Injection casting pressure control method, system and equipment for semi-solid magnesium alloy

Abstract

The invention relates to the technical field of high-quality magnesium material manufacturing, in particular to a semi-solid magnesium alloy-oriented injection casting pressure control method, system and equipment, and the method comprises the following steps: extracting all edges in a magnesium alloy product grey-scale map produced each time, analyzing the change rate of the grey-scale values of all pixel points on each edge, and calculating the gray-scale value of the magnesium alloy product; measuring the distance from the center pixel point on each edge to the center pixel point of the magnesium alloy product grey-scale map where the edge is located, and determining a first defect evaluation value; and the extreme distribution condition and the dispersion degree of the gray values of all the pixel points in the window where each edge is located and the dispersion degree of the gray values of all the pixel points in the magnesium alloy gray-scale map are analyzed, a second defect evaluation value is determined, and the injection casting pressure of the semi-solid magnesium alloy is controlled in combination with the first defect evaluation value. The invention aims to improve the timeliness of adjusting the injection casting pressure of the semi-solid magnesium alloy.

Description

Technical Field

[0001] The present application relates to the technical field of high-quality magnesium material manufacturing, and particularly to a shot casting pressure control method, system and equipment for semi-solid magnesium alloy. Background Art

[0002] With the development of science and technology, the use of alloys has become increasingly widespread. Among them, semi-solid magnesium alloy, due to its characteristics of light weight and high strength, has been increasingly used in automotive structural parts and 3C products. Since the vast majority of magnesium alloys have a hexagonal close-packed structure (HCP) with low symmetry and few room-temperature slip systems, their room-temperature plastic deformation and pressure processing forming capabilities are poor. Therefore, the current forming process of magnesium alloy structural parts mainly relies on semi-solid injection molding casting. During the process of semi-solid injection molding casting, one of the important factors affecting the production quality of magnesium alloy is the control of shot casting pressure. When the molten material is injected into the mold cavity, due to the relatively fast cooling rate of the material, a certain shot casting pressure is required to ensure that the injection speed meets the standard, so as to ensure the complete filling of the product. Too high or too low shot casting pressure will affect the product quality, resulting in porosity, cold shut, poor filling, etc. Therefore, high-response and high-precision shot casting pressure control is required to ensure the production quality of magnesium alloy.

[0003] Currently, the parameter adjustment method for shot casting pressure control usually involves numerical simulation and analysis of the metallographic structure of the product, so as to evaluate the current production quality and the suitability of the parameters. However, the numerical simulation method is usually carried out in the early stage of production and cannot adapt to all production environments. And the method of analyzing the metallographic structure of the product requires complicated detection processes, resulting in a long response time for controlling and adjusting the shot casting pressure using the above two methods, with obvious hysteresis and difficulty in timely adjusting and controlling the shot casting pressure. Summary of the Invention

[0004] In a first aspect, an embodiment of the present application provides a shot casting pressure control method for semi-solid magnesium alloy, the method comprising the following steps:

[0005] Obtain grayscale images of magnesium alloy products produced multiple times before the current semi-solid magnesium alloy shot casting process;

[0006] Extract all edges in the grayscale images of the magnesium alloy products produced each time, analyze the change rate of the grayscale values of all pixel points on each edge, and determine the grayscale change difference of the magnesium alloy products produced each time; measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, determine the edge distribution value of the magnesium alloy products produced each time, and combine the grayscale change difference to determine the first defect evaluation value of the magnesium alloy products produced each time;

[0007] In each magnesium alloy grayscale image produced, divide a window for each edge, analyze the extreme distribution and dispersion degree of the grayscale values of all pixel points in the window where each edge is located, as well as the dispersion degree of the grayscale values of all pixel points in the magnesium alloy grayscale image, and determine the second defect evaluation value of the magnesium alloy product produced each time;

[0008] Based on the first defect evaluation value and the second defect evaluation value, determine the urgency of pressure regulation for the magnesium alloy product produced each time, and control the injection pressure of the semi-solid magnesium alloy at the current moment.

[0009] Preferably, the method for determining the grayscale change difference of the magnesium alloy product produced each time is as follows:

[0010] In the grayscale image of the magnesium alloy product produced each time, calculate the mean value of the slopes at all pixel points on each edge, and record it as the edge change rate of each edge;

[0011] Calculate the difference between the edge change rate of each edge and the average edge change rate of all the other edges, and take the sum of the differences of all edges as the grayscale change difference of the magnesium alloy product produced each time.

[0012] Preferably, the method for determining the edge distribution value of the magnesium alloy product produced each time is as follows:

[0013] In the grayscale image of the magnesium alloy product produced each time, calculate the distance from the central pixel point of each edge to the central pixel point in the grayscale image of the magnesium alloy product, and take the mean value of the distances of all edges as the edge distribution value of the magnesium alloy product produced each time.

[0014] Preferably, the expression of the first defect evaluation value of the magnesium alloy product produced each time is: In the formula, A i represents the first defect evaluation value of the i-th produced magnesium alloy product; B i represents the grayscale change difference of the i-th produced magnesium alloy product; C i represents the edge distribution value of the i-th produced magnesium alloy product; ε represents a preset constant greater than 0.

[0015] Preferably, the process of dividing a window for each edge is as follows:

[0016] Obtain the minimum circumscribed rectangle of each edge, keep the center of the minimum circumscribed rectangle unchanged, expand all side lengths of the minimum circumscribed rectangle by a preset number of times, and use the expanded rectangle as the window for each edge.

[0017] Preferably, the method for determining the second defect evaluation value of the magnesium alloy product produced each time is:

[0018] Calculate the range and variance of the gray values of all pixel points in the window of each edge respectively, and record them as the gray range of each edge and the gray variance of each edge;

[0019] The second defect evaluation value D of the magnesium alloy product produced in the i-th time i The expression of is: D i = E i + F i ; In the formula, E i represents the sum value of the average gray range and the average gray variance of all edges in the gray scale image of the magnesium alloy product produced in the i-th time; F i represents the variance of the gray values of all pixel points in the gray scale image of the magnesium alloy product produced in the i-th time.

[0020] Preferably, the expression of the pressure regulation urgency of each produced magnesium alloy product is: G i = A i × D i ; In the formula, G i represents the pressure regulation urgency of the magnesium alloy product produced in the i-th time; A i represents the first defect evaluation value of the magnesium alloy product produced in the i-th time; D i represents the second defect evaluation value of the magnesium alloy product produced in the i-th time.

[0021] Preferably, controlling the injection pressure of the semi-solid magnesium alloy at the current moment includes:

[0022] Before the current semi-solid magnesium alloy injection process, if the pressure regulation urgency of the magnesium alloy product produced in the nearest previous time adjacent to the current time is greater than or equal to the segmentation threshold, then obtain the pressure data of all moments during the injection process of the magnesium alloy product corresponding to the minimum regulation urgency before the current time, record it as the ideal pressure data, and obtain the pressure data of the current moment during the current semi-solid magnesium alloy injection process. Take the pressure data of the current moment and the corresponding ideal pressure data as the input of the PID control algorithm, output a pressure control signal, and control the pressure of the current moment during the current semi-solid magnesium alloy injection process; otherwise, do not adjust the injection pressure of the current semi-solid magnesium alloy.

[0023] In a second aspect, an embodiment of the present application provides an injection pressure control system for semi-solid magnesium alloy, and the system includes:

[0024] A magnesium alloy data acquisition module, configured to obtain the gray scale images of the magnesium alloy products produced multiple times before the current semi-solid magnesium alloy injection process;

[0025] The magnesium alloy weight acquisition module is used to extract all edges in the grayscale image of the magnesium alloy product produced each time, analyze the change rate of the grayscale values of all pixel points on each edge, and determine the grayscale change difference of the magnesium alloy product produced each time; measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, determine the edge distribution value of the magnesium alloy product produced each time, and combine the grayscale change difference to determine the first defect evaluation value of the magnesium alloy product produced each time.

[0026] In the grayscale image of the magnesium alloy produced each time, divide windows for each edge, analyze the extreme distribution and dispersion degree of the grayscale values of all pixel points in the window where each edge is located, and the dispersion degree of the grayscale values of all pixel points in the grayscale image of the magnesium alloy, and determine the second defect evaluation value of the magnesium alloy product produced each time.

[0027] The magnesium alloy injection pressure regulation module is used to determine the urgency of pressure regulation of the magnesium alloy product produced each time based on the first defect evaluation value and the second defect evaluation value, and control the injection pressure of the semi-solid magnesium alloy at the current moment.

[0028] In a third aspect, an embodiment of the present application further provides an injection pressure control device for semi-solid magnesium alloy, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of the injection pressure control method for semi-solid magnesium alloy described in any one of the above are implemented.

[0029] As can be seen from the above embodiments, the injection pressure control method for semi-solid magnesium alloy provided by the embodiments of the present application has at least the following beneficial effects:

[0030] By analyzing the edge change rate in the grayscale image of the magnesium alloy product and the position of the edge relative to the central pixel point of the grayscale image of the magnesium alloy product, the present application constructs a first defect evaluation value, which can help timely detect quality problems caused by injection pressure deviation, timely adjust the injection pressure, and avoid the lag in adjusting the injection pressure; further, by analyzing the distribution of the grayscale values of the pixel points in the grayscale image of the magnesium alloy product, a second defect evaluation value is constructed, which can judge whether there are problems such as poor cold mold, and improve the timeliness of adjusting the injection pressure by evaluating the quality of the magnesium alloy product; further, by combining the first defect evaluation value and the second defect evaluation value, the urgency of pressure regulation is constructed, which can effectively solve the lag in adjusting the injection pressure in the traditional method, improve the timeliness of adjusting the injection pressure, and thus improve the stability of the magnesium alloy product production process and the quality of the product. By analyzing the quality of the magnesium alloy products produced in previous batches, the present application predicts and evaluates the pressure in the current injection process, improving the timeliness of adjusting the injection pressure of the semi-solid magnesium alloy. Description of the Drawings

[0031] To more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a flowchart of the steps of a shot casting pressure control method for semi-solid magnesium alloy provided by an embodiment of the present application;

[0033] Figure 2 It is a schematic diagram of the pressure regulation urgency extraction process provided by an embodiment of the present application;

[0034] Figure 3 It is a block diagram of a shot casting pressure control system for semi-solid magnesium alloy provided by an embodiment of the present application. Detailed implementation manners

[0035] To further elaborate on the technical means and effects adopted by the present application to achieve the intended invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, elaborate in detail on the shot casting pressure control method, system and equipment for semi-solid magnesium alloy proposed according to the present application, their specific implementation manners, structures, features and effects. 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.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs.

[0037] The following will specifically describe the specific solutions of the shot casting pressure control method, system and equipment for semi-solid magnesium alloy provided by the present application in conjunction with the accompanying drawings.

[0038] Please refer to Figure 1 , which shows a flowchart of the steps of a shot casting pressure control method for semi-solid magnesium alloy provided by an embodiment of the present application. The method includes the following steps:

[0039] Step S1: Obtain the grayscale images of magnesium alloy products produced multiple times before the current semi-solid magnesium alloy shot casting process.

[0040] A CMOS high-definition camera and an industrial light source are set at the mold of the semi-solid injection molding equipment for magnesium alloys. After each demolding of the magnesium alloy, the magnesium alloy finished product is illuminated from the front and a high-definition RGB image is taken to obtain the images of the magnesium alloy products produced in a preset number of times before the current semi-solid magnesium alloy injection casting process. To simplify the analysis, the RGB image is converted into a grayscale image, which is denoted as the grayscale image of the magnesium alloy product.

[0041] It should be noted that the value of the preset number is set manually. In this embodiment, the value of the preset number is 50. The implementer can also set it by combining specific situations, and this embodiment does not make special restrictions.

[0042] It should be understood that the selected magnesium alloy products are products with the same material composition and processing technological process.

[0043] Step S2: Extract all the edges in the grayscale image of the magnesium alloy product produced each time, analyze the change rate of the grayscale values of all the pixel points on each edge, and measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, so as to determine the first defect evaluation value of the magnesium alloy product produced each time.

[0044] Generally, when the injection casting pressure is suitable for the current production situation, the surface of the produced magnesium alloy product is relatively smooth and the stripes are clear. However, when there is a certain deviation in the injection casting pressure, shrinkage cavities, shrinkage porosity, etc. will occur, which will cause irregular holes or shrinkage porosity cracks that are locally dense and overall dispersed to appear on the surface of the magnesium alloy product. In the grayscale image of the magnesium alloy product, it is mainly manifested as irregular edges and closed contours appearing in local areas, showing the characteristics of local aggregation and overall dispersion. There are significant morphological differences from the holes and stripes in the magnesium alloy product under normal circumstances.

[0045] Therefore, based on the grayscale image of the magnesium alloy product, all the edges in the grayscale image of the magnesium alloy product are extracted. If the bending degree of the edge is greater and the regularity degree is lower, it is more likely to be the edge formed by shrinkage cavities and shrinkage porosity; on the contrary, if the bending degree of the edge is smaller and the regularity degree is higher, it means that the edge is more likely to be the normal edge on the surface of the magnesium alloy. Among them, in this embodiment, the canny edge detection is used to obtain the edges in the grayscale image of the magnesium alloy product. In the actual application process, the implementer can also use other edge extraction algorithms such as erosion and dilation. There are no special restrictions on the selection of the edge extraction algorithm in this embodiment. The canny edge detection algorithm is a well-known technology, and its specific principle will not be elaborated here.

[0046] In the grayscale image of the magnesium alloy product produced each time, calculate the mean value of the slopes at all the pixel points on each edge, which is denoted as the edge change rate of each edge;

[0047] It should be noted that in this embodiment, the Sobel operator is used to calculate the slope at the pixel point. The Sobel operator is a well-known technology, and its specific principle will not be elaborated here.

[0048] Furthermore, calculate the difference between the edge change rate of each edge and the average edge change rate of all the other edges, and take the sum of the accumulations of the differences of all the edges as the gray-scale change difference of each produced magnesium alloy product.

[0049] It should be noted that there are many methods to measure the difference between data. In this embodiment, for all the content related to calculating the difference between data, the method of taking the absolute value of the difference is adopted. In the actual application process, as other implementation manners, the implementer can also adopt other methods to measure the difference between data, such as the square or ratio of the difference. Regarding the selection of the method to measure the difference between data, no special limitation is made in this embodiment.

[0050] From the gray-scale change difference of each produced magnesium alloy product, it can be understood that if the mean value of the slopes at all the pixel points on the current edge is larger, that is, the edge change rate is larger, and the difference between the edge change rate of the current edge and the average edge change rate of all the other edges is larger, then the bending degree of the current edge is larger and the regularity degree is lower, indicating that this edge is more likely to be caused by shrinkage porosity and shrinkage cavity when the injection pressure is deviated, and the finally obtained gray-scale change difference is also larger; on the contrary, if the mean value of the slopes at all the pixel points on the current edge is smaller, that is, the edge change rate is smaller, and the difference between the edge change rate of the current edge and the average edge change rate of all the other edges is smaller, then the bending degree of the current edge is smaller and the regularity degree is higher, indicating that this edge is more likely to be a normal edge on the surface of the magnesium alloy.

[0051] In addition, the general rule of the solidification sequence of magnesium alloy castings is that the thinner parts and the places where the alloy liquid stops flowing first often solidify first, and the thicker parts and the places where the alloy liquid flows for the longest time and is filled last often solidify last, and the positions of shrinkage porosity and shrinkage cavity are most likely to be concentrated in the parts where the casting solidifies last. Usually, the injection port is at the center of the mold, so the irregular edge contours formed by shrinkage porosity and shrinkage cavity are more likely to be concentrated at the center of the gray-scale image of the magnesium alloy product.

[0052] Thus, by analyzing the distance between the central pixel point of the edge and the central pixel point of the gray-scale image of the magnesium alloy product, the edge distribution value is determined, specifically as follows:

[0053] In the gray-scale image of each produced magnesium alloy product, calculate the distance from the central pixel point of each edge to the central pixel point in the gray-scale image of the magnesium alloy product, and take the mean value of the distances of all the edges as the edge distribution value of each produced magnesium alloy product.

[0054] It can be understood from the edge distribution value of each produced magnesium alloy product that if the distance from the central pixel point of each edge to the central pixel point in the grayscale image of the magnesium alloy product is smaller, the edge distribution value is smaller, indicating that the edges in the grayscale image of the magnesium alloy product are mostly irregular edges formed by shrinkage cavities and porosity in the magnesium alloy caused by injection pressure deviation. Therefore, in order to avoid the occurrence of shrinkage cavities and porosity during the injection of magnesium alloy, it is necessary to adjust the injection pressure; conversely, if the distance from the central pixel point of each edge to the central pixel point in the grayscale image of the magnesium alloy product is larger, the edge distribution value is larger, indicating that the edges in the grayscale image of the magnesium alloy product are mostly normal edges in the magnesium alloy product.

[0055] Furthermore, based on the grayscale change difference and the edge distribution value, a first defect evaluation value is further determined to judge whether there are shrinkage cavities and porosity in the magnesium alloy product, so as to adjust the injection pressure and avoid the generation of shrinkage cavities and porosity. Specifically:

[0056] The expression of the first defect evaluation value of the magnesium alloy product produced for the i-th time is: In the formula, A i represents the first defect evaluation value of the magnesium alloy product produced for the i-th time; B i represents the grayscale change difference of the magnesium alloy product produced for the i-th time; C i represents the edge distribution value of the magnesium alloy product produced for the i-th time; ε represents a preset constant greater than 0, which is used to prevent the denominator from being 0. In this embodiment, the value of ε is set artificially. In this embodiment, the value of ε is 0.01. On the premise of ensuring that the denominator is not 0 and does not overly affect the calculation result, the implementer can also set it according to the specific situation. This embodiment does not make special restrictions.

[0057] It can be understood from the first defect evaluation value of each produced magnesium alloy product that when there are shrinkage cavities or porosity in the magnesium alloy product produced for the i-th time, irregular edges will appear on the surface of the magnesium alloy product. The regularity of these edges is relatively low, that is, the grayscale change difference is relatively large, and the edge distribution value is relatively small. The larger the first defect evaluation value obtained, the greater the possibility that there are defects on the surface of the magnesium alloy product, indicating that the degree of inappropriateness of the pressure during the injection process is higher, and it is more necessary to control and adjust the pressure during the injection process; conversely, when there are no shrinkage cavities and porosity in the magnesium alloy product produced for the i-th time, the regularity of the edges on the surface of the magnesium alloy product is relatively large, that is, the grayscale change difference is relatively small, and the edge distribution value is relatively large. The smaller the first defect evaluation value obtained, the smaller the possibility that there are defects on the surface of the magnesium alloy product, indicating that the degree of appropriateness of the pressure during the injection process is higher.

[0058] Step S3: In each produced grayscale image of the magnesium alloy, divide windows for each edge, analyze the extreme distribution and dispersion degree of the grayscale values of all pixel points in the window where each edge is located, as well as the dispersion degree of the grayscale values of all pixel points in the grayscale image of the magnesium alloy, and determine the second defect evaluation value of each produced magnesium alloy product.

[0059] When the injection pressure is too small, which will lead to a low injection speed, problems such as cold shut and poor filling will also occur during the production process of the magnesium alloy. Severe cold shut and poor filling will cause obvious irregular sunken linear patterns on the surface of the magnesium alloy product, as well as incomplete filling in local areas of the magnesium alloy product. When the degree of cold shut and poor filling is relatively light, the sunken linear pattern is relatively close to the pattern on the surface of an ordinary magnesium alloy product. The incomplete filling in local areas of the magnesium alloy product may be misjudged as uneven thickness in local areas of the magnesium alloy product. It is difficult to distinguish cold shut and poor filling only through the above methods, thus misjudging the product quality of the magnesium alloy and having a deviation in the judgment of the appropriate degree of injection pressure. Therefore, further analysis is required, and the specific analysis process is as follows:

[0060] When a relatively light cold shut phenomenon occurs, the sunken linear pattern presented on the surface of the magnesium alloy is relatively light. However, since cold shut will cause local sunken areas on the surface of the magnesium alloy product, resulting in a decrease in smoothness, under the illumination of the light source, the reflectivity in the sunken area decreases. Therefore, there is a significant difference in the reflectivity of the surface of the magnesium alloy product on both sides of the edge of the sunken linear pattern caused by cold shut. Specifically, in the grayscale image of the magnesium alloy product, it is manifested as a large difference in grayscale values between the two regions on both sides of the edge, and the change in grayscale values in the sunken area is even more obvious.

[0061] In addition, when a relatively light filling defect occurs in the magnesium alloy product, the filling defect will cause uneven thickness in local areas, or the thickness changes as the position gets farther away from the injection port. The farther away from the injection port, the greater the possibility of filling defect. In the grayscale image of the surface of the magnesium alloy product, it shows uneven brightness change, and the position with weaker brightness is farther away from the injection port.

[0062] Therefore, by analyzing the extreme distribution and dispersion degree of the grayscale values of all pixel points in the local area where each edge is located, and combining the dispersion degree of the grayscale values of all pixel points in the grayscale image of the magnesium alloy, determine the second defect evaluation value of each produced magnesium alloy product, specifically:

[0063] In each produced grayscale image of the magnesium alloy, obtain the minimum circumscribed rectangle of each edge. Keep the center of the minimum circumscribed rectangle unchanged, expand all side lengths of the minimum circumscribed rectangle by a preset number of times, and use the expanded rectangle as the window for each edge.

[0064] It should be noted that the value of the preset quantity multiple is set artificially. In this embodiment, the value of the preset quantity multiple is 3 times. The implementer can also set it according to the specific situation by himself / herself, and this embodiment does not make special restrictions.

[0065] Further, calculate the range and variance of the gray values of all pixel points in the window of each edge respectively, and record them as the gray range of each edge and the gray variance of each edge.

[0066] The second defect evaluation value D of the magnesium alloy product produced at the i-th time i The expression of is: D i = E i + F i ; In the formula, E i represents the sum of the average gray range and the average gray variance of all edges in the gray scale image of the magnesium alloy product produced at the i-th time; F i represents the variance of the gray values of all pixel points in the gray scale image of the magnesium alloy product produced at the i-th time.

[0067] It can be understood from the second defect evaluation value of the magnesium alloy product produced each time that when the suitability of the injection pressure in the semi-solid magnesium alloy injection process is relatively low, the greater the degree of light difference around the edge, the greater the difference in brightness change in the image, that is, the greater the sum of the average gray range and the average gray variance, and the greater the variance of the gray values of all pixel points in the gray scale image of the magnesium alloy product, the greater the obtained second defect evaluation value, indicating that the possibility of cold shut and poor filling on the surface of the magnesium alloy product is greater. At this time, it is more necessary to adjust the pressure in the current injection process;

[0068] On the contrary, when the injection pressure in the semi-solid magnesium alloy injection process is suitable, the smaller the degree of light difference around the edge, the smaller the difference in brightness change in the image, that is, the smaller the sum of the average gray range and the average gray variance, and the smaller the variance of the gray values of all pixel points in the gray scale image of the magnesium alloy product, the smaller the obtained second defect evaluation value, indicating that the possibility of cold shut and poor filling on the surface of the magnesium alloy product is smaller.

[0069] Step S4: Based on the first defect evaluation value and the second defect evaluation value, determine the pressure adjustment urgency of the magnesium alloy product produced each time, and control the injection pressure of the semi-solid magnesium alloy at the current moment.

[0070] According to steps S2 - S3, the first defect evaluation value and the second defect evaluation value of the magnesium alloy product produced each time before the current semi-solid magnesium alloy injection process are obtained. Therefore, by comprehensively considering the first defect evaluation value and the second defect evaluation value, the pressure in the injection process is adjusted. The specific process is as follows:

[0071] The expression of the pressure adjustment urgency of the magnesium alloy product produced at the i-th time is: Gi = A i × D i ; wherein, G i represents the pressure regulation urgency of the magnesium alloy product produced in the i-th time; A i represents the first defect evaluation value of the magnesium alloy product produced in the i-th time; D i represents the second defect evaluation value of the magnesium alloy product produced in the i-th time.

[0072] It can be understood from the pressure regulation urgency of the magnesium alloy product produced each time that if the first defect evaluation value of the magnesium alloy product produced in the i-th time is larger and the second defect evaluation value is larger, the obtained pressure regulation urgency is larger, indicating that the possibility of cold shut and poor filling on the surface of the magnesium alloy product is greater. At this time, it is more necessary to adjust the pressure during the current injection casting process; conversely, if the first defect evaluation value of the magnesium alloy product produced in the i-th time is smaller and the second defect evaluation value is smaller, the obtained pressure regulation urgency is smaller, indicating that the possibility of cold shut and poor filling on the surface of the magnesium alloy product is smaller.

[0073] Preferably, the schematic diagram of the pressure regulation urgency extraction process provided in this embodiment is as Figure 2 shown.

[0074] Furthermore, the pressure regulation urgencies of the magnesium alloy products produced in all previous times before the current semi-solid magnesium alloy injection casting process are used as the input of the threshold segmentation algorithm, and the segmentation threshold is output;

[0075] It should be noted that there are many common threshold segmentation algorithms. In this embodiment, the Otsu threshold segmentation algorithm is adopted. In the actual application process, as other implementation manners, the implementer can also adopt other threshold segmentation methods. There is no special limitation on the selection of the threshold segmentation method in this embodiment.

[0076] Among them, the Otsu threshold segmentation algorithm is a well-known technology, and its specific principle will not be elaborated here.

[0077] Furthermore, before the current semi-solid magnesium alloy injection casting process, if the pressure regulation urgency of the magnesium alloy product produced in the closest previous time to the current time is greater than or equal to the segmentation threshold, then the pressure data at all times during the injection casting process of the magnesium alloy product corresponding to the minimum regulation urgency before the current time is obtained, denoted as the ideal pressure data, and the pressure data at the current time during the current semi-solid magnesium alloy injection casting process is obtained. The pressure data at the current time and the ideal pressure data at the corresponding time are used as the input of the PID control algorithm, and the pressure control signal is output to control the pressure at the current time during the current semi-solid magnesium alloy injection casting process; conversely, the injection casting pressure of the current semi-solid magnesium alloy is not adjusted.

[0078] It should be noted that in this embodiment, it is aimed at semi-solid magnesium alloy products of the same batch with the same type and material. Therefore, the operations in each stage of the injection casting process are the same, and the corresponding operation durations are also the same. Therefore, the operations at the corresponding moments are consistent.

[0079] So far, by analyzing the defect situation of magnesium alloy products in this embodiment and then adjusting the injection pressure, the complexity of data processing is effectively reduced, and at the same time, the real-time performance of injection pressure control is improved.

[0080] Based on the same inventive concept as the above method, the embodiment of the present application also provides an injection pressure control system for semi-solid magnesium alloy, including:

[0081] A magnesium alloy data acquisition module, configured to obtain the grayscale images of magnesium alloy products produced multiple times before the current semi-solid magnesium alloy injection casting process;

[0082] A magnesium alloy weight acquisition module, configured to extract all edges in the grayscale image of each produced magnesium alloy product, analyze the change rate of the grayscale values of all pixel points on each edge, and determine the grayscale change difference of each produced magnesium alloy product; measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, determine the edge distribution value of each produced magnesium alloy product, and combine the grayscale change difference to determine the first defect evaluation value of each produced magnesium alloy product;

[0083] In the grayscale image of each produced magnesium alloy, divide windows for each edge, analyze the extreme distribution and dispersion degree of the grayscale values of all pixel points in the window where each edge is located, and the dispersion degree of the grayscale values of all pixel points in the magnesium alloy grayscale image, and determine the second defect evaluation value of each produced magnesium alloy product;

[0084] A magnesium alloy injection pressure regulation module, configured to determine the urgency of pressure regulation of each produced magnesium alloy product based on the first defect evaluation value and the second defect evaluation value, and control the injection pressure of the semi-solid magnesium alloy at the current moment.

[0085] The block diagram of the injection pressure control system for semi-solid magnesium alloy provided by the embodiment of the present application is as Figure 3 shown.

[0086] Based on the same inventive concept as the above method, the embodiment of the present application also provides an injection pressure control device for semi-solid magnesium alloy, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above injection pressure control methods for semi-solid magnesium alloy.

[0087] It should be noted that: the above order of the embodiments of the present application is only for description and does not represent the superiority or inferiority of the embodiments. In addition, the specific embodiments of this specification have been described. Moreover, the processes depicted in the drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0088] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

[0089] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for controlling injection casting pressure of a semi-solid magnesium alloy, characterized in that: The method comprises the following steps: Obtain grayscale images of magnesium alloy products produced multiple times before the current semi-solid magnesium alloy injection casting process; Extract all edges in the grayscale image of the magnesium alloy product produced each time, analyze the change rate of the grayscale value of all pixels on each edge, and determine the grayscale change difference of the magnesium alloy product produced each time; measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, determine the edge distribution value of the magnesium alloy product produced each time, and determine the first defect assessment value of the magnesium alloy product produced each time in combination with the grayscale change difference; In the magnesium alloy grayscale image produced each time, a window is divided for each edge, and the extreme distribution and discrete degree of the grayscale values ​​of all pixels in the window where each edge is located, as well as the discrete degree of the grayscale values ​​of all pixels in the magnesium alloy grayscale image, are analyzed to determine the second defect evaluation value of the magnesium alloy product produced each time; Based on the first defect assessment value and the second defect assessment value, the urgency of pressure adjustment of the magnesium alloy product produced each time is determined, and the injection casting pressure of the semi-solid magnesium alloy at the current moment is controlled.

2. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The method for determining the grayscale variation difference of the magnesium alloy product produced each time is as follows: In the grayscale image of each magnesium alloy product produced, the average slope of all pixel points on each edge is calculated and recorded as the edge change rate of each edge; The difference between the edge change rate of each edge and the average edge change rate of all other edges is calculated, and the cumulative sum of the differences of all edges is used as the grayscale change difference of the magnesium alloy product produced each time.

3. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The method for determining the marginal distribution value of the magnesium alloy product produced each time is: In the grayscale image of the magnesium alloy product produced each time, the distance from the central pixel point of each edge to the central pixel point in the grayscale image of the magnesium alloy product is calculated, and the average of the distances of all edges is taken as the edge distribution value of the magnesium alloy product produced each time.

4. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The expression of the first defect evaluation value of the magnesium alloy product produced each time is: In the formula, A i represents the first defect evaluation value of the magnesium alloy product produced for the i-th time; B i represents the grayscale change difference of the magnesium alloy product produced for the i-th time; C i represents the marginal distribution value of the magnesium alloy product produced for the i-th time; ε represents a constant preset to be greater than 0.

5. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The process of dividing the window for each edge is as follows: Get the minimum bounding rectangle of each edge, keep the center of the minimum bounding rectangle unchanged, expand all sides of the minimum bounding rectangle by a preset number of times, and use the expanded rectangle as the window of each edge.

6. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The method for determining the second defect evaluation value of the magnesium alloy product produced each time is: Calculate the range and variance of the grayscale values ​​of all pixels in the window of each edge respectively, and record them as the grayscale range and grayscale variance of each edge; The second defect evaluation value D of the magnesium alloy product produced for the i-th time i The expression is: D i =E i +F i Where, E i represents the sum of the average grayscale range and the average grayscale variance of all edges in the grayscale image of the magnesium alloy product produced for the i-th time; F i Represents the variance of the grayscale values ​​of all pixels in the grayscale image of the magnesium alloy product produced for the i-th time.

7. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The expression of the urgency of pressure regulation of the magnesium alloy product produced each time is: G i =A i ×D i Where G i A represents the urgency of pressure regulation of the magnesium alloy product produced for the i-th time; i represents the first defect evaluation value of the magnesium alloy product produced for the i-th time; D i represents the second defect evaluation value of the magnesium alloy product produced for the i-th time.

8. The injection casting pressure control method for semi-solid magnesium alloy according to claim 1, characterized in that: The control of the injection casting pressure of the semi-solid magnesium alloy at the current moment includes: The pressure regulation urgency of all magnesium alloy products produced before the current semi-solid magnesium alloy injection casting process is used as the input of the threshold segmentation algorithm, and the segmentation threshold is output; Before the current semi-solid magnesium alloy injection-casting process, if the pressure adjustment urgency of the most recently produced magnesium alloy product adjacent to the current one is greater than or equal to the segmentation threshold, the pressure data at all moments in the injection-casting process of the magnesium alloy product corresponding to the minimum adjustment urgency before the current one is obtained and recorded as the ideal pressure data, and the pressure data at the current moment in the current semi-solid magnesium alloy injection-casting process is obtained, and the pressure data at the current moment and the ideal pressure data at the corresponding moment are used as inputs of the PID control algorithm, and a pressure control signal is output to control the pressure at the current moment in the current semi-solid magnesium alloy injection-casting process; otherwise, the pressure of the current semi-solid magnesium alloy injection-casting process is not adjusted.

9. An injection casting pressure control system for semi-solid magnesium alloys, realizing the injection casting pressure control method for semi-solid magnesium alloys as claimed in claim 1, characterized in that: The system comprises: The magnesium alloy data acquisition module is used to obtain grayscale images of magnesium alloy products produced multiple times before the current semi-solid magnesium alloy injection casting process; A magnesium alloy weight acquisition module is used to extract all edges in the grayscale image of the magnesium alloy product produced each time, analyze the change rate of the grayscale values ​​of all pixels on each edge, and determine the grayscale change difference of the magnesium alloy product produced each time; measure the distance from the central pixel point on each edge to the central pixel point of the grayscale image of the magnesium alloy product where the edge is located, determine the edge distribution value of the magnesium alloy product produced each time, and determine the first defect assessment value of the magnesium alloy product produced each time in combination with the grayscale change difference; In the magnesium alloy grayscale image produced each time, a window is divided for each edge, and the extreme distribution and discrete degree of the grayscale values ​​of all pixels in the window where each edge is located, as well as the discrete degree of the grayscale values ​​of all pixels in the magnesium alloy grayscale image, are analyzed to determine the second defect evaluation value of the magnesium alloy product produced each time; The magnesium alloy injection casting pressure control module is used to determine the urgency of pressure adjustment of each magnesium alloy product produced based on the first defect assessment value and the second defect assessment value, and control the injection casting pressure of the semi-solid magnesium alloy at the current moment.

10. An injection casting pressure control device for semi-solid magnesium alloy, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the injection casting pressure control method for semi-solid magnesium alloys as described in any one of claims 1 to 8 are implemented.

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