Rolling method for large-size titanium alloy workpiece with low strain rate

Abstract

The invention relates to the technical field of workpiece rolling, in particular to a rolling method for a large-size titanium alloy workpiece with a low strain rate. According to the method, for a real-time rolling section, the temperature stress risk degree under each rolling pass is obtained according to the difference of temperature data between different positions under each rolling pass and the rolling speed; according to the change trend of the rolling pressure and the rolling speed under different rolling passes and the temperature stress risk degree distribution, the pressure adjustment feasibility of the real-time rolling section is obtained; the local stress extensibility of each rolling pass of the real-time rolling section is obtained according to the workpiece thickness variable quantity corresponding to each position in different rolling section ranges under each rolling pass of the real-time rolling section; and then the rolling pressure adjusting coefficient of the real-time rolling section is obtained. According to the method, appropriate rolling pressure in the workpiece rolling process is obtained, low-strain-rate rolling is ensured, and the workpiece rolling effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of workpiece rolling, in particular to a large-size titanium alloy workpiece rolling method with low strain rate. BACKGROUND

[0002] Titanium alloy is widely used in the fields of aerospace, automobile manufacturing, medical devices and marine engineering due to its excellent mechanical properties, corrosion resistance and lightweight characteristics; with the development of industrial technology, the demand for large-size titanium alloy workpieces is increasing, and the strength and toughness requirements of large structural parts are more stringent; in the rolling process of large-size titanium alloy workpieces, a suitable forming process is needed to reduce the strain rate to avoid stress concentration, crack generation and other adverse effects caused by high-speed deformation.

[0003] In the prior art, low strain rate rolling methods are used for titanium alloy processing, but the adjustment between rolling pressure and rolling speed lacks a systematic optimization model, which leads to stress concentration and uneven deformation in the workpiece under different working conditions, and the rolling effect of the workpiece is poor. SUMMARY

[0004] In order to solve the technical problem that the adjustment between rolling pressure and rolling speed lacks a systematic optimization model, and the rolling effect of the workpiece is poor, the purpose of the present application is to provide a large-size titanium alloy workpiece rolling method with low strain rate, and the technical solution adopted is as follows: The present application provides a large-size titanium alloy workpiece rolling method with low strain rate, which comprises the following steps: Obtain the rolling pressure, rolling speed, temperature data and workpiece thickness change of each position under each rolling pass of different rolling sections of the workpiece; For the real-time rolling section, obtain the temperature stress risk degree of each rolling pass according to the difference between the temperature data of different positions under each rolling pass and the rolling speed; obtain the pressure adjustment feasibility of the real-time rolling section according to the change trend of the rolling pressure and the rolling speed under different rolling passes and the temperature stress risk degree distribution; According to the workpiece thickness change of each position in the range of different rolling sections corresponding to each rolling pass of the real-time rolling section, obtain the local stress extensibility of each rolling pass of the real-time rolling section; According to the local stress extensibility of each rolling pass of the real-time rolling section and the pressure adjustment feasibility, obtain the rolling pressure adjustment coefficient of the real-time rolling section; According to the rolling pressure adjustment coefficient and the rolling pressure of the real-time rolling section, obtain the rolling adjustment pressure, and perform low strain rate rolling on the workpiece.

[0005] Further, the method for obtaining the temperature stress risk degree comprises: For the real-time rolling section, the temperature gradient span of each rolling pass under the real-time rolling section is obtained according to the difference between the temperature data of different positions under each rolling pass. The product of the temperature gradient span and the rolling speed of each rolling pass under the real-time rolling section is obtained as the temperature stress risk degree of each rolling pass under the real-time rolling section.

[0006] Further, the method for obtaining the temperature gradient span comprises: For the real-time rolling section, the average of the difference between the temperature data of different positions under each rolling pass is obtained as the temperature gradient span of each rolling pass under the real-time rolling section.

[0007] Further, the method for obtaining the pressure adjustment feasibility comprises: For the real-time rolling section, the pressure fitting curve fitted by the rolling pressures of all rolling passes is obtained, and the speed fitting curve fitted by the rolling speeds of all rolling passes is obtained. For the pressure fitting curve or the speed fitting curve, the slope value between each two adjacent passes in each fitting curve is obtained, and the adjacent passes with positive slope values in the pressure fitting curve are taken as target passes. According to the difference between the slope values of the pressure fitting curve and the speed fitting curve between the adjacent target passes, and the deviation of the temperature stress risk degrees between the corresponding adjacent target passes, the pressure adjustment feasibility of the real-time rolling section is obtained.

[0008] Further, the method for obtaining the pressure adjustment feasibility of the real-time rolling section comprises: The ratio of the temperature stress risk degree between each rolling pass and the previous adjacent rolling pass is obtained as the stress risk change rate. The difference between the slope values of the adjacent target passes is negatively correlated and mapped as the adjustment credibility. The average of the product between the adjustment credibility and the stress risk change rate of all target passes is obtained as the pressure adjustment feasibility of the real-time rolling section.

[0009] Further, the method for obtaining the local stress extension comprises: According to the workpiece thickness variation amount of different positions within the corresponding real-time rolling section range under each rolling pass of the real-time rolling section, the workpiece deformation fluctuation of each rolling pass under the real-time rolling section is obtained. The average of the workpiece thickness variation amount of all positions within the corresponding next rolling section range under each rolling pass of the real-time rolling section is obtained as the workpiece deformation influence of the real-time rolling section on the next rolling section. Obtain the product of the workpiece deformation fluctuation and the workpiece deformation influence as the local stress elongation under each rolling pass of the real-time rolling section.

[0010] Further, the workpiece deformation fluctuation obtaining method comprises: Obtain the mean value of the workpiece thickness change amount of all positions in the corresponding real-time rolling section range under each rolling pass of the real-time rolling section as the thickness change level. Obtain the difference between the thickness change level and the preset thickness ideal change level as the thickness change fluctuation. Obtain the product of the thickness change level and the thickness change fluctuation as the workpiece deformation fluctuation.

[0011] Further, the rolling pressure adjustment coefficient obtaining method comprises: Fuse the local stress elongation under each rolling pass of the real-time rolling section and the pressure adjustment feasibility, and perform negative correlation mapping as the rolling pressure adjustment coefficient of the real-time rolling section.

[0012] Further, the rolling adjustment pressure obtaining method comprises: Obtain the product of the rolling adjustment coefficient and the rolling pressure as the rolling adjustment pressure.

[0013] Further, the negative correlation mapping is performed by using an exponential function with a natural constant as the base.

[0014] The present application has the following beneficial effects: For the real-time rolling section, the temperature stress risk degree under each rolling pass is obtained according to the difference between the temperature data of different positions under each rolling pass and the rolling speed, and the stress on each rolling pass under the change of cold and hot temperature is quantified; the pressure adjustment feasibility of the real-time rolling section is obtained according to the change trend of the rolling pressure and the rolling speed under different rolling passes and the temperature stress risk degree distribution, which is helpful for dynamically adjusting the pressure in the rolling process of the real-time rolling section; the local stress elongation under each rolling pass of the real-time rolling section is obtained according to the workpiece thickness change amount of each position in the corresponding different rolling section range under each rolling pass of the real-time rolling section, the thickness fluctuation caused by local stress concentration is identified, and the deformation uniformity of the workpiece under different rolling passes is evaluated; the rolling pressure adjustment coefficient of the real-time rolling section is obtained according to the local stress elongation under each rolling pass of the real-time rolling section and the pressure adjustment feasibility, which is helpful for regulating the material flow and optimizing the rolling pressure in the rolling process; the rolling adjustment pressure is obtained according to the rolling pressure adjustment coefficient and the rolling pressure of the real-time rolling section, and the workpiece is rolled at a low strain rate. The present application can obtain a suitable rolling pressure in the rolling process of the workpiece, ensure low strain rate rolling, and improve the rolling effect of the workpiece. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the drawings required to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0016] Figure 1 A flow chart of a low strain rate large-size titanium alloy workpiece rolling method provided by an embodiment of the present application.

[0017] Figure 2 A flow chart of a pressure regulation feasibility acquisition method provided by an embodiment of the present application. Figure 3 A flow chart of a local stress extensionality acquisition method provided by an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects of a low strain rate large-size titanium alloy workpiece rolling method according to the present application are described in detail as follows in combination with the drawings and preferred embodiments. 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.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0020] The specific scheme of a low strain rate large-size titanium alloy workpiece rolling method provided by the present application is specifically described below in combination with the drawings.

[0021] Please refer to Figure 1 which shows a flow chart of a low strain rate large-size titanium alloy workpiece rolling method provided by an embodiment of the present application, and the specific method comprises: Step S1: acquiring the rolling pressure, rolling speed and temperature data and workpiece thickness change of each position of the workpiece under each rolling pass of different rolling sections.

[0022] In the embodiment of the present application, in order to avoid the uneven local stress in the rolling process of the workpiece, the excessively high strain rate will cause the plastic deformation ability of the material to decrease, cracks or uneven deformation will occur, and it is necessary to ensure that the workpiece is rolled at a low strain rate. The present application determines the adjustment degree of the rolling process in the rolling process, so that the strain rate of the workpiece in the rolling process of the titanium alloy workpiece meets the expected low strain rate.

[0023] Firstly, a large-size titanium alloy blank suitable for rolling is selected. In order to reduce the deformation amount of each rolling section and avoid local excessive deformation of the material, the large-size titanium alloy workpiece is divided into multiple rolling sections, and each rolling section is rolled only once. During each rolling pass, appropriate temperature sensors and strain gauges are installed at different positions to monitor the temperature of the workpiece and the thickness change of the workpiece. Temperature data under each rolling pass and the thickness change of the workpiece relative to the previous rolling pass are collected. A pressure sensor is installed on the rolling equipment to monitor the rolling pressure applied to the workpiece during each rolling pass. A rotary encoder or a speed meter is used to monitor the rolling speed of the rolling equipment at different times during each rolling pass. The average rolling speed at all times is taken as the rolling speed under each rolling pass. Therefore, the rolling pressure, rolling speed and temperature data and thickness change of the workpiece at each position under each rolling pass of the workpiece in different rolling sections are obtained.

[0024] It should be noted that, in order to facilitate subsequent data processing, the obtained data is not considered to have dimension effect, and the data can be standardized to eliminate dimension. The specific means is a technology known to those skilled in the art, which is not described here.

[0025] Step S2: For the real-time rolling section, the temperature stress risk degree under each rolling pass is obtained according to the difference between the temperature data at different positions and the rolling speed. The pressure adjustment feasibility of the real-time rolling section is obtained according to the change trend of the rolling pressure and the rolling speed under different rolling passes and the temperature stress risk degree distribution.

[0026] Local overheating or overcooling of temperature affects the organization and performance of the workpiece. The greater the temperature gradient, the greater the difference in strain rate of each part of the workpiece, and the influence of additional internal stress exists. The overall strain rate distribution deviates from the expected uniform range. For the real-time rolling section, the temperature stress risk degree under each rolling pass is obtained according to the difference between the temperature data at different positions and the rolling speed.

[0027] Preferably, in one embodiment of the present application, the temperature stress risk degree is obtained by: For the real-time rolling section, the temperature gradient span of each rolling pass is obtained based on the temperature data difference between different positions in each rolling pass. It should be noted that, in one embodiment of the present invention, the method for obtaining the temperature gradient span includes: For the real-time rolling section, the average difference in temperature data between different positions under each rolling pass is obtained as the temperature gradient span of each rolling pass in the real-time rolling section; The product of the temperature gradient span and the rolling speed in each rolling pass of the real-time rolling section is obtained as the temperature stress risk level in each rolling pass of the real-time rolling section.

[0028] In one embodiment of the present invention, the formula for the temperature stress risk level for each rolling pass is expressed as follows: ; in, Indicates the first Temperature stress risk level for each rolling pass in each rolling section; Indicates the first The rolling speed of each rolling pass in each rolling section; Indicates the first Each rolling pass in each rolling section Temperature data for each location; Indicates the first Each rolling pass in each rolling section Temperature data for each location; Indicates the order of temperature differences between adjacent locations on the workpiece; This indicates the number of temperature differences between all adjacent locations on the workpiece.

[0029] In the formula for the degree of temperature stress risk, Indicates the calculation of the first The average difference in temperature data between different positions under each rolling pass of each rolling section is used as the temperature gradient span of each rolling pass in the real-time rolling section. The larger the temperature gradient span, the greater the difference in temperature data between different positions, indicating that there is a greater gradient change in temperature data at different positions. The higher the rolling speed, the faster the material deformation rate during rolling, and the greater the risk of temperature stress.

[0030] During the rolling process of titanium alloy workpieces, the pressure can be dynamically adjusted to maintain a low strain rate. The more consistent the changes in pressure and speed, the more uniform the deformation of the workpiece will be, thus meeting the expectation of a low strain rate in the rolling process. Therefore, based on the changing trends of rolling pressure and rolling speed under different rolling passes, as well as the distribution of temperature stress risk, the feasibility of real-time pressure adjustment in the rolling section can be obtained.

[0031] Preferably, in one embodiment of the present application, the method for obtaining the pressure regulation feasibility comprises the following steps: Figure 2 , which shows a flow chart of a method for obtaining the pressure regulation feasibility, comprising: Step S201: For the real-time rolling section, obtain the pressure fitting curve fitted by the rolling pressures under all rolling passes; obtain the speed fitting curve fitted by the rolling speeds under all rolling passes.

[0032] It should be noted that in the embodiments of the present application, the rolling pressures and rolling speeds under all rolling passes can be fitted by using existing fitting methods such as the least square method or polynomial fitting, to obtain the pressure fitting curve and the speed fitting curve, so that the change trend of the data can be more intuitively understood; the specific means is the numerical technical means known to those skilled in the art, which will not be described here.

[0033] Step S202: For the pressure fitting curve or the speed fitting curve, obtain the slope value between every two adjacent passes in each fitting curve, and take the adjacent passes with positive slope values in the pressure fitting curve as target passes.

[0034] It should be noted that the method for obtaining the slope value between the adjacent passes is to calculate the difference of the vertical coordinates divided by the difference of the horizontal coordinates, i.e., the ratio of the difference between the latter pass and the former pass to the difference between the data of the latter pass and the former pass; the specific means is the technical means known to those skilled in the art, which will not be described here.

[0035] The positive slope value indicates that the rolling pressure is continuously increasing, which may result in a rolling process with stress concentration, and thus the rolling state needs to be analyzed more.

[0036] Step S203: Obtain the pressure regulation feasibility of the real-time rolling section according to the difference of the slope values between the adjacent target passes and the deviation of the temperature stress risk degrees between the corresponding adjacent target passes.

[0037] It should be noted that in one embodiment of the present application, obtaining the pressure regulation feasibility of the real-time rolling section comprises: obtaining the ratio of the temperature stress risk degree between each rolling pass and the adjacent rolling pass as the stress risk change rate; performing negative correlation mapping on the difference of the slope values between the adjacent target passes as the adjustment credibility; obtaining the average product of the adjustment credibility and the stress risk change rate between all target passes as the pressure regulation feasibility of the real-time rolling section.

[0038] In one embodiment of the present application, for the first target pass, the adjustment credibility is obtained by the following formula: The formula for the feasibility of pressure adjustment in each rolling section is expressed as follows: ; in, Indicates the first Feasibility of pressure adjustment in each rolling section; The pressure fitting curve indicates the first... The slope value between adjacent target passes in a group; The velocity fitting curve represents the first... The slope value between adjacent target passes; Indicates the first The first rolling section The previous rolling pass in adjacent target passes Temperature stress risk level; Indicates the first The first rolling section The previous rolling pass in adjacent target passes Temperature stress risk level is represented by the first The first rolling section The previous rolling pass in adjacent target passes Temperature stress risk level; This represents the function for calculating the average value.

[0039] In the formula for the feasibility of pressure regulation, and Add 0.01 to avoid the formula being meaningless when the denominator is 0. This indicates that the pressure fitting curve and the velocity fitting curve are at the 1st... The difference in slope values ​​between adjacent target tracks is negatively correlated and mapped to adjust the reliability. The smaller the difference in slope values, the higher the pressure also increases when the velocity changes. The more consistent the velocity and pressure changes, the more reliable the pressure adjustment. This represents the ratio of the temperature stress risk between each rolling pass and the previous adjacent rolling pass, which serves as the rate of change of stress risk. The larger the ratio, the greater the rate of change of stress risk, the more necessary it is to adjust the pressure to maintain a low strain rate, and the greater the feasibility of pressure adjustment.

[0040] Step S3: Based on the change in workpiece thickness at each position within different rolling passes of the real-time rolling section, obtain the local stress extensibility of each rolling pass of the real-time rolling section.

[0041] During the rolling process, the rolling section is subjected to stress, and the thickness at that position will change. Since the workpiece is a continuous body, the sudden change in the thickness of a certain rolling section may affect the thickness change of adjacent rolling sections. If the thickness change of adjacent rolling sections is greater, the stress transmission is greater and the local stress extension is greater. Based on the workpiece thickness change at each position within different rolling sections under each rolling pass of the real-time rolling section, the local stress extension under each rolling pass of the real-time rolling section is obtained.

[0042] Preferably, in one embodiment of the present invention, the method for obtaining local stress ductility is described in [reference needed]. Figure 3 It illustrates a flowchart of a method for obtaining local stress extensibility, including: Step S301: Based on the change in workpiece thickness at different positions within the real-time rolling section for each rolling pass, obtain the workpiece deformation fluctuation for each rolling pass in the real-time rolling section.

[0043] The change in workpiece thickness at each location can reflect the workpiece's plastic deformation behavior and help to understand the workpiece's strain level. The greater the change in workpiece thickness, the greater the strain rate the workpiece experiences, and the more likely it is to produce larger deformation fluctuations.

[0044] Preferably, in one embodiment of the present invention, the method for obtaining workpiece deformation fluctuation includes: The average thickness variation of the workpiece at all positions within the real-time rolling section for each rolling pass is obtained as the thickness variation level. The difference between the thickness variation level and the preset ideal thickness variation level is used as the thickness variation variability. The product of the thickness variation level and the thickness variation variability is obtained as the workpiece deformation variability.

[0045] In one embodiment of the present invention, the formula for the workpiece shape fluctuation is expressed as: ; in, Indicates the first The first rolling section Workpiece shape fluctuation under each rolling pass; Indicates the first The first rolling section The average thickness variation of the workpiece at all positions within the real-time rolling section under each rolling pass, i.e., the thickness variation level. This indicates the preset ideal variation level of thickness.

[0046] In the formula for workpiece shape fluctuation, the greater the change in workpiece thickness, the higher the strain rate. This represents the difference between the calculated thickness variation level and the preset ideal thickness variation level. As the thickness variation variability, the greater the thickness variation variability, the greater the difference between the thickness variation level and the preset ideal thickness variation level, that is, the further away from the thickness variation amount under ideal conditions, the worse the morphological uniformity, and the greater the morphological variability of the workpiece.

[0047] It should be noted that, in the embodiments of the present invention, the method for obtaining the preset ideal thickness variation level is as follows: the implementer determines the ideal low strain rate in advance based on relevant professional knowledge, and at the low strain rate, the thickness variation of the workpiece in each rolling pass is obtained as the preset ideal thickness variation level; the specific means are technical means well known to those skilled in the art, and will not be described in detail here.

[0048] Step S302: Obtain the average value of the workpiece thickness change at all positions within the range of the next rolling segment under each rolling pass of the real-time rolling segment, as the influence of each rolling pass of the real-time rolling segment on the workpiece deformation of the next rolling segment.

[0049] The overall level of workpiece thickness variation at the location within the next rolling segment is quantified by averaging the values, reflecting the impact of rolling the real-time rolling segment on the next rolling segment and reflecting the strain rate level of the rolling process.

[0050] Step S303: Obtain the product of workpiece deformation fluctuation and workpiece deformation influence as the local stress extension under each rolling pass of the real-time rolling section.

[0051] In one embodiment of the present invention, the formula for local stress ductility is expressed as: ; in, Indicates the first The first rolling section Local stress ductility under each rolling pass; Indicates the first The first rolling section Workpiece shape fluctuation under each rolling pass; Indicates the first The first rolling section The first rolling pass corresponds to the first rolling section within the next rolling segment. The change in workpiece thickness at each location; Indicates the first +1 number of positions within the rolling section; This indicates the adjustment parameter.

[0052] In the formula for local stress ductility Indicates the calculation of the first The first rolling section The corresponding rolling pass is the first The average thickness variation of the workpiece at all positions within the +1 rolling segment represents the influence of each rolling pass in the real-time rolling segment on the workpiece deformation in the next rolling segment. The greater the influence of workpiece deformation, the greater the thickness variation of the workpiece at different positions, indicating that the first rolling pass has a greater influence on the workpiece deformation in the next rolling segment. Excessive pressure on the rolling section causes the stress rate to extend; the greater the fluctuation in workpiece shape, the less it conforms to the expectation of low strain rate, the greater the influence of workpiece deformation, and the greater the local stress extension.

[0053] It should be noted that, in the embodiments of the present invention, in order not to affect the calculation of the formula, it is necessary to introduce adjustment parameters. To avoid the formula being 0, a non-zero constant in the range of 0-0.1 can be used, such as 0.01.

[0054] Step S4: Based on the local stress elongation under each rolling pass of the real-time rolling section and the feasibility of pressure adjustment, obtain the rolling pressure adjustment coefficient of the real-time rolling section.

[0055] Local stress extensibility reflects the material flow capacity and stress transmission characteristics of the workpiece due to thickness changes. The higher the local stress extensibility, the easier it is for plastic deformation to occur in the real-time rolling section and the greater the strain rate. The feasibility assessment of pressure adjustment determines whether the pressure can be adjusted under the current rolling conditions. The greater the feasibility of pressure adjustment, the more necessary it is to adjust the pressure to meet the low strain rate. By combining the analysis of local stress extensibility and pressure adjustment feasibility, the degree of pressure adjustment can be more comprehensively evaluated.

[0056] Preferably, in one embodiment of the present invention, the method for obtaining the rolling pressure adjustment coefficient includes: The local stress extensibility and pressure adjustment feasibility of each rolling pass in the real-time rolling section are integrated and negatively correlated to form the rolling pressure adjustment coefficient of the real-time rolling section.

[0057] It should be noted that in some embodiments of the present invention, fusion can be achieved by addition or multiplication. The specific means are well known to those skilled in the art and will not be described in detail here.

[0058] In one embodiment of the present invention, the formula for the rolling pressure adjustment coefficient is expressed as: ; in, This indicates the rolling pressure adjustment coefficient; Indicates the first The first rolling section Local stress elongation under each rolling pass; Indicates the first Feasibility of pressure adjustment in each rolling section; represents an exponential function with a natural constant as a base.

[0059] In the formula of the rolling pressure adjustment coefficient, the greater the local stress ductility, the greater the stress rate, the greater the pressure adjustment feasibility, the more necessary the appropriate reduction of the pressure, and the smaller the rolling pressure adjustment coefficient.

[0060] Step S5: obtaining the rolling adjustment pressure according to the rolling pressure adjustment coefficient and the rolling pressure of the real-time rolling section, and performing low strain rate rolling on the workpiece.

[0061] After adjusting the rolling pressure, the intensity of the rolling process is effectively adjusted to realize the adjustment conforming to the low strain rate.

[0062] It should be noted that, in an embodiment of the present application, the method for obtaining the rolling adjustment pressure comprises: obtaining the product of the rolling adjustment coefficient and the rolling pressure as the rolling adjustment pressure.

[0063] After obtaining the rolling adjustment pressure, the rolling pressure is adjusted in time to avoid excessive rolling during the rolling process of the workpiece, the pressure adjustment coefficient is continuously optimized according to the rolling effect, and the workpiece is rolled at a low strain rate to improve the stability of the rolling process and the material quality.

[0064] To sum up, for the real-time rolling section, the temperature stress risk degree under each rolling pass is obtained according to the difference between the temperature data of different positions under each rolling pass and the rolling speed; the pressure adjustment feasibility of the real-time rolling section is obtained according to the change trend of the rolling pressure and the rolling speed under different rolling passes and the temperature stress risk degree distribution; the local stress ductility under each rolling pass of the real-time rolling section is obtained according to the difference in the thickness of the workpiece at each position in the corresponding different rolling section range between each rolling pass of the real-time rolling section and the previous rolling pass; and then the rolling pressure adjustment coefficient of the real-time rolling section is obtained. The present application ensures low strain rate rolling by obtaining the appropriate rolling pressure during the rolling process of the workpiece, and improves the rolling effect of the workpiece.

[0065] It should be noted that the above-mentioned embodiment of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0066] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment mainly describes the difference from other embodiments.

Claims

1. A method for rolling large-size titanium alloy workpieces with low strain rates, characterized in that, The method includes: Obtain rolling pressure, rolling speed, temperature data at each location, and workpiece thickness variation for each rolling pass in different rolling sections; For the real-time rolling section, the temperature stress risk level for each rolling pass is obtained based on the temperature data differences between different positions under each rolling pass and the rolling speed; the feasibility of pressure adjustment for the real-time rolling section is obtained based on the changing trends of rolling pressure and rolling speed under different rolling passes and the distribution of temperature stress risk level. Based on the change in workpiece thickness at each position within different rolling ranges under each rolling pass of the real-time rolling section, the local stress extensibility under each rolling pass of the real-time rolling section is obtained. Based on the local stress elongation under each rolling pass of the real-time rolling section and the feasibility of pressure adjustment, the rolling pressure adjustment coefficient of the real-time rolling section is obtained. Based on the rolling pressure adjustment coefficient and rolling pressure of the real-time rolling section, the rolling adjustment pressure is obtained, and the workpiece is rolled at a low strain rate.

2. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 1, characterized in that, The method for obtaining the temperature stress risk level includes: For the real-time rolling section, the temperature gradient span of each rolling pass is obtained based on the temperature data difference between different positions in each rolling pass. The product of the temperature gradient span and the rolling speed in each rolling pass of the real-time rolling section is obtained as the temperature stress risk level in each rolling pass of the real-time rolling section.

3. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 2, characterized in that, The method for obtaining the temperature gradient span includes: For the real-time rolling section, the average difference in temperature data between different positions under each rolling pass is obtained as the temperature gradient span under each rolling pass of the real-time rolling section.

4. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 1, characterized in that, The methods for obtaining the feasibility of pressure regulation include: For the real-time rolling section, pressure fitting curves are obtained by fitting the rolling pressure under all rolling passes; speed fitting curves are obtained by fitting the rolling speed under all rolling passes. For pressure fitting curves or velocity fitting curves, obtain the slope value between every two adjacent passes in each fitting curve, and take the adjacent passes with positive slope values ​​in the pressure fitting curve as the target passes. Based on the difference in slope values ​​between adjacent target passes between the pressure fitting curve and the speed fitting curve, and the deviation in temperature stress risk between adjacent target passes, the feasibility of pressure adjustment in the real-time rolling section is obtained.

5. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 4, characterized in that, The feasibility of obtaining real-time pressure regulation in the rolling section includes: The ratio of the temperature stress risk level between each rolling pass and the previous adjacent rolling pass is obtained as the rate of change of stress risk. Negative correlation mapping is performed on the differences in slope values ​​between adjacent target passes to adjust the confidence level; The average product of the adjustment credibility and the rate of change of stress risk among all target passes is obtained as the feasibility of pressure regulation in the real-time rolling section.

6. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 1, characterized in that, The method for obtaining the local stress ductility includes: Based on the change in workpiece thickness at different positions within the real-time rolling section for each rolling pass, the workpiece deformation fluctuation under each rolling pass of the real-time rolling section is obtained. The average value of the workpiece thickness change at all positions within the range of the next rolling segment under each rolling pass of the real-time rolling segment is obtained as the influence of each rolling pass of the real-time rolling segment on the workpiece deformation of the next rolling segment. The product of the workpiece deformation fluctuation and the workpiece deformation influence is obtained as the local stress extension under each rolling pass in the real-time rolling section.

7. A method for rolling large-size titanium alloy workpieces with low strain rate according to claim 6, characterized in that, The method for obtaining the workpiece deformation fluctuation includes: The average thickness variation of the workpiece at all positions within the real-time rolling section for each rolling pass is obtained as the thickness variation level. The difference between the thickness variation level and the preset ideal thickness variation level is used as the thickness variation variability. The product of the thickness variation level and the thickness variation variability is obtained as the workpiece deformation variability.

8. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 1, characterized in that, The method for obtaining the rolling pressure adjustment coefficient includes: The local stress extensibility and pressure adjustment feasibility of each rolling pass in the real-time rolling section are integrated and negatively correlated to form the rolling pressure adjustment coefficient of the real-time rolling section.

9. The method for rolling large-size titanium alloy workpieces with low strain rate according to claim 1, characterized in that, The method for obtaining the rolling adjustment pressure includes: The product of the rolling adjustment coefficient and the rolling pressure is obtained as the rolling adjustment pressure.

10. A method for rolling large-size titanium alloy workpieces with low strain rate according to claim 8, characterized in that, Negative correlation mapping is performed using an exponential function with the natural constant as the base.

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