A method for precisely controlling the weight of a steel rail

Abstract

The present application relates to the technical field of steel rail, and proposes a steel rail single weight precision control method, which comprises the following steps: step a, determining the correlation between the main dimensions of the steel rail to be controlled and the influence on the single weight of the steel rail; step b, according to the correlation, determining at least one main dimension with the greatest influence on the single weight of the steel rail as a key dimension; step c, in the process of rolling the steel rail to be controlled, under the premise of ensuring that each main dimension is within the standard specified tolerance range, setting the rolling target value of the key dimension as the lower limit value of the tolerance range of the key dimension, and adjusting the rolling process to make the actual value of the key dimension reach the lower limit value, so that the single weight of the steel rail to be controlled is lower than the single weight when the lower limit value is not adjusted. The present application reduces the single weight of the steel rail relative to the single weight when the rolling target value of the key dimension is not set as the lower limit value, thereby reducing metal consumption, improving the steel rail yield, and reducing production cost under the condition of ensuring that all dimensions are qualified.

Description

Technical Field

[0001] This invention relates to the field of steel rolling technology, and in particular to a method for precise control of the single weight of a steel rail. Background Technology

[0002] Steel rails are primarily used to manufacture railway tracks, and the industry typically delivers them based on their theoretical unit weight. Precise control of rail unit weight can save significant amounts of metal, increase rail yield, and reduce rail consumption per unit, thereby substantially lowering production costs, increasing economic benefits, and giving companies a competitive edge in the market. However, precisely controlling rail unit weight is a complex issue. Due to the complex cross-sectional shape of rails, standards require control of numerous dimensions, such as rail height, head width, web thickness, bottom width, and flange thickness, all of which must meet the tolerances specified in the standards. In actual rolling production, these key dimensions are interrelated, and different dimensions have varying degrees of influence on rail unit weight, making it difficult to distinguish which dimensions have the greatest impact.

[0003] Existing technologies lack effective means to identify the correlation between major dimensions and rail weight, making it impossible to accurately identify the critical dimensions with the greatest impact on weight from among numerous major dimensions. Consequently, it is difficult to implement targeted and precise control over these critical dimensions. In conventional rolling processes, major dimensions are typically controlled near the midpoint of the tolerance range, failing to fully utilize the adjustment space allowed by the tolerance range. This results in the rail weight remaining consistently at a high level, making it difficult to further improve the yield rate. Summary of the Invention

[0004] To address the technical problems of high rail weight and low yield caused by numerous main dimensions, unclear influence, lack of key dimension identification and targeted control methods in existing technologies, this invention proposes a method for precise control of rail weight, comprising: Step a: Determine the correlation between the influence of multiple key dimensions of the rail to be controlled on the single weight of the rail; Step b: Based on the aforementioned correlation, determine at least one major dimension that has the greatest impact on the single weight of the rail as the critical dimension; Step c: During the rolling process of the rail to be controlled, under the premise of ensuring that all its main dimensions are within the tolerance range specified by the standard, the rolling target value of the key dimension is set as the lower limit of the tolerance range of the key dimension, and the rolling process is adjusted so that the actual value of the key dimension reaches the lower limit value, so that the unit weight of the rail to be controlled is lower than the unit weight when the lower limit value is not adjusted.

[0005] In some embodiments, in step a, the main dimensions include rail height, head width, waist thickness, bottom width, and leg tip thickness.

[0006] In some embodiments, step a includes: Calculate the positive limit unit weight when all major dimensions of the rail to be controlled are within the positive limit tolerance, and the negative limit unit weight when all are within the negative limit tolerance. Based on the difference between the positive limit unit weight and the negative limit unit weight, the comprehensive influence of the tolerances of the multiple main dimensions on the unit weight of the rail to be controlled is determined, and this is used as the correlation between the influence of the multiple main dimensions on the unit weight of the rail.

[0007] In some embodiments, step b includes: Based on the overall impact, at least one major dimension with the largest tolerance bandwidth among the multiple major dimensions is determined as the critical dimension.

[0008] In some embodiments, step a includes: Multiple rails of different lengths were randomly selected for control. The actual values ​​of each of their main dimensions and their corresponding actual unit weight were measured for each rail. A regression model reflecting the quantitative relationship between each main dimension and the rail unit weight was established based on regression analysis. This model was used as the correlation between the influence of the multiple main dimensions on the rail unit weight.

[0009] In some embodiments, the formula for the regression model is as follows: G=k+aXt+bXy+cXg+dXd+eXh; Where G is the weight of a single rail in kg / m, k is a constant in kg / m, Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm, and a, b, c, d, and e are regression coefficients, dimensionless.

[0010] In some embodiments, step b includes: The absolute values ​​of the regression coefficients corresponding to each independent variable in the regression model are sorted, and at least one major dimension with the largest absolute value of the regression coefficient is determined as the key dimension.

[0011] In some embodiments, the rail to be controlled is a 60kg / m rail, and the regression model established in step a is: G=-28.283-0.008Xt+1.524Xy+0.184Xg+0.11Xd+1.225Xh; Where G is the rail weight per unit, in kg / m, and Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm.

[0012] In some embodiments, step b includes: determining the critical dimensions as waist thickness and toe thickness.

[0013] In some embodiments, step c includes: In the process design of rail finishing mills, the actual values ​​of the key dimensions are made to reach the set lower limit by setting the finishing mill pass shape or rolling parameters.

[0014] The present invention provides a method for precise control of rail unit weight. First, it determines the correlation between the influence of multiple main dimensions of the rail to be controlled on its unit weight. Then, based on this correlation, it identifies the critical dimension with the greatest impact on the unit weight. While ensuring that all main dimensions are within the standard tolerance range, it sets the rolling target value of the critical dimension to the lower limit of its tolerance range. By adjusting the rolling process, the actual value of the critical dimension reaches this lower limit. This reduces the rail unit weight compared to when the critical dimension rolling target value is not set to the lower limit, thereby reducing metal consumption, increasing rail yield, and lowering production costs while ensuring all dimensions are within acceptable limits.

[0015] Step a quantifies the correlation between major dimensions and rail weight, providing a reliable basis for selecting critical dimensions. Step b accurately selects the critical dimensions with the greatest impact on weight from numerous major dimensions, transforming the complex problem of comprehensive multi-dimensional control into centralized control of a few critical dimensions, thus improving the targeting and efficiency of control. Step c fully utilizes the adjustment space allowed by the tolerance range by setting the rolling target value of the critical dimensions at the lower limit within the tolerance range and ensuring that the actual value reaches the lower limit. This maximizes the reduction of weight without affecting dimensional compliance, resulting in increased yield and economic benefits. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0017] Figure 1 The flowchart shown is a method for precise control of a single rail weight according to an embodiment of the present invention; Figure 2 The diagram shown is a schematic representation of a rail provided according to an embodiment of the present invention. Detailed Implementation

[0018] The following describes embodiments of the present invention. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms.

[0019] Furthermore, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that comprises a list of elements may include not only those elements but also elements not expressly listed or inherent to such process, method, article, or apparatus.

[0020] One or more embodiments of the present invention will now be described with reference to the accompanying drawings.

[0021] For the purposes mentioned above, refer to Figure 1-2 This invention proposes an embodiment of a method for precise control of the single weight of a rail. For example... Figure 1 As shown, a method for precise control of a single rail weight includes: Step a: Determine the correlation between the influence of multiple key dimensions of the rail to be controlled on the rail's unit weight.

[0022] The unit weight of a rail is the theoretical weight per unit length of the rail, usually measured in kg / m. It is a core economic indicator for measuring the metal consumption and yield of rails. The closer the unit weight is to the theoretical lower limit while all dimensions are still qualified, it means that more finished rail lengths can be rolled from the same weight of raw materials.

[0023] In some embodiments, the main dimensions include rail height, head width, web thickness, bottom width, and leg tip thickness. These five dimensions cover key structural parts of the rail cross-section, including the height direction, head, web, bottom, and leg tips. They are core parameters that are explicitly specified in the standard as requiring control, and their actual values ​​directly determine the size of the rail cross-sectional area, thus affecting the metal volume and unit weight per meter of rail. It is understandable that the types of main dimensions may be adjusted according to different types or standards of rails. For example, some rail standards may also include parameters such as leg thickness and head side angle; as long as their changes can have a measurable impact on the unit weight, they can be included in the category of main dimensions.

[0024] Step a above quantifies the relationship between each major dimension and the single weight of the rail, providing a reliable basis for the selection of key dimensions.

[0025] Step b: Based on the correlation, determine at least one major dimension that has the greatest impact on the single weight of the rail as the critical dimension.

[0026] Among them, critical dimensions refer to one or more major dimensions that have a significantly greater impact on the weight of the rail than other dimensions. Their selection is not based on subjective experience, but is objectively determined after quantitative analysis of the relationship between each dimension and the weight.

[0027] Step b above enables the accurate selection of the key dimensions that have the greatest impact on the unit weight from many major dimensions, transforming the complex problem of comprehensive control of multiple dimensions into centralized control of a few key dimensions, thereby improving the targeting and efficiency of the control.

[0028] Step c: During the rolling process of the rail to be controlled, on the premise of ensuring that all its main dimensions are within the tolerance range specified in the standard, the rolling target value of the critical dimension is set as the lower limit of the tolerance range of the critical dimension, and the rolling process is adjusted so that the actual value of the critical dimension reaches the lower limit, so that the unit weight of the rail to be controlled is lower than the unit weight when the lower limit is not adjusted.

[0029] Among them, the tolerance range is the allowable variation range of each major dimension specified in the rail standard. Its upper limit is called the upper deviation, and its lower limit is called the lower deviation. The tolerance bandwidth is the difference between the upper deviation and the lower deviation.

[0030] The rolling target value is the dimensional control target point aimed at when the rolling mill is set, rather than the upper and lower limits of the tolerance itself. By setting the target value and adjusting the rolling process, the actual size can be made to stably approach the target value.

[0031] Step c above, by setting the rolling target value of the key dimension to the lower limit within the tolerance range and making its actual value reach the lower limit, makes full use of the adjustment space allowed by the tolerance range, and achieves the maximum reduction of unit weight without affecting the dimensional qualification, resulting in improved yield and increased economic benefits.

[0032] This invention provides a method for precise control of rail weight. Instead of indiscriminately equalizing numerous rail dimensions, it first establishes the correlation between each major dimension and the rail weight, identifying one or more key dimensions that have the greatest impact on the weight. Then, during the rolling process, these key dimensions are precisely and selectively controlled, intentionally bringing their actual dimensions close to the lower limit of the standard tolerance. This minimizes metal consumption per meter of rail, reduces rail weight, and increases yield while ensuring all dimensions are fully qualified. Those skilled in the art will understand that yield refers to the ratio of the weight of qualified finished rails to the weight of raw materials used in production. A higher yield results in higher raw material utilization and lower production costs.

[0033] According to several embodiments of the present invention, determining the correlation in step a can be achieved through theoretical calculation. Specifically, CAD drawings are used to calculate the positive limit unit weight when all major dimensions of the rail to be controlled are within positive limit tolerances, and the negative limit unit weight when all are within negative limit tolerances. This includes: using CAD drawings to calculate the positive limit unit weight when all major dimensions of the rail to be controlled are within positive limit tolerances, and the negative limit unit weight when all are within negative limit tolerances; based on the difference between the positive and negative limit unit weights, the comprehensive influence of the tolerances of the multiple major dimensions on the unit weight of the rail to be controlled is determined, and this is used as the correlation relationship between the influence of the multiple major dimensions on the rail unit weight.

[0034] In one specific embodiment, a precise model of the rail is created in CAD software based on the standard cross-sectional view. Then, the parameters of each major dimension are replaced with their upper and lower tolerance limits. The software automatically calculates the corresponding cross-sectional area, which is then multiplied by the steel density to obtain the corresponding unit weight. The positive limit unit weight is the maximum possible unit weight when all major dimensions are taken at the upper tolerance, and the negative limit unit weight is the minimum possible unit weight when all major dimensions are taken at the lower tolerance. Based on the difference between the positive and negative limit unit weights, the comprehensive influence of the tolerances of multiple major dimensions on the unit weight of the rail under control can be determined. This comprehensive influence is used as the correlation between the influence of each major dimension on the rail unit weight. For example, for a certain specification of rail, CAD calculations show that the deviation between the positive limit unit weight and the negative limit unit weight can reach several percent. For instance, the positive limit tolerance corresponds to a unit weight deviation of +3.6%, and the negative limit tolerance corresponds to a unit weight deviation of -2.9%. The total deviation between the two is about 6.5%. This deviation directly reflects the significant comprehensive impact of dimensional tolerances on unit weight, and also verifies the feasibility and potential of reducing unit weight by adjusting the main dimensions.

[0035] According to several embodiments of the present invention, step b includes: determining at least one major dimension with the largest tolerance bandwidth among multiple major dimensions as the critical dimension based on the degree of comprehensive influence.

[0036] Understandably, dimensions with larger tolerance bandwidths allow for greater adjustment ranges during actual rolling, and intentionally controlling these dimensions to their lower limits does not increase the risk of exceeding tolerances. Conversely, dimensions with narrow tolerance bandwidths, even if they significantly impact unit weight, have very limited absolute adjustable ranges. Focusing control on these dimensions not only fails to effectively reduce unit weight but may also significantly increase the risk of exceeding tolerances due to the narrow operating window. For example, if the web thickness tolerance bandwidth is 1.0 mm while the head width tolerance bandwidth is only 0.5 mm, then under the same conditions, the web thickness should be prioritized as the critical dimension. This is because the web thickness can be adjusted to its lower limit within a 1.0 mm range, while the head width only has a 0.5 mm adjustment space, making the former more likely to reduce unit weight.

[0037] As another embodiment, determining the correlation in step a can be achieved by combining measured data with statistical analysis. Specifically, this includes: randomly selecting multiple rails of different lengths to be controlled, measuring the actual values ​​of each of their main dimensions and the corresponding actual unit weight, establishing a regression model based on regression analysis to reflect the quantitative relationship between each main dimension and the rail unit weight, and using this model as the correlation between the influence of multiple main dimensions on the rail unit weight.

[0038] Among these methods, sampling rails of different lengths helps ensure that the sample covers normal fluctuations in the production process, making the regression model more representative; measuring each rail individually means recording all the dimensions and unit weight of each rail sample separately to obtain one-to-one corresponding data pairs.

[0039] In one specific embodiment, please refer to Figure 2 The formula for the regression model is as follows: G=k+aXt+bXy+cXg+dXd+eXh; Where G is the rail weight per unit length (kg / m), k is a constant (kg / m), Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm. a, b, c, d, and e are regression coefficients, dimensionless. The sign of the regression coefficient indicates a positive or negative correlation between the dimension and the rail weight. The absolute value of the coefficient represents the change in rail weight corresponding to a change of one unit (1 mm) in the dimension; the larger the absolute value, the more sensitive the dimension is to the influence on the rail weight.

[0040] According to several embodiments of the present invention, step b includes: sorting the absolute values ​​of the regression coefficients corresponding to the independent variables in the regression model, and determining at least one major dimension with the largest absolute value of the regression coefficient as the key dimension. The larger the absolute value of the regression coefficient, the greater the change in weight per unit length of that dimension. Therefore, adjusting its lower limit within the same tolerance bandwidth can produce the most significant weight reduction effect.

[0041] As a specific implementation, the above regression model was applied to 60kg / m rails. Twenty 60kg / m rails of different lengths were randomly selected, and the actual values ​​of their head width, web thickness, rail height, bottom width, and flange thickness, as well as their corresponding actual unit weight, were measured for each rail. A unit weight control model for this rail specification was established using regression analysis techniques: G=-28.283-0.008Xt+1.524Xy+0.184Xg+0.11Xd+1.225Xh; Where G is the rail weight per unit, in kg / m, and Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm.

[0042] The determination coefficient R of the above model was calculated. 2 The model meets the statistical significance requirement and shows a good overall fit. The magnitude of each regression coefficient in the model directly reflects the degree of influence of the corresponding dimensions on the unit weight: the coefficient for waist thickness Xy is 1.524, the coefficient for rail height Xg is 0.184, the coefficient for bottom width Xd is 0.11, the coefficient for head width Xt is -0.008, and the coefficient for leg tip thickness is 1.225. Ranking the absolute values ​​of the regression coefficients, the absolute value of the waist thickness coefficient (1.524) is the largest, followed by the absolute value of the leg tip thickness coefficient (1.225). Therefore, the key dimensions are determined to be waist thickness and leg tip thickness.

[0043] After determining the web thickness and flange thickness as critical dimensions, step c specifically includes: In the process design of the finishing mill for 60kg / m rails, under the premise of ensuring that all major dimensions such as rail height, head width, web thickness, bottom width, and flange thickness are within the tolerance range specified in the standard, the rolling target value of the web thickness is set as the lower limit of its tolerance range, and the rolling target value of the flange thickness is also set as the lower limit of its tolerance range. By setting the finishing mill pass or rolling parameters, that is, by grinding the finishing mill pass or adjusting the rolling parameters (such as roll gap value, rolling force, rolling speed, etc.), the actual values ​​of the web thickness and flange thickness reach their respective lower limits. During the rolling process, the shape and size of the finishing mill pass directly determine the geometric parameters of the final rail cross-section. By precisely grinding the areas corresponding to the web and flange parts in the pass, the metal reduction in the corresponding parts during rolling can be increased, thereby stably controlling the web thickness and flange thickness near the lower limit values.

[0044] The following comparative data illustrates the specific effects of this embodiment. Table 1 below compares the main dimensions (web thickness, flange thickness, rail height, head width, bottom width) and rail weight in a conventional rolling process without this method and after precise control using the method of this invention: Table 1

[0045] As shown in Table 1 above, in conventional rolling processes without implementing this method, the main dimensions are habitually controlled near the midpoint of the tolerance range. After implementing this method for precise control, the web thickness is reduced to 16.51 mm, the flange tip thickness is reduced to 12.24 mm, the rail height is 175.68 mm, the head width is 72.90 mm, and the bottom width is 149.50 mm, corresponding to an average single weight of 60 kg / m rail reduced to 60.13 kg / m.

[0046] Calculations show that after implementing the precise control method of this invention, the average weight of a 60kg / m rail decreased by 1.25%, meaning the yield of a 60kg / m rail increased by 1.25%. For a typical production enterprise with an annual output of hundreds of thousands of tons of rails, a 1.25% increase in yield translates to savings of thousands of tons of high-quality steel annually, resulting in significant economic benefits. Furthermore, all dimensional data in the table are within the acceptable range specified by the standard, verifying that this method reduces weight without sacrificing any dimensional accuracy.

[0047] The aforementioned method for precise control of rail unit weight first determines the correlation between the influence of multiple main dimensions of the rail to be controlled on its unit weight. Then, based on this correlation, it identifies the critical dimension with the greatest impact on the unit weight. Under the premise of ensuring that all main dimensions are within the standard tolerance range, the rolling target value of the critical dimension is set as the lower limit of its tolerance range. By adjusting the rolling process, the actual value of the critical dimension reaches the lower limit value, thereby reducing the rail unit weight compared to when the rolling target value of the critical dimension is not set as the lower limit value. This reduces metal consumption, improves the rail yield, and lowers production costs while ensuring that all dimensions are qualified.

[0048] In some embodiments, the adjustment of the rolling process in step c above specifically includes, during the process design of the rail finishing mill, setting the finishing mill pass or rolling parameters to ensure that the actual value of the critical dimension reaches the set lower limit value. The finishing mill is a key piece of equipment in the rail rolling production line that determines the final dimensional accuracy of the finished product. Its pass design directly determines the flow distribution of metal in various parts and the final cross-sectional shape. By adjusting the groove depth, width, or sidewall angle of the corresponding critical dimension part in the finishing mill pass, the amount of metal filling in that part can be precisely controlled, so that the rolled value of the critical dimension converges to the target lower limit value. The adjustment methods of rolling parameters include, but are not limited to, adjusting the roll gap value to change the gap between the rolls, adjusting the rolling force to change the degree of metal deformation, adjusting the rolling temperature to change the plastic flow characteristics of the metal, and adjusting the rolling speed to affect the deformation rate and the final dimensional springback. These adjustment methods can be used individually or in combination, and those skilled in the art can flexibly select them according to the equipment configuration and process conditions of the actual production line.

[0049] In some embodiments, when the rail to be controlled is of other specifications, such as 50kg / m rail or 70kg / m rail, the same steps can be followed: first, obtain the unit weight correlation of the corresponding specifications through CAD analysis or sampling regression modeling; then, identify the key dimensions under that specification; and finally, implement precise lower limit control on them in the finishing mill process design. The key dimensions of rails of different specifications may vary, depending on the cross-sectional shape characteristics of that specification and the setting of tolerance zones for each dimension, but the overall logical framework of the method remains consistent.

[0050] In some embodiments, when determining the correlation in step a, CAD theoretical calculations can be combined with experimental regression analysis for mutual verification. For example, CAD methods can be used to quickly determine the overall influence of tolerances on unit weight and the relative magnitude of tolerance bandwidths for each dimension. Then, sampling regression analysis can be used to accurately obtain the quantitative ranking of each dimension coefficient. The two methods are combined to finally determine the critical dimension, thereby improving the reliability and robustness of critical dimension identification.

[0051] Furthermore, when determining critical dimensions, in addition to ranking based on the absolute value of regression coefficients or the size of tolerance bandwidth, the actual operability of the production process can also be considered. For example, if a certain dimension has a large absolute value of coefficient in the regression model, but it is already at a high level of process capability index control on the production line, with very little room for further downward adjustment and a high risk of process instability, its priority can be appropriately lowered, and a dimension with a slightly lower absolute value of coefficient but more room for adjustment can be selected as the critical dimension. This approach of fine-tuning based on engineering experience also falls within the scope of protection of this invention.

[0052] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0053] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0054] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for precise control of the single weight of a rail, characterized in that, include: Step a: Determine the correlation between the influence of multiple key dimensions of the rail to be controlled on the single weight of the rail; Step b: Based on the aforementioned correlation, determine at least one major dimension that has the greatest impact on the single weight of the rail as the critical dimension; Step c: During the rolling process of the rail to be controlled, under the premise of ensuring that all its main dimensions are within the tolerance range specified by the standard, the rolling target value of the key dimension is set as the lower limit of the tolerance range of the key dimension, and the rolling process is adjusted so that the actual value of the key dimension reaches the lower limit value, so that the unit weight of the rail to be controlled is lower than the unit weight when the lower limit value is not adjusted.

2. The method for precise control of rail single weight according to claim 1, characterized in that, In step a, the main dimensions include rail height, head width, waist thickness, bottom width, and leg tip thickness.

3. The method for precise control of rail single weight according to claim 1, characterized in that, Step a includes: Calculate the positive limit unit weight when all major dimensions of the rail to be controlled are within the positive limit tolerance, and the negative limit unit weight when all are within the negative limit tolerance. Based on the difference between the positive limit unit weight and the negative limit unit weight, the comprehensive influence of the tolerances of the multiple main dimensions on the unit weight of the rail to be controlled is determined, and this is used as the correlation between the influence of the multiple main dimensions on the unit weight of the rail.

4. The method for precise control of rail single weight according to claim 3, characterized in that, Step b includes: Based on the overall impact, at least one major dimension with the largest tolerance bandwidth among the multiple major dimensions is determined as the critical dimension.

5. The method for precise control of rail single weight according to claim 1, characterized in that, Step a includes: Multiple rails of different lengths were randomly selected for control. The actual values ​​of each of their main dimensions and their corresponding actual unit weight were measured for each rail. A regression model reflecting the quantitative relationship between each main dimension and the rail unit weight was established based on regression analysis. This model was used as the correlation between the influence of the multiple main dimensions on the rail unit weight.

6. The method for precise control of rail single weight according to claim 5, characterized in that, The formula for the regression model is as follows: G=k+aXt+bXy+cXg+dXd+eXh; Where G is the weight of a single rail in kg / m, k is a constant in kg / m, Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm, and a, b, c, d, and e are regression coefficients, dimensionless.

7. The method for precise control of rail single weight according to claim 5, characterized in that, Step b includes: The absolute values ​​of the regression coefficients corresponding to each independent variable in the regression model are sorted, and at least one major dimension with the largest absolute value of the regression coefficient is determined as the key dimension.

8. The method for precise control of rail single weight according to claim 7, characterized in that, The rail to be controlled is a 60kg / m rail, and the regression model established in step a is: G=-28.283-0.008Xt+1.524Xy+0.184Xg+0.11Xd+1.225Xh; Where G is the rail weight per unit, in kg / m, and Xt, Xy, Xg, Xd, and Xh are the head width, web thickness, rail height, bottom width, and flange tip thickness, respectively, all in mm.

9. The method for precise control of rail single weight according to claim 8, characterized in that, Step b includes: determining the key dimensions as waist thickness and toe thickness.

10. The method for precise control of rail single weight according to claim 1, characterized in that, Step c includes: In the process design of rail finishing mills, the actual values ​​of the key dimensions are made to reach the set lower limit by setting the mill pass shape or rolling parameters.

Images