Continuous casting rod blank quality monitoring method

Abstract

The invention provides a continuous casting rod blank quality monitoring method, and belongs to the field of metal continuous casting. The continuous casting rod blank quality monitoring method comprises the steps that before formal drawing, a continuous casting rod blank is drawn in advance, the drawing force of the continuous casting rod blank is detected in real time in the pre-drawing process, and data of the drawing force changing along with time are recorded; when the actual change rate of the drawing force is larger than a rate threshold value or the actual change amplitude of the drawing force is larger than an amplitude threshold value, it is judged that the continuous casting rod blank has defects, the defect positions of the continuous casting rod blank are marked so as to be used for tracing the continuous casting process parameters of the marked continuous casting rod blank, and therefore the corresponding parameters are adjusted and optimized. According to the method, whether the continuous casting rod blank has defects or not is judged according to the change rate evaluation basis of the drawing force of the continuous casting rod blank, and compared with the prior art, the screening efficiency of the defects of the continuous casting rod blank is higher and the cost is lower.

Description

Technical Field

[0001] The invention belongs to the field of metal continuous casting, and in particular relates to a method for monitoring the quality of a continuous casting rod blank. Background Art

[0002] Continuous casting is a process in which a molten metal is rapidly solidified and crystallized in a mold. The casting is then pulled out of the mold using a traction device. After cooling, it is finally cut into continuous cast rod billets of a certain length. Continuous cast rod billets are rod-shaped raw products directly produced using the continuous casting process. Generally, multiple drawing passes are required to form wire-like products.

[0003] Due to factors such as improper process parameter settings during the continuous casting process, cracks, shrinkage cavities, shrinkage porosity, and uneven microstructure may appear on the surface and inside the continuous casting rod billet. These defects need to be monitored during the production process to promptly remove unqualified products and adjust the production process.

[0004] An existing Chinese invention patent application with production publication number CN115388956A discloses a quality inspection method based on a continuous casting process flow. The method includes: detecting internal defects of a continuously cast rod billet using an internal defect detection device to obtain internal defect detection data, performing quality evaluation on the continuously cast rod billet, and if the quality evaluation passes, collecting a surface image of the continuously cast rod billet to obtain an image collection set; after positioning the continuously cast rod billet, identifying and locating defect features using the image collection set to obtain a defect set, generating a first quality evaluation parameter; generating a second quality evaluation parameter based on a defect impact dimension and a standard control dimension; and performing quality management of the continuously cast rod billet using the first quality evaluation parameter and the second quality evaluation parameter.

[0005] Internal defect detection devices include eddy current detectors, ultrasonic detectors, far-infrared detectors, and infrared thermal imaging devices. Devices for capturing images of the continuously cast rod surface include video cameras and still cameras. These devices first detect the continuously cast rod and generate a detection image, which is then analyzed in the background to obtain the final detection results. This delay in obtaining these detection results leads to inefficient defect screening for continuously cast rod, hindering efficient production. Furthermore, these devices are generally expensive, and equipping all continuous casting production lines with them would result in high production costs for continuously cast rod. Summary of the Invention

[0006] The object of the present invention is to provide a method for monitoring the quality of a continuously cast rod blank, so as to solve the technical problems of low efficiency and high cost in defect screening of continuously cast rod blanks in the prior art.

[0007] To achieve the above-mentioned purpose, the technical solution of the continuous casting rod billet quality monitoring method provided by the present invention is: A method for monitoring the quality of continuously cast rod billets is disclosed. The method comprises the following steps: pre-drawing the continuously cast rod billets before they are formally drawn for the purpose of producing wire-shaped products, and detecting the drawing force of the continuously cast rod billets in real time. Data on the drawing force changing over time is recorded. Based on production experience or experiments, the maximum rate of change of the drawing force of a defect-free continuously cast rod billet is used as a rate threshold. When the actual rate of change of the drawing force is greater than the rate threshold, the continuously cast rod billet is judged to have a defect. Alternatively, the maximum amplitude of change of the drawing force of a defect-free continuously cast rod billet is used as an amplitude threshold. When the actual amplitude of change of the drawing force is greater than the amplitude threshold, the continuously cast rod billet is judged to have a defect. The defect position of the continuously cast rod billet is marked for tracing the continuous casting process parameters of the marked continuously cast rod billet, thereby adjusting and optimizing the corresponding parameters.

[0008] As a further improvement, the drawing force detection process of the continuously cast rod blank is set on the continuous casting production line, and the process is located downstream of the secondary cooling process and upstream of the continuously cast rod blank cutting process.

[0009] As a further improvement, the drawing force detection process of the continuous casting rod blank is arranged between the billet straightening process and the continuous casting rod blank cutting process.

[0010] As a further improvement, the drawing force detection process of the continuous casting rod billet is arranged between the secondary cooling process and the billet straightening process.

[0011] As a further improvement, a drawing force detection process of the continuous casting rod blank is performed after the secondary cooling process, followed by the continuous casting rod blank cutting process. The drawing force detection process is used to detect the drawing force of the continuous casting rod blank and straighten the continuous casting rod blank by drawing.

[0012] As a further improvement, the drawing force detection process of the continuously cast rod blank is set on the drawing production line for forming the rod blank into a wire-shaped product, and the drawing force detection process of the continuously cast rod blank is used as the first drawing process on the drawing production line.

[0013] As a further improvement, a graph showing the change of the pulling force over time is generated, and the graph is read and identified manually. When the actual rate of change of the pulling force is greater than a rate threshold, the pulling force curve shows a steep increase or steep decrease. A graph showing the change of the pulling force over time is generated, and the graph is read and identified manually. When the actual rate of change of the pulling force is greater than a rate threshold, the pulling force curve shows a steep increase or steep decrease. When the actual change amplitude of the pulling force is greater than an amplitude threshold, a large increase or large decrease occurs. A steep increase, steep decrease, large increase, or large decrease in the pulling force curve is used as a sign of a defect, and the continuous casting rod billet is manually marked when the above sign appears.

[0014] As a further improvement, the marked continuous casting rod blanks are sent for inspection to determine the specific defect content, and the continuous casting process parameters are adjusted according to the specific defect content.

[0015] As a further improvement, a relevant database is established based on the changes in the drawing force of the continuous casting rod blank and the corresponding defect content, so as to preliminarily determine the type of defects occurring on the continuous casting rod blank according to the changes in the drawing force during production.

[0016] As a further improvement, when the actual rate of change of the drawing force is greater than the rate threshold, or when the actual amplitude of the change of the drawing force is greater than the amplitude threshold, the dimensional deviation of the continuous casting rod blank, the surface quality of the continuous casting rod blank, the wear condition of the drawing die and the lubrication condition are checked at the same time.

[0017] The beneficial effect is that the method for monitoring the quality of continuously cast rod billets provided by the present invention is a groundbreaking invention. This method links the variation in the pullout force of continuously cast rod billets with their quality. By pre-pulling the continuously cast rod billets, changes in the pullout force are detected. Defects are determined using the rate or magnitude of change in the pullout force. Compared to existing technologies, this method is simpler and more effective, capable of quickly screening defective continuously cast rod billets. It is also flexible and easy to implement, can be retrofitted to existing production lines, and is more cost-effective than existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the relevant structure for realizing the pulling force detection in the first embodiment of the continuous casting rod billet quality monitoring method of the present invention.

[0019] Description of reference numerals: 1. Drawing die; 2. Drawing hole; 3. Base; 4. Slide rail; 5. Baffle; 6. Piercing hole; 7. Pressure sensor; 8. Force measuring instrument; 9. Continuous casting rod blank. DETAILED DESCRIPTION

[0020] The present invention is described in further detail below with reference to the examples.

[0021] Specific implementation method 1 of the continuous casting rod billet quality monitoring method provided by the present invention: This method is used to monitor the quality of continuous casting rod billets in real time, remove defective continuous casting rod billets in a timely manner, and make timely adjustments to the continuous casting process. The specific contents of this method are as follows: A drawing force detection process for the continuous casting rod blank is set up on the continuous casting production line. This process is located between the billet straightening process and the continuous casting rod blank cutting process. The drawing force detection process uses a drawing die to pre-draw the continuous casting rod blank and detects the drawing force of the continuous casting rod blank in real time during the pre-drawing process.

[0022] Conventional continuous casting production lines typically involve crystallization of the molten metal in a mold, secondary cooling, straightening, and shearing. After secondary cooling, the continuously cast rod billet is fully solidified, and after straightening, the billet is essentially formed. In this embodiment, the drawing force detection step is placed between the straightening and shearing steps. This facilitates pre-drawing operations, as the billet is essentially formed and has not yet been sheared.

[0023] See attached Figure 1 The die used in the drawing force testing process is a drawing die 1 for a continuous casting rod blank. This die is provided with a drawing hole 2 for the continuous casting rod blank 9 to pass through, and its inner diameter is smaller than that of the continuous casting rod blank. During the passage of the continuous casting rod blank 9, it is squeezed by the drawing hole 2, causing its diameter to decrease. The drawing die 1 is mounted on a base 3, which is provided with a slide rail 4. The drawing die 1 is provided with a mating groove that slidably engages with the slide rail 4. The extension direction of the slide rail 4 is the same as that of the continuous casting rod blank 9, allowing the drawing die 1 to move in the drawing direction during the drawing of the continuous casting rod blank 9. A baffle 5 is provided on the base 3. The baffle 5 is located on one side of the drawing die 1 in the drawing direction. The baffle 5 is provided with a through-hole 6 for the continuous casting rod blank to pass through. A pressure sensor 7 is provided on the side of the baffle 5 facing the drawing die 1. The pressure sensor 7 is connected to a force measuring instrument 8. The drawing force detection process is also provided with a traction device for pulling the continuous casting rod blank to complete the pre-drawing operation. During the pre-drawing process of the continuous casting rod blank 9, the drawing die 1 is subjected to the force of the continuous casting rod blank 9 and moves toward the baffle 5. After contacting the pressure sensor 7, the force is transmitted to the pressure sensor 7. The pressure sensor 7 converts the pressure received into an electrical signal and transmits it to the force measuring instrument 8. Finally, the force measuring instrument 8 processes the signal and generates a curve graph of the drawing force changing with time.

[0024] The reading and identification of the curve graph is completed by on-site staff. When the on-site staff observes an abnormality in the pull-out force curve, they use a marking pen to mark the corresponding position of the continuous casting rod blank. The marked continuous casting rod blank will then be sent for inspection to determine whether there is a defect at the marked position and the specific type of defect.

[0025] Under normal circumstances, the pullout force of a continuously cast rod will fluctuate due to factors such as the crystallization of the rod, changes in its internal structure, and dimensional errors. However, these fluctuations are relatively gentle and small. If cracks appear on the surface of the rod or defects such as shrinkage cavities or porosity appear inside the rod, the structural strength of the corresponding locations will be weakened. During drawing, stress concentration will first occur at the defective locations, causing a sharp increase in the pullout force, followed by a sharp drop in the force due to material fracture or failure. If protrusions or oxide scale appear on the surface of the rod, these increases the frictional resistance between the rod and the drawing hole, requiring greater force for passage. This makes it difficult for the rod to pass through the drawing hole at the corresponding location, and the pullout force curve will initially increase sharply, then disappear after passage, and then drop sharply. If the internal structure of the rod is uneven, the pullout force will fluctuate irregularly with the changes in the uneven area.

[0026] The sharp increase or decrease in the pull-out force curve is the above-mentioned abnormality. When there are defects in the continuous casting rod billet, the sharp increase or decrease in the pull-out force curve is very obvious, which can be observed very directly and accurately by personnel. In addition, the manual operation is highly flexible and convenient for marking the defective continuous casting rod billets, which is easy to promote and implement.

[0027] The maximum rate of change of the pullout force of a defect-free continuous cast rod blank is used as the rate threshold to determine whether the continuous cast rod blank has defects. This essentially involves comparing the actual rate of change of the pullout force of the continuous cast rod blank with the rate threshold. When the actual rate of change of the pullout force exceeds the rate threshold, it indicates a defect in the continuous cast rod blank, manifested as a sharp increase or decrease in the pullout force curve. It should be noted that the rate of change of the pullout force refers to the rate of change of the absolute value of the pullout force. In reality, the pullout force has two trends: increasing and decreasing. While the pullout force curve can reflect this trend, it is not considered in numerical comparisons.

[0028] Manual judgment of whether the pull-out force curve shows a sharp increase or decrease mainly relies on operator observation and relatively rough judgment. However, since the change in pull-out force when defects occur is quite different from that when there are no defects, the rate of change of the pull-out force when defects occur is quite different from the rate threshold, making it less likely to make a misjudgment.

[0029] In other implementations, a computer can also be used to accurately compare the actual rate of change of the pulling force with a rate threshold. When the actual rate of change of the pulling force exceeds the rate threshold, an alarm is issued, or a robotic arm is controlled to mark the continuously cast rod. This approach does not require the generation of a graph showing the pulling force over time; instead, it only requires recording the data on the pulling force over time. However, this implementation requires the development of relevant software, resulting in a high initial investment.

[0030] The rate threshold can be determined based on production experience or through extensive testing. The specific method for determining the rate threshold through testing is to sample a large number of continuous casting rods and conduct testing and analysis. The pull-out force values ​​of the defect-free samples are statistically analyzed, and the maximum pull-out force value among the defect-free samples is used as the rate threshold.

[0031] The marked continuous casting rods are sent to a specialized testing center for metallographic examination or nondestructive testing to confirm the specific type of defects and the severity of the defects. Staff then use the marked rods' production data to trace the continuous casting process parameters used. They analyze the causes of the defects based on these parameters and develop optimization plans. Once the parameters are optimized, the marked rods are melted and returned to the furnace for recasting.

[0032] Testing the pull-out force of continuously cast rod billets can quickly screen for defective continuously cast rod billets. Compared with the existing technology of equipping each production line with non-destructive testing and surface flaw detection equipment, it has the advantages of simple structure, easy operation and lower cost.

[0033] Alternatively, the pull-out force variation can be used as a criterion for evaluating defects in continuously cast rods. Specifically, based on production experience or testing, the maximum pull-out force variation for defect-free continuously cast rods is used as a threshold. When the actual pull-out force variation exceeds the threshold, the continuously cast rod is considered defective. It should be noted that the pull-out force variation refers to the variation in the absolute value of the pull-out force. In reality, the pull-out force exhibits both increasing and decreasing trends. While the pull-out force variation trend can be reflected in the pull-out force curve, it is not considered in numerical comparisons.

[0034] When a single change in the pull-out force curve significantly exceeds the normal single change, that is, a significant increase or decrease, it is an abnormal situation and can also be used to determine the presence of defects in the continuous casting rod. If the actual change in the pull-out force is calculated using a computer, it is necessary to compare the current pull-out force value when the pull-out force trend changes with the value at the time of the previous change in the pull-out force trend to determine the actual change in the pull-out force. The actual change in the pull-out force is then accurately compared with the threshold value, and an alarm is issued when the actual change in the pull-out force exceeds the threshold.

[0035] In addition to defects in the continuous casting rod, the drawing force of the continuous casting rod can also reflect, to a certain extent, the dimensional deviation of the continuous casting rod, the wear of the drawing die, the surface quality of the continuous casting rod, and the lubrication condition. For example, when the continuous casting rod is too large, the drawing force will increase; when the continuous casting rod is too small, the drawing force will decrease; when the drawing die is severely worn, the drawing force will increase; and when the lubrication condition is poor, the drawing force will increase. Therefore, if the drawing force of the continuous casting rod fluctuates rapidly or significantly, it is also necessary to check the dimensional deviation of the continuous casting rod, the wear of the drawing die, the surface quality of the continuous casting rod, and the lubrication condition.

[0036] The quality of continuously cast rod slabs is only related to the rate of change of the pull-out force, not the magnitude of the pull-out force. This is because the pull-out force is closely related to the material composition and the type of continuous casting process. Even slight changes in the material composition and the type of continuous casting process can lead to significant changes in the pull-out force. Furthermore, the factors that influence the pull-out force can overlap, making it difficult to determine the relationship between the pull-out force and defects. Therefore, focusing solely on the pull-out force is meaningless for monitoring the quality of continuously cast rod slabs.

[0037] The present invention uses the rate of change and the amplitude of the pull-out force as a basis for judging defects in the continuously cast rod blank. The form of change of the pull-out force when the continuously cast rod blank has defects is significantly different from the form of change of the pull-out force when the continuously cast rod blank has no defects. Therefore, when the rate of change and the amplitude of the pull-out force are used to judge defects in the continuously cast rod blank, the influence of other factors is small, and the judgment result is more accurate.

[0038] After obtaining detailed inspection results, the rate of change of the pull-out force can be correlated with the corresponding defect type and severity of the defect. This database can then be established to allow preliminary identification of defect types on continuously cast rod slabs based on pull-out force variations during production. This allows for more targeted inspections, improving efficiency and accuracy. With a more complete database, it is also possible to identify significant defects on continuously cast rod slabs solely based on the rate and magnitude of change in pull-out force, eliminating the need to inspect all problematic rod slabs.

[0039] In addition, corresponding continuous casting process parameters can be added to the database to continuously optimize the continuous casting process parameters and realize the transformation from "experience-driven production" to "data-driven production".

[0040] In other implementations, if the production scale is small, it is also possible not to establish a database, and only use the continuous casting rod billet quality monitoring method as a defect screening method.

[0041] Specific implementation method 2 of the continuous casting rod billet quality monitoring method provided by the present invention: This embodiment is based on embodiment 1, and differs from embodiment 1 in that, in this embodiment, the drawing force detection process is placed between the secondary cooling process and the billet straightening process. The purpose of this is that the continuous casting rod blank before the billet straightening process retains the most original state of the continuous casting rod blank, especially the structure of its surface. The protrusions or depressions on the surface can also directly affect the changes in the drawing force of the continuous casting rod blank, thereby more effectively reflecting the suitability of the continuous casting process parameters.

[0042] Specific implementation method 3 of the continuous casting rod billet quality monitoring method provided by the present invention: This embodiment is based on embodiment 1, and differs from embodiment 1 in that, in this embodiment, the drawing force detection process replaces the original billet straightening process. After pre-drawing, the continuous casting rod billet can be in a relatively straight state, and the drawing force detection process can provide traction force for billet drawing. Therefore, the drawing force detection process in this embodiment plays the dual roles of drawing force detection and billet straightening.

[0043] Specific implementation method 4 of the continuous casting rod billet quality monitoring method provided by the present invention: This embodiment is based on the first embodiment, and differs from the first embodiment in that, in this embodiment, the drawing force detection process is provided on the drawing production line.

[0044] The drawing line is primarily used to process segmented, continuously cast rod billets through multiple drawing passes, ultimately producing a wire-like product. In this embodiment, the drawing force detection process serves as the first drawing step on the drawing line. After testing the continuous cast rod billets in the drawing force detection process, if any defects are found, the billets are marked and sent for inspection. This information is then fed back to the continuous casting line for adjustment of the continuous casting process parameters. If no defects are found, the drawn billets are sent to the second drawing step on the drawing line for the final drawing process. After completing these drawing steps, the finished wire-like product is obtained.

[0045] When continuously cast rod billets are delivered to the drawing line, they retain their relatively pristine state after continuous casting. Therefore, testing the drawing force as the first drawing step effectively detects defects in the billets and provides timely guidance for optimizing the continuous casting process. However, after multiple drawing steps, the billets become thinner and begin to transition to a thread-like shape. At this point, testing the drawing force to accurately determine whether defects exist is no longer possible. Furthermore, if defects necessitate the removal of the billet, previously completed drawing operations are wasted, resulting in low efficiency. Furthermore, after multiple drawing steps, the billets may break directly at the defective location, negating the purpose of quality monitoring.

[0046] On existing drawing production lines, drawing force tests are also performed in the last few drawing processes, but the purpose of these tests is only to determine whether wire breakage occurs, and they are not used as a basis for determining defects.

[0047] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments without inventive effort, or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for monitoring the quality of a continuous casting rod blank, characterized in that: Before formally drawing the continuously cast rod billet for the purpose of producing a wire-like product, a pre-drawing is performed, and the drawing force of the continuously cast rod billet is detected in real time, and the data of the drawing force changing with time is recorded. Based on production experience or experiments, the maximum value of the rate of change of the drawing force of the defect-free continuously cast rod billet is used as the rate threshold. When the actual rate of change of the drawing force is greater than the rate threshold, the continuously cast rod billet is determined to have a defect. Alternatively, the maximum value of the amplitude of change of the drawing force of the defect-free continuously cast rod billet is used as the amplitude threshold. When the actual amplitude of change of the drawing force is greater than the amplitude threshold, the continuously cast rod billet is determined to have a defect. The defect position of the continuously cast rod billet is marked for tracing the continuous casting process parameters of the marked continuously cast rod billet, so as to adjust and optimize the corresponding parameters.

2. The method for monitoring the quality of continuous casting rod billets according to claim 1, wherein: The drawing force detection process of the continuous casting rod blank is set on the continuous casting production line, and the process is located downstream of the secondary cooling process and upstream of the continuous casting rod blank cutting process.

3. The method for monitoring the quality of continuous casting rod blanks according to claim 2, wherein: The drawing force detection process of the continuous casting rod blank is arranged between the billet straightening process and the continuous casting rod blank cutting process.

4. The method for monitoring the quality of continuous casting rod billets according to claim 2, wherein: The drawing force detection process of the continuous casting rod billet is set between the secondary cooling process and the billet straightening process.

5. The method for monitoring the quality of continuous casting rod billets according to claim 2, wherein: After the secondary cooling process, the continuous casting rod blank is subjected to a drawing force detection process, followed by the continuous casting rod blank cutting process. The drawing force detection process is used to detect the drawing force of the continuous casting rod blank and straighten the continuous casting rod blank by drawing.

6. The method for monitoring the quality of continuous casting rod billets according to claim 1, wherein: The drawing force detection process of the continuously cast rod blank is arranged on a drawing production line for forming the rod blank into a wire-shaped product, and the drawing force detection process of the continuously cast rod blank is used as the first drawing process on the drawing production line.

7. The method for monitoring the quality of a continuous casting rod according to any one of claims 1 to 6, wherein: A graph showing the change of the drawing force over time is generated. The graph is read and identified manually. When the actual rate of change of the drawing force is greater than a rate threshold, the drawing force curve shows a steep increase or decrease. When the actual amplitude of the change of the drawing force is greater than an amplitude threshold, a large increase or large decrease occurs. A steep increase, steep decrease, large increase, or large decrease in the drawing force curve is used as a sign of a defect. When the above sign appears, the continuous casting rod billet is manually marked.

8. The method for monitoring the quality of a continuous casting rod according to any one of claims 1 to 6, wherein: The marked continuous casting rod blanks are sent for inspection to determine the specific defect content, and the continuous casting process parameters are adjusted according to the specific defect content.

9. The method for monitoring the quality of continuous casting rod blanks according to claim 8, wherein: According to the changes in the pull-out force of the continuous casting rod blank and the corresponding defect content, a relevant database is established to preliminarily judge the type of defects on the continuous casting rod blank according to the changes in the pull-out force in production.

10. The method for monitoring the quality of a continuous casting rod according to any one of claims 1 to 6, wherein: When the actual change rate of the drawing force is greater than the rate threshold, or the actual change amplitude of the drawing force is greater than the amplitude threshold, the dimensional deviation of the continuous casting rod blank, the surface quality of the continuous casting rod blank, the wear condition of the drawing die and the lubrication condition are checked simultaneously.

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