial moment of the elevator braking simulation to The time variable within a given moment, This is the wear reference temperature. The temperature-dependent hardness of the safety clamp material at time t; The temperature-dependent hardness of the safety clamp material The specific formula used for the calculation is as follows: ； In the formula, The room temperature hardness of the safety clamp material. For the softening slope of the safety clamp material, This refers to the glass transition temperature of the safety clamp material.

7. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 6, characterized in that: The specific logic used to select the failure risk zone is as follows: After terminating the entire elevator braking simulation process, the micro-wear depth If the mesh is found to be severely worn, it is marked as a failure risk zone. After terminating the entire elevator braking simulation process, the micro-wear depth If the wear of the mesh is deemed to meet the requirements, the mesh will be excluded from further analysis. This is the microscopic critical failure threshold.

8. The method for macro- and micro-scale cross-scale analysis of the tribological properties of elevator safety clamps according to claim 6, characterized in that: The vibration characteristic information includes vibration amplitude and vibration frequency. The braking fade coefficient is characterized by this vibration characteristic information, and the specific formula used to calculate the braking fade coefficient is as follows: ； In the formula, This is the braking fade coefficient. This refers to the amplitude of elevator vibration. This is the reference amplitude for elevator vibration. The frequency of elevator vibration. The elevator vibration reference frequency, and These are the weighting coefficients for vibration amplitude and vibration frequency, respectively. and and All are greater than 0; The friction performance of the elevator safety gear under test is comprehensively judged by combining the braking fade coefficient with the wear depth of the failure risk zone, and corresponding usage opinions are issued based on the judgment results. The specific logic is as follows: when and If the friction performance of the safety brake of the elevator under test is poor and the brake fade is at level one, the elevator under test should be taken out of service and the safety brake should be replaced. when and If the friction performance of the elevator safety brake is good, and the brake fade is at level one, further investigation into the cause of the elevator vibration should be conducted. when and When the condition is as described, it indicates that the friction performance of the elevator safety gear under test is good, and the braking fade condition is level two. The safety gear should be repaired in a timely manner. when and When the value is 0, it indicates that the friction performance of the elevator safety brake under test is excellent, the braking fade is level three, and the braking performance of the elevator under test meets the requirements. in, and These represent the braking fade threshold and the wear risk threshold, respectively. In order to be in At any given moment, the average micro-wear depth of the failure risk zone.

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