Feed rate control method for a numerical control system

Abstract

The application relates to the technical field of numerical control, in particular to a feed ratio control method of a numerical control system. The method comprises the following steps: acquiring current, power and vibration amplitude at each moment; acquiring an abrasion rate based on the collected parameters, the change characteristics of a grinding wheel and a feed speed; determining an optimal feed speed based on the abrasion rate change in a speed increasing interval; determining a real-time feed speed at each moment based on the abrasion rate difference and the abrasion rate growth rate in the corresponding speed increasing interval at the current moment; acquiring an adjustment interval and an optimal interval based on the speed change amount, and adjusting the real-time feed speed based on the abrasion rate difference of the two intervals to acquire a current optimal feed speed; acquiring an abrasion proportion coefficient based on the current optimal feed speed, and determining an optimal real-time feed speed by combining the current optimal feed speed; and controlling based on the optimal real-time feed speed. The application can adaptively adjust the feed ratio and improve the workpiece surface quality.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of numerical control, in particular to a feed ratio control method of a numerical control system. BACKGROUND

[0002] The grinding wheel polishing numerical control system is a highly automated precision machining control system. It accurately controls the multi-axis linkage movement of the machine tool, the rotation speed of the grinding wheel, the feed speed, the cutting depth and the cooling liquid supply and other parameters through a computer program, and drives the grinding wheel to precisely machine the surface of metal, ceramic, composite material and other workpieces. The grinding wheel polishing numerical control system combines the high precision and high repeatability of numerical control technology with the strong cutting and flexible contact characteristics of grinding wheel polishing, and is particularly good at efficiently and stably machining high-hardness materials or completing the precision polishing task of complex curved surfaces and contours, significantly improving machining efficiency, consistency and surface quality, while reducing the difficulty and intensity of manual operation.

[0003] In the process of controlling the grinding wheel polishing by the numerical control system, the feed speed preset by the program needs to be adjusted in real time and dynamically according to the machining state, so as to optimize the machining efficiency, ensure the machining safety, prevent the damage of the grinding wheel or the workpiece, adapt to the on-site working condition fluctuation and improve the final surface quality. In the prior art, the feed ratio control of the existing grinding wheel polishing numerical control system only relies on manual experience or preset program to adjust the feed speed, ignoring the dynamic influence of the real-time service life state of the grinding wheel on the machining parameters. The defect is that the feed ratio control logic and the service life decay law do not realize the adaptive feed adjustment guided by the service life, which finally leads to the decline of machining stability, the uneven surface quality of the workpiece, the increase of grinding wheel replacement frequency and the rise of comprehensive production cost. SUMMARY

[0004] In order to solve the technical problem of unstable workpiece quality, the application provides a feed ratio control method of a numerical control system, and the technical scheme is as follows:

[0005] The application provides a feed ratio control method of a numerical control system, which comprises the following steps:

[0006] The current, power and vibration amplitude at each time are obtained, and the current sequence, power sequence and vibration sequence are respectively formed;

[0007] The interval of the feed speed growth when the grinding wheel is polished for the first time is recorded as a growth interval; the grinding specific energy and the cross-sectional grinding area at each time are obtained, and the product of the grinding specific energy, the cross-sectional grinding area and the feed speed is recorded as the actual polishing power; a window is established at each time, and the wear rate at each time is determined based on the maximum value of the current variance and the vibration amplitude in the window and the actual polishing power; in the growth interval, the preferred degree of the feed speed at each time is obtained according to the difference between the growth rate of the wear rate at each time and the maximum value of the growth rate of all previous times and the feed speed; the feed speed corresponding to the maximum preferred degree is taken as the optimal feed speed;

[0008] When polishing is performed by the optimal feed speed, the wear index at each time is obtained based on the difference between the wear rate at each time and the wear rate at the same time corresponding to the same feed speed in the growth interval; the real-time feed speed at each time is calculated based on the average of the growth rates of all wear indices, the difference between the growth rate of the wear index at each time and the feed speed at each time;

[0009] The speed variation of the growth interval is obtained, the real-time feed speed is uniformly reduced to the minimum feed speed based on the speed variation to obtain an adjustment interval, the interval from the start of the growth interval to the optimal feed speed is recorded as an optimal interval, and the necessity of increasing the real-time feed speed is obtained based on the difference between the wear rates in the adjustment interval and the optimal interval; the real-time feed speed is adjusted in the adjustment interval based on the comparison between the necessity of increasing and an increase threshold to obtain a current optimal feed speed; the wear proportion coefficient is obtained based on the current optimal feed speed of different polishing times, and the optimal real-time feed speed is obtained in combination with the current optimal feed speed;

[0010] The feed ratio is obtained based on the optimal real-time feed speed, and the numerical control system is controlled.

[0011] In the above scheme, during the grinding process of the grinding wheel, too fast wear will cause current fluctuation, mechanical efficiency reduction and vibration increase, so the application quantifies the wear during the polishing process by constructing a wear efficiency, and obtains an optimal feed speed. Continuous polishing will cause wear of the grinding wheel, which will cause the grinding wheel to mismatch with the initial feed speed-wear rate. The application adjusts the real-time feed speed of the grinding wheel by constructing a grinding wheel wear index; during the polishing process, the material of the workpiece will change, which will cause the model of the speed-wear rate to change. The application adjusts the polishing process to adaptively obtain the real-time feed speed after the workpiece is replaced, and realizes adaptive adjustment of the feed ratio of the grinding wheel polishing numerical control system to realize stable machining of the workpiece.

[0012] In one embodiment, the growth interval is the time period required for the grinding wheel to uniformly increase from the minimum feed speed allowed by the grinding wheel when the grinding wheel starts polishing for the first time to the maximum feed speed.

[0013] In one embodiment, the wear rate is positively correlated with the maximum value of the vibration amplitude and the variance of the current, and is negatively correlated with the power and the difference between the actual grinding power and the optimal grinding power.

[0014] In one embodiment, the method for obtaining the preferred degree of the feed speed at each time according to the difference between the growth rate of the wear rate at each time and the maximum value of the growth rate of the wear rate at all previous times and the feed speed is:

[0015] All wear rates in the acceleration interval form a wear rate sequence, and the difference between the element value in the wear rate sequence and the previous element value is recorded as the growth rate at this time.

[0016] E a = exp(-|F a -F a,max |) × G a , E a is the preferred degree of the feed speed at the a-th time; F a is the growth rate of the wear rate corresponding to the a-th time in the wear rate sequence; F a,max is the maximum value of the growth rate of the wear rate corresponding to all previous times before the a-th time in the wear rate sequence; G a is the feed speed at the a-th time in the wear rate sequence; exp() represents the exponential function with the natural constant as the base.

[0017] In one embodiment, the wear index is the difference between the wear rate at each time and the wear rate at the corresponding time with the same feed speed in the acceleration interval.

[0018] In one embodiment, the wear index growth rate is the difference between the wear index at each time and the wear index at the previous time.

[0019] In one embodiment, the real-time feed speed is negatively correlated with the difference between the average of all wear index growth rates and the wear index growth rate at each time, and is positively correlated with the feed speed at each time.

[0020] In one embodiment, the necessity of increasing the real-time feed speed is negatively correlated with the difference between the variance of all wear rates in the adjustment interval and the variance of all wear rates in the optimal interval.

[0021] In one embodiment, the method for obtaining the current optimal feed speed by adjusting the real-time feed speed in the adjustment interval based on the comparison between the necessity of increasing and the increase threshold is:

[0022] If the necessity of increasing is greater than the increasing threshold value continuously from the start time of uniform speed reduction within the preset time in the adjustment interval, the real-time feeding speed is increased uniformly according to the speed change amount until the necessity of increasing is less than the increasing threshold value, and the feeding speed at this time is taken as the current optimal feeding speed; if the above condition is not met, the real-time feeding speed is reduced uniformly according to the speed change amount, and the reduction continues until the value N is greater than the increasing threshold value continuously for t seconds, and then the feeding speed corresponding to the time before the preset time at this time is taken as the current optimal feeding speed.

[0023] In one embodiment, the wear proportion coefficient is positively correlated with the ratio of the wear rate proportion coefficient of the material in the last polishing, the wear rate corresponding to the current optimal feeding speed in this polishing, and the wear rate corresponding to the final current optimal feeding speed in the last polishing; the product of the corresponding wear rate and the wear rate proportion coefficient obtained in the increasing speed interval is taken as the wear rate of the material corresponding to the increasing speed interval in this polishing; and the real-time feeding speed is calculated based on the wear rate of the material corresponding to the increasing speed interval in this polishing, the current optimal feeding speed in this polishing, and the wear rate to obtain the optimal real-time feeding speed.

[0024] The application has the following beneficial effects:

[0025] In the process of grinding wheel polishing, excessive wear will cause current fluctuation, mechanical efficiency reduction, and vibration increase, so the application quantifies the wear in the polishing process by constructing a wear efficiency, and obtains an optimal feeding speed. Continuous polishing will cause wear of the grinding wheel, which will cause the grinding wheel to be incompatible with the initial feeding speed-wear rate. The application adjusts the real-time feeding speed of the grinding wheel by constructing a grinding wheel wear index; in the process of polishing, the material of the workpiece will change, which will cause the speed-wear rate model to change. The application adjusts the polishing process to adaptively obtain the real-time feeding speed after the workpiece is replaced, and realizes adaptive adjustment of the feeding ratio of the grinding wheel polishing numerical control system to realize stable machining of the workpiece. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 A flow chart of a feeding ratio control method of a numerical control system provided by one embodiment of the application. DETAILED DESCRIPTION

[0028] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined object, the specific implementation, structure, features and effects of the feed ratio control method of the numerical control system according to the present application are described in detail as follows in combination with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0029] 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.

[0030] Embodiment of the feed ratio control method of the numerical control system:

[0031] The specific scheme of the feed ratio control method of the numerical control system provided by the present application is described in detail below in combination with the drawings.

[0032] Please refer to Figure 1 , which shows the flow chart of the feed ratio control method of the numerical control system according to one embodiment of the present application, which comprises the following steps:

[0033] Step S001, the current, power and vibration amplitude at each time are obtained, and the current sequence, power sequence and vibration sequence are formed respectively.

[0034] Before using the numerical control system to control the grinding of the grinding wheel, first arrange the sensor at the corresponding position for subsequent collection of the processing data of the grinding numerical control system; in the three-phase power supply cable of the main shaft motor, install a high-precision Hall current sensor and a power transmitter at the output end of the frequency converter for subsequent collection of the current and power of the main shaft motor; install a three-axis high-frequency acceleration sensor on the back of the main shaft flange for collecting vibration data during the grinding process. The collected data is normalized to obtain the current, power and vibration amplitude at each time. The current sequence, power sequence and vibration sequence are formed respectively.

[0035] At this point, the current, power and vibration amplitude at each time are obtained.

[0036] Step S002, the wear rate is obtained based on the collected parameters and the change characteristics of the grinding wheel and the feed speed; the optimal feed speed is determined based on the change of the wear rate in the speed increasing interval.

[0037] A brand new grinding wheel is installed on the machine, and the machine to be ground is ground. When the grinding wheel starts to grind for the first time, the minimum allowable feed speed of the grinding wheel is uniformly increased to the maximum feed speed for grinding. The time interval of this process is referred to as the speed increasing interval.

[0038] In the process of using the grinding wheel polishing numerical control system for processing, the real-time speed of the grinding wheel feed will affect the real-time wear rate of the grinding wheel, and the wear of the grinding wheel is mainly reflected in the current, power and vibration performance of the grinding wheel during polishing, so as to construct the wear rate of the grinding wheel.

[0039] In the process of using the grinding wheel polishing numerical control system for processing, the grinding wheel will be consumed and worn during polishing, and the real-time wear rate of the grinding wheel is mainly reflected in the fluctuation of current and the amplitude of vibration. When the fluctuation of current is larger and the amplitude of vibration is larger, the mechanical efficiency of the grinding wheel during polishing is lower, which indicates that the wear rate of the grinding wheel is higher.

[0040] For any moment, a window with a length of 11 is established around the moment, and in the current sequence, the variance of all currents in the window is calculated as the current fluctuation index of the moment. In the vibration sequence, the maximum value of the vibration amplitude in the window is recorded as the vibration index of the moment.

[0041] The grinding specific energy and cross-sectional grinding area of each moment are obtained, and the product of the grinding specific energy, cross-sectional grinding area and feed speed is recorded as the actual polishing power.

[0042] Based on the difference between the power and the actual polishing power of each moment, the vibration index and the current fluctuation index, the wear rate of each moment is calculated.

[0043] The wear rate is positively correlated with the vibration index and the current fluctuation index, and is negatively correlated with the difference between the power and the actual polishing power.

[0044] It should be noted that positive correlation means that when one variable increases, the other variable also increases, and the two variables change in the same direction. When one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large. The specific relationship is determined by actual application, and the present application does not make special limitation.

[0045] It should be noted that negative correlation means that when one variable increases, the other variable decreases, and the two variables change in opposite directions. When one variable changes from large to small or from small to large, the other variable also changes from small to large or from large to small. The specific relationship is determined by actual application, and the present application does not make special limitation.

[0046] Preferably, in the present embodiment, the expression of the wear rate is:

[0047] A a is the wear rate of the grinding wheel at the a-th moment; B ′ a is the actual polishing power at the a-th moment; B a is the power at the a-th moment; C ais the vibration index of the a-th moment; D a is the current fluctuation index of the a-th moment, and norm() represents a normalization function.

[0048] The greater the difference between the power and the actual polishing power, the greater the polishing power. The higher the mechanical efficiency, the lower the wear rate.

[0049] The wear rate is normalized, and in this embodiment, the normalization method is the maximum-minimum value normalization.

[0050] During polishing, a large feed speed is required to ensure the efficiency of the polishing process, while the wear rate of the grinding wheel during the polishing process needs to be low, so as to ensure the polishing efficiency while reducing the wear of the grinding wheel. In the process of the grinding wheel from the minimum speed to the maximum speed, the wear rate of the grinding wheel is obtained in real time, and then the wear rate of the grinding wheel and the feed speed need to be balanced to achieve the optimal feed speed.

[0051] In the process of gradually increasing the feed speed, the wear rate of the grinding wheel gradually increases, but when the feed speed exceeds the critical point, the wear rate will increase exponentially due to vibration, and the wear is dominated by chatter.

[0052] In the process from the minimum feed speed to the maximum feed speed, i.e. in the speed-up interval, the wear rate sequence is formed by all wear rates, and the difference between the element value in the wear rate sequence and the previous element value is denoted as the growth rate at this moment.

[0053] According to the difference between the growth rate at each moment and the maximum value of the growth rate at all previous moments and the feed speed, the preferred degree of the feed speed at each moment is obtained.

[0054] Preferably, the expression of the preferred degree is:

[0055] E a = exp(-|F a -F a,max |) × G a , E a is the preferred degree of the feed speed corresponding to the a-th moment; F a is the growth rate corresponding to the a-th moment in the wear rate sequence; F a,max is the maximum value of the growth rate corresponding to all moments before the a-th moment in the wear rate sequence; G a is the feed speed at the a-th moment in the wear rate sequence; and exp() represents the exponential function with the natural constant as the base.

[0056] The feed speed corresponding to the most preferred moment is recorded as the optimal feed speed, and after reaching the maximum feed speed, the polishing is carried out according to the optimal feed speed. The optimal feed speed at this time is taken as the feed speed of each subsequent moment.

[0057] At this point, the feed speed at each moment is obtained.

[0058] In step S003, the real-time feed speed at each moment is determined based on the current moment and the difference in wear rate and the wear rate growth rate in the corresponding speed-up interval.

[0059] In the process of polishing with a grinding wheel, when the wear state of the grinding wheel is different, the allowed feed speed of the grinding wheel is also different to ensure the safety and quality of polishing. Therefore, it is necessary to judge the real-time wear state of the grinding wheel.

[0060] Wear is essentially a manifestation of the degradation of the cutting ability of the grinding wheel. When the grinding wheel is sharp, the abrasive grains efficiently cut the workpiece at the same feed speed, the friction heat and micro-impact are small, and the wear rate is low. After the grinding wheel is passivated, the sliding ratio of abrasive grains increases at the same feed speed, the cutting force fluctuates, leading to a sharp increase in useless friction heat and abnormal fracture of abrasive grains, and the wear rate increases significantly. Therefore, the wear index of the grinding wheel is obtained according to the change of the wear rate of the grinding wheel.

[0061] After obtaining the feed speed at each moment through the above steps, the grinding wheel is polished based on the feed speed at each moment, the wear rate at each subsequent moment is calculated, and the wear index at each moment is obtained based on the difference between the wear rate at this moment and the wear rate at the moment corresponding to the same feed speed in the speed-up interval.

[0062] Preferably, the expression of the wear index is:

[0063] H i =A i -A ′ i , H i is the wear index of the i-th moment; A i is the wear rate of the i-th moment; A ′ i is the wear rate of the i-th moment corresponding to the same feed speed in the speed-up interval.

[0064] After obtaining the wear index, in order to ensure the efficiency of polishing and the effect of workpiece polishing, it is necessary to adjust the feed speed in real time according to the wear index of the grinding wheel during polishing. When the grinding wheel wears with the progress of the polishing process, the wear index of the grinding wheel increases, and the wear index directly represents the degree of attenuation of the health of the grinding wheel. When the change rate of the wear index increases, it indicates that the wear acceleration slope increases sharply, and at this time the feed speed needs to be dynamically adjusted according to the gradient of the deviation change rate.

[0065] The wear index growth rate at each time is obtained by subtracting the wear index at the previous time from the wear index at the current time.

[0066] The real-time feed speed at each time is calculated based on the mean of all wear index growth rates and the difference between the wear index growth rate at each time and the feed speed at each time.

[0067] The real-time feed speed is negatively correlated with the mean of all wear index growth rates and the difference between the wear index growth rate at each time, and is positively correlated with the feed speed at each time.

[0068] Preferably, in the embodiment, the expression of the real-time feed speed is:

[0069] K i is the real-time feed speed at the i-th time; M i is the feed speed at the i-th time; L i is the wear index growth rate at the i-th time; is the mean of all wear index growth rates before the i-th time; exp() represents the exponential function with the natural constant as the base.

[0070] After obtaining the real-time feed speed of the grinding wheel, the ratio of the feed speed at each time to the preset feed speed is recorded as the feed ratio of the grinding wheel numerical control system, and the numerical control system is adjusted in real time according to the ratio.

[0071] At this point, the real-time feed speed at each time is obtained.

[0072] Step S004, based on the speed change amount, the adjustment interval and the optimal interval are obtained, and the real-time feed speed is adjusted based on the difference in wear rate between the two intervals to obtain the current optimal feed speed; based on this, the wear proportion coefficient is obtained, and the optimal real-time feed speed is determined in combination with the current optimal feed speed.

[0073] Since the material of the workpiece is different when the workpiece is polished by the grinding wheel numerical control system, if a different material is used in the subsequent polishing process than the first polishing, the wear rate and the acceleration interval of the feed speed will lose reference. However, even if the material of the workpiece changes, the law of grinding wheel wear is similar, that is, the wear rate of the grinding wheel will rapidly increase when the feed speed of the grinding wheel is too fast, so the optimal feed speed needs to be obtained for the new material, and is mapped with the grinding wheel feed speed-grinding wheel wear rate of the first processed material, so as to update the wear rate at each time in the acceleration interval.

[0074] Before each processing starts, if the workpiece material changes, the real-time feed speed needs to be adjusted. Therefore, the workpiece material needs to be analyzed at the start of each processing.

[0075] Firstly, in the acceleration interval, the speed variation quantity can be obtained based on the ratio of the speed difference and the time difference, because the feed speed in the acceleration interval increases uniformly. The real-time feed speed decreases uniformly by the speed variation quantity until the minimum feed speed allowed by the grinding wheel is reached. The time interval of this process is recorded as the adjustment interval. The interval in which the start time reaches the optimal feed time in the acceleration interval is recorded as the optimal interval. The wear rate at each time is obtained for the adjustment interval and the optimal interval, respectively, and the variance of all wear rates in the adjustment interval and the optimal interval is calculated, respectively. The necessity of increasing the real-time feed speed is determined according to the difference between the variances of the two intervals.

[0076] The necessity of increasing the real-time feed speed is negatively correlated with the difference between the variances.

[0077] Preferably, in the present embodiment, the expression of the necessity of increasing the real-time feed speed is:

[0078] N is the necessity of increasing the real-time feed speed; P is the variance of all wear rates in the adjustment interval; P ′ is the variance of all wear rates in the optimal interval; exp() represents the exponential function with the natural constant as the base.

[0079] The purpose of the above formula is to compare whether the wear rate variation in the current uniform reduction process has a similar trend to the wear rate variation in the optimal interval. If they are similar, that is, the difference between the variances of the two intervals is small, it means that the current wear rate is in a suitable range interval, and the feed speed needs to be increased to find the optimal feed speed of the current material. If they are not similar, the feed speed needs to be reduced to find the optimal feed speed of the current material.

[0080] If in the adjustment interval, the value of N is always greater than the increase threshold for t seconds from the start time of the uniform reduction, the real-time feed speed is uniformly increased by the speed variation quantity until the value of N is less than the increase threshold, and the feed speed at this time is taken as the current optimal feed speed. If the above condition is not met, the real-time feed speed is uniformly reduced by the speed variation quantity, and the reduction continues until the value of N is always greater than the increase threshold for t seconds. The feed speed corresponding to the time t seconds ago is taken as the current optimal feed speed. In the present embodiment, the value of t is 3 seconds, and the value of the increase threshold is 0.9.

[0081] After the current optimal feed speed adjustment obtains the real-time feed speed, since the wear rate in the speed-up interval needs to be used during the adjustment, and after the material is changed, the speed-up interval of the previous material cannot be used, so the wear rate in the speed-up interval needs to be adjusted.

[0082] The wear rate proportionality coefficient of the material during the current polishing is determined by the wear rate proportionality coefficient of the material during the previous polishing, the ratio of the wear rate corresponding to the current optimal feed speed during the current polishing to the wear rate corresponding to the final current optimal feed speed during the previous polishing.

[0083] The wear rate proportionality coefficient of the material during the current polishing is determined by the wear rate proportionality coefficient of the material during the previous polishing, the ratio of the wear rate corresponding to the current optimal feed speed during the current polishing to the wear rate corresponding to the final current optimal feed speed during the previous polishing.

[0084] Preferably, the expression of the wear rate proportionality coefficient is:

[0085] S ′ is the wear rate proportionality coefficient of the material during the previous polishing; Q" is the wear rate corresponding to the current optimal feed speed during the current polishing; Q ′ is the wear rate corresponding to the final current optimal feed speed during the previous polishing, and S is the wear rate proportionality coefficient of the material during the current polishing.

[0086] The product of the wear rate corresponding to the speed-up interval and the wear rate proportionality coefficient is taken as the wear rate of the speed-up interval corresponding to the material during the current polishing.

[0087] Based on the wear rate of the speed-up interval corresponding to the material during the current polishing, the optimal real-time feed speed is obtained by combining the current optimal feed speed during the current polishing and the wear rate.

[0088] Thus, the optimal real-time feed speed is obtained.

[0089] Step S005, based on the optimal real-time feed speed, the feed rate is obtained, and the numerical control system is controlled.

[0090] According to the optimal real-time feed speed at each moment, the ratio of the optimal real-time feed speed at each moment to the preset feed speed is taken as the feed rate of the grinding wheel numerical control system, and in this embodiment, the value of the preset feed speed is 4 mm / s; and the numerical control system is adjusted in real time according to this rate, which guarantees the efficiency of workpiece polishing while guaranteeing the surface quality of the workpiece.

[0091] It should be noted that the above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

[0092] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment mainly explains the difference from other embodiments.

Claims

1. A method for feed rate control in a numerical control system, characterized in that, The method includes the following steps: The current, power, and vibration amplitude at each moment are obtained, and current sequence, power sequence, and vibration sequence are constructed respectively. The feed rate increase interval during the first grinding of the grinding wheel is denoted as the growth rate interval; the grinding specific energy and cross-sectional grinding area at each moment are obtained, and the product of the grinding specific energy, cross-sectional grinding area, and feed rate is denoted as the actual grinding power; a window is established for each moment, and the wear rate at each moment is determined based on the current variance, the maximum value of the vibration amplitude, and the actual grinding power within the window; within the growth rate interval, the optimization degree of the feed rate at each moment is obtained based on the difference between the growth rate of the wear rate at each moment and the maximum value of the growth rate at all previous moments, as well as the feed rate; the feed rate corresponding to the maximum optimization degree is taken as the optimal feed rate; When grinding at the optimal feed rate, the wear index at each moment is obtained based on the wear rate at each moment and the wear rate at the same feed rate at the corresponding moment within the growth range; the real-time feed rate at each moment is calculated based on the average growth rate of all wear indices, the difference in the growth rate of wear indices at each moment, and the feed rate at each moment. The speed change within the growth range is obtained. Based on this speed change, the real-time feed rate is uniformly reduced to the minimum feed rate to obtain the adjustment range. The interval from the start of the growth range to the optimal feed rate is defined as the optimal range. The necessity of increasing the real-time feed rate is determined based on the difference in wear rate between the adjustment range and the optimal range. The real-time feed rate is adjusted within the adjustment range based on a comparison between the necessity of increasing the rate and the threshold for increasing the rate to obtain the current optimal feed rate. The wear ratio coefficient is obtained based on the current optimal feed rate for different grinding passes, and combined with the current optimal feed rate, the optimal real-time feed rate is obtained. The feed rate is obtained based on the optimal real-time feed speed, and the CNC system is controlled accordingly.

2. The feed rate control method for a CNC system as described in claim 1, characterized in that, The growth rate range is the time interval required for the minimum allowable feed rate of the grinding wheel to increase uniformly to the maximum feed rate when the grinding wheel first starts grinding.

3. The feed rate control method for a CNC system as described in claim 1, characterized in that, The wear rate is positively correlated with the maximum vibration amplitude and the current variance, and negatively correlated with the difference between power and actual grinding power.

4. The feed rate control method for a CNC system as described in claim 1, characterized in that, The method for determining the optimality of the feed rate at each moment based on the difference between the growth rate of the wear rate at each moment and the maximum value of the growth rate at all previous moments, and the feed rate, is as follows: The wear rate sequence is formed by constructing all wear rates within the growth rate range. The difference between the element value and the previous element value in the wear rate sequence is recorded as the growth rate at that moment. E a =exp(-|F a -F a,max |)×G a E a F represents the optimality of the feed rate at time a. a F represents the growth rate at time a in the wear rate sequence. a,max G represents the maximum growth rate corresponding to all times preceding the a-th time in the wear rate sequence; a Let be the feed rate at time a in the wear rate sequence; exp() represents an exponential function with the natural constant as the base.

5. The feed rate control method for a CNC system as described in claim 1, characterized in that, The wear index is the difference between the wear rate at each moment and the wear rate at the same feed rate within the growth rate interval.

6. The feed rate control method for a CNC system as described in claim 1, characterized in that, The wear index growth rate is the difference between the wear index at each moment and the wear index at the previous moment.

7. The feed rate control method for a CNC system as described in claim 6, characterized in that, The real-time feed rate is negatively correlated with the mean of all wear index growth rates and the difference in wear index growth rate at each moment, and positively correlated with the feed rate at each moment.

8. The feed rate control method for a CNC system as described in claim 1, characterized in that, The necessity of increasing the real-time feed rate is negatively correlated with the difference between the variance of all wear rates within the adjustment range and the variance of all wear rates within the optimal range.

9. The feed rate control method for a CNC system as described in claim 1, characterized in that, The method for adjusting the real-time feed rate within the adjustment range based on the comparison between increasing necessity and increasing threshold to obtain the current optimal feed rate is as follows: Within the adjustment range, if the necessity for increasing the feed rate is consistently greater than the increase threshold for a preset time period starting from the moment of uniform decrease, the real-time feed rate is increased uniformly according to the speed change until the necessity for increasing the feed rate is less than the increase threshold. The feed rate at that moment is taken as the current optimal feed rate. If the above conditions are not met, the real-time feed rate is decreased uniformly according to the speed change until the N value is consistently greater than the increase threshold for a preset time period. The feed rate at that moment is taken as the current optimal feed rate.

10. The feed rate control method for a CNC system as described in claim 1, characterized in that, The wear ratio coefficients are positively correlated with the wear rate ratio coefficient of the material in the previous polishing, the wear rate corresponding to the current optimal feed rate in the current polishing, and the wear rate corresponding to the final current optimal feed rate in the previous polishing. The product of the wear rate obtained in the growth interval and the wear rate ratio coefficient is taken as the wear rate of the material in the growth interval corresponding to the current polishing. Based on the wear rate of the growth interval corresponding to the material in the current polishing, combined with the current optimal feed rate and wear rate, the real-time feed rate is calculated as the optimal real-time feed rate.

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