Method and system for checking whether zero calibration of screw feeder is accurate or not

Abstract

The invention relates to a method and system for checking whether zero calibration of a spiral feeder is accurate or not. The method comprises the steps that the spiral rotating speed and the corresponding discharging amount of the spiral feeder in the normal working period are obtained; performing data cleaning on the spiral rotation speed of the spiral feeder and the corresponding blanking amount data to obtain data after data cleaning; carrying out normality verification and descriptive statistics on the spiral rotation speed in the same blanking amount interval; when the statistical result of the data is in abnormal distribution, data cleaning is carried out again; when the statistical result of the data is normal distribution, determining a normal operation range of the spiral rotation speed by using a probability density function of the normal distribution; and when the spiral rotation speed of the target spiral feeder continuously exceeds the normal operation range, an abnormal calibration alarm is given out. According to the method, the normal operation range of the spiral rotation speed is defined according to the statistical rule (normal distribution interval), and the operation reliability and the production stability of the spiral feeder can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of screw feeders, in particular to a method and system for verifying whether zero-point calibration of a screw feeder is accurate. BACKGROUND

[0002] Screw feeders are widely used in metallurgy, power, chemical industry, pharmaceutical industry, building materials industry and other industries to provide accurate material quantity for material blending in production process. The main working principle of the screw feeder is to move the material in the closed trough through the rotating movement of the screw blade. The material is detected for weight when passing through the weighing bridge, and the speed sensor measures the running speed of the feeder. The weight signal and the speed signal are sent to the controller together, the controller calculates the instantaneous flow, and compares it with the set flow to control the frequency converter to change the rotating speed, thereby realizing quantitative feeding. If the zero point of the weight sensor is not accurate, the feedback material weight signal will be incorrect, which will cause the control system to make incorrect adjustment and cannot accurately control the feeding quantity. Calibrating the zero point can ensure the accuracy of the weight signal, stabilize the operation of the feeding system, and keep the feeding quantity around the set value. In the actual production process of the factory, the difference in professional quality of personnel may cause inaccurate zero-point calibration, thereby causing a significant difference in the actual feeding quantity of the screw feeder under the same set feeding quantity before and after calibration. SUMMARY

[0003] To solve the above problems, the purpose of the embodiments of the present application is to provide a method and system for verifying whether zero-point calibration of a screw feeder is accurate.

[0004] A method for verifying whether zero-point calibration of a screw feeder is accurate, comprising:

[0005] Step 1: obtaining the screw rotating speed of the screw feeder and the corresponding feeding quantity during normal operation;

[0006] Step 2: data cleaning of the screw rotating speed and the corresponding feeding quantity data of the screw feeder to obtain the data cleaned screw rotating speed and the feeding quantity data;

[0007] Step 3: normality verification and descriptive statistics of the screw rotating speed in the same feeding quantity interval;

[0008] Step 4: when the statistical result of the data is not normally distributed, re-performing data cleaning;

[0009] Step 5: when the statistical result of the data is normally distributed, using the probability density function of the normal distribution to determine the normal operating range of the screw rotating speed;

[0010] Step 6: when the screw rotating speed of the target screw feeder exceeds the normal operating range, an abnormal calibration alarm is issued.

[0011] Preferably, in step 3, the screw rotation speed within the same feed rate range is subjected to an Anderson-darling normality test. When the p-value of the test result is within a preset range, the statistical result of the data is a normal distribution.

[0012] Preferably, step 6 further includes:

[0013] Calculate the average value of the normal operating range of the screw rotation speed;

[0014] If the rotational speed of the target screw feeder is continuously distributed on one side above the average value or on one side below the average value for multiple consecutive times, a calibration abnormality warning will be issued.

[0015] This invention also provides a system for verifying the accuracy of zero-point calibration of a screw feeder, comprising:

[0016] The data acquisition module is used to acquire the screw rotation speed and corresponding feed rate of the screw feeder during normal operation.

[0017] The data cleaning module is used to clean the screw rotation speed and corresponding feed rate data of the screw feeder to obtain cleaned screw rotation speed and feed rate data.

[0018] The normality verification module is used to perform normality verification and descriptive statistics on the screw rotation speed within the same feed rate range;

[0019] The judgment module is used to re-clean the data when the statistical results of the data are not normally distributed;

[0020] The normal operating range determination module is used to determine the normal operating range of the helical rotation speed using the probability density function of the normal distribution when the statistical result of the data is normally distributed.

[0021] The abnormal alarm module is used to issue a calibration abnormality alarm when the screw rotation speed of the target screw feeder exceeds the normal operating range.

[0022] Preferably, in the normality verification module, the Anderson-darling normality test is performed on the spiral rotation speed within the same feed rate range. When the p-value of the test result is within a preset range, the statistical result of the data is a normal distribution.

[0023] Preferably, the abnormal alarm module also includes:

[0024] Calculate the average value of the normal operating range of the screw rotation speed;

[0025] If the rotational speed of the target screw feeder is continuously distributed on one side above the average value or on one side below the average value for multiple consecutive times, a calibration abnormality warning will be issued.

[0026] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0027] This invention relates to a method for verifying the accuracy of zero-point calibration of a screw feeder. Compared with the prior art, this invention uses statistical laws (normal distribution intervals) to define the "normal operating range" of the screw rotation speed, which can improve the operational reliability and production stability of the screw feeder.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A flowchart of a method for verifying the accuracy of zero-point calibration of a screw feeder provided by the present invention;

[0031] Figure 2 This is a schematic diagram of the normality test provided by the present invention;

[0032] Figure 3 This is a schematic diagram of the normal distribution provided by the present invention;

[0033] Figure 4 This is a schematic diagram of the operation of the screw feeder provided by the present invention. Detailed Implementation

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Please see Figure 1 A method for verifying the accuracy of zero-point calibration of a screw feeder, comprising:

[0038] Step 1: Obtain the screw rotation speed and corresponding feed rate of the screw feeder during normal operation;

[0039] Step 2: Perform data cleaning on the screw rotation speed and corresponding feed rate data of the screw feeder to obtain the cleaned screw rotation speed and feed rate data;

[0040] Step 3: Perform normality verification and descriptive statistics on the screw rotation speed within the same feed rate range;

[0041] In step 3, the Anderson-darling normality test is performed on the spiral rotation speed within the same feed rate range. When the p-value of the test result is within the preset range, the statistical result of the data is a normal distribution.

[0042] Step 4: When the statistical results of the data are not normally distributed, perform data cleaning again;

[0043] Step 5: When the statistical result of the data is normally distributed, use the probability density function of the normal distribution to determine the normal operating range of the spiral rotation speed;

[0044] Step 6: When the rotation speed of the target screw feeder exceeds the normal operating range, a calibration abnormality alarm will be issued.

[0045] Step 6 also includes:

[0046] Calculate the average value of the normal operating range of the screw rotation speed;

[0047] If the rotational speed of the target screw feeder is continuously distributed on one side above the average value or on one side below the average value for multiple consecutive times, a calibration abnormality warning will be issued.

[0048] The present invention will further illustrate the above process with reference to specific embodiments below:

[0049] A. Collect the operating speed and corresponding feed rate of the screw feeder during normal production in the batching process. Data cleaning: Remove data from periods when the material in the screw feeder exhibits significantly abnormal properties affecting flowability, such as moisture content or particle size. Data used before and after calibration must be collected under the premise that the shape of the screw feeder's discharge port and hopper remains consistent. Establish a dataset for the screw feeder's normal operation. Collect data for commonly used feed rate ranges, requiring at least 30 data points.

[0050] like Figure 2 As shown in Table 1, the actual feed rate and screw speed of the screw feeder during normal production are statistically analyzed. The feed rate is stratified according to its actual feed rate, and the range should not be too wide, otherwise the accuracy of the analysis will be reduced. As can be seen from Table 1, the daily actual feed rate of this screw feeder is mainly concentrated between 9 and 10. Therefore, descriptive statistics are performed on the screw speeds corresponding to actual feed rates between 9 and 10:

[0051] Table 1

[0052]

[0053]

[0054] The Anderson-darling normality test showed a p-value of 0.088 > 0.05. The descriptive statistics and the p-value of the normality test indicate that the screw speed data within the feed rate range of 9-10 follow a normal distribution with a mean of 17.07 and a standard deviation of 0.7828.

[0055] B, such as Figure 3 As shown, the feed rate of the screw feeder conforms to the central limit theorem regarding the screw speed. Under the premise of no structural changes and no abnormal changes in the flowability of the conveyed material, its feed rate is mainly related to the screw rotation speed. Within a sufficiently narrow weight distribution range, the corresponding rotational speed distribution is a normal distribution. The normal operating range is calculated using the probability density function of the normal distribution, excluding the values ​​with a 5% probability for each tail. The probability density function of the normal distribution (also known as the Gaussian distribution) describes the symmetrical distribution of data around the mean; its distribution function is: Where μ is the mean, which determines the center of the distribution; σ is the standard deviation, which determines the width of the distribution; σ 2 It is the variance, and x is the value of the random variable.

[0056] Based on the probability density function of the normal distribution, the screw feeder under normal conditions, when the feed rate is 9-10, the screw speed (or frequency) is distributed between 15.78 and 18.36 at 90% of the time. The operating range is a symmetrical distribution area with the mean as the axis of symmetry. The above area (15.78-18.36) is defined as the normal operating range of the screw feeder speed (or frequency) with a feed rate of 9-10.

[0057] C. Set the feed rate of the screw feeder to between 9 and 10, and plot the screw speed in a graph showing the normal operating limits.

[0058] D. Abnormal Warning:

[0059] like Figure 4 As shown in the diagram, the spiral rotation speed after point 36, after recalibrating the zero point, continuously exceeds the upper limit, which indicates that the zero point has drifted.

[0060] This invention also provides a system for verifying the accuracy of zero-point calibration of a screw feeder, comprising:

[0061] The data acquisition module is used to acquire the screw rotation speed and corresponding feed rate of the screw feeder during normal operation.

[0062] The data cleaning module is used to clean the screw rotation speed and corresponding feed rate data of the screw feeder to obtain cleaned screw rotation speed and feed rate data.

[0063] The normality verification module is used to perform normality verification and descriptive statistics on the screw rotation speed within the same feed rate range;

[0064] The judgment module is used to re-clean the data when the statistical results of the data are not normally distributed;

[0065] The normal operating range determination module is used to determine the normal operating range of the helical rotation speed using the probability density function of the normal distribution when the statistical result of the data is normally distributed.

[0066] The abnormal alarm module is used to issue a calibration abnormality alarm when the screw rotation speed of the target screw feeder exceeds the normal operating range.

[0067] Preferably, in the normality verification module, the Anderson-darling normality test is performed on the spiral rotation speed within the same feed rate range. When the p-value of the test result is within a preset range, the statistical result of the data is a normal distribution.

[0068] Preferably, the abnormal alarm module also includes:

[0069] Calculate the average value of the normal operating range of the screw rotation speed;

[0070] If the rotational speed of the target screw feeder is continuously distributed on one side above the average value or on one side below the average value for multiple consecutive times, a calibration abnormality warning will be issued.

[0071] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0072] This invention relates to a method for verifying the accuracy of zero-point calibration of a screw feeder. Compared with the prior art, this invention uses statistical laws (normal distribution intervals) to define the "normal operating range" of the screw rotation speed, which can improve the operational reliability and production stability of the screw feeder.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of verifying the accuracy of a zero calibration of a screw feeder, characterized by, The method comprises the following steps: Step 1: obtaining the screw rotation speed of the screw feeder during normal operation and the corresponding discharging amount; Step 2: performing data cleaning on the screw rotation speed and the corresponding discharging amount data of the screw feeder to obtain the data-cleaning screw rotation speed and the discharging amount data; Step 3: performing normality verification and descriptive statistics on the screw rotation speed in the same discharging amount interval; Step 4: when the statistical result of the data is non-normal distribution, re-performing data cleaning; Step 5: when the statistical result of the data is normal distribution, using the probability density function of the normal distribution to determine the normal operation range of the screw rotation speed; Step 6: when the screw rotation speed of the target screw feeder exceeds the normal operation range, an abnormal calibration warning is issued.

2. A method of verifying the accuracy of the zero calibration of a screw feeder as claimed in claim 1, wherein, In the step 3, the Anderson-darling normality test is performed on the screw rotation speed in the same discharging amount interval, and when the p value of the test result is within a preset range, the statistical result of the data is normal distribution.

3. A method of verifying the accuracy of the zero calibration of a screw feeder as claimed in claim 2, wherein, In the step 6, further comprising: calculating the mean value of the normal operation range of the screw rotation speed; when the screw rotation speed of the target screw feeder is continuously distributed on one side above the mean value or on one side below the mean value for multiple times, an abnormal calibration warning is issued.

4. A system for verifying the accuracy of a zero calibration of a screw feeder, comprising: The method comprises the following steps: a data acquisition module for obtaining the screw rotation speed of the screw feeder during normal operation and the corresponding discharging amount; a data cleaning module for performing data cleaning on the screw rotation speed and the corresponding discharging amount data of the screw feeder to obtain the data-cleaning screw rotation speed and the discharging amount data; a normality verification module for performing normality verification and descriptive statistics on the screw rotation speed in the same discharging amount interval; a judgment module for re-performing data cleaning when the statistical result of the data is non-normal distribution; a normal operation range determination module for using the probability density function of the normal distribution to determine the normal operation range of the screw rotation speed when the statistical result of the data is normal distribution; an abnormal warning module for issuing an abnormal calibration warning when the screw rotation speed of the target screw feeder exceeds the normal operation range or is continuously distributed on one side of the mean value.

5. A system for verifying the accuracy of the zero calibration of a screw feeder as recited in claim 4, wherein, In the normality verification module, the Anderson-darling normality test is performed on the screw rotation speed in the same discharging amount interval, and when the p value of the test result is within a preset range, the statistical result of the data is normal distribution.

6. A system for verifying the accuracy of the zero calibration of a screw feeder as recited in claim 5, wherein, In the abnormal warning module, further comprising: calculating the mean value of the normal operation range of the screw rotation speed; when the screw rotation speed of the target screw feeder is continuously distributed on one side above the mean value or on one side below the mean value for multiple times, an abnormal calibration warning is issued.

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