A CNC grinding machine control system for a dual-head rotary grinding machine

Abstract

This application relates to the field of CNC machine tool control technology, specifically to a CNC grinding machine control system for a dual-head rotary grinding machine. The system includes: a CNC grinding machine data acquisition module, which collects the three-dimensional grinding force and the temperature of each grinding head during the workpiece grinding process; a data analysis module, responsible for analyzing the acquired data during the grinding process, evaluating the grinding force error in real time, and feeding it back to the grinding machine control compensation module via a data transmission module to achieve grinding force step control during the workpiece grinding process; a grinding machine control compensation module, which determines the proportional term of the PID control for each grinding head at the initial moment of each processing interval to control the grinding force of each grinding head; and a data transmission module, responsible for data transmission between the modules in the CNC grinding machine control system of the dual-head rotary grinding machine. This application aims to ensure the accuracy of grinding processes that improve workpiece surface quality.

Description

Technical Field

[0001] This application relates to the field of CNC machine tool control technology, specifically to a CNC grinding machine control system for a dual-head rotatable grinding machine. Background Technology

[0002] The CNC control system of a dual-head rotary grinder integrates multi-axis linkage and high-precision intelligent control technology, enabling independent control of two rotating grinding spindles. By adjusting the motion trajectory, rotation angle, and machining parameters of the grinding heads in real time, the system achieves high-precision coordinated control. Compared to the machining accuracy loss caused by repeated workpiece clamping and repositioning in traditional single-head grinding machines, the CNC control of a dual-head rotary grinder allows for single-clamp compound grinding of complex parts, eliminating handling and reference errors, significantly improving machining accuracy, and meeting the urgent needs of high-end manufacturing for high efficiency, high precision, and high flexibility.

[0003] In the control process of CNC grinding machines with dual-head rotary grinding machines, traditional CNC grinding machine control systems mostly use PID technology for grinding force compensation control during the grinding process. However, as the grinding process progresses, fluctuations in material hardness and insufficient self-sharpening of the grinding head and grinding wheel can cause instability of the constant grinding force, resulting in uneven surface quality of the processed material and accelerating the dulling of the grinding head and grinding wheel. At the same time, the high temperature generated during the grinding process can cause structural thermal deformation, causing changes in the relative position of the grinding head and workpiece, resulting in the actual grinding depth deviating from the set value. The fixed proportional term parameter of the traditional grinding force PID control will further exacerbate the grinding force control error caused by the above problems, thus damaging the workpiece machining accuracy. Summary of the Invention

[0004] In view of the above, it is necessary to provide a CNC grinding machine control system for a dual-head rotary grinding machine to solve the above problems.

[0005] One embodiment of this application provides a CNC grinding machine control system for a dual-head rotary grinding machine, the system comprising:

[0006] The CNC grinding machine data acquisition module is used to collect axial force, tangential force, normal force, and temperature of each grinding head of the workpiece during the grinding process of a dual-head rotary grinding machine.

[0007] The data analysis module is used to preset processing intervals, analyze the energy distribution characteristics of normal and axial forces in the frequency domain within each processing interval, and determine the grinding force imbalance in each processing interval by combining the numerical abrupt changes of axial and tangential forces. It also performs linear fitting on all temperature data of each grinding head in each processing interval and analyzes the similarity of temperature fluctuations in the processing areas of different grinding heads in each processing interval to determine the asynchronous state of grinding thermal deformation of each grinding head in each processing interval. Based on the grinding force imbalance, it constructs the proportional term adjustment factor for the PID control of each grinding head in each processing interval.

[0008] The grinding machine control compensation module determines the proportional term of the PID control for each grinding head at the initial moment of each processing interval based on the difference between the proportional term adjustment factor of each processing interval and the previous processing interval during the grinding process of each grinding head, and controls the grinding force of each grinding head.

[0009] The data transmission module is responsible for data transmission between various modules in the CNC grinding machine control system of the dual-head rotary grinding machine.

[0010] Preferably, the specific steps for determining the grinding force imbalance in each processing zone include:

[0011] Obtain the frequency domain representation of all axial forces and all normal forces in each processing zone; record the frequency domain components that are greater than or equal to the preset values ​​as high-frequency components, otherwise record them as low-frequency components;

[0012] Abrupt change detection is performed on all axial forces and all tangential forces in each processing interval to obtain the abrupt change points of axial forces and tangential forces; for the same data, the time interval between each abrupt change point and the next abrupt change point is taken as the abrupt change interval of each abrupt change point;

[0013] Based on the energy standard deviation of the low-frequency component of the normal force in each processing interval, combined with the overall distribution characteristics of the axial force in the mutation interval corresponding to each axial force mutation point and the frequency domain distribution characteristics of the axial force, the abrasive resistance passivation status of each processing interval is determined.

[0014] Analyze the distribution differences of tangential force between the mutation points of tangential force in each processing interval, and combine the energy distribution characteristics of the low-frequency components of tangential force to determine the abnormal tangential friction conditions in each processing interval.

[0015] Based on the abrasive obstruction and passivation status and the tangential friction anomaly status, the grinding force imbalance in each processing zone is determined, wherein the grinding force imbalance is positively correlated with both the abrasive obstruction and passivation status and the tangential friction anomaly status.

[0016] Preferably, the specific process for determining the abrasive resistance passivation status of each processing zone is as follows:

[0017] Obtain the dispersion of the axial force within the abrupt change interval corresponding to each axial force in each processing interval, and accumulate the dispersion of all axial forces corresponding to the abrupt change intervals to obtain the first accumulation result;

[0018] Calculate the degree of disorder of the energy of all axial forces in all frequency domain components within each processing interval;

[0019] The ratio of the first accumulated result to the degree of disorder is positively fused with the energy standard deviation to obtain the abrasive passivation status of each processing interval.

[0020] Preferably, the specific process for determining the abnormal tangential friction condition in each processing zone is as follows:

[0021] Calculate the average tangential force in the interval corresponding to each tangential force mutation point within each processing interval, and sum the differences between the average tangential forces in the intervals corresponding to all two adjacent tangential force mutation points to obtain the second summation result;

[0022] The interquartile range of the energy of all low-frequency components corresponding to the tangential force in each processing interval is obtained and positively fused with the second accumulation result to obtain the tangential friction anomaly status of each processing interval.

[0023] Preferably, the grinding force imbalance is specifically the normalized value of the product of the abrasive grain obstruction and passivation condition and the tangential friction abnormality condition.

[0024] Preferably, determining the asynchronous state of grinding thermal deformation of each grinding head in each processing zone specifically involves:

[0025] The peak values ​​of all temperature data for each grinding head in each processing zone are obtained and formed into a peak temperature sequence.

[0026] The cumulative result of the deviation between all temperature data of each grinding head in each processing interval and its corresponding temperature fitting data is recorded as the third cumulative result;

[0027] Calculate the coefficient of variation of all temperature data for each grinding head in each processing zone;

[0028] Based on the third cumulative result and the coefficient of variation, the degree of thermal risk of each grinding head in each processing interval is obtained;

[0029] The distance metric between the peak temperature data sequence of each grinding head and the processing area of ​​another grinding head in each processing interval is obtained; based on the distance metric and the degree of thermal deformation risk, the asynchronous status of grinding thermal deformation of each grinding head in each processing interval is determined; the asynchronous status of grinding thermal deformation is positively correlated with both the distance metric and the degree of thermal deformation risk.

[0030] Preferably, the degree of thermal change risk of each grinding head in each processing interval is specifically the product between the third cumulative result obtained by each grinding head in each processing interval and the coefficient of variation.

[0031] Preferably, the asynchronous state of grinding thermal deformation is specifically the normalized value of the product of the distance metric and the degree of thermal deformation risk.

[0032] Preferably, the proportional term adjustment factor of the PID control for each processing interval is specifically the product of the grinding force imbalance and the asynchronous state of grinding thermal deformation in each processing interval.

[0033] Preferably, determining the proportional term of the PID control for each grinding head at the initial moment of each processing interval is specifically the sum of the proportional term adjustment factor of each grinding head in each processing interval and the difference.

[0034] This application has at least the following beneficial effects:

[0035] This application first provides a quantitative calculation method for grinding force imbalance and asynchronous grinding thermal deformation, which more accurately evaluates the abrasive penetration resistance and passivation status, the increase in tangential friction ratio, and the severe asynchronous nature of high-temperature thermal deformation during workpiece grinding. This provides a data basis for constant grinding force control to avoid grinding wheel chatter, cumulative machining errors, and asymmetric thermal deformation.

[0036] Furthermore, by adjusting the proportional term adjustment factor of the grinding force proportional term of each grinding head in the dual-head rotary grinder, the drawback of the traditional PID fixed proportional term parameter exacerbating the grinding force control error is avoided. It can effectively adjust the grinding force in real time according to the material hardness fluctuation, the self-sharpening property of the grinding wheel and the high temperature of grinding. On the basis of ensuring constant grinding force, it ensures the steady-state accuracy of grinding process of workpiece surface quality and reduces the risk of uneven grinding quality and grinding defects on the workpiece surface. Attached Figure Description

[0037] Figure 1 A block diagram of a CNC grinding machine control system for a dual-head rotary grinding machine provided in this application;

[0038] Figure 2 A flowchart illustrating the specific process for controlling the grinding force of each grinding head, as provided in this application. Detailed Implementation

[0039] In the description of the embodiments in this application, the words "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary," "or," and "for example" is intended to present the relevant concepts in a specific manner.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] It should also be noted that the terms "first" and "second" in this application and its accompanying drawings are used to distinguish similar objects, rather than to describe a specific order or sequence. The methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of protection of this application, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0043] The following description, in conjunction with the accompanying drawings, details the specific scheme of the CNC grinding machine control system for a dual-head rotary grinding machine provided in this application.

[0044] Please see Figure 1 The diagram illustrates a block diagram of a CNC grinding machine control system for a dual-head rotatable grinding machine according to an embodiment of this application. The system includes: a CNC grinding machine data acquisition module, a data analysis module, a grinding machine control compensation module, and a data transmission module.

[0045] This application first proposes a CNC grinding machine control system for a dual-head rotary grinding machine, applied in the field of CNC machine tool control technology. The system includes:

[0046] CNC grinding machine data acquisition module: collects axial force, tangential force, normal force, and temperature of each grinding head of the workpiece during the grinding process of the workpiece on the dual-head rotary grinding machine.

[0047] This application achieves high-precision motion control of the dual grinding heads and workpiece fixture through six-axis coordination (X / Y / Z + rotary axis), and uses servo motors and ball screws for driving.

[0048] This application deploys piezoelectric force sensors in the contact area between the spindle of each grinding head and the workpiece in a dual-head rotary grinding machine, and deploys infrared thermal sensing devices in the grinding head-workpiece processing area to acquire real-time data on the three-dimensional grinding forces (normal force, tangential force, and axial force) and the temperature time series data of the workpiece processing area during the grinding process of each grinding head. The sampling frequency of the three-dimensional grinding forces and temperature data is 100Hz, and the timestamps are aligned with a GPS clock.

[0049] To prevent the different dimensions of different data from affecting the analysis, this application uses the obtained triaxial grinding force data sequence and temperature data sequence as inputs, and uses Z-Score normalization to unify the dimensions of the data. Since Z-Score normalization is a well-known technology, the specific acquisition process will not be described in detail.

[0050] Thus, the triaxial grinding force data sequence of each grinding head and the temperature data sequence of the workpiece processing area can be obtained through the above method during the grinding process of a dual-head rotary grinder.

[0051] Data Analysis Module: Preset processing intervals; analyze the energy distribution characteristics of normal and axial forces in the frequency domain within each processing interval; combine the numerical abrupt changes in axial and tangential forces to determine the grinding force imbalance in each processing interval; perform linear fitting on all temperature data of each grinding head in each processing interval; analyze the similarity of temperature fluctuations in the processing areas of different grinding heads in each processing interval to determine the asynchronous state of grinding thermal deformation of each grinding head in each processing interval; and, based on the grinding force imbalance, construct the proportional term adjustment factor for the PID control of each grinding head in each processing interval.

[0052] During the workpiece grinding process of a dual-head rotary grinder, as the grinding process proceeds, fluctuations in the hardness of the workpiece material and insufficient self-sharpening of the grinding wheel can cause hard phases to hinder grinding penetration and cause blockage on the grinding wheel surface. This leads to elastoplastic deformation of the workpiece surface and mass eccentricity of the grinding wheel, resulting in instability of the grinding force constant in the workpiece processing area. Consequently, improper grinding force causes uneven surface quality and serious processing errors in the processing area.

[0053] Specifically, during the workpiece grinding process on a dual-head rotary grinder, the more severe the fluctuations in workpiece material hardness and the insufficient self-sharpening of the grinding wheel, the more pronounced the high-frequency oscillation of the normal force in the workpiece grinding area becomes. This is due to the hard phase hindering abrasive grain penetration and the reduction of effective cutting edges caused by dulled abrasive grains. Furthermore, changes in workpiece material hardness and non-uniform shedding of abrasive grains can induce axial forced resonance in the grinding wheel, leading to higher amplitude axial force fluctuations and stronger low-frequency energy concentration. Simultaneously, according to the energy distribution principle, an increase in the negative rake angle of dulled abrasive grains increases abrasive cutting resistance and the friction ratio, resulting in a more stepped increase in the tangential force data in the workpiece machining area and a concentration of low-frequency energy migration. In such cases, it is crucial to reduce the proportional term in the PID control of the grinding force to avoid exacerbating grinding wheel chatter and grinding defects caused by errors or lightning strikes, thus restoring the steady-state accuracy of the grinding process.

[0054] Based on the above analysis, this application takes the relevant data of any one grinding head in a dual-head rotary grinder as an example for subsequent analysis. A preset time length is used as a processing interval to construct grinding force imbalance, which is used to characterize the abrasive cutting resistance passivation and the degree of increase in tangential friction ratio during the workpiece grinding process. In this embodiment, the preset time length is 1 minute. The triaxial grinding force data sequence of each processing interval is used as input, and the frequency domain representation of the triaxial grinding force in each processing interval is obtained by using Fast Fourier Transform (FFT). The frequency components of the normal force and axial force in each processing interval during the workpiece grinding process that are greater than or equal to 500Hz are recorded as high-frequency components, and those that are less than 500Hz are recorded as low-frequency components.

[0055] The axial force data sequence and tangential force data sequence of each processing interval during the workpiece grinding process are used as input. A Bayesian mutation point detection algorithm is used to obtain all axial force mutation points and tangential force mutation points in each processing interval. The time interval between each axial force mutation point and the next axial force mutation point in the processing interval is recorded as the mutation interval of each axial force mutation point. Similarly, the mutation intervals of each tangential force in the processing interval can be obtained.

[0056] Calculate the energy standard deviation of the high-frequency components corresponding to the normal force within each processing interval; obtain the dispersion of the axial force within the abrupt change interval corresponding to each axial force in each processing interval, and accumulate the dispersion of all abrupt change intervals corresponding to axial forces to obtain a first accumulation result; calculate the disorder of the energy of all axial forces in all frequency domain components within each processing interval; and positively fuse the ratio of the first accumulation result to the disorder with the energy standard deviation to obtain the abrasive passivation status of each processing interval. In this embodiment, the dispersion of multiple variables is calculated using range values; the disorder of multiple variables is calculated using information entropy; and the positive fusion of multiple variables is performed using a multiplication method.

[0057] Furthermore, the average tangential force in the corresponding mutation interval for each tangential force mutation point within each processing interval is calculated. The differences between the average tangential force values ​​in the corresponding mutation intervals for all adjacent tangential force mutation points are accumulated to obtain a second accumulated result. The interquartile range of the energy of all low-frequency components corresponding to the tangential force in each processing interval is obtained and positively fused with the second accumulated result to obtain the tangential friction anomaly condition of each processing interval. In this embodiment, the positive fusion of multiple variables adopts a multiplication calculation method.

[0058] The normalized value of the product of the abrasive obstruction and passivation condition and the tangential friction anomaly condition in each machining zone is taken as the grinding force imbalance in each machining zone. In this embodiment, the sigmoid function is selected as the normalization function.

[0059] It should be understood that grinding force imbalance reflects the degree of abrasive grain penetration resistance and passivation in various processing zones during the workpiece grinding process, as well as the increase in the proportion of tangential friction. Abrasive grain penetration resistance and passivation indicate that the presence of hard phases on the workpiece during grinding hinders the smooth penetration of abrasive grains, thus increasing the difficulty of grinding. Simultaneously, when abrasive grains become passivated during cutting, it causes instability in the cutting forces, especially the normal force, which exhibits high-frequency oscillations, while the axial force may show significant fluctuations and concentrate energy in the low-frequency range. These force fluctuations indicate poor stability of the grinding process. The abnormal condition of tangential friction characterizes the degree of step increase in tangential force and the concentration of low-frequency energy caused by the increased proportion of tangential friction in each processing zone during the workpiece grinding process. During the workpiece grinding process, the more severe the fluctuation of workpiece material hardness and the insufficient self-sharpening of the grinding wheel, the more obvious the high-frequency oscillation of the normal force in the workpiece grinding area, the larger the amplitude of axial force fluctuation, and the stronger the concentration of low-frequency energy, that is, the greater the abrasive resistance and passivation. At the same time, the greater the degree of step increase in tangential force due to the increase in the proportion of tangential friction, the more obvious the energy concentration of the low-frequency component of tangential force, that is, the greater the abnormal condition of tangential friction.

[0060] In the CNC grinding process of a dual-head rotary grinder, relying solely on the imbalance of grinding force during workpiece grinding to assess the grinding force control error still has certain drawbacks. Specifically, it ignores the impact of structural thermal deformation caused by high grinding temperatures on the relative position of the grinding head and the workpiece, and lacks risk analysis of thermal deformation and grinding depth deviation caused by high grinding temperatures of different grinding heads. This may exacerbate the grinding force feedback control error during workpiece grinding, resulting in damage to the workpiece grinding accuracy and synchronous failure of the grinding head.

[0061] Specifically, during the workpiece grinding process on a dual-head rotary grinder, when the high-temperature thermal deformation in the grinding area intensifies and the thermal deformation of different grinding heads is inconsistent, the temperature changes in each grinding area of ​​the workpiece will exhibit a significant non-linear upward trend. Furthermore, the instability of material hardness and insufficient self-sharpening of the grinding wheel will exacerbate thermal oscillations caused by high temperatures during grinding; simultaneously, the lower the temperature correlation between the two grinding head processing areas due to inconsistent grinding temperatures, the better. In this case, the proportional gain in the PID control of the grinding force should be reduced to suppress the oscillation risk caused by high-temperature thermal inertia and to reduce the risk of asymmetric thermal deformation caused by differences in grinding head temperatures.

[0062] Based on the above analysis, this application constructs an asynchronous grinding thermal deformation condition to characterize the severity of high-temperature thermal deformation experienced by the workpiece during grinding and the inconsistency of grinding thermal deformation in different grinding head processing areas. Specifically: the temperature data sequence of the processing area corresponding to each grinding head in each processing interval is used as input, and the least squares method is used to obtain a fitted straight line of temperature data for the processing area of ​​each grinding head in each processing interval. The temperature data sequence corresponding to each grinding head in each processing interval during the workpiece grinding process is used as input, and the APMD (Automatic Multiscale-based Peak Detection) multiscale peak detection algorithm is used to obtain all peaks in the temperature data sequence corresponding to each grinding head in each processing interval. The sequence composed of all peak temperature data corresponding to the processing area of ​​each grinding head in the processing interval is recorded as the peak temperature data sequence of each grinding head. Since the least squares method and the AMPD multiscale peak detection algorithm are both known technologies, the specific acquisition process will not be described in detail.

[0063] The cumulative result of the deviations between all temperature data and their corresponding temperature fitting data for each grinding head in each processing interval is obtained and recorded as the third cumulative result. The coefficient of variation of all temperature data for each grinding head in each processing interval is calculated. The distance metric between the peak temperature data sequences of each grinding head and the processing area of ​​another grinding head in each processing interval is obtained and positively fused with the third cumulative result and the coefficient of variation. After normalization, the asynchronous status of grinding thermal deformation of each grinding head in each processing interval is obtained. In this embodiment, the product of the third cumulative result obtained by each grinding head in each processing interval and the coefficient of variation is used as the degree of thermal deformation risk of each grinding head in each processing interval. The deviation between data is calculated using the absolute value of the difference. The distance metric between sequences is calculated using the DTW distance. The positive fusion of multiple variables is performed by multiplication. The normalization function is the sigmoid function.

[0064] It should be understood that the asynchronous state of grinding thermal deformation reflects the severity of the high-temperature thermal deformation experienced by each grinding head's grinding area within the processing range, as well as the asynchrony between the thermal deformation experienced by different grinding heads. The degree of thermal deformation risk reflects the intensity of the nonlinear increase in temperature data and the high-temperature thermal oscillation state of each grinding head's grinding area within the processing range. The high-temperature difference between grinding heads characterizes the degree of low correlation with the high-temperature grinding experienced by different grinding heads. In the workpiece grinding process of a dual-grinding-head rotary grinder, the more severe the high-temperature thermal deformation experienced by the workpiece's grinding area and the more severe the asynchrony in the grinding thermal deformation of different grinding heads, the more obvious the nonlinear growth trend of the temperature data of the corresponding workpiece grinding area of ​​each grinding head, the higher the degree of high-temperature grinding oscillation, that is, the greater the degree of thermal deformation risk. At the same time, the lower the correlation between the high-temperature peaks of the two grinding heads caused by the inconsistency of grinding temperatures, the greater the asynchronous state of grinding thermal deformation.

[0065] In the workpiece grinding process of a dual-head rotary grinder, the higher the imbalance of grinding force in the processing zone and the more serious the asynchronous situation of grinding thermal deformation, the more obvious the material hardness fluctuation and insufficient self-sharpening of the grinding wheel are during the grinding process. The higher the risk of high-temperature thermal deformation of the grinding head during the workpiece grinding process and the more serious the asynchronous situation of grinding temperature with the other grinding head, the more important it is to reduce the proportional term in the PID control of the grinding force of the grinder to avoid grinding defects and asymmetric thermal deformation quality damage caused by grinding wheel vibration, high-temperature thermal inertia and high temperature difference of grinding head.

[0066] Based on the above analysis, this application constructs a proportional term adjustment factor for PID control to characterize the degree of proportional term gain adjustment in the PID control process of grinding force in a dual-head rotary grinder. The proportional term adjustment factor can be obtained through grinding force imbalance and asynchronous grinding thermal deformation. Specifically, in one processing case of this application, the product of grinding force imbalance and asynchronous grinding thermal deformation in each processing interval during the workpiece grinding process is recorded as the proportional term adjustment factor. When the proportional term adjustment factor is larger, it indicates that the workpiece material hardness fluctuation and insufficient self-sharpening of the grinding wheel are more severe in the processing interval, and the high-temperature thermal deformation during grinding is more severe, and the asynchronous high-temperature grinding conditions of different grinding heads are more obvious.

[0067] Thus, the proportional gain adjustment factor for any processing interval during the workpiece grinding process can be obtained through the above method and transmitted to the grinding machine control compensation module via the data transmission module.

[0068] Grinding machine control compensation module: Based on the difference between the proportional term adjustment factor of each processing interval and the previous processing interval during the grinding process of each grinding head, the proportional term of the PID control of each grinding head at the initial moment of each processing interval is determined, and the grinding force of each grinding head is controlled.

[0069] The real-time three-dimensional grinding force data sequence, temperature data sequence, and expected grinding force in each processing interval of the workpiece grinding process are used as inputs. A PID control algorithm is used to control the grinding force of each grinding head in the rotary grinding machine. The default initial parameters of the proportional, integral, and derivative terms in the PID control system of the dual-grinding-head rotary grinding machine are set to 0.5, 0.4, and 0.55, respectively. The difference between the proportional term adjustment factor of each processing interval and the corresponding proportional term adjustment factor of the previous processing interval during the grinding process of any grinding head is recorded as the proportional term gain of the grinding head in each processing interval. The sum of the proportional term adjustment factor and the proportional term gain in each processing interval during the grinding process of any grinding head is used as the proportional term of the grinding head at the first moment of the next processing interval. The PID control algorithm outputs a control signal, and the drive circuit in the servo motor converts the control signal output by the PID algorithm into an electrical signal. Multi-axis linkage control is used to control the grinding force of each grinding head in the dual-grinding-head rotary grinding machine.

[0070] The specific flowchart for controlling the grinding force of each grinding head is as follows: Figure 2 As shown.

[0071] Data transmission module: Responsible for data transmission processing between modules in the CNC grinding machine control system of the dual-head rotary grinding machine.

[0072] The data transmission module specifically includes:

[0073] Industrial bus unit: responsible for instruction synchronization between grinding head controller, servo driver and I / O module;

[0074] Protocol conversion unit: It adopts RS485 or CAN bus conversion chip to solve the compatibility problem between heterogeneous devices and can meet the multi-sensor communication needs in the data acquisition module of CNC grinding machine.

[0075] Data caching unit: Built-in dual-port RAM + Flash memory to temporarily store transmitted data and processing instructions, buffer high-speed data streams, and prevent frame loss due to instantaneous overload;

[0076] Security verification unit: Integrating median filling method and hardware watchdog, it monitors the data transmission integrity of the CNC grinding machine data acquisition module in real time. When data loss occurs during data transmission due to external environmental interference, the median filling method is used to fill in the missing values.

[0077] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description; sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0078] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A CNC grinding machine control system for a dual-head rotary grinding machine, characterized in that, The system includes: The CNC grinding machine data acquisition module is used to collect axial force, tangential force, normal force, and temperature of each grinding head of the workpiece during the grinding process of a dual-head rotary grinding machine. The data analysis module is used to preset processing intervals, analyze the energy distribution characteristics of normal and axial forces in the frequency domain within each processing interval, and determine the grinding force imbalance in each processing interval by combining the numerical abrupt changes of axial and tangential forces. It also performs linear fitting on all temperature data of each grinding head in each processing interval and analyzes the similarity of temperature fluctuations in the processing areas of different grinding heads in each processing interval to determine the asynchronous state of grinding thermal deformation of each grinding head in each processing interval. Based on the grinding force imbalance, it constructs the proportional term adjustment factor for the PID control of each grinding head in each processing interval. The grinding machine control compensation module determines the proportional term of the PID control for each grinding head at the initial moment of each processing interval based on the difference between the proportional term adjustment factor of each processing interval and the previous processing interval during the grinding process of each grinding head, and controls the grinding force of each grinding head. The data transmission module is responsible for data transmission between various modules in the CNC grinding machine control system of the dual-head rotary grinding machine; The specific steps for determining the grinding force imbalance in each machining zone include: Obtain the frequency domain representation of all axial forces and all normal forces in each processing zone; record the frequency domain components that are greater than or equal to the preset values ​​as high-frequency components, otherwise record them as low-frequency components; Abrupt change detection is performed on all axial forces and all tangential forces in each processing interval to obtain the abrupt change points of axial forces and tangential forces; for the same data, the time interval between each abrupt change point and the next abrupt change point is taken as the abrupt change interval of each abrupt change point; Based on the energy standard deviation of the low-frequency component of the normal force in each processing interval, combined with the overall distribution characteristics of the axial force in the mutation interval corresponding to each axial force mutation point and the frequency domain distribution characteristics of the axial force, the abrasive resistance passivation status of each processing interval is determined. Analyze the distribution differences of tangential force between the mutation points of tangential force in each processing interval, and combine the energy distribution characteristics of the low-frequency components of tangential force to determine the abnormal tangential friction conditions in each processing interval. Based on the abrasive obstruction and passivation status and the tangential friction anomaly status, the grinding force imbalance in each processing zone is determined, wherein the grinding force imbalance is positively correlated with both the abrasive obstruction and passivation status and the tangential friction anomaly status.

2. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The specific process for determining the abrasive resistance passivation status of each processing zone is as follows: Obtain the dispersion of the axial force within the abrupt change interval corresponding to each axial force in each processing interval, and accumulate the dispersion of all axial forces corresponding to the abrupt change intervals to obtain the first accumulation result; Calculate the degree of disorder of the energy of all axial forces in all frequency domain components within each processing interval; The ratio of the first accumulated result to the degree of disorder is positively fused with the energy standard deviation to obtain the abrasive passivation status of each processing interval.

3. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The specific process for determining the abnormal tangential friction conditions in each processing zone is as follows: Calculate the average tangential force in the interval corresponding to each tangential force mutation point within each processing interval, and sum the differences between the average tangential forces in the intervals corresponding to all two adjacent tangential force mutation points to obtain the second summation result; The interquartile range of the energy of all low-frequency components corresponding to the tangential force in each processing interval is obtained and positively fused with the second accumulation result to obtain the tangential friction anomaly status of each processing interval.

4. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The grinding force imbalance is specifically the normalized value of the product of the abrasive grain obstruction and passivation condition and the abnormal tangential friction condition.

5. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The determination of the asynchronous grinding thermal deformation status of each grinding head in each processing zone specifically involves: The peak values ​​of all temperature data for each grinding head in each processing zone are obtained and formed into a peak temperature sequence. The cumulative result of the deviation between all temperature data of each grinding head in each processing interval and its corresponding temperature fitting data is recorded as the third cumulative result; Calculate the coefficient of variation of all temperature data for each grinding head in each processing zone; Based on the third cumulative result and the coefficient of variation, the degree of thermal risk of each grinding head in each processing interval is obtained; The distance metric between the peak temperature data sequence of each grinding head and the processing area of ​​another grinding head in each processing interval is obtained; based on the distance metric and the degree of thermal deformation risk, the asynchronous status of grinding thermal deformation of each grinding head in each processing interval is determined; the asynchronous status of grinding thermal deformation is positively correlated with both the distance metric and the degree of thermal deformation risk.

6. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 5, characterized in that, The degree of thermal risk of each grinding head in each processing interval is specifically the product between the third cumulative result obtained by each grinding head in each processing interval and the coefficient of variation.

7. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 5, characterized in that, The asynchronous state of grinding thermal deformation is specifically the normalized value of the product of the distance metric and the degree of thermal deformation risk.

8. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The proportional term adjustment factor for the PID control in each processing interval is specifically the product of the grinding force imbalance and the asynchronous state of grinding thermal deformation in each processing interval.

9. The CNC grinding machine control system for a dual-head rotary grinding machine as described in claim 1, characterized in that, The determination of the proportional term of the PID control for each grinding head at the initial moment of each processing interval is specifically the sum of the proportional term adjustment factor of each grinding head in each processing interval and the difference therebetween.

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