A punch clutch brake friction plate wear online monitoring and early warning method and system

Abstract

The present application relates to the technical field of punch press, and particularly discloses a punch press clutch brake friction plate wear online monitoring and early warning method and system, which comprises the following steps: acquiring real-time angle sequence data of a crankshaft of the punch press, acquiring a brake starting angle value and a brake ending angle value according to the real-time angle sequence data, and acquiring an original brake angle value according to the brake starting angle value and the brake ending angle value; acquiring a current running speed value of the punch press, acquiring a reference brake angle value under the current speed according to the current running speed value and a preset speed-brake angle reference curve; acquiring a temperature signal of a friction plate of the punch press, separating a temperature dynamic component from the temperature signal, and identifying a thermal time constant of the friction plate according to the temperature dynamic component. The present application effectively improves the angle measurement accuracy by acquiring the real-time angle sequence data of the crankshaft of the punch press and acquiring the brake starting angle value in a hardware latching mode.

Description

Technical Field

[0001] This invention relates to the field of punch press technology, and in particular to a method and system for online monitoring and early warning of wear of friction pads in a punch press clutch and brake. Background Technology

[0002] As a core stamping equipment in modern manufacturing, punch presses are widely used in automobile manufacturing, home appliance production, hardware processing, and electronic component manufacturing due to their high efficiency, high precision, and good process adaptability. With the rapid development of stamping production lines towards automation and intelligence, customers are placing higher demands on the operational reliability, ease of maintenance, and full lifecycle management capabilities of punch press equipment. Intelligent punch presses with online sensing of key component status, early fault warning, and remaining life prediction functions are becoming the mainstream trend in the industry.

[0003] Currently, the mainstream monitoring method for wear of clutch brake friction pads in punch presses in the industry is periodic shutdown and disassembly inspection. This involves maintenance personnel disassembling the brake housing after a certain number of punches, using a micrometer to measure the remaining thickness of the friction pads at multiple points, and manually determining whether replacement is necessary. This method requires periodic shutdowns for each punch press, relying on professional maintenance personnel to disassemble, measure, record, and reassemble each machine individually. The entire process is time-consuming and labor-intensive, and installation deviations may be introduced during disassembly and reassembly, leading to a decrease in brake performance. Furthermore, this method is an offline, random inspection; wear occurring between two maintenance intervals is completely unpredictable, failing to achieve true online monitoring and early warning, and posing a safety hazard of sudden brake failure. Some existing technologies employ a pre-embedded contact monitoring scheme, where metal contacts are pre-embedded inside the friction pads. When the friction pads wear to a certain extent, the contacts are exposed, activating the circuit and triggering an alarm. This solution also has inherent limitations. The contact can only provide a binary judgment of "limit reached / not yet reached," failing to reflect the continuous evolution of wear. The contact is prone to oxidation in high-temperature, dusty environments, leading to poor contact and signal reliability. Furthermore, it cannot predict remaining lifespan or provide trend warnings. Some existing technologies employ displacement sensor-based monitoring, indirectly obtaining the wear of the friction plates by measuring the axial displacement of the connecting plate with a displacement sensor installed at the brake connection plate. However, this approach requires installing displacement sensors and specialized testing fixtures on each punch press, necessitating mechanical modifications to existing equipment, resulting in high hardware and installation / maintenance costs. Moreover, the displacement sensors are exposed to harsh conditions of high temperature, high dust, and strong vibration, making them prone to temperature drift, zero drift, and mechanical loosening, causing measured values ​​to deviate from the true values, resulting in high false alarm and false negative rates. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for online monitoring and early warning of wear of friction pads in a punch press clutch brake, so as to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for online monitoring and early warning of wear of friction pads in a punch press clutch brake includes: The real-time angle sequence data of the punch press crankshaft is obtained, and the braking start angle value and braking end angle value are obtained based on the real-time angle sequence data. The original braking angle value is obtained based on the braking start angle value and braking end angle value. Obtain the current operating speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current operating speed value and the preset speed-braking angle reference curve; The temperature signal of the friction plate of the punch press is acquired, the dynamic temperature component is separated from the temperature signal, and the thermal time constant of the friction plate is identified based on the dynamic temperature component. The wear state of the friction plate is determined by the ratio of the thermal time constant to the initial thermal time constant during the first run. The calibrated braking angle increment value after speed-temperature dual normalization is obtained based on the original braking angle value, the reference braking angle value, and the temperature dynamic component. The ratio of the thermal time constants is obtained based on the thermal time constant and the initial thermal time constant during the first run, and the wear state judgment result of the friction plate is obtained based on the ratio of the thermal time constants. The remaining life prediction value is obtained based on the wear stage identification results and the calibrated braking angle increment value. Multi-level early warning information is generated based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value.

[0006] Preferably, the step of acquiring the temperature signal of the punch press friction plate, separating the dynamic temperature component from the temperature signal, and identifying the thermal time constant of the friction plate based on the dynamic temperature component includes: Obtain the existing temperature signal from the punch press electrical control system, or estimate the friction plate temperature signal based on the kinetic energy dissipation and heat dissipation model during braking. The temperature signal is low-pass filtered to obtain the steady-state temperature component, and the temperature signal is subtracted from the steady-state temperature component to obtain the dynamic temperature component. After the braking process ends, the attenuation curve of the dynamic temperature component is obtained, and the attenuation curve is subjected to exponential fitting to obtain the thermal time constant of the friction plate.

[0007] Preferably, the step of obtaining the speed-temperature double-normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value, and the temperature dynamic component includes: The temperature compensation amount is obtained based on the dynamic temperature component and the preset temperature-angle coupling coefficient. Subtract the reference braking angle value from the original braking angle value to obtain the initial braking angle increment value; Subtracting the temperature compensation amount from the initial braking angle increment value yields the calibrated braking angle increment value after speed-temperature dual normalization. The first trend feature is obtained based on the calibrated braking angle increment value, and the wear state discrimination result of the friction plate is obtained based on the ratio of the first trend feature and the thermal time constant.

[0008] Preferably, the step of obtaining the ratio of the thermal time constant based on the thermal time constant and the initial thermal time constant during the first run, and obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constant, includes: Obtain the initial thermal time constant of the friction pad during its first operation, and obtain the thermal time constant of the current single braking process; When the amount of historical data is less than a preset threshold, the thermal time constant ratio is obtained based on the ratio of the thermal time constant of the current single braking process to the initial thermal time constant, and the wear stage identification result in the cold start mode is obtained based on the thermal time constant ratio and the temperature rise rate of the single braking process. When the amount of historical data is greater than or equal to the preset threshold, the moving average sequence data is obtained based on the time series data of the calibration braking angle increment value, the slope value of the rate of change and the second-order rate of change value are obtained based on the moving average sequence data, and the wear stage identification result in steady state mode is obtained based on the ratio of the slope value of the rate of change, the second-order rate of change value and the thermal time constant. Based on the comparison results of historical data volume and preset threshold, the system switches between cold start mode and steady state mode, and uses weighted fusion near the switching point to obtain the wear stage identification results.

[0009] Preferably, the step of obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run includes: Obtain the first trend characteristic of the calibrated braking angle increment value; Obtain the second trend characteristic of the response time value of the punch press solenoid valve; A consistency judgment result is obtained based on the first and second trend characteristics; When the consistency discrimination result is that the first change trend feature and the second change trend feature change synchronously, a friction pad wear discrimination result is generated; When the consistency discrimination result is that the first change trend feature changes while the second change trend feature does not change, a non-friction plate type fault discrimination result is generated. The wear judgment result of the friction plate is verified based on the ratio of thermal time constants. When the ratio of thermal time constants is less than the preset threshold value, the wear judgment result of the friction plate is confirmed.

[0010] Preferably, the step of obtaining the remaining life prediction value based on the wear stage identification result and the calibrated braking angle increment value includes: When the wear stage identification result is a stable wear stage, the first remaining life prediction value is obtained based on the slope value of the rate of change under the steady-state mode and the preset braking angle limit value. When the wear stage identification result is a severe wear stage, the slope value of the rate of change, the second rate of change value, and the braking angle limit value are obtained based on the steady-state mode, and a second remaining life prediction value is obtained based on the slope value of the rate of change, the second rate of change value, and the braking angle limit value. Obtain the stamping frequency parameter value, stamping load parameter value, and ambient temperature parameter value of the punch press, and based on the stamping... The first remaining life prediction value or the second remaining life prediction value is corrected according to the operating condition correction coefficient to obtain the corrected remaining life prediction value.

[0011] Preferably, it further includes an online self-calibration step for the reference value, the online self-calibration step for the reference value including: Obtain historical sequence data of the calibration braking angle increment value; The minimum moving value is obtained based on the historical sequence data; The change type discrimination result is obtained based on the historical sequence data and the moving minimum value. The change type discrimination result includes gradual change type and step change type. When the change type determination result is a step change type, it is determined that a reference drift has occurred, and the reference value of the speed-braking angle reference curve is updated according to the minimum movement value; When the change type determination result is a gradual change type and the calibrated braking angle increment value shows a continuous monotonically increasing trend, it is determined to be real wear, and the reference value of the speed-braking angle reference curve remains unchanged.

[0012] Preferably, the step of generating multi-level early warning information based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value includes: Obtain the moving average value of the calibration braking angle increment; The joint state discrimination result is obtained based on the moving average value, the slope value of the rate of change and the second-order rate of change value under the steady-state mode, the thermal time constant ratio, and the wear state discrimination result. Based on the joint state discrimination results, the present invention includes normal level, attention level, early warning level and alarm level; The triggering condition for the normal level is that the wear is in the running-in wear stage or the early stage of stable wear, and the wear state judgment result is friction plate wear. The triggering condition for the attention level is entering the middle to late stage of stable wear and tear and the moving average value reaches a preset first threshold. The triggering condition corresponding to the warning level is that the second-order rate of change value is greater than zero and the wear state judgment result is friction plate wear, or the thermal time constant ratio is less than the preset thermal time constant ratio threshold. The triggering condition corresponding to the alarm level is that the moving average value reaches the braking angle limit or the remaining life prediction value is lower than the safety threshold.

[0013] Preferably, the step of obtaining the braking start angle value and braking end angle value based on the real-time angle sequence data, and obtaining the original braking angle value based on the braking start angle value and braking end angle value, includes: Obtain the braking command signal issued by the punch press control system, and use the braking command signal as a hardware latch trigger signal; In response to the rising edge of the braking command signal, the real-time angle sequence data is latched at the instantaneous angle value at the rising edge by the external latch trigger input of the high-speed counting module, and the instantaneous angle value is used as the braking start angle value. Monitor the real-time angle sequence data. When the real-time angle sequence data remains unchanged for multiple consecutive control cycles, it is determined that the crankshaft has completely stopped. The current value of the real-time angle sequence data after the crankshaft has completely stopped is obtained as the braking termination angle value. The original braking angle value is obtained based on the difference between the braking termination angle value and the braking start angle value.

[0014] This invention also discloses an online monitoring and early warning system for wear of friction pads in a punch press clutch brake, comprising: The data acquisition module is used to acquire real-time angle sequence data of the punch press crankshaft, acquire braking start angle value and braking end angle value based on the real-time angle sequence data, and acquire the original braking angle value based on the braking start angle value and braking end angle value. The speed normalization module is used to obtain the current running speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current running speed value and the preset speed-braking angle reference curve. The temperature dynamic feature extraction module is used to acquire the temperature signal of the punch press friction plate, separate the temperature dynamic component from the temperature signal, and identify the thermal time constant of the friction plate based on the temperature dynamic component. The wear condition discrimination module is used to obtain the wear condition discrimination result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run; The dual normalization processing module is used to obtain the speed-temperature dual normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value and the temperature dynamic component. The dual-mode stage identification module is used to obtain the ratio of the thermal time constant based on the thermal time constant and the initial thermal time constant during the first run, and to obtain the wear state discrimination result of the friction plate based on the ratio of the thermal time constant. The life prediction module is used to obtain the remaining life prediction value based on the wear stage identification result and the calibration braking angle increment value. The early warning output module is used to generate multi-level early warning information based on the wear status judgment result, the wear stage identification result, and the remaining life prediction value.

[0015] The beneficial effects of this application are as follows: This invention effectively improves angle measurement accuracy by acquiring real-time angle sequence data of the punch press crankshaft and using hardware latching to obtain the braking start angle value; it achieves speed normalization by querying a preset speed-braking angle reference curve to obtain the reference braking angle value; by acquiring the friction plate temperature signal, separating the dynamic temperature component, and identifying the thermal time constant, temperature is transformed from an interference quantity into an independent wear information dimension, thereby obtaining the calibrated braking angle increment value after speed-temperature dual normalization, eliminating the interference of speed changes and dynamic temperature fluctuations on wear judgment; and by combining the thermal time constant ratio with the calibrated braking angle increment value and employing a dual-mode switching logic of cold start mode and steady-state mode, it achieves… This system continuously identifies the wear stages of friction pads throughout their entire lifecycle, from installation to replacement, resolving monitoring failures due to insufficient historical data during cold starts. Through dual-signal trend consistency discrimination and thermal time constant verification, it effectively distinguishes friction pad wear from other fault modes such as solenoid valve malfunction and brake disc deformation. Online self-calibration of the reference value automatically differentiates between actual wear and reference drift, ensuring the accuracy of the measurement reference during long-term operation. By introducing a working condition correction coefficient to correct the wear rate, it achieves dual adaptive remaining life prediction with both stage-adaptive and working condition-adaptive capabilities. Finally, based on the wear state discrimination results, wear stage identification results, and remaining life prediction values, it generates multi-level early warning information, achieving full coverage from early trend warnings to extreme alarms. The entire solution requires no additional sensors or mechanical modifications, utilizing all existing signals from the punch press's electronic control system. This significantly improves monitoring accuracy under varying working conditions, identification speed during cold starts, fault differentiation capabilities, and remaining life prediction accuracy while reducing hardware costs, providing a reliable basis for precise maintenance of the friction pads in the punch press's clutch and brake system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a method flow according to an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the system structure according to an embodiment of this application.

[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] like Figure 1 As shown, this application provides a method for online monitoring and early warning of wear of friction pads in a punch press clutch brake, including: S1. Obtain real-time angle sequence data of the punch press crankshaft, obtain the braking start angle value and braking end angle value based on the real-time angle sequence data, and obtain the original braking angle value based on the braking start angle value and braking end angle value. S2. Obtain the current running speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current running speed value and the preset speed-braking angle reference curve; S3. Obtain the temperature signal of the punch press friction plate, separate the temperature dynamic component from the temperature signal, and identify the thermal time constant of the friction plate based on the temperature dynamic component. S4. Obtain the wear state judgment result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run; S5. Obtain the calibrated braking angle increment value after speed-temperature dual normalization based on the original braking angle value, the reference braking angle value, and the temperature dynamic component. S6. Obtain the ratio of thermal time constants based on the thermal time constant and the initial thermal time constant during the first run, and obtain the wear state judgment result of the friction plate based on the ratio of thermal time constants. When the amount of historical data is less than a preset threshold, a cold start mode is adopted, and the wear stage identification result is obtained based on the ratio of thermal time constants and the temperature rise rate of a single braking process. When the amount of historical data is greater than or equal to the preset threshold, a steady state mode is adopted, and the wear stage identification result is obtained based on the temporal statistical characteristics of the calibration braking angle increment value. S7. Obtain the remaining life prediction value based on the wear stage identification result and the calibration braking angle increment value; S8. Generate multi-level early warning information based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value.

[0020] As described in steps S1-S8 above, this invention acquires real-time angle sequence data of the press crankshaft, extracts the braking start angle and braking end angle values ​​from it, and then calculates the original braking angle value, providing basic data for subsequent wear monitoring. In traditional solutions, friction plate wear monitoring mainly relies on periodic shutdowns for disassembly and inspection or the installation of displacement sensors, which is costly in terms of hardware and cannot provide continuous online monitoring. This invention utilizes the existing crankshaft angle encoder signal in the press's electronic control system, eliminating the need for additional sensors to acquire the angle changes of the crankshaft during braking. The real-time angle sequence data refers to the instantaneous value sequence of the crankshaft rotation angle collected and output by the crankshaft angle encoder in each control cycle. This sequence is sent to the high-speed counting module or PLC counting channel of the press control system, forming an angle data stream arranged in chronological order. The crankshaft angle encoder can be an absolute rotary encoder or an incremental rotary encoder, and its resolution can be selected according to the press control accuracy requirements; a typical resolution is [missing information - likely a value per revolution]. to Each pulse. The braking start angle value refers to the angle value of the crankshaft at the moment the punch press control system issues the braking command; the braking end angle value refers to the final angle value of the crankshaft after it has come to a complete stop during braking; the original braking angle value refers to the angle rotated by the crankshaft from the moment of braking start to the moment of complete stop, that is, the difference between the braking end angle value and the braking start angle value. Obtaining the braking start angle value through hardware latching can eliminate the scanning cycle jitter error caused by software polling, improving the measurement accuracy to the microsecond level.

[0021] Next, the current operating speed of the punch press is obtained, and the reference braking angle value at the current speed is obtained according to the preset speed-braking angle reference curve. The current operating speed refers to the operating speed of the punch press in the current work cycle, usually expressed as the number of punches per minute, and can be calculated from the speed setting parameters of the punch press control system or the pulse frequency of the crankshaft angle encoder. The speed-braking angle reference curve is a pre-established curve reflecting the corresponding relationship of standard braking angles at different operating speeds, and its expression is: ; in, This represents the current running speed value. This is the reference braking angle value at that speed. , , The parameters for the fitted curve are given. The choice of the quadratic polynomial model is based on the physical mechanism of the braking process: the crankshaft sliding angle is approximately proportional to the square of the velocity (kinetic energy). Braking power , Meanwhile, the angular contribution from mechanical lag time (solenoid valve actuation time, air circuit charging / discharging time) is proportional to the first power of velocity. Curve parameters , , The data is obtained by acquiring multiple braking angle measurements corresponding to various preset speed values ​​of the punch press while the friction plates are in brand new condition. The number of preset speed values ​​is no less than [number missing]. One, and covering the commonly used speed range of punch presses (such as spm to (spm) Multiple braking angle measurements are performed at each preset speed value, and the average value is taken as the braking angle measurement value at that speed; then, least squares curve fitting is performed based on multiple preset speed values ​​and multiple braking angle measurement values ​​to solve for the sum of squared residuals. Minimum parameter , , The three parameters obtained from the fitting are stored in the non-volatile memory of the control system for subsequent online querying. The reference braking angle value refers to the standard braking angle value corresponding to the current operating speed, obtained from the speed-braking angle reference curve. By performing speed normalization processing, the interference of operating speed changes on braking angle measurement can be eliminated, solving the common problem of frequent false alarms or delayed omissions in fixed threshold schemes under varying operating conditions.

[0022] Furthermore, the temperature signal of the stamping press friction plate is acquired, and the dynamic temperature component is separated from the temperature signal. The thermal time constant of the friction plate is then identified based on the dynamic temperature component. Traditional solutions treat temperature as an interference quantity and eliminate it through hardware insulation or software filtering, but they fail to recognize that the dynamic temperature response itself contains information about the wear state of the friction plate. This invention innovatively decomposes temperature into a steady-state temperature component and a dynamic temperature component: the steady-state temperature component is mainly affected by average operating conditions such as operating speed and stamping load; the dynamic temperature component is directly related to the heat capacity and thermal resistance of the friction plate, both of which decrease as the friction plate thickness decreases. Therefore, the dynamic temperature component can serve as an independent dimension of wear information. The dynamic temperature component refers to the high-frequency fluctuation component remaining after removing the low-frequency steady-state component from the temperature signal, and its attenuation characteristics are determined by the thermal time constant of the friction plate. The thermal time constant refers to the heat capacity of the friction plate... With thermal resistance The product of: ; in, The friction plate has a thermal resistance (unit: K / W). The heat capacity of the friction plate (unit: J / K). The thermal time constant (unit: seconds) is obtained by fitting the exponential decay curve of the temperature dynamic component after the braking process ends. The fitting model is as follows: ; in, After braking ends, the first The dynamic components of temperature at any given time, The initial value of the dynamic temperature component at the moment of braking termination. Let be the thermal time constant. The physical meaning of this formula is: after braking ends, the friction pads no longer receive new heat input, and their dynamic temperature component decays exponentially, with the decay rate determined by the thermal time constant. Decision. As the friction pad wears down, its thickness decreases, and its heat capacity... and thermal resistance Both decrease, thermal time constant The temperature decreases significantly, and this change is unaffected by operating speed, relating only to wear condition. There are two possible sources for acquiring the temperature signal: Method 1: Read from an existing temperature sensor in the punch press's electronic control system. The temperature sensor is installed near the brake housing or friction pads, and the sampling frequency is no less than [missing information]. Hz; Method 2: Estimate the friction pad temperature signal through a braking energy model, based on the kinetic energy dissipation during braking. And the heat dissipation model estimates the temperature rise of the friction plate, where The moment of inertia of the crankshaft and flywheel. For the initial angular velocity of braking, This is the braking termination angular velocity.

[0023] Then, the wear state of the friction pad is determined based on the ratio of the stated thermal time constant to the initial thermal time constant during the first operation. The initial thermal time constant during the first operation refers to the thermal time constant identified during the first braking process after the friction pad is installed, denoted as... This reflects the individual characteristics of the friction plate. The thermal time constant ratio refers to the current thermal time constant. With the initial thermal time constant The ratio: ; in, This is the ratio of thermal time constants (dimensionless). The current thermal time constant, This is the initial thermal time constant during the first run. The physical meaning is: when near When the friction pad thickness is close to the initial state, the wear is slight; when Significantly smaller than Time (e.g., less than) This indicates a significant reduction in friction pad thickness, resulting in decreased heat capacity and thermal resistance, and severe wear. Simultaneously, a consistency judgment is made by combining the changing trends of the calibrated braking angle increment and the solenoid valve response time to differentiate friction pad wear from other fault modes such as solenoid valve failure and brake disc deformation. Friction pad wear leads to increased piston stroke and prolonged braking response time, causing the braking angle increment and solenoid valve response time to change synchronously. When both change synchronously, it is determined to be friction pad wear; when they change asynchronously, it suggests a possible non-friction pad fault. This dual-signal cross-validation mechanism significantly reduces the false diagnosis rate.

[0024] Next, the speed-temperature dual-normalized calibrated braking angle increment is obtained based on the original braking angle value, the reference braking angle value, and the temperature dynamic component. Specifically, the temperature compensation amount is obtained based on the temperature dynamic component and a preset temperature-angle coupling coefficient. The reference braking angle value is subtracted from the original braking angle value to obtain the initial braking angle increment. Then, the temperature compensation amount is subtracted from the initial braking angle increment to obtain the speed-temperature dual-normalized calibrated braking angle increment. The calculation formula is as follows: ; in, The value of the calibrated braking angle increment (in degrees) is obtained after speed-temperature double normalization. This is the original braking angle value (unit: degrees). The reference braking angle value (unit: degrees). This is the temperature-angle coupling coefficient (unit: degrees / °C). Temperature dynamic component (unit: °C). Temperature-angle coupling coefficient. The data was obtained through calibration experiments. With the friction plates in brand new condition, the press was controlled to run at the same speed, and the change in braking angle was measured under different temperature dynamic components. The change in temperature was then calculated. The change in braking angle corresponding to ℃, typically valued at ℃. - Temperature / ℃. This calibrated braking angle increment eliminates both speed and temperature dynamics, directly reflecting the additional braking angle caused by friction pad wear. Its value increases monotonically with the degree of friction pad wear.

[0025] Furthermore, the ratio of the thermal time constants is obtained based on the thermal time constant and the initial thermal time constant during the first run, and the wear state judgment result of the friction pad is obtained based on the ratio of the thermal time constants. Traditional wear stage identification methods rely on time-series statistics such as moving averages and rate of change slopes, which require the accumulation of a large amount of historical data and cannot output effective results during the cold start stage. This invention adopts a dual-mode switching logic: when the amount of historical data is less than a preset threshold, the cold start mode is used, and the wear stage identification result is obtained based on the ratio of the thermal time constants of a single braking process and the temperature rise rate; when the amount of historical data is greater than or equal to the preset threshold, the steady-state mode is used, and the wear stage identification result is obtained based on the time-series statistical characteristics of the calibration braking angle increment value. Here, the amount of historical data refers to the number of braking process data points accumulated since the friction pad was installed; the preset threshold is the critical value of the amount of data for switching between the cold start mode and the steady-state mode, with a typical value of ,in The moving average window length, The window length is typically used to calculate the slope. , The preset threshold is One control cycle. In cold start mode, the initial thermal time constant of the friction pad during its first operation is obtained. and the thermal time constant of a single braking process Calculate the ratio of thermal time constants And obtain the temperature rise rate during a single braking process, where the temperature rise rate refers to the maximum rate of increase of the dynamic temperature component during a single braking process: ; in, The maximum time derivative (unit: °C / s) of the temperature dynamic component during braking can be obtained by differentiating the temperature dynamic component with respect to time and taking the maximum value. According to... The combined criterion of temperature rise rate identifies the wear stage: when And the rate of temperature rise When the second threshold is reached, it is determined to be in the running-in wear stage; when Between and When the temperature rise rate is between the fourth and second thresholds, it is considered to be in the stable wear stage; when... And the rate of temperature rise At the fifth threshold, the system is identified as being in a severe wear stage. In steady-state mode, time-series data of the calibration braking angle increment values ​​are acquired, and a moving average sequence is calculated. ; in, For the first The moving average over a control period. The moving average window length (typically taken as...) to (one control cycle) For the first The calibration braking angle increment value for each control cycle. Moving average is a low-pass filtering method used to suppress random noise in a single measurement (such as encoder signal jitter, mechanical vibration interference, etc.) and extract the long-term trend of the calibration braking angle increment value. The slope value of the rate of change is obtained from the moving average sequence data: ; in, For the first The slope value of the rate of change per control cycle (unit: degree / control cycle). For the first The moving average over a control period. For the first The moving average over a control period. The calculation window length is set to the preset slope (typically taken as...). to (One control cycle). The slope value of the rate of change reflects the growth rate of the calibrated braking angle increment, i.e., the wear rate. The second-order rate of change value is obtained from the slope value: ; in, For the first The second-order rate of change for each control cycle (unit: degree / control cycle²). For the first The slope value of the rate of change over each control cycle For the first The slope value of the rate of change over each control cycle The calculation window length is set to the preset slope. The second-order rate of change value is used to identify the transition points between wear stages, and its sign is determined by the three-stage wear theory in tribology: In the running-in wear stage, the microscopic protrusions on the friction plate surface are gradually worn down, and the wear rate changes from fast to slow, which is manifested as... During the stable wear stage, the wear rate is low and constant, exhibiting the following characteristics: During the severe wear stage, the wear rate increases sharply after the friction pad thickness decreases to a certain extent, manifesting as... The stage is determined based on the sign combination of the slope value of the rate of change and the second-order rate of change: when and At that time, it is determined to be in the running-in wear stage; when and Time (Engineering criteria) , The preset second-order rate of change threshold is typically taken as... historical average - ), is determined to be in the stable wear stage; when and When the wear level is reached, it is determined to be in the severe wear stage. The stage determination result is then corrected based on the ratio of thermal time constants. Even at that time and Even if the criterion does not indicate severe wear, it is still forcibly upgraded to the severe wear stage. Based on the comparison results of historical data volume and preset thresholds, it switches between cold start mode and steady state mode, and uses weighted fusion near the switching point: in, The weighted fusion coefficient increases with the amount of data. linear decay to That is, when the amount of historical data equals a preset threshold When the amount of historical data is equal to a preset threshold hour Through dual-mode switching logic, continuous monitoring of the entire lifecycle of the friction pads, from installation to replacement, is achieved, reducing the cold start identification time from... The secondary compression is shortened to... Secondary stamping.

[0026] In one embodiment, the step of obtaining the braking start angle value and braking end angle value based on the real-time angle sequence data, and obtaining the original braking angle value based on the braking start angle value and braking end angle value, includes: Obtain the braking command signal issued by the punch press control system, and use the braking command signal as a hardware latch trigger signal; In response to the rising edge of the braking command signal, the real-time angle sequence data is latched at the instantaneous angle value at the rising edge by the external latch trigger input of the high-speed counting module, and the instantaneous angle value is used as the braking start angle value. Monitor the real-time angle sequence data. When the real-time angle sequence data remains unchanged for multiple consecutive control cycles, it is determined that the crankshaft has completely stopped. The current value of the real-time angle sequence data after the crankshaft has completely stopped is obtained as the braking termination angle value. The original braking angle value is obtained based on the difference between the braking termination angle value and the braking start angle value.

[0027] As described above, this invention obtains the braking start angle value through hardware latching, completely eliminating measurement errors caused by PLC scan cycle jitter. Specifically, the braking command signal refers to the digital output signal issued by the punch press control system when the crankshaft reaches a predetermined position, used to trigger the clutch brake action. This signal is typically a high-level or low-level active switching signal, output by the PLC's digital output channel. The braking command signal is simultaneously routed to the external latch trigger input of the high-speed counting module, so that the braking command signal not only drives the solenoid valve to perform the braking action, but also serves as the trigger signal for the high-speed counting module to latch the current crankshaft angle. The high-speed counting module is a dedicated module in the punch press control system used to process high-speed pulse signals and has an external latching function. When the external latch trigger input of the high-speed counting module detects the rising edge of the braking command signal, the high-speed counting module immediately latches the encoder count value at the current moment into a dedicated register. This latching action is directly completed by the hardware circuit. In subsequent scan cycles, the control system reads this latched value from the latch register of the high-speed counting module and converts it into an angle value as the braking start angle value. The braking start angle value obtained through hardware latching is far more accurate than that obtained through software polling, completely eliminating measurement errors caused by PLC scan cycle jitter. For the braking end angle value, real-time angle sequence data is monitored. When the real-time angle sequence data remains unchanged for multiple consecutive control cycles, it is determined that the crankshaft has completely stopped. Multiple consecutive control cycles refer to a threshold number of consecutive control cycles used to determine whether the crankshaft has completely stopped; for example, it can be set to continuous... to One control cycle. When the real-time angle sequence data output by the crankshaft angle encoder remains unchanged for several consecutive control cycles, it indicates that the crankshaft has stopped rotating. At this time, the current angle value of the crankshaft angle encoder is read as the braking termination angle value. The original braking angle value is obtained based on the difference between the braking termination angle value and the braking start angle value. This original braking angle value includes the combined effect of speed factors and friction plate wear factors.

[0028] In one embodiment, the steps of acquiring the temperature signal of the punch press friction plate, separating the dynamic temperature component from the temperature signal, and identifying the thermal time constant of the friction plate based on the dynamic temperature component include: Obtain the existing temperature signal from the punch press's electrical control system, or estimate the friction plate temperature signal based on the kinetic energy dissipation and heat dissipation model during the braking process; The temperature signal is low-pass filtered to obtain the steady-state temperature component, and the temperature signal is subtracted from the steady-state temperature component to obtain the dynamic temperature component. After the braking process ends, the attenuation curve of the dynamic temperature component is obtained, and the attenuation curve is subjected to exponential fitting to obtain the thermal time constant of the friction plate.

[0029] As described above, this invention obtains the existing temperature signal from the punch press's electronic control system, or estimates the friction plate temperature signal based on the kinetic energy dissipation and heat dissipation model during braking, without requiring additional temperature sensors. The temperature signal can be read from existing temperature sensors in the punch press's electronic control system (such as a brake housing temperature sensor), or it can be estimated using a braking energy model based on the kinetic energy dissipation during braking. And a heat dissipation model is used to estimate the temperature rise of the friction plate, where The moment of inertia of the crankshaft and flywheel (unit: kg·m², which can be obtained from the punch press's factory parameters). The braking initiation angular velocity (unit: rad / s, calculated from the crankshaft speed at the moment corresponding to the braking initiation angle value) is given. The braking termination angular velocity (usually 100 rpm) The temperature signal is low-pass filtered to obtain the steady-state temperature component. The low-pass filter cutoff frequency is set according to the braking period, with a typical value of [value missing]. - Hz. Subtracting the steady-state temperature component from the temperature signal yields the dynamic temperature component: ; in, For dynamic temperature components (unit: °C). This is the temperature signal of the friction plate (unit: °C). This represents the steady-state temperature component (unit: °C), i.e., the output of the temperature signal after low-pass filtering. The attenuation curve of the dynamic temperature component after the braking process is obtained, and an exponential fit is performed on the attenuation curve. The fitting model is as follows: The fitted result The thermal time constant is the current thermal time constant. The thermal time constant refers to the heat capacity of the friction plate. With thermal resistance The product of, i.e. As the friction pad wears down, its thickness decreases, leading to a reduction in both heat capacity and thermal resistance, and consequently, a decrease in the thermal time constant. The change is significantly reduced and is unaffected by operating speed, relating only to wear condition. The ratio of the thermal time constant is obtained based on the thermal time constant and the initial thermal time constant during the first run. ,when Less than the preset thermal time constant ratio threshold (e.g.) When the temperature reaches a certain level, it is judged as significant wear. By using the time constant of the dynamic temperature component as an independent wear characteristic, the technical bias of "temperature = interference" is broken, and high-precision wear discrimination under varying operating conditions is achieved.

[0030] In one embodiment, the step of obtaining the speed-temperature double-normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value, and the temperature dynamic component includes: The temperature compensation amount is obtained based on the dynamic temperature component and the preset temperature-angle coupling coefficient. Subtract the reference braking angle value from the original braking angle value to obtain the initial braking angle increment value; Subtracting the temperature compensation amount from the initial braking angle increment value yields the calibrated braking angle increment value after speed-temperature dual normalization. The first trend feature is obtained based on the calibrated braking angle increment value, and the wear state discrimination result of the friction plate is obtained based on the ratio of the first trend feature and the thermal time constant.

[0031] As described in the steps above, this invention corrects the initial braking angle increment value by using a temperature compensation amount to obtain a calibrated braking angle increment value after speed-temperature dual normalization. Specifically, the temperature compensation amount is based on the dynamic temperature component. and preset temperature-angle coupling coefficient The calculation results are as follows: ; in, Temperature compensation amount (unit: degrees). This is the temperature-angle coupling coefficient (unit: degrees / °C). For dynamic temperature components (unit: °C). The data was obtained through calibration experiments. With the friction plates in brand new condition, the press was controlled to run at the same speed, and the change in braking angle was measured under different temperature dynamic components. The change in temperature was then calculated. The change in braking angle corresponding to ℃, typically valued at ℃. - degrees / ℃. The initial braking angle increment is the difference between the original braking angle value and the reference braking angle value. ; in, This is the initial braking angle increment (unit: degrees). This is the original braking angle value (unit: degrees). The reference braking angle value (unit: degrees). The calibrated braking angle increment value is the value obtained by subtracting the temperature compensation amount from the initial braking angle increment value. ; in, This is the calibrated braking angle increment value (unit: degrees) after speed-temperature dual normalization. This calibrated braking angle increment value simultaneously eliminates the influence of speed and dynamic temperature, directly reflecting the additional braking angle caused by friction plate wear. Its value increases monotonically with the increase of friction plate wear. A first trend feature is obtained based on the calibrated braking angle increment value. This first trend feature refers to the trend information of the calibrated braking angle increment value changing with time, which can be determined by calculating the slope of the rate of change of the calibrated braking angle increment value within a preset time window. The wear state discrimination result of the friction plate is obtained based on the first trend feature and the thermal time constant ratio. When the first trend feature shows that the calibrated braking angle increment value has a continuously monotonically increasing trend, and the thermal time constant ratio is less than the preset thermal time constant ratio threshold, it is determined that the friction plate is worn. Through speed-temperature dual normalization processing, the interference of operating speed changes and dynamic temperature fluctuations on braking angle measurement is effectively eliminated, solving the common problem of frequent false alarms or delayed omissions under varying operating conditions in fixed threshold schemes.

[0032] In one embodiment, the step of obtaining the ratio of the thermal time constants based on the thermal time constant and the initial thermal time constant during the first run, and obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constants, includes: Obtain the initial thermal time constant of the friction pad during its first operation, and obtain the thermal time constant of the current single braking process; When the amount of historical data is less than a preset threshold, the thermal time constant ratio is obtained based on the ratio of the thermal time constant of the current single braking process to the initial thermal time constant, and the wear stage identification result in the cold start mode is obtained based on the thermal time constant ratio and the temperature rise rate of the single braking process. When the amount of historical data is greater than or equal to the preset threshold, the moving average sequence data is obtained based on the time series data of the calibration braking angle increment value, the slope value of the rate of change and the second-order rate of change value are obtained based on the moving average sequence data, and the wear stage identification result in steady state mode is obtained based on the ratio of the slope value of the rate of change, the second-order rate of change value and the thermal time constant. Based on the comparison results of historical data volume and preset threshold, the system switches between cold start mode and steady state mode, and uses weighted fusion near the switching point to obtain the wear stage identification results.

[0033] As described in the steps above, this invention employs a dual-mode switching logic to obtain wear stage identification results, solving the problem that traditional methods cannot identify wear stages during the cold start phase due to insufficient historical data. Specifically, it obtains the initial thermal time constant of the friction pad during its first operation. This value is identified during the first braking process after the friction pads are installed, reflecting the individual characteristics of the friction pads. The thermal time constant of the current single braking process is obtained. When the amount of historical data is less than a preset threshold, a cold start mode is adopted, and the ratio of thermal time constants is calculated. The temperature rise rate during a single braking process is obtained, where the temperature rise rate refers to the maximum rate of increase of the dynamic temperature component during a single braking process, i.e. .according to The combined criterion of temperature rise rate identifies the wear stage: when And the rate of temperature rise When the second threshold is reached, it is determined to be in the running-in wear stage; when When the temperature rise rate is between the fourth threshold and the second threshold, it is determined to be in the stable wear stage; when And the rate of temperature rise At the fifth threshold, the system is identified as being in a severe wear stage. When the amount of historical data is greater than or equal to a preset threshold, a steady-state mode is adopted to acquire time-series data of the calibration braking angle increment and calculate the moving average sequence. ,in This is the moving average window length, typically taking the value of... to One control period. The slope value of the rate of change is obtained from the moving average sequence data. ,in The window length for slope calculation is typically set to a value of [value to be filled in]. to One control cycle. The second-order rate of change value is obtained based on the slope value of the rate of change. The stage is determined based on the sign combination of the slope value of the rate of change and the second-order rate of change: when and At that time, it is determined to be in the running-in wear stage; when and When, it is determined to be in the stable wear stage; when and When the wear level is reached, it is determined to be in the severe wear stage. The stage determination result is then corrected based on the ratio of thermal time constants. Even at that time and Even if the criterion does not indicate severe wear, it is still forcibly upgraded to the severe wear stage. Based on the comparison results of historical data volume and preset threshold, it switches between cold start mode and steady state mode, and uses weighted fusion near the switching point: Stage discrimination results Cold start mode results Steady-state model results, in which As the amount of data increases from linear decay to Through dual-mode switching logic, continuous monitoring of the entire lifecycle of the friction pads, from installation to replacement, is achieved, reducing the cold start identification time from... The secondary compression is shortened to... Secondary stamping.

[0034] In one embodiment, the step of obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run includes: Obtain the first trend characteristic of the calibrated braking angle increment value; Obtain the second trend characteristic of the response time value of the punch press solenoid valve; A consistency judgment result is obtained based on the first and second trend characteristics; When the consistency discrimination result is that the first change trend feature and the second change trend feature change synchronously, a friction pad wear discrimination result is generated; When the consistency discrimination result is that the first change trend feature changes while the second change trend feature does not change, a non-friction plate type fault discrimination result is generated. The wear judgment result of the friction plate is verified based on the ratio of thermal time constants. When the ratio of thermal time constants is less than the preset threshold value, the wear judgment result of the friction plate is confirmed.

[0035] As described above, this invention obtains the wear state discrimination result of the friction plate through a dual-signal cross-validation mechanism, effectively distinguishing friction plate wear from other fault modes such as solenoid valve failure and brake disc deformation. Specifically, it obtains the first trend feature of the calibration braking angle increment value, which refers to the trend information of the calibration braking angle increment value changing with time, and can be judged by calculating the slope of the rate of change of the calibration braking angle increment value within a preset time window. It also obtains the second trend feature of the response time value of the punch press solenoid valve, which refers to the time delay between the control system issuing the solenoid valve drive command and the actual action of the solenoid valve (current rising edge or falling edge), and can be directly read from the solenoid valve drive current signal of the punch press electronic control system and calculated without adding any sensors.

[0036] Specifically, the solenoid valve response time value includes the clutch disengagement response delay and the brake engagement response delay: the clutch disengagement response delay refers to the time difference between the clutch disengagement command issued by the control system and the rising edge of the clutch solenoid valve drive current; the brake engagement response delay refers to the time difference between the brake engagement command issued by the control system and the rising edge of the brake solenoid valve drive current. The second trend feature refers to the trend information of the solenoid valve response time value changing with time, which can be determined by calculating the slope of the rate of change of the solenoid valve response time value within a preset time window. Consistency judgment results are obtained based on the first and second trend features: when the first and second trend features change synchronously (i.e., increase or decrease simultaneously), it indicates that the current increase in braking angle is caused by friction plate wear, generating a friction plate wear judgment result; when the first trend feature changes but the second trend feature does not change, it indicates that the current increase in braking angle is not caused by friction plate wear, and there may be other faults such as brake disc deformation, generating a non-friction plate fault judgment result. Furthermore, the wear judgment result of the friction plate is verified based on the ratio of thermal time constants. When the ratio of thermal time constants is less than the preset threshold (e.g., ...), the wear judgment result is verified. When the wear of the friction plate is confirmed, the result is verified. A triple verification mechanism, employing dual-signal cross-validation and thermal time constant verification, significantly reduces the false diagnosis rate and solves the problem that existing technologies cannot distinguish friction plate wear from other fault modes.

[0037] In one embodiment, the step of obtaining the remaining life prediction value based on the wear stage identification result and the calibrated braking angle increment value includes: When the wear stage identification result is a stable wear stage, the first remaining life prediction value is obtained based on the slope value of the rate of change under the steady-state mode and the preset braking angle limit value. When the wear stage identification result is a severe wear stage, the slope value of the rate of change, the second rate of change value, and the braking angle limit value are obtained based on the steady-state mode, and a second remaining life prediction value is obtained based on the slope value of the rate of change, the second rate of change value, and the braking angle limit value. Obtain the stamping frequency parameter value, stamping load parameter value, and ambient temperature parameter value of the punch press, and based on the stamping... The first remaining life prediction value or the second remaining life prediction value is corrected according to the operating condition correction coefficient to obtain the corrected remaining life prediction value.

[0038] As described above, this invention employs different remaining life prediction methods based on the wear stage identification results and introduces condition-adaptive correction, achieving dual adaptive prediction of stage and condition. Specifically, when the wear stage identification result is a stable wear stage, since the wear rate is constant, a linear extrapolation method is used to predict the remaining life: ; in, This is the first remaining life prediction value (unit: remaining stamping times). This is the limit value of the braking angle (unit: degrees). This is the current braking angle value (unit: degrees). This represents the slope value of the rate of change under steady-state mode (unit: degrees / control period). The information is obtained from the upper limit threshold of the braking angle specified in the factory technical parameters of the punch press equipment or relevant safety standards. When the braking angle exceeds this value, it indicates that the friction plate has been worn to the limit and needs to be replaced immediately. The data is obtained from the current moving average. To eliminate the influence of single-point measurement noise, when the wear stage identification result is a severe wear stage, a nonlinear prediction method is used due to the accelerated increase in wear rate. ; in, This is the second remaining life prediction value (unit: remaining stamping times). This is the current braking angle value (unit: degrees). This is the limit value of the braking angle (unit: degrees). This is the current slope value of the rate of change (unit: degrees / control period). This is a function of the second-order rate of change over time. The physical meaning of this formula is: remaining life equals the path integral from the current braking angle to the braking angle limit, where the denominator contains... The term represents the sum of the current wear rate and the cumulative acceleration. In practical engineering applications, the above continuous integral is recursively calculated in each control cycle of the control system using discrete numerical methods (such as the trapezoidal method or Simpson's method). Further, the stamping frequency parameter, stamping load parameter, and ambient temperature parameter values ​​of the punch press are obtained. The stamping frequency parameter refers to the operating speed of the punch press in the current work cycle, expressed as the number of stampings per minute; the stamping load parameter refers to the stamping tonnage or load force of the punch press in the current work cycle, which can be read from the punch press's load monitoring system; the ambient temperature parameter refers to the temperature of the workshop environment where the punch press is located, which can be read from the existing temperature sensor on the punch press. Based on these operating parameters, the operating condition correction coefficient is obtained: ; in, This is the working condition correction factor (dimensionless). This is the stamping frequency parameter value. These are the stamping load parameter values. This refers to the ambient temperature parameter value. , , These are the baseline operating condition parameter values. , , These are the regression coefficients obtained by fitting historical data. The physical basis of this formula comes from Arcard's law of wear, which states that the amount of wear is proportional to the normal force and the sliding distance: stamping frequency. This reflects the number of sliding friction cycles per unit time; the higher the frequency, the greater the wear per unit time; stamping load. The wear rate is faster due to the higher the load, which reflects the magnitude of the normal pressure; ambient temperature also plays a role. The mechanical properties of friction materials are affected, and the material strength decreases at high temperatures, leading to accelerated wear. , , The source of information is the rated operating parameters of the punch press, which can be obtained from the equipment's factory parameters. , , The data was obtained through regression fitting of historical operating data under baseline conditions. High load, high frequency, high temperature environment (Accelerated wear), under low load, low frequency, and low temperature conditions (Deceleration Wear). The first or second remaining life prediction value is corrected based on the operating condition correction factor to obtain the corrected remaining life prediction value: In the stable wear stage, the corrected remaining life prediction value is: ; During the severe wear stage, the effective wear rate value is used to replace the original rate of change slope value for nonlinear prediction. Through condition-adaptive correction, the remaining life prediction value can dynamically adapt to changes in actual operating conditions, solving the problem of serious prediction inaccuracies caused by existing technologies that use fixed wear rates or simple linear extrapolation.

[0039] In one embodiment, an online self-calibration step for the reference value is further included, the online self-calibration step for the reference value comprising: Obtain historical sequence data of the calibration braking angle increment value; The minimum moving value is obtained based on the historical sequence data; The change type discrimination result is obtained based on the historical sequence data and the moving minimum value. The change type discrimination result includes gradual change type and step change type. When the change type determination result is a step change type, it is determined that a reference drift has occurred, and the reference value of the speed-braking angle reference curve is updated according to the minimum movement value; When the change type determination result is a gradual change type and the calibrated braking angle increment value shows a continuous monotonically increasing trend, it is determined to be real wear, and the reference value of the speed-braking angle reference curve remains unchanged.

[0040] As described above, this invention solves the problem of uncorrectable measurement reference drift after long-term operation through an online self-calibration step. Specifically, it acquires historical sequence data of calibration braking angle increment values. This historical sequence data refers to the sequence of historical calibration braking angle increment values ​​stored in the control system. In each control cycle, the control system stores the currently calculated calibration braking angle increment value into the historical data buffer, forming historical sequence data. The minimum movement value is then obtained based on the historical sequence data. ; in, This represents the minimum movement value (unit: degrees). For the first The calibration braking angle increment value for each control cycle. This is the current control cycle number. The tracking of the minimum moving value is based on the fundamental physical law that "friction pad wear is a unidirectional and irreversible process." The friction pad will only become thinner with wear, and the calibrated braking angle increment will only monotonically increase with increasing wear, not spontaneously decrease. Therefore, the minimum value in the historical sequence represents the "state with the least wear" since the current friction pad installation, i.e., the measurement reference state. The change type discrimination result is obtained based on the historical sequence data and the minimum moving value. The change type discrimination result includes gradual change type and step change type. Gradual change refers to the calibrated braking angle increment increasing slowly and continuously over time, which conforms to the physical law of friction pad wear, which is a unidirectional and irreversible gradual process. Step change refers to the calibrated braking angle increment changing abruptly in a short period of time, which is usually caused by reference drift due to factors such as changes in mechanical clearance or loose installation. When the change type is determined to be a step change, a reference drift is identified, and the reference value of the speed-braking angle reference curve is updated based on the minimum movement value. This resets the current calibrated braking angle increment value to the new reference value, completing online self-calibration. When the change type is determined to be a gradual change and the calibrated braking angle increment value shows a continuously monotonically increasing trend, it is identified as true wear, and the reference value of the speed-braking angle reference curve remains unchanged. Through this online reference value self-calibration step, true wear and reference drift can be automatically distinguished, ensuring the accuracy of the measurement reference during long-term operation and avoiding false alarms and missed alarms caused by reference drift.

[0041] In one embodiment, the step of generating multi-level early warning information based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value includes: Obtain the moving average value of the calibration braking angle increment; The joint state discrimination result is obtained based on the moving average value, the slope value of the rate of change and the second-order rate of change value under the steady-state mode, the thermal time constant ratio, and the wear state discrimination result. Based on the joint state discrimination results, the present invention includes normal level, attention level, early warning level and alarm level; The triggering condition for the normal level is that the wear is in the running-in wear stage or the early stage of stable wear, and the wear state judgment result is friction plate wear. The triggering condition for the attention level is entering the middle to late stage of stable wear and tear and the moving average value reaches a preset first threshold. The triggering condition corresponding to the warning level is that the second-order rate of change value is greater than zero and the wear state judgment result is friction plate wear, or the thermal time constant ratio is less than the preset thermal time constant ratio threshold. The triggering condition corresponding to the alarm level is that the moving average value reaches the braking angle limit or the remaining life prediction value is lower than the safety threshold.

[0042] As described above, this invention generates multi-level early warning information through a multi-condition joint triggering mechanism, effectively suppressing false alarms caused by random noise in a single measurement. Specifically, it obtains the moving average value of the calibration braking angle increment. The calculation method is as follows: ; in This is the moving average window length, typically taking the value of... to One control period. Based on the moving average. The slope of the rate of change in steady-state mode and second-order rate of change ratio of thermal time constant The wear condition judgment results are used to obtain a combined condition judgment result. Based on the combined condition judgment result, a warning level is determined: the trigger condition for the normal level is that the wear is in the running-in wear stage or the early stage of stable wear, and the wear condition judgment result is friction plate wear. This indicates that the friction plate wear is normal, and the press can continue to operate. The trigger condition for the attention level is that the wear has entered the middle to late stage of stable wear, and the moving average value reaches a preset first threshold (such as the reference braking angle value). At this point, it indicates accelerated wear of the friction pads, requiring close monitoring and continuous attention to the wear trend. The trigger condition for the early warning level is a second-order rate of change greater than zero and a wear status determination result indicating friction pad wear, or a thermal time constant ratio less than a preset thermal time constant ratio threshold. This indicates the friction pads have entered a severe wear stage or the thermal time constant has significantly decreased, nearing the end of their lifespan, necessitating a replacement plan. The trigger condition for the alarm level is a moving average reaching the braking angle limit or a remaining lifespan prediction value lower than a safety threshold. This indicates the friction pads have worn to their limit and must be immediately shut down and replaced, or a remaining lifespan prediction value lower than a safety threshold, also triggering an alarm level. This four-level early warning mechanism achieves full coverage from early warning to extreme alarms, providing sufficient basis for maintenance decisions.

[0043] Example 2 Embodiment 2 of the present invention provides an online monitoring and early warning system for wear of friction pads in a punch press clutch brake. Figure 2 This is a block diagram illustrating an online monitoring and early warning system for wear of friction pads in a punch press clutch brake, according to an exemplary embodiment. (Refer to...) Figure 2 The system includes: The data acquisition module is used to acquire real-time angle sequence data of the punch press crankshaft, acquire braking start angle value and braking end angle value based on the real-time angle sequence data, and acquire the original braking angle value based on the braking start angle value and braking end angle value. The speed normalization module is used to obtain the current running speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current running speed value and the preset speed-braking angle reference curve. The temperature dynamic feature extraction module is used to acquire the temperature signal of the punch press friction plate, separate the temperature dynamic component from the temperature signal, and identify the thermal time constant of the friction plate based on the temperature dynamic component. The wear condition discrimination module is used to obtain the wear condition discrimination result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run; The dual normalization processing module is used to obtain the speed-temperature dual normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value and the temperature dynamic component. The dual-mode stage identification module is used to obtain the ratio of the thermal time constant based on the thermal time constant and the initial thermal time constant during the first run, and to obtain the wear state discrimination result of the friction plate based on the ratio of the thermal time constant. The life prediction module is used to obtain the remaining life prediction value based on the wear stage identification result and the calibration braking angle increment value. The early warning output module is used to generate multi-level early warning information based on the wear status judgment result, the wear stage identification result, and the remaining life prediction value.

[0044] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent results or equivalent process transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for online monitoring and early warning of wear of friction pads in a punch press clutch brake, characterized in that, include: The real-time angle sequence data of the punch press crankshaft is obtained, and the braking start angle value and braking end angle value are obtained based on the real-time angle sequence data. The original braking angle value is obtained based on the braking start angle value and braking end angle value. Obtain the current operating speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current operating speed value and the preset speed-braking angle reference curve; The temperature signal of the friction plate of the punch press is acquired, the dynamic temperature component is separated from the temperature signal, and the thermal time constant of the friction plate is identified based on the dynamic temperature component. The wear state of the friction plate is determined by the ratio of the thermal time constant to the initial thermal time constant during the first run. The calibrated braking angle increment value after speed-temperature dual normalization is obtained based on the original braking angle value, the reference braking angle value, and the temperature dynamic component. The ratio of the thermal time constants is obtained based on the thermal time constant and the initial thermal time constant during the first run, and the wear state judgment result of the friction plate is obtained based on the ratio of the thermal time constants. The remaining life prediction value is obtained based on the wear stage identification results and the calibrated braking angle increment value. Multi-level early warning information is generated based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value.

2. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The steps of acquiring the temperature signal of the punch press friction plate, separating the dynamic temperature component from the temperature signal, and identifying the thermal time constant of the friction plate based on the dynamic temperature component include: Obtain the existing temperature signal from the punch press electrical control system, or estimate the friction plate temperature signal based on the kinetic energy dissipation and heat dissipation model during braking. The temperature signal is low-pass filtered to obtain the steady-state temperature component, and the temperature signal is subtracted from the steady-state temperature component to obtain the dynamic temperature component. After the braking process ends, the attenuation curve of the dynamic temperature component is obtained, and the attenuation curve is subjected to exponential fitting to obtain the thermal time constant of the friction plate.

3. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The step of obtaining the speed-temperature double-normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value, and the temperature dynamic component includes: The temperature compensation amount is obtained based on the dynamic temperature component and the preset temperature-angle coupling coefficient. Subtract the reference braking angle value from the original braking angle value to obtain the initial braking angle increment value; Subtracting the temperature compensation amount from the initial braking angle increment value yields the calibrated braking angle increment value after speed-temperature dual normalization. The first trend feature is obtained based on the calibrated braking angle increment value, and the wear state discrimination result of the friction plate is obtained based on the ratio of the first trend feature and the thermal time constant.

4. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The step of obtaining the ratio of the thermal time constant based on the thermal time constant and the initial thermal time constant during the first run, and obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constant, includes: Obtain the initial thermal time constant of the friction pad during its first operation, and obtain the thermal time constant of the current single braking process; When the amount of historical data is less than a preset threshold, the thermal time constant ratio is obtained based on the ratio of the thermal time constant of the current single braking process to the initial thermal time constant, and the wear stage identification result in the cold start mode is obtained based on the thermal time constant ratio and the temperature rise rate of the single braking process. When the amount of historical data is greater than or equal to the preset threshold, the moving average sequence data is obtained based on the time series data of the calibration braking angle increment value, the slope value of the rate of change and the second-order rate of change value are obtained based on the moving average sequence data, and the wear stage identification result in steady state mode is obtained based on the ratio of the slope value of the rate of change, the second-order rate of change value and the thermal time constant. Based on the comparison results of historical data volume and preset threshold, the system switches between cold start mode and steady state mode, and uses weighted fusion near the switching point to obtain the wear stage identification results.

5. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The step of obtaining the wear state judgment result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run includes: Obtain the first trend characteristic of the calibrated braking angle increment value; Obtain the second trend characteristic of the response time value of the punch press solenoid valve; A consistency judgment result is obtained based on the first and second trend characteristics; When the consistency discrimination result is that the first change trend feature and the second change trend feature change synchronously, a friction pad wear discrimination result is generated; When the consistency discrimination result is that the first change trend feature changes while the second change trend feature does not change, a non-friction plate type fault discrimination result is generated. The wear judgment result of the friction plate is verified based on the ratio of thermal time constants. When the ratio of thermal time constants is less than the preset threshold value, the wear judgment result of the friction plate is confirmed.

6. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The step of obtaining the remaining life prediction value based on the wear stage identification result and the calibrated braking angle increment value includes: When the wear stage identification result is a stable wear stage, the first remaining life prediction value is obtained based on the slope value of the rate of change under the steady-state mode and the preset braking angle limit value. When the wear stage identification result is a severe wear stage, the slope value of the rate of change, the second rate of change value, and the braking angle limit value are obtained based on the steady-state mode, and a second remaining life prediction value is obtained based on the slope value of the rate of change, the second rate of change value, and the braking angle limit value. Obtain the stamping frequency parameter value, stamping load parameter value, and ambient temperature parameter value of the punch press, and based on the stamping... The first remaining life prediction value or the second remaining life prediction value is corrected according to the operating condition correction coefficient to obtain the corrected remaining life prediction value.

7. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, It also includes an online self-calibration step for the reference value, which includes: Obtain historical sequence data of the calibration braking angle increment value; The minimum moving value is obtained based on the historical sequence data; The change type discrimination result is obtained based on the historical sequence data and the moving minimum value. The change type discrimination result includes gradual change type and step change type. When the change type determination result is a step change type, it is determined that a reference drift has occurred, and the reference value of the speed-braking angle reference curve is updated according to the minimum movement value; When the change type determination result is a gradual change type and the calibrated braking angle increment value shows a continuous monotonically increasing trend, it is determined to be real wear, and the reference value of the speed-braking angle reference curve remains unchanged.

8. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 6, characterized in that, The step of generating multi-level early warning information based on the wear state discrimination result, the wear stage identification result, and the remaining life prediction value includes: Obtain the moving average value of the calibration braking angle increment; The joint state discrimination result is obtained based on the moving average value, the slope value of the rate of change and the second-order rate of change value under the steady-state mode, the thermal time constant ratio, and the wear state discrimination result. Based on the joint state discrimination results, the present invention includes normal level, attention level, early warning level and alarm level; The triggering condition for the normal level is that the wear is in the running-in wear stage or the early stage of stable wear, and the wear state judgment result is friction plate wear. The triggering condition for the attention level is entering the middle to late stage of stable wear and tear and the moving average value reaches a preset first threshold. The triggering condition corresponding to the warning level is that the second-order rate of change value is greater than zero and the wear state judgment result is friction plate wear, or the thermal time constant ratio is less than the preset thermal time constant ratio threshold. The triggering condition corresponding to the alarm level is that the moving average value reaches the braking angle limit or the remaining life prediction value is lower than the safety threshold.

9. The method for online monitoring and early warning of wear of friction pads in a punch press clutch and brake according to claim 1, characterized in that, The step of obtaining the braking start angle value and braking end angle value based on the real-time angle sequence data, and obtaining the original braking angle value based on the braking start angle value and braking end angle value, includes: Obtain the braking command signal issued by the punch press control system, and use the braking command signal as a hardware latch trigger signal; In response to the rising edge of the braking command signal, the real-time angle sequence data is latched at the instantaneous angle value at the rising edge by the external latch trigger input of the high-speed counting module, and the instantaneous angle value is used as the braking start angle value. Monitor the real-time angle sequence data. When the real-time angle sequence data remains unchanged for multiple consecutive control cycles, it is determined that the crankshaft has completely stopped. The current value of the real-time angle sequence data after the crankshaft has completely stopped is obtained as the braking termination angle value. The original braking angle value is obtained based on the difference between the braking termination angle value and the braking start angle value.

10. An online monitoring and early warning system for wear of friction pads in a punch press clutch and brake, characterized in that, include: The data acquisition module is used to acquire real-time angle sequence data of the punch press crankshaft, acquire braking start angle value and braking end angle value based on the real-time angle sequence data, and acquire the original braking angle value based on the braking start angle value and braking end angle value. The speed normalization module is used to obtain the current running speed value of the punch press, and obtain the reference braking angle value at the current speed based on the current running speed value and the preset speed-braking angle reference curve. The temperature dynamic feature extraction module is used to acquire the temperature signal of the punch press friction plate, separate the temperature dynamic component from the temperature signal, and identify the thermal time constant of the friction plate based on the temperature dynamic component. The wear condition discrimination module is used to obtain the wear condition discrimination result of the friction plate based on the ratio of the thermal time constant to the initial thermal time constant during the first run; The dual normalization processing module is used to obtain the speed-temperature dual normalized calibration braking angle increment value based on the original braking angle value, the reference braking angle value and the temperature dynamic component. The dual-mode stage identification module is used to obtain the ratio of the thermal time constant based on the thermal time constant and the initial thermal time constant during the first run, and to obtain the wear state discrimination result of the friction plate based on the ratio of the thermal time constant. The life prediction module is used to obtain the remaining life prediction value based on the wear stage identification result and the calibration braking angle increment value. The early warning output module is used to generate multi-level early warning information based on the wear status judgment result, the wear stage identification result, and the remaining life prediction value.

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