A method for preparing NbTi / Cu superconducting wire based on copper ratio test

Abstract

This invention discloses a method for preparing NbTi / Cu superconducting wires based on copper ratio testing, relating to the field of superconducting wire processing technology. The method includes: obtaining a preliminary NbTi / Cu superconducting wire; stretching the wire and collecting real-time data on the length and total weight of the stretched wire; plotting a total weight-length variation curve, calculating a linear density-length variation curve, and calculating a copper ratio-length variation curve; determining a critical point, removing portions that do not meet the copper ratio requirements, and performing subsequent twisting and final stretching processes to obtain NbTi / Cu superconducting wires with a qualified copper ratio. This application improves the efficiency and accuracy of preparing wires with a qualified copper ratio by real-time data collection of the stretched wire length and total weight, sequentially plotting and calculating the variation curves of total weight, linear density, and copper ratio versus length, and determining the critical point.

Description

Technical Field

[0001] This application relates to the field of superconducting wire processing technology, and in particular to a method for preparing NbTi / Cu superconducting wires based on copper ratio testing. Background Technology

[0002] The copper ratio of NbTi / Cu superconducting wire refers to the ratio of the area of ​​the copper region to the area of ​​the superconducting region (i.e., the NbTi region) in the superconducting wire, and it is one of the important performance indicators of NbTi / Cu superconducting wire. However, due to the large non-uniform regions generated at the ingot head and tail during the extrusion process of NbTi / Cu superconducting ingots, the copper ratio of the wire exceeds the required range. To ensure the final performance of NbTi / Cu superconducting wire is qualified, these non-uniform regions need to be detected and removed as early as possible. Current copper ratio testing methods include the paper-cutting method, resistance method, density method, and image method, all of which can only be sampled and tested after stretching, and the single test time is long, affecting the efficiency of copper ratio testing. In addition, since the location of the non-conforming region of the wire is unknown, multiple tests are required to explore the boundary of the non-conforming region, which is cumbersome and easily leads to waste of wire.

[0003] In the prior art, Chinese patent CN119338817A discloses a copper ratio testing system and method for NbTi / Cu superconducting wires based on image recognition, including the following steps: S1: Acquire metallographic image data of the cross-section of the NbTi / Cu superconducting wire sample and obtain the true copper ratio through the density method; S2: Calculate the copper ratio based on the number of pixels in the binarized image; S3: Use the metallographic image data, the true copper ratio, and the calculated copper ratio as a dataset, and train a support vector regression model using the dataset; S4: Acquire the cross-sectional image of the NbTi / Cu superconducting wire to be tested, and input the cross-sectional image and the calculated copper ratio obtained from the cross-sectional image in S2 into the support vector regression model in S3 to obtain the actual copper ratio.

[0004] However, the existing technologies mentioned above have not studied or solved the above problems. When the copper ratio testing methods of the existing technologies are introduced into the NbTi / Cu superconducting wire preparation process, the preparation efficiency and accuracy of wires with qualified copper ratios are poor. Summary of the Invention

[0005] This application provides a method for preparing NbTi / Cu superconducting wires based on copper ratio testing, which solves the problem of poor preparation efficiency and accuracy of wires with qualified copper ratios when introducing existing copper ratio testing methods into the NbTi / Cu superconducting wire preparation process.

[0006] On the one hand, this application provides a method for preparing NbTi / Cu superconducting wires based on copper ratio testing, including the following steps: Step 1: The NbTi / Cu superconducting composite ingot is extruded, cold drawn, aged heat treated and stretched to obtain a preliminary NbTi / Cu superconducting wire.

[0007] Step 2: Stretch the preliminary NbTi / Cu superconducting wire and collect the stretched wire length and total weight of the preliminary NbTi / Cu superconducting wire in real time.

[0008] Step 3: Based on the real-time collected data on the length and total weight of the stretched wire, plot the total weight-length variation curve; calculate the linear density-length variation curve based on the total weight-length variation curve; and calculate the copper ratio-length variation curve based on the linear density-length variation curve.

[0009] Step four: Determine the critical point where the initial NbTi / Cu superconducting wire exceeds the copper ratio requirement range by using the copper ratio-length change curve. Remove the portion that does not meet the copper ratio requirement range based on the critical point, and then perform subsequent twisting and final stretching processes to obtain an NbTi / Cu superconducting wire with a qualified copper ratio.

[0010] In one possible implementation, in step two, a meter counter is used to collect the length of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time, and a gravity sensor is used to collect the total weight of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time.

[0011] In one possible implementation, in step three, the formula for calculating the linear density-length variation curve is as follows: , in, This represents the linear density when the length of the stretched wire is L. This represents the unit change in the total weight of the stretched wire when the length of the stretched wire is L. , These represent the lengths of the stretched wire as L and L, respectively. The total weight of the stretched wire at that time. Indicates the length of the data collection interval.

[0012] In one possible implementation, in step three, the calculation formula for the wire copper ratio-length variation curve is as follows: , , in, This indicates the copper ratio of the wire when the drawn wire length is L. and These represent the density of the superconducting phase and the density of pure copper, respectively. =6.06g / cm 3 , =8.93 g / cm 3 , This indicates the cross-sectional area of ​​the hole in the stretching die. This indicates the diameter of the hole in the stretching die.

[0013] In one possible implementation, each time the length and total weight of the stretched wire are collected, the total weight-length change curve, the linear density-length change curve, and the wire copper ratio-length change curve are updated synchronously online.

[0014] In one possible implementation, the process for determining the critical point in step four is as follows: The dataset consisting of the latest point and all previous points of the copper ratio-length variation curve of the wire is statistically analyzed. The mean and standard deviation of the dataset are calculated, and then the confidence interval of the latest point is calculated.

[0015] If the confidence interval of the latest point exceeds the copper ratio requirement, and the confidence interval of the next point is within the copper ratio requirement, then the location of the next point is recorded as the critical point.

[0016] If the confidence interval of the latest point is within the copper ratio requirement range, and the confidence interval of the next point after the latest point exceeds the copper ratio requirement range, then the location of the latest point is recorded as the critical point.

[0017] The critical point for eliminating the uneven area of ​​the spindle head.

[0018] The method for preparing NbTi / Cu superconducting wire based on copper ratio testing in this application has the following advantages: By collecting the length and total weight of the stretched wire in real time, and plotting and calculating the curves of total weight, linear density, copper ratio and length, the critical point is determined. This rapid copper ratio test is introduced into the NbTi / Cu superconducting wire preparation process, which improves the preparation efficiency and accuracy of qualified copper ratio wires. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic flowchart illustrating a method for preparing NbTi / Cu superconducting wires based on copper ratio testing, provided for embodiments of this application; Figure 2The total weight-length variation curve provided for Embodiment 1 of this application; Figure 3 Line density-length variation curve provided in Embodiment 1 of this application; Figure 4 This is a graph showing the change in copper ratio and length of the wire provided in Embodiment 1 of this application; Figure 5 The total weight-length variation curve provided for Embodiment 2 of this application; Figure 6 This is a line density-length variation curve provided in Embodiment 2 of this application; Figure 7 This is a graph showing the change in copper ratio and length of the wire provided in Embodiment 2 of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] like Figure 1 As shown in the figure, this application provides a method for preparing NbTi / Cu superconducting wires based on copper ratio testing, including the following steps: Step 1: The NbTi / Cu superconducting composite ingot is extruded, cold drawn, aged heat treated and stretched to obtain a preliminary NbTi / Cu superconducting wire.

[0023] Step 2: Stretch the preliminary NbTi / Cu superconducting wire and collect the stretched wire length and total weight of the preliminary NbTi / Cu superconducting wire in real time.

[0024] Step 3: Based on the real-time collected data on the length and total weight of the stretched wire, plot the total weight-length variation curve; calculate the linear density-length variation curve based on the total weight-length variation curve; and calculate the copper ratio-length variation curve based on the linear density-length variation curve.

[0025] Step four: Determine the critical point where the initial NbTi / Cu superconducting wire exceeds the copper ratio requirement range by using the copper ratio-length change curve. Remove the portion that does not meet the copper ratio requirement range based on the critical point, and then perform subsequent twisting and final stretching processes to obtain an NbTi / Cu superconducting wire with a qualified copper ratio.

[0026] Specifically, in step one, the designed copper ratio of the NbTi / Cu superconducting composite ingot is between 0.5 and 10. The NbTi / Cu superconducting composite ingot can be assembled using either drilling or stacking methods. The initial NbTi / Cu superconducting wire is a semi-finished product. The distance from the qualified copper ratio NbTi / Cu superconducting wire (i.e., the finished product) should be less than three processing passes, with each pass having a processing rate of less than 20%. This avoids large deformation caused by excessive processing passes, which could affect the accurate judgment of the wire's copper ratio.

[0027] Specifically, in step two, the preliminary NbTi / Cu superconducting wire is sequentially passed through a pay-off machine, tension wheel, stretching die, washing tank, dryer, straightener, meter counter, and take-up machine to stretch the preliminary NbTi / Cu superconducting wire. The diameter of the hole in the stretching die should be between 0.700 and 3.000 mm, and the processing rate should be less than 20%. The stretching speed is 60 to 120 m / min, and the stretching process should ensure that the equipment is stable without significant fluctuations.

[0028] For example, in step two, a meter counter is used to collect the length of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time, and a gravity sensor is used to collect the total weight of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time.

[0029] Specifically, the meter counter is either a tracked meter counter or a laser meter counter. The meter counter collects the initial stretched length of the NbTi / Cu superconducting wire at regular intervals (i.e., the acquisition interval length) and uploads the data to the computer. A gravity sensor is installed in the take-up unit and synchronizes with the meter counter's acquisition. The acquisition interval length of the meter counter should be less than 10m; the smaller the acquisition interval length, the more accurate the subsequent copper ratio test results.

[0030] For example, in step three, the calculation formula for the linear density-length variation curve is as follows: , in, This represents the linear density when the length of the stretched wire is L. This represents the unit change in the total weight of the stretched wire when the length of the stretched wire is L. , These represent the lengths of the stretched wire as L and L, respectively. The total weight of the stretched wire at that time. Indicates the length of the data collection interval.

[0031] For example, in step three, the calculation formula for the copper ratio-length variation curve of the wire is as follows: , , in, This indicates the copper ratio of the wire when the drawn wire length is L. and These represent the density of the superconducting phase and the density of pure copper, respectively. =6.06g / cm 3 , =8.93 g / cm 3 , This indicates the cross-sectional area of ​​the hole in the stretching die. This indicates the diameter of the hole in the stretching die.

[0032] For example, each time the length of the stretched wire and the total weight of the stretched wire are collected, the total weight-length change curve, the linear density-length change curve, and the wire copper ratio-length change curve are updated online synchronously.

[0033] For example, in step four, the process for determining the critical point is as follows: The dataset consisting of the latest point and all previous points of the copper ratio-length variation curve of the wire is statistically analyzed. The mean and standard deviation of the dataset are calculated, and then the confidence interval of the latest point is calculated.

[0034] If the confidence interval of the latest point exceeds the copper ratio requirement, and the confidence interval of the next point is within the copper ratio requirement, then the location of the next point is recorded as the critical point.

[0035] If the confidence interval of the latest point is within the copper ratio requirement range, and the confidence interval of the next point after the latest point exceeds the copper ratio requirement range, then the location of the latest point is recorded as the critical point.

[0036] The critical point for eliminating the uneven area of ​​the spindle head.

[0037] Specifically, since the wire stretching process is under the same operating conditions, the data fluctuations should conform to a normal distribution, therefore the copper ratio data also conforms to a normal distribution. Let the latest point of the wire copper ratio-length variation curve be... ,but The confidence interval is ( , ),in, This represents the average value of the dataset. Let n represent the standard deviation of the dataset, n represent the number of samples in the dataset, and z represent the quantile corresponding to the confidence level. In this application, the confidence level is taken as 95%, and z = 1.96.

[0038] Specifically, in step four, based on the location of the critical point, the portion of the initial NbTi / Cu superconducting wire that does not meet the copper ratio requirement is removed, and subsequent twisting and final stretching processes are performed to obtain an NbTi / Cu superconducting wire with a qualified copper ratio.

[0039] Example 1: Step 1: The design copper ratio of the NbTi / Cu superconducting composite ingot is 2.65, and the copper ratio requirement range is 2.6~2.7. The NbTi / Cu superconducting composite ingot is assembled by drilling. Through extrusion, cold drawing, aging heat treatment and stretching processes, a preliminary NbTi / Cu superconducting wire is obtained. The diameter of the preliminary NbTi / Cu superconducting wire is 0.740mm.

[0040] Step two involves sequentially passing the preliminary NbTi / Cu superconducting wire through a pay-off machine, tension wheel, stretching die, washing tank, dryer, straightener, meter counter, and take-up machine to stretch the wire. The meter counter continuously records the stretched length of the preliminary NbTi / Cu superconducting wire, and a gravity sensor continuously records the total weight of the stretched wire. The stretching die has a hole diameter of 0.720 mm, and the stretching speed is 80 m / min. The meter counter is a laser meter counter with a data acquisition interval of 5 m.

[0041] Step 3: The computer draws a graph based on the real-time collected data on the length and total weight of the stretched wire. The total weight-length variation curve is as follows: Figure 2 As shown; according to The total weight-length variation curve was calculated. Linear density-length variation curve as shown Figure 3 As shown; according to The linear density-length variation curve was calculated. The copper ratio-length variation curve of the wire is as follows: Figure 4 As shown.

[0042] Step four, through The copper ratio-length variation curve of the wire indicates that the critical points exceeding the copper ratio requirement range for the preliminary NbTi / Cu superconducting wire are 145m, 185m, 935m, and 6460m. Among them, 145m and 185m are in the uneven area of ​​the spindle head and are discarded. Therefore, the actual critical points are 935m and 6460m. That is, the part between 935m and 6460m meets the copper ratio requirement range. The part that does not meet the copper ratio requirement range is removed, and subsequent twisting and final stretching processes are carried out to obtain NbTi / Cu superconducting wire with qualified copper ratio.

[0043] Example 2: Step 1: The design copper ratio of the NbTi / Cu superconducting composite ingot is 7.5, and the copper ratio requirement range is 7.0~8.0. The NbTi / Cu superconducting composite ingot is assembled by drilling. Through extrusion, cold drawing, aging heat treatment and stretching processes, a preliminary NbTi / Cu superconducting wire is obtained. The diameter of the preliminary NbTi / Cu superconducting wire is 0.930mm.

[0044] Step two involves sequentially passing the preliminary NbTi / Cu superconducting wire through a pay-off machine, tension wheel, stretching die, washing tank, dryer, straightener, meter counter, and take-up machine to stretch the wire. The meter counter continuously records the stretched length of the preliminary NbTi / Cu superconducting wire, and a gravity sensor continuously records the total weight of the stretched wire. The stretching die has a hole diameter of 0.900 mm, and the stretching speed is 100 m / min. The meter counter is a laser meter counter with a data acquisition interval of 5 m.

[0045] Step 3: The computer draws a graph based on the real-time collected data on the length and total weight of the stretched wire. The total weight-length variation curve is as follows: Figure 5 As shown; according to The total weight-length variation curve was calculated. Linear density-length variation curve as shown Figure 6 As shown; according to The linear density-length variation curve was calculated. The copper ratio-length variation curve of the wire is as follows: Figure 7 As shown.

[0046] Step four, through The copper ratio-length variation curve of the wire indicates that the critical points exceeding the copper ratio requirement range for the preliminary NbTi / Cu superconducting wire are 25m, 45m, 385m, and 7835m. Among them, 25m and 45m are in the uneven area of ​​the spindle head and are discarded. Therefore, the actual critical points are 385m and 7835m. That is, the part between 385m and 7835m meets the copper ratio requirement range. The part that does not meet the copper ratio requirement range is removed, and subsequent twisting and final stretching processes are carried out to obtain NbTi / Cu superconducting wire with qualified copper ratio.

[0047] This application embodiment acquires the length and total weight of the stretched wire in real time, and sequentially plots and calculates the change curves of total weight, linear density, copper ratio and length to determine the critical point. This rapid copper ratio test is introduced into the NbTi / Cu superconducting wire preparation process, which improves the preparation efficiency and accuracy of qualified copper ratio wires.

[0048] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0049] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for preparing a NbTi / Cu superconducting wire based on a copper ratio test, characterized by, Includes the following steps: Step 1: The NbTi / Cu superconducting composite ingot is extruded, cold drawn, aged heat treated and stretched to obtain a preliminary NbTi / Cu superconducting wire. Step 2: Stretch the preliminary NbTi / Cu superconducting wire and collect the stretched wire length and total weight of the preliminary NbTi / Cu superconducting wire in real time. Step 3: Based on the real-time collected data on the length and total weight of the stretched wire, plot the total weight-length variation curve; calculate the linear density-length variation curve based on the total weight-length variation curve; and calculate the copper ratio-length variation curve based on the linear density-length variation curve. Step four: Determine the critical point where the initial NbTi / Cu superconducting wire exceeds the copper ratio requirement range by using the copper ratio-length change curve. Remove the portion that does not meet the copper ratio requirement range based on the critical point, and then perform subsequent twisting and final stretching processes to obtain an NbTi / Cu superconducting wire with a qualified copper ratio.

2. The method of claim 1, wherein the NbTi / Cu superconducting wire is prepared based on a copper ratio test. In step two, a meter counter is used to collect the length of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time, and a gravity sensor is used to collect the total weight of the stretched wire of the preliminary NbTi / Cu superconducting wire in real time.

3. The method of claim 1, wherein the NbTi / Cu superconducting wire is prepared based on a copper ratio test. In step three, the formula for calculating the linear density-length variation curve is as follows: ， wherein, denotes the linear density of the drawn wire at a length L, denotes the unit change in the total weight of the drawn wire at a length L, , denote the total weight of the drawn wire at a length L, , denotes the collection interval length.

4. The method for preparing NbTi / Cu superconducting wire based on copper ratio testing according to claim 3, characterized in that, In step three, the calculation formula for the copper ratio-length variation curve of the wire is as follows: ， ， in, This indicates the copper ratio of the wire when the drawn wire length is L. and These represent the density of the superconducting phase and the density of pure copper, respectively. =6.06g / cm 3 , =8.93 g / cm 3 , This indicates the cross-sectional area of ​​the hole in the stretching die. This indicates the diameter of the hole in the stretching die.

5. The method for preparing NbTi / Cu superconducting wire based on copper ratio testing according to claim 1, characterized in that, Each time the length and total weight of the stretched wire are collected, the total weight-length change curve, the linear density-length change curve, and the wire copper ratio-length change curve are updated synchronously online.

6. The method for preparing NbTi / Cu superconducting wire based on copper ratio testing according to claim 1, characterized in that, In step four, the process for determining the critical point is as follows: The dataset consisting of the latest point and all previous points of the copper ratio-length change curve of the wire is statistically analyzed. The mean and standard deviation of the dataset are calculated, and then the confidence interval of the latest point is calculated. If the confidence interval of the latest point exceeds the copper ratio requirement, and the confidence interval of the next point is within the copper ratio requirement, then the location of the next point is recorded as the critical point. If the confidence interval of the latest point is within the copper ratio requirement range, and the confidence interval of the next point after the latest point exceeds the copper ratio requirement range, then the location of the latest point is recorded as the critical point. The critical point for eliminating the uneven area of ​​the spindle head.

Images