Online compensation method for roll grinding accuracy, compensation system, CNC system for grinding machine and grinding machine

Abstract

This invention provides an online compensation method, compensation system, grinding machine CNC system, and grinding machine, relating to the field of grinding machine control technology. The method involves simultaneous grinding and measurement, collecting roll position and diameter data, and calculating roll shape error based on theoretical roll shape. Roundness error and high-frequency interference are filtered out using adaptive filtering, and the data is stored in a circular queue. Fitting intervals are divided according to the roll shape monotonicity, and a continuous grinding error curve is generated using adaptive fitting and smoothing processing. A compensation curve is generated by scaling the error curve, allowing dynamic adjustment of the compensation intensity and setting overload protection. The compensation curve and roll shape curve are interpolated in parallel and then applied to grinding. This invention solves the problem that existing grinding machines can only measure but not compensate, improving grinding accuracy and process stability, and is adaptable to various roll shapes and processing scenarios.

Description

Technical Field

[0001] This invention relates to the field of grinding machine control technology, and in particular to an online compensation method, compensation system, grinding machine CNC system, and grinding machine for roll grinding accuracy. Background Technology

[0002] During CNC roll grinding, various factors can affect the grinding accuracy, causing it to fall short of actual requirements. Therefore, the grinding machine should be able to measure the current grinding result (i.e., the roll grinding accuracy) while grinding the roll, and make corresponding compensation adjustments based on this result to improve the grinding accuracy of the roll.

[0003] Existing CNC roll grinding machines with online measurement capabilities only have the ability to display the roll diameter at the current measurement position, but cannot process and compensate for the accuracy measurement results. Summary of the Invention

[0004] Objective: To overcome the problems existing in the prior art, this invention proposes an online compensation method, compensation system, grinding machine CNC system, and grinding machine for roll grinding accuracy. The method involves a measuring device synchronously acquiring the current roll grinding accuracy results. After obtaining the complete measurement results of the roll, a roll accuracy error curve is further obtained based on these results and the theoretical roll trajectory. The grinding machine then generates a grinding accuracy compensation curve based on this error curve and applies it during grinding. Each time a complete measurement result of the roll is obtained, a new compensation curve is generated for iterative processing, thereby improving the roll grinding accuracy.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] Firstly, a method for online compensation of rolling mill grinding accuracy is proposed, including the following steps:

[0007] While the rolls are being ground, the rolls are measured at predetermined time intervals to obtain roll position and diameter data. Combined with the theoretical roll trajectory expression, the actual roll shape and roll shape error are calculated. The measurement results are described in the form of a preset structure.

[0008] The measurement results are filtered and then stored in a circular queue.

[0009] Based on the monotonicity of the roll shape curve, the discrete measurement results corresponding to the roll shape error are divided into multiple fitting intervals;

[0010] For each fitting interval, the corresponding fitting method is selected according to the type of roller curve to obtain the fitting curve for each interval;

[0011] For the connection points of adjacent fitting intervals, a smooth curve is used to replace the connection region of the original fitting curve, so that the first derivative at the connection point is continuous and meets the preset smoothness error constraint condition, thus obtaining the grinding error curve.

[0012] The grinding error curve is scaled to generate a compensation curve;

[0013] The roller curve and the compensation curve are interpolated simultaneously in each interpolation cycle, and the accumulated interpolation result is sent to the driver of the corresponding axis to perform online grinding accuracy compensation.

[0014] As a preferred embodiment of the first aspect, measuring heads are arranged on both radial sides of the roll, and the line connecting the two measuring heads passes through the center of the roll cross section. The diameter data D at the current point is obtained by adding the readings of the two measuring heads to a preset constant.

[0015] The theoretical roll profile trajectory is used to express the theoretical shape of the roll, satisfying... ; This indicates the current position of the roll. This represents the theoretical roll shape value obtained.

[0016] The actual roll shape at the current point is represented as:

[0017]

[0018] In the formula, For z i The diameter data corresponding to when it equals 0; This represents the actual roll shape value obtained. For z i The theoretical roll shape value corresponding to a value of 0;

[0019] Roll shape error e is expressed as .

[0020] As a preferred option in the first aspect, a second-order underdamped low-pass filtering algorithm is used to filter the measurement results, automatically match the corresponding coefficients according to the current roll speed, and then perform discretization processing.

[0021] As a preferred embodiment of the first aspect, the circular queue is a structure array. When the CNC system stores the measurement results at the bottom of the structure array, it automatically jumps to the head of the structure array the next time it stores them.

[0022] As a preferred option in the first aspect, based on the monotonicity characteristics of the roller curve, it is divided into a single decreasing interval and a single non-increasing interval as the fitting interval.

[0023] If the global monotonicity of the roller curve is either decreasing or not increasing, then the midpoint is used to divide it into two fitting intervals.

[0024] As a preferred option in the first aspect, for each fitting interval, the corresponding fitting method is selected according to the type of roller curve, specifically including:

[0025] If the roller curve within the fitting interval is a polynomial curve, use a polynomial curve of the same degree for fitting; for a polynomial curve with the highest term of 0, use a first-degree curve for fitting.

[0026] If the roller curve within the fitting interval is a sine function curve, a cubic polynomial curve fitting method is used.

[0027] As a preferred embodiment of the first aspect, for the connection points between adjacent fitting intervals, a cubic polynomial curve is used as a smooth curve to replace the original fitting curve, specifically including:

[0028] The Z-coordinate of the connection point is z0, and the Z-coordinate range of the smooth interval is z1≤z≤z2; when z1≤z≤z0, the fitted curve expression is s1(z); when z0≤z≤z2, the fitted curve expression is s2(z).

[0029] The equation of the smooth curve is:

[0030]

[0031] For a given smooth interval, the equation of the smooth curve satisfies the following condition:

[0032]

[0033]

[0034] The equation of the smooth curve must satisfy the following smoothness error constraint at the junction points:

[0035]

[0036] In the formula, The maximum allowable error is set when defining the range of values ​​for the smooth interval; e0 is the roll shape error value at the connection point.

[0037] As a preferred embodiment of the first aspect, if the connection point is not in the circular queue, the roll shape error value e0 at the connection point is obtained by linear interpolation between two adjacent points in the circular queue:

[0038]

[0039] In the formula, z p and z n e represents the Z-coordinate of the circular queue points adjacent to the connection point; p and e n This represents the corresponding roller shape error value.

[0040] As a preferred embodiment of the first aspect, the compensation curve C(z) is obtained by scaling the grinding error curve E(z), and is expressed as:

[0041]

[0042] In the formula, The result is the compensation result; K is the compensation intensity coefficient, i.e., the scaling factor, with a value range of 0 ≤ K ≤ 1.2;

[0043] The absolute value judgment condition of the grinding error curve is as follows: Where A is the maximum allowable value of the grinding error curve. When this judgment condition is met, it indicates that the depth of cut of the grinding machine is too large. At this time, the CNC system will force K to be set to 0.

[0044] As a preferred embodiment of the first aspect, during the online compensation of grinding accuracy performed by the driver of the corresponding axis, such as the grinding wheel motor, the torque load of the grinding wheel motor is monitored in real time. ,like The interpolation result of the compensation curve remains unchanged until... .

[0045] A second aspect of the present invention provides an online compensation system for the grinding accuracy of rolls, the online compensation system comprising:

[0046] The measuring device consists of measuring head A and measuring head B arranged on both radial sides of the roll. While the roll is being ground, measuring head A and measuring head B measure the roll at predetermined time intervals to obtain the roll position and diameter data. Combined with the theoretical roll shape trajectory expression, the actual roll shape and roll shape error are calculated. The measurement results are described in the form of a preset structure.

[0047] The filtering module is used to filter the measurement results and then store them in a circular queue.

[0048] Fitting interval division module; the fitting interval division module divides the discrete measurement results corresponding to the roller error into multiple fitting intervals based on the monotonicity characteristics of the roller curve;

[0049] First curve generation unit; The first curve generation unit selects the corresponding fitting method according to the roller curve type for each fitting interval to obtain the fitting curve for each interval;

[0050] The second curve generation unit uses a smooth curve to replace the connection area of ​​the original fitting curve at the connection point of adjacent fitting intervals, so that the first derivative at the connection point is continuous and meets the preset smoothness error constraint condition, thus obtaining the grinding error curve.

[0051] The third curve generation unit is used to scale the grinding error curve to generate a compensation curve;

[0052] The interpolation module is used to interpolate the roller curve and the compensation curve simultaneously in each interpolation cycle, and send the accumulated interpolation result to the driver of the corresponding axis to perform online compensation;

[0053] The monitoring module is used to monitor the torque load of the grinding wheel motor. When the torque load exceeds the maximum allowable value, the interpolation result of the compensation curve remains unchanged.

[0054] A third aspect of the present invention provides a CNC system for a grinding machine, the CNC system comprising a processor and a memory storing computer program instructions; the processor, when executing the computer program instructions, implements the online compensation method for roll grinding accuracy disclosed in the first aspect and its preferred embodiments.

[0055] In a fourth aspect, the present invention provides a grinding machine equipped with the grinding machine CNC system described in the third aspect.

[0056] In a fifth aspect of the invention, a grinding machine is provided that performs the online compensation method for roll grinding accuracy disclosed in the first aspect and its preferred embodiments.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] (1) By using the second-order underdamped low-pass adaptive filtering algorithm, the filtering coefficient is dynamically matched according to the roll speed, effectively filtering out the periodic roundness error and high-frequency interference caused by the roll rotation, making the measurement data closer to the real roll trajectory, and providing a precise data basis for subsequent compensation.

[0059] (2) The combination scheme of “dividing the fitting interval according to monotonicity + adaptive fitting + third-order polynomial smoothing” is adopted, which not only adapts to the characteristics of polynomial, sine function and combined roller curve, but also ensures the continuity of the error curve (continuous first derivative) within the whole roller length range, avoids sudden changes in position and speed during compensation, and ensures the consistency of compensation accuracy.

[0060] (3) A new compensation curve is generated after each complete measurement result is obtained. By iteratively reducing the deviation between the theoretical roll shape and the actual roll shape, compared with the existing grinding machine that can only display the measurement results, it is upgraded from "passive monitoring" to "active correction", which greatly reduces the systematic grinding error.

[0061] (4) The compensation strength coefficient allows operators to intervene in real time according to the actual grinding situation. At the same time, an error threshold is set. When the absolute value of the grinding error exceeds the error threshold, the compensation is forcibly turned off to avoid the grinding machine's depth of cut exceeding the standard due to excessive error, thus protecting the grinding wheel and rolls from damage. In addition, the torque load of the grinding wheel motor is monitored synchronously during the parallel interpolation process. When the load exceeds the maximum allowable value, the interpolation result of the compensation curve remains unchanged until the load returns to normal, effectively avoiding problems such as motor overload, accelerated grinding wheel wear, or scratches on the roll surface, and improving the stability of the processing process.

[0062] (5) All data processing (filtering, fitting, interpolation) is performed according to the time cycle of the CNC system. The compensation curve is generated within the reversing gap of the roll grinding, which meets the real-time requirements of online compensation and does not affect the processing efficiency. Attached Figure Description

[0063] Figure 1 This is a flowchart of the online compensation method for roll grinding accuracy according to the present invention.

[0064] Figure 2 This is a schematic diagram of the grinding accuracy in the embodiment.

[0065] Figure 3 This is a schematic diagram of roller trajectory measurement in the embodiment. Detailed Implementation

[0066] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0067] This embodiment proposes an online compensation method for roll grinding accuracy. While the grinding machine controls the roll grinding, a measuring device simultaneously acquires the current roll grinding accuracy results. After obtaining the complete measurement results of the roll, a roll accuracy error curve is further obtained based on these results and the theoretical roll trajectory. The grinding machine generates a grinding accuracy compensation curve based on this error curve and applies it during grinding. Each time a complete measurement result of the roll is obtained, a new compensation curve is generated for iterative processing, thereby improving the roll grinding accuracy.

[0068] See Figure 1 The specific implementation plan is as follows:

[0069] 1. Measurement data reading

[0070] A rolling mill roll can be considered a body of revolution obtained by rotating its roll profile curve around its own axis of rotation. Therefore, in rolling mill roll grinding, the grinding accuracy is actually the error between the theoretical roll trajectory (the theoretical roll profile curve) and the actually measured roll trajectory (the actual roll trajectory). For ease of explanation, Figure 2 A schematic diagram of grinding accuracy is provided.

[0071] exist Figure 2 In this context, a roll can be considered a rotating body obtained by rotating the theoretical roll trajectory around the Z-axis. Grinding accuracy is the difference between the theoretical roll trajectory and the actual roll trajectory, which is also a single trajectory.

[0072] The actual trajectory of the roll can be obtained by measuring the diameter of the roll using a measurement system, such as... Figure 3 As shown.

[0073] exist Figure 3 In this process, the line connecting probes AB passes through the center of the roll section, and it is not required that this line be parallel or perpendicular to one of the three axes X, Y, and Z. Therefore, the diameter D of the current point can be expressed as:

[0074]

[0075] In equation (1), d A and d B These are the readings of measuring heads AB, respectively, and C is a constant.

[0076] Let the theoretical roll profile trajectory expression be:

[0077]

[0078] In formula (2), such as Figure 2 As shown, z i x represents the current position of the roll. i This represents the obtained theoretical roll shape value. The theoretical roll shape trajectory expresses the roll shape designed by the rolling mill according to the specific requirements of the rolled plate. For rolls, the theoretical trajectory expression type is generally a sine function curve segment, a polynomial function curve segment, or a curve segment composed of a sine function and a polynomial function, etc.

[0079] Therefore, combining equations (1) and (2), the actual roll shape at the current point can be expressed as:

[0080]

[0081] Further, from equations (2) and (3), we can obtain the trajectory error, i.e., the grinding accuracy, as follows:

[0082]

[0083] Since the CNC system of the grinding machine is a discrete control system, the CNC system controls the measurement system to measure the rolls at each time cycle. The measurement results are described in the following structure:

[0084] TYPE Roll_Meas_Result_Str :

[0085] STRUCT

[0086] index : ULINT; / / Index number

[0087] z_pos : LREAL; / / Roll position

[0088] dia : LREAL; / / Current roll diameter

[0089] shape_ideal : LREAL; / / Theoretical roll shape

[0090] shape_act : LREAL; / / Actual roll shape

[0091] shape_error : LREAL; / / Roller shape error

[0092] END_STRUCT

[0093] END_TYPE

[0094] The code language involved in this embodiment is ST (Structured Text) language, which is part of the IEC6113-3 programming language.

[0095] 2. Adaptive filtering of measurement results

[0096] like Figure 3 As shown, the roll is rotating during the grinding process. Since the roll cross-section is not a perfect circle, meaning there is a roundness error, the measurement results, including this roundness error, fail to reflect the true roll trajectory when the measurement system measures the roll shape. Therefore, the roundness error negatively impacts subsequent compensation functions, necessitating filtering of the measurement results to minimize its negative influence.

[0097] Since the roundness error is introduced by the rotation of the roll, this error can be considered periodic. Therefore, a low-pass filtering algorithm is used to process the measurement results to reduce the influence of roundness error and other high-frequency interference on the actual measurement results of the roll shape. Here, a second-order underdamped low-pass filtering algorithm is used to process the result of equation (3), and the transfer function corresponding to this algorithm can be expressed as:

[0098]

[0099] In equation (5), the reciprocal of T is the cutoff angular frequency; ξ is the damping coefficient, which is greater than 0 and less than 1; s is a complex variable; Y(s) is the Laplace transform expression of the result obtained after filtering the value of equation (3); and X(s) is the Laplace transform expression of the result without filtering.

[0100] Since the filtering algorithm is implemented by the CNC system of the grinding machine, it needs to be discretized according to the time cycle of the CNC system, which can be expressed as:

[0101]

[0102] In equation (6), a0, a1, a2, b1, b2 are coefficients related to T and ξ in equation (5); y0, y1, y2 are the output results of the filtering algorithm for the current, previous sampling time, and the second-to-last sampling time, respectively; x0, x1, x2 are the input results of the filtering algorithm for the current, previous sampling time, and the second-to-last sampling time, respectively.

[0103] The filtering algorithm in equation (5) needs to adapt to different roll speeds, that is, the coefficients in the filtering algorithm equations (5) and (6) are automatically changed according to the different roll speeds.

[0104] Before each measurement begins, the CNC system automatically matches the appropriate filtering algorithm coefficients based on the current roll speed, and then begins to filter the measurement results.

[0105] 3. The results are stored in a circular queue.

[0106] To facilitate subsequent processing, the measurement results acquired by the CNC system in sections 1 and 2 above need to be stored in a fixed area. Since the number of measurement results acquired by the CNC system is not fixed and is related to many factors such as grinding feed speed and roll length, the CNC system stores the measurement results in a circular queue to ensure that the results can be effectively stored and processed by subsequent functions.

[0107] The circular queue is an array of structures. When the CNC system stores the measurement result at the bottom of the array, it automatically jumps to the head of the array the next time it stores the result. Example code is shown below:

[0108] Roll_Shape_Result : ARRAY [0..Data_Len] OF Roll_Meas_Result_Str; / / Circular queue definition

[0109] k := index MOD len; / / Position of the circular queue, modulo operation

[0110] / / Storing measurement results

[0111] Roll_Shape_Result[k].index := index;

[0112] Roll_Shape_Result[k].z_pos := z_roll;

[0113] Roll_Shape_Result[k].dia := dia;

[0114] Roll_Shape_Result[k].shape_ideal := u;

[0115] Roll_Shape_Result[k].shape_act := act;

[0116] Roll_Shape_Result[k].shape_error := u - act;

[0117] / / Index number update

[0118] index := index + 1;

[0119] 4. Fitting interval division

[0120] Since the measurement results are discrete points, it is necessary to fit the discrete points corresponding to the roll shape error results in equation (4) into a continuous curve before they can be used for subsequent processing. In order to improve the accuracy and convenience of the fitting results, the measurement results are divided into multiple intervals, and then the curves are fitted separately for each interval.

[0121] Considering the characteristics of roll grinding, the division of the fitting interval is determined by the characteristics of the roll profile curve. Based on the monotonicity of the roll profile curve, the curve can be divided into monotonically decreasing and monotonically non-increasing intervals. These monotonic intervals serve as the fitting interval.

[0122] If the global monotonicity characteristics of the roller curve are all decreasing or not increasing, then the midpoint is used to divide it into two fitting intervals.

[0123] This part of the work can be done when the roller curve information is obtained.

[0124] 5. Adaptive fitting of accuracy curves within the interval

[0125] The online compensation function of this patent requires that a corresponding compensation curve be generated as soon as possible after the online measurement of the roll shape is completed. This is necessary to achieve the compensation function when the roll grinding process is completed and restarted. Otherwise, the function cannot function effectively. Therefore, the accuracy curve fitting and subsequent parts in this section need to have a certain degree of real-time performance, and the relevant data processing must be completed within a limited time.

[0126] The main types of roller curves are: polynomial curves (the highest degree of the term generally does not exceed 8), sine function curves (the range of radians is between 0 and π), and combined curves composed of the above two types of curves.

[0127] Therefore, in order to ensure that the fitting process meets the time constraints and to ensure the fitting accuracy, the curve fitting method is adaptive fitting, that is, according to the characteristics of the roller curve in the current fitting interval, different forms of fitting curves are used to fit.

[0128] For the roller curve within the fitting interval that is a polynomial curve, a polynomial curve of the same degree is used for fitting. For polynomial curves with a highest degree of 0, a first-degree curve is used for fitting. Therefore, the expression for the fitted curve is:

[0129]

[0130] Since the sine function can be expanded into a polynomial function using the Taylor formula, and its value range is less than half a period when used as a roller curve, a sine function within the fitting interval can be fitted using a cubic polynomial curve, which can be expressed as:

[0131]

[0132] 6. Smooth transitions between accuracy curves in different intervals.

[0133] Over the entire roll length, the fitting curves represented by equations (7) and (8) are piecewise curves, meaning that the fitting curves of adjacent fitting intervals cannot be guaranteed to be continuous at the junction of the intervals, or continuous but not smooth (the first derivative is discontinuous).

[0134] To ensure that the position and speed at the junctions of different intervals do not change abruptly when the compensation curves are applied during the grinding process, the first derivatives of each compensation curve should remain continuous at the corresponding junctions. Therefore, if either of the two discontinuities mentioned above occurs, the junctions need to be smoothed to meet the continuity requirement.

[0135] Similar to curve fitting, smoothing must also be completed within a finite time. To satisfy the first derivative continuity condition mentioned above, a third-order polynomial curve is used for smoothing, that is, the original fitted curve is replaced by the smoothed curve in an interval near the junction point.

[0136] Let the Z-coordinate of the connection point be z0, and the range of the Z-coordinate in the smooth interval be z1≤z≤z2. When z1≤z≤z0, the fitted curve expression is s1(z). When z0≤z≤z2, the fitted curve expression is s2(z). Meanwhile, let the equation of the smooth curve be:

[0137]

[0138] For a given smooth interval, the equation of the smooth curve (9) must satisfy the following condition:

[0139]

[0140]

[0141] The unknown coefficients of the smooth curve equation (9) can be solved from equations (10) and (11).

[0142] The range of values ​​for the smoothing interval is set when dividing the fitting interval. The smooth curve obtained by equation (9) must satisfy the smoothing error constraint at the junction point, which can be expressed as:

[0143]

[0144] In equation (12), ε is the maximum allowable error, set when defining the range of values ​​for the smooth interval; e0 is the value of the roll shape error at the connection point, i.e., the data in the circular queue in Part 3. If the connection point is not in the circular queue, it can be obtained by linear interpolation between two adjacent points in the circular queue, and can be expressed as:

[0145]

[0146] In equation (13), z0 is the Z-coordinate of the connection point; z p and z n e represents the Z-coordinate of a point in one of two adjacent circular queues at the connection point. p and e n This represents the corresponding roller shape error value.

[0147] 7. Compensation curve generation and compensation intensity adjustment

[0148] Based on the content of Parts 5 and 6, the current grinding error results of the rolls have been fitted and smoothed into a continuous curve. Based on the obtained error curve, the compensation curve C(z) can be obtained by scaling the error curve, expressed as:

[0149]

[0150] In equation (14), E(z) is the grinding error curve, i.e., the results of parts 5 and 6; x c The result is the compensation. K is the compensation strength coefficient, i.e., the scaling factor, with a value range of 0 ≤ K ≤ 1.2.

[0151] The compensation strength coefficient K is mainly used by the operator to intervene in the compensation curve. The operator can modify this coefficient in real time according to the actual grinding situation.

[0152] For the grinding error curve E(z), if its absolute value is too large, it can lead to negative consequences such as excessive depth of cut when the compensation curve takes effect. Therefore, when the grinding error curve E(z) appears as follows,

[0153]

[0154] In equation (15), A is the maximum value allowed by the grinding error curve. At this time, the CNC system forces the compensation strength coefficient K to be set to 0, that is, the compensation curve has no actual effect.

[0155] 8. The compensation curve is applied to the grinding process.

[0156] In order to leverage the role of the compensation curve in improving grinding accuracy, the compensation curve formula (14) needs to be applied to the actual grinding process. Here, the compensation curve is directly applied to the interpolation module of the CNC system. In the actual interpolation process, the CNC system adopts parallel interpolation control, that is, in each interpolation cycle, the roller curve and the compensation curve are interpolated simultaneously, and then the two interpolation results are accumulated and sent to the driver of the corresponding axis.

[0157] While performing the interpolation calculations described above, the interpolation module of the CNC system also collects and monitors the torque load of the grinding wheel motor. When the grinding wheel motor torque load T... s When the value exceeds the allowable value, the following situations occur:

[0158]

[0159] In equation (16), T A This represents the maximum permissible torque load of the grinding wheel motor. At this point, the interpolation result of the compensation curve will remain unchanged; that is, the interpolation result will not be updated until the torque load of the grinding wheel motor is less than the maximum permissible value.

[0160] In order to successfully implement all or part of the processes disclosed in the above embodiments, this embodiment discloses an online compensation system for roll grinding accuracy. The compensation system consists of a measuring device, a filtering module, a fitting interval division module, a first curve generation unit, a second curve generation unit, a third curve generation unit, an interpolation module, and a monitoring module.

[0161] The measuring device consists of measuring head A and measuring head B arranged on both radial sides of the roll (see...). Figure 3 (As shown). While the roll is being ground, measuring head A and measuring head B measure the roll at predetermined time intervals to obtain the roll position and diameter data. Combined with the theoretical roll profile trajectory expression, the actual roll profile and roll profile error are calculated. The measurement results are described in the form of a preset structure.

[0162] The filtering module is used to filter the measurement results and then store them in a circular queue.

[0163] The fitting interval division module divides the discrete measurement results corresponding to the roller error into multiple fitting intervals based on the monotonicity characteristics of the roller curve. If the roller curve is monotonically decreasing or not increasing globally, it is divided into two fitting intervals based on the midpoint.

[0164] The first curve generation unit selects the corresponding fitting method according to the type of roller curve for each fitting interval, and obtains the fitting curve for each interval.

[0165] The second curve generation unit replaces the connection region of the original fitted curve with a smooth curve for the connection point of adjacent fitting intervals, so that the first derivative at the connection point is continuous and meets the preset smoothness error constraint condition, thus obtaining the grinding error curve.

[0166] The third curve generation unit is used to scale the grinding error curve to generate a compensation curve.

[0167] The interpolation module is used to interpolate the roller curve and the compensation curve simultaneously in each interpolation cycle, and sends the accumulated interpolation result to the driver of the corresponding axis to perform online compensation;

[0168] The monitoring module is used to monitor the torque load of the grinding wheel motor. When the torque load exceeds the maximum allowable value, the interpolation result of the compensation curve remains unchanged.

[0169] The naming of each module / unit above does not imply any limitation on itself. In practical applications, they can be partially merged or disassembled.

[0170] As another embodiment, a CNC system for a grinding machine is disclosed. This system includes a processor and a memory storing computer program instructions. When the processor executes the computer program instructions, it implements the online compensation method for roll grinding accuracy disclosed in the above embodiments.

[0171] In this grinding machine CNC system, the adaptive fitting scheme can match polynomial curves with a maximum term degree of no more than 8, sine function curves with an radian range of 0-π, and combined curves. The filtering coefficients and circular queue storage length can be adapted to different roll diameters, lengths, and grinding feed speeds, eliminating the need for developing new algorithms for specific rolls. The compensation strength coefficient can be manually modified in real time, and parameters such as error thresholds and torque load thresholds can be set as needed. Furthermore, the scheme is compatible with existing measuring devices and drive systems through the grinding machine CNC system's interface module, requiring no significant modifications to the mechanical structure and facilitating the technical upgrade of existing grinding machines. All core algorithms (filtering, fitting, interpolation) are executed in parallel by the CNC system, and data is stored cyclically in a circular queue, completing processing without waiting for grinding to stop and without affecting the normal machining cycle. The compensation process is fully automated, requiring only fine-tuning of the compensation strength coefficient by the operator based on actual conditions. This eliminates the need for professional personnel to perform complex algorithm parameter settings, lowering the technical application threshold and making it suitable for mass production scenarios.

[0172] In this CNC grinding machine system, the memory and processor are electrically connected directly or indirectly to achieve data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines, such as a bus connection. The memory stores computer-executable instructions that implement data access control methods, including at least one software functional module that can be stored in the memory in the form of software or firmware. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory.

[0173] Memory includes, but is not limited to, Random Access Memory (RAM), Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), and Electrically Erasable Programmable Read-Only Memory (EEPROM). Memory stores programs, which are then executed by the processor upon receiving execution instructions. Furthermore, the software programs and modules within the aforementioned memory may also include an operating system, which can include various software components and / or drivers for managing system tasks and can communicate with various hardware or software components to provide an operating environment for other software components.

[0174] A processor can be an integrated circuit chip with signal processing capabilities. The aforementioned processor can be a general-purpose processor, including a Central Processing Unit (CPU). It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. It is understood that in practical applications, there may be more or fewer components than shown in this embodiment, or a different configuration than that shown in this embodiment. Each component can be implemented in hardware and / or software.

[0175] As another embodiment, a grinding machine equipped with the grinding machine CNC system described in the above embodiments is disclosed. This grinding machine can execute part or all of the process of the online compensation method for roll grinding accuracy disclosed in the above embodiments, which will not be elaborated here.

[0176] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for online compensation of grinding accuracy of rolls, characterized in that, Includes the following steps: While the roll is being ground, the roll is measured at predetermined intervals to obtain the roll position and diameter data. Combined with the theoretical roll trajectory expression, the actual roll shape and roll shape error are calculated. The above measurement results are described in the form of a preset structure. Among them, measuring heads are arranged on both sides of the roll radially, and the line connecting the two measuring heads passes through the center of the roll cross section. The diameter data D at the current point is obtained by adding the readings of the two measuring heads to a preset constant. The theoretical roll profile trajectory is used to express the theoretical shape of the roll, satisfying... ; This indicates the current position of the roll. This represents the theoretical roll shape value obtained. The actual roll shape at the current point is represented as: ； In the formula, For z i The diameter data corresponding to when it equals 0; This represents the actual roll shape value obtained. For z i The theoretical roll shape value corresponding to a value of 0; Roll shape error e is expressed as ; The measurement results are filtered and then stored in a circular queue. Based on the monotonicity of the roll shape curve, the discrete measurement results corresponding to the roll shape error are divided into multiple fitting intervals, specifically including: The Z-coordinate of the connection point is z0, and the Z-coordinate range of the smooth interval is z1≤z≤z2; when z1≤z≤z0, the fitted curve expression is s1(z); when z0≤z≤z2, the fitted curve expression is s2(z). The equation of the smooth curve is: ； For a given smooth interval, the equation of the smooth curve satisfies the following condition: ； ； The equation of the smooth curve must satisfy the following smoothness error constraint at the junction points: ； In the formula, The maximum allowable error is set when defining the range of values ​​for the smooth interval; e0 is the roll shape error value at the connection point. For each fitting interval, the corresponding fitting method is selected according to the type of roller curve to obtain the fitting curve for each interval; For the connection points of adjacent fitting intervals, a smooth curve is used to replace the connection region of the original fitting curve, so that the first derivative at the connection point is continuous and meets the preset smoothness error constraint condition, thus obtaining the grinding error curve. The grinding error curve is scaled to generate a compensation curve; The roller curve and the compensation curve are interpolated simultaneously in each interpolation cycle, and the accumulated interpolation result is sent to the driver of the corresponding axis to perform online grinding accuracy compensation.

2. The method for online compensation of rolling mill grinding accuracy according to claim 1, characterized in that, The measurement results are filtered using a second-order underdamped low-pass filtering algorithm. The corresponding coefficients are automatically matched according to the current roll speed, and then discretization is performed.

3. The online compensation method for roll grinding accuracy according to claim 1, characterized in that, The circular queue is a structure array. When the CNC system stores the measurement results at the bottom of the structure array, it will automatically jump to the head of the structure array the next time it stores them.

4. The online compensation method for the grinding accuracy of rolls according to claim 1, characterized in that, Based on the monotonicity characteristics of the roller curve, it is divided into a single decreasing interval and a single non-increasing interval as the fitting interval; If the global monotonicity of the roller curve is either decreasing or not increasing, then the midpoint is used to divide it into two fitting intervals.

5. The online compensation method for the grinding accuracy of rolls according to claim 1, characterized in that, For each fitting interval, the corresponding fitting method is selected according to the type of roller curve, specifically including: If the roller curve within the fitting interval is a polynomial curve, use a polynomial curve fitting of the same degree; for a polynomial curve with the highest term of 0, use a first-degree curve fitting. If the roller curve within the fitting interval is a sine function curve, a cubic polynomial curve fitting method is used.

6. The online compensation method for the grinding accuracy of rolls according to claim 1, characterized in that, If the connection point is not in the circular queue, the roll shape error value e0 at the connection point is obtained by linear interpolation between two adjacent points in the circular queue: ； In the formula, z p and z n e represents the Z-coordinate of the circular queue points adjacent to the connection point; p and e n This represents the corresponding roller shape error value.

7. The online compensation method for the grinding accuracy of rolls according to claim 1, characterized in that, The compensation curve C(z) is obtained by scaling the grinding error curve E(z), and is expressed as: ； In the formula, The result is the compensation result; K is the compensation intensity coefficient, i.e., the scaling factor, with a value range of 0 ≤ K ≤ 1.2; The absolute value judgment condition of the grinding error curve is as follows: Where A is the maximum allowable value of the grinding error curve. When this judgment condition is met, it indicates that the depth of cut of the grinding machine is too large. At this time, the CNC system will force K to be set to 0.

8. The online compensation method for the grinding accuracy of rolls according to claim 1, characterized in that, During the online compensation of grinding accuracy performed by the driver of the corresponding axis of the grinding wheel motor, the torque load of the grinding wheel motor is monitored in real time. ,like The interpolation result of the compensation curve remains unchanged until... .

9. A roll grinding accuracy online compensation system, used to execute the roll grinding accuracy online compensation method according to any one of claims 1 to 8, characterized in that, include: The measuring device consists of measuring head A and measuring head B arranged on both radial sides of the roll. While the roll is being ground, measuring head A and measuring head B measure the roll at predetermined time intervals to obtain the roll position and diameter data. Combined with the theoretical roll shape trajectory expression, the actual roll shape and roll shape error are calculated. The measurement results are described in the form of a preset structure. The filtering module is used to filter the measurement results and then store them in a circular queue. Fitting interval division module; the fitting interval division module divides the discrete measurement results corresponding to the roller error into multiple fitting intervals based on the monotonicity characteristics of the roller curve; First curve generation unit; The first curve generation unit selects the corresponding fitting method according to the roller curve type for each fitting interval to obtain the fitting curve for each interval; The second curve generation unit uses a smooth curve to replace the connection area of ​​the original fitting curve at the connection point of adjacent fitting intervals, so that the first derivative at the connection point is continuous and meets the preset smoothness error constraint condition, thus obtaining the grinding error curve. The third curve generation unit is used to scale the grinding error curve to generate a compensation curve; The interpolation module is used to interpolate the roller curve and the compensation curve simultaneously in each interpolation cycle, and send the accumulated interpolation result to the driver of the corresponding axis to perform online compensation; The monitoring module is used to monitor the torque load of the grinding wheel motor. When the torque load exceeds the maximum allowable value, the interpolation result of the compensation curve remains unchanged.

10. A CNC system for a grinding machine, characterized in that, include: Processor and memory storing computer program instructions; When the processor executes the computer program instructions, it implements the online compensation method for roll grinding accuracy as described in any one of claims 1 to 8.

11. A grinding machine equipped with the grinding machine CNC system of claim 10.

12. A grinding machine that implements the online compensation method for rolling mill grinding accuracy according to any one of claims 1 to 8.

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