Method for accurately controlling length of tail ruler of finished hot-rolled bar

Abstract

The invention belongs to the technical field of steel rolling, and particularly relates to a method for accurately controlling the tail ruler length of a hot-rolled bar finished product. The method comprises the following steps: calculating a fixed-length section number; and calculating the tail ruler length of the hot-rolled bar finished product. Rolled metal tail rulers corresponding to casting blanks of various specifications are calculated through a tail ruler accurate calculation method, reasonable optimization and combination are achieved, the number of blank types is reduced to the maximum extent, and production is guaranteed. And production is conducted according to the calculated blank reorganization, waste products caused by short-scale materials of the tail scale are avoided, and the actual yield of all specifications of rolled materials is kept at a good level.

Description

Technical Field

[0001] This invention belongs to the technical field of steel rolling, specifically relating to a method for precisely controlling the length of the finished hot-rolled bar stock. Background Technology

[0002] In the steel rolling process, after the billet undergoes plastic processing through multiple rolling mills, it needs to be trimmed at the head and tail, and then cut into sections of the required length according to customer needs. For bar production, yield and length ratio are the two most critical technical and economic indicators. During normal production, the following aspects affect the yield and length ratio: (1) Billet weight stability: depends on the billet control level of the steelmaking workshop. Currently, continuous casting can be controlled by a fixed length and fixed weight equipment system.

[0003] (2) Heating loss: depends on the equipment structure, heating capacity and heating process of the workshop heating furnace, and is a fixed value.

[0004] (3) Shear loss during intermediate process: Under the premise of ensuring rolling stability, the length of the head and tail cut should be kept to a minimum and the equipment should be kept stable.

[0005] (4) Finished product cutting loss: To minimize cutting loss, it is necessary to ensure that only a tail section is produced after the head and tail of the finished material is cut off, and the length of the tail section meets the standard requirements. Therefore, it is necessary to accurately calculate and control the length of the finished product tail section.

[0006] Based on the above conditions, it can be seen that the stability control of billet weight, heating loss, and intermediate process shearing loss are all controllable items. The key issue is how to accurately calculate and control the length of the finished product tail, ensure the minimum amount of finished product cutting loss, and ensure that the final length meets the requirements.

[0007] For calculating the length of the rolled piece's tail section, volume conversion or weight conversion methods are commonly used. Volume conversion follows the law of constant volume: billet volume = cuboid volume; rolled product volume = cylinder volume. Weight conversion uses the actual weight of the billet after weighing. The weight of the rolled product is calculated as the steel length multiplied by the national standard theoretical weight per meter.

[0008] In actual production, it was found that the theoretical length calculated using the two methods mentioned above deviated significantly from the actual length, failing to provide guidance for production. The main reasons are: the different densities of the billet and the finished product lead to different weight bases when calculating volume, affecting the calculation results. Furthermore, the theoretical weight per meter of the finished product deviated considerably from the actual weight per meter. Factors such as the basic dimensions of the die design, the actual operating habits of the work crew, and the density of the steel grade all influence the actual weight per meter.

[0009] Due to wear on the continuous casting machine's crystallizer, the actual dimensions of the billet's cross-section differ from the theoretical dimensions. Furthermore, the actual weight per meter of steel varies due to the influence of the steel's shrinkage coefficient and dimensional control during rolling. Summary of the Invention

[0010] The purpose of this invention is to provide a method for precisely controlling the tail length of hot-rolled bar products, addressing the aforementioned deficiencies. This method tracks actual production conditions and combines actual production data to accurately calculate and control the tail length of the finished hot-rolled bar products, thereby ensuring minimal cutting loss and maintaining the tail length within the range of 4-6 meters, reducing short-length scrap. This control method features low error, high operability, and can meet actual production needs, providing technical support for improving technical and economic indicators and maximizing economic benefits.

[0011] The technical solution of this invention is: a method for precisely controlling the length of the finished hot-rolled bar, comprising the following steps: (1) Calculation of the number of fixed length sections: First, calculate the number of fixed-length segments according to formula ①; Number of fixed-length segments = Formula ①.

[0012] In formula ①, the actual weight of the billet = the measured length of the billet × the actual weight per meter of the billet.

[0013] The actual weight per meter of the billet is obtained through the following steps: according to the rolling specifications of the rolling line, 50 heats are sampled, 10 bundles of steel are sampled from each heat, each bundle contains 30 steel pieces, and the length is 6 meters. The actual weight per meter of the billet is calculated based on the actual weight measured on the scale.

[0014] Yield = 100% - Oxidation loss coefficient of rolling line - Cutting loss coefficient; both the oxidation loss coefficient and the cutting loss coefficient are percentages.

[0015] The oxidation loss coefficient of the rolling mill is obtained by tracking production data, as follows: Track and statistically analyze the monthly oxidation loss rate of the rolling mill. Monthly oxidation loss rate = ; The monthly oxidation burn-off rate production data for two years were statistically analyzed, and the average value was taken as the oxidation burn-off coefficient of the rolling mill.

[0016] The aforementioned cutting loss coefficient is obtained by tracking production data, as detailed below: Track and analyze the monthly loss rate. Monthly loss rate = ; The monthly production data of the cutting loss rate for a year were collected, and the average value was taken as the cutting loss coefficient.

[0017] Weight of the large shear head for rolled products = length of the shear head × cross-sectional area of ​​the rolled product × density of the steel; The weight of the rolled product after large shearing = the length of the cut tail × the cross-sectional area of ​​the rolled product × the density of the steel.

[0018] Alternatively, the yield rate can be directly taken as the actual yield rate under stable production conditions. Based on the rolling specifications of the rolling line, select one year's production data for steel; the actual yield rate = .

[0019] The actual weight per meter of the finished product is obtained through the following steps: First, calculate the actual weight of each bundle of finished product per meter in the sample. Actual weight of each bundle of finished product per meter = ; Then, take the average value, which is the actual weight of the finished product per unit of rice.

[0020] The actual length of the specified length is the average level of the specified length control, obtained by tracking and measuring production data, as follows: First, during the production process, 50 heats are randomly selected according to the rolling specifications of the rolling line; during hot shearing, the fixed length is set to 6 meters. Then, after cooling, measure the actual length, take the average value, and obtain the actual length of the fixed length.

[0021] (2) Calculate the length of the tail rod. The tail length = the decimal part of the number of fixed length segments calculated in step (1) × the actual fixed length. This can effectively control the tail length of the bar stock within 4-6 meters, reducing short-length scrap.

[0022] The beneficial effects of this invention are as follows: The method for precisely controlling the tail length of hot-rolled bars described in this invention calculates the tail length of the rolled product corresponding to each specification of cast billet using a precise tail length calculation method, and rationally optimizes the combination to minimize the number of billets and ensure production. Production is organized according to the calculated billet weight, avoiding scrap caused by short tail lengths, and maintaining a good actual yield rate for each specification of rolled product.

[0023] The method described above, through in-depth analysis of the production process and statistical application of process big data, becomes a precise and practical control method. Detailed Implementation

[0024] The technical solution of the present invention will be described in detail below.

[0025] Example 1 In this embodiment, Φ55mm bars are rolled to a fixed length of 6 meters with a tolerance of 0-50mm.

[0026] The end face dimensions of the billet are 180mm × 220mm, and the billet length is 3100mm.

[0027] The specific steps of the method for precisely controlling the length of the finished hot-rolled bar stock are as follows: (1) Calculate the number of length segments: Based on the actual shrinkage data of the steel, the hot-cut length of the steel is set at 6.05 meters. After cooling, the length of the steel can be ensured to be between 6.0 and 6.05 meters, which meets the cut-length requirements.

[0028] According to the measured data, the actual weight per meter of the billet is 309 kg; therefore, the actual weight of the billet = the measured length of the billet × the actual weight per meter of the billet = 3.1 × 309 = 957.9 kg.

[0029] Based on one year's production data for this specification of steel, the actual yield rate was calculated to be 97.01% by using the ratio of the weight of qualified steel to the weight of inspected steel.

[0030] The actual weight per meter of the finished product of this specification was calculated to be 15.88 kg / m based on sampling. The actual length was also measured to be 6.03 meters.

[0031] Therefore, the number of fixed-length segments = = =9.704 segments.

[0032] (2) Calculate the tail length of the finished hot-rolled bar: The length of the tail gauge = the decimal part of the number of fixed gauge segments calculated in step (1) × the actual length of the fixed gauge = 0.704 × 6.03 = 4.25 meters.

[0033] Verification showed that the actual tailpiece length in production ranged from 4.18m to 4.5m, and the calculated data largely matched the actual production data. Therefore, the method described in this invention can accurately calculate and control the tailpiece length.

[0034] Example 2 In this embodiment, Φ50mm bars are rolled to a fixed length of 6 meters with a tolerance of 0-50mm.

[0035] The end face dimensions of the billet are 180mm × 220mm, and the billet length is 3040mm.

[0036] The specific steps of the method for precisely controlling the length of the finished hot-rolled bar stock are as follows: (1) Calculate the number of length segments: Based on the actual shrinkage data of the steel, the hot-cut length of the steel is set at 6.05 meters. After cooling, the length of the steel can be ensured to be between 6.0 and 6.05 meters, which meets the cut-length requirements.

[0037] According to the measured data, the actual weight per meter of the billet is 309 kg; therefore, the actual weight of the billet = the measured length of the billet × the actual weight per meter of the billet = 3.04 × 309 = 939.36 kg.

[0038] Based on one year's production data for this specification of steel, the actual yield rate was calculated to be 96.90% by using the ratio of the weight of qualified steel to the weight of inspected steel.

[0039] The actual weight per meter of the finished product of this specification was calculated to be 15.5 kg / m based on sampling. The actual length of the finished product was also measured to be 6.03 meters.

[0040] Therefore, the number of fixed-length segments = = =9.739 segments.

[0041] (2) Calculate the tail length of the finished hot-rolled bar: The length of the tail gauge = the decimal part of the number of fixed gauge segments calculated in step (1) × the actual length of the fixed gauge = 0.739 × 6.03 = 4.46 meters.

[0042] Verification showed that the actual length of the tailpiece in the production process ranged from 4.3m to 4.6m, and the calculated data was basically consistent with the actual production data.

[0043] Example 3 In this embodiment, Φ52mm bars are rolled to a fixed length of 6 meters with a tolerance of 0-50mm.

[0044] The end face dimensions of the billet are 180mm × 220mm, and the billet length is 3000mm.

[0045] The specific steps of the method for precisely controlling the length of the finished hot-rolled bar stock are as follows: (1) Calculate the number of length segments: Based on the actual shrinkage data of the steel, the hot-cut length of the steel is set at 6.05 meters. After cooling, the length of the steel can be ensured to be between 6.0 and 6.05 meters, which meets the cut-length requirements.

[0046] According to the measured data, the actual weight per meter of the billet is 309 kg; therefore, the actual weight of the billet = measured length of the billet × actual weight per meter of the billet = 3.0 × 309 = 927 kg.

[0047] Based on one year's production data for this specification of steel, the actual yield rate was calculated to be 96.85% by using the ratio of the weight of qualified steel to the weight of inspected steel.

[0048] The actual weight per meter of the finished product of this specification was calculated to be 16.8 kg / m based on sampling. The actual length of the product was also measured to be 6.03 meters.

[0049] Therefore, the number of fixed-length segments = = =8.862 segments.

[0050] (2) Calculate the tail length of the finished hot-rolled bar: The length of the tail gauge = the decimal part of the number of fixed gauge segments calculated in step (1) × the actual length of the fixed gauge = 0.862 × 6.03 = 5.20 meters.

[0051] Verification showed that the actual length of the tailpiece in the production process ranged from 5.1m to 5.6m, and the calculated data was basically consistent with the actual production data.

Claims

1. A method for precisely controlling the length of the finished hot-rolled bar stock, characterized in that, Includes the following steps: (1) Calculate the number of length segments: The number of fixed-length segments is calculated according to formula ①; Standard length number of sections = ,①; In formula ①, the actual weight of the billet = the measured length of the billet × the actual weight per meter of the billet; (2) Calculate the tail length of the finished hot-rolled bar: Tail length = decimal part of the number of fixed length segments calculated in step (1) × actual fixed length.

2. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 1, characterized in that, The actual weight per meter of billet in step (1) is obtained through the following steps: according to the rolling specifications of the rolling line, 50 heats are sampled, 10 bundles of steel are sampled from each heat, each bundle contains 30 steel pieces, and the length is 6 meters. The actual weight per meter of billet is calculated based on the actual weight measured by weighing.

3. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 1, characterized in that, In step (1), the yield rate = 100% - rolling mill oxidation loss coefficient - cutting loss coefficient; both the oxidation loss coefficient and the cutting loss coefficient are percentages.

4. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 3, characterized in that, The oxidation loss coefficient of the rolling mill is obtained by tracking production data, as follows: Track and statistically analyze the monthly oxidation loss rate of the rolling mill. Monthly oxidation loss rate = ; The monthly oxidation burn-off rate production data for two years were statistically analyzed, and the average value was taken as the oxidation burn-off coefficient of the rolling mill.

5. The method for precisely controlling the tail length of hot-rolled bar products according to claim 3, characterized in that, The aforementioned cutting loss coefficient is obtained by tracking production data, as detailed below: Track and analyze the monthly loss rate. Monthly loss rate = ; The monthly production data of the cutting loss rate for a year were collected, and the average value was taken as the cutting loss coefficient.

6. The method for precisely controlling the tail length of hot-rolled bar stock according to claim 5, characterized in that, Weight of the large shear head for rolled products = length of the shear head × cross-sectional area of ​​the rolled product × density of the steel; The weight of the rolled product after large shearing = the length of the cut tail × the cross-sectional area of ​​the rolled product × the density of the steel.

7. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 1, characterized in that, In step (1), the yield rate is equal to the actual yield rate under stable production conditions; based on the rolling specifications of the rolling line, one year's production data of steel is selected, and the actual yield rate is equal to... .

8. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 1, characterized in that, The actual weight per meter of the finished product in step (1) is obtained through the following steps: First, calculate the actual weight per unit of meter for each bundle of finished product in the sample, where: Actual weight of each bundle of finished product per meter = ; Then, take the average value, which is the actual weight of the finished product per unit of rice.

9. The method for precisely controlling the length of the finished hot-rolled bar stock according to claim 1, characterized in that, The actual length of the fixed length in steps (1) and (2) is the actual average level of the fixed length control, which is obtained by tracking and measuring production data, as follows: First, during the production process, 50 heats are randomly selected according to the rolling specifications of the rolling line; during hot shearing, the fixed length is set to 6 meters. Then, after cooling, measure the actual length, take the average value, and obtain the actual length of the fixed length.

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