Defect detection device and detection method for high-temperature superconducting strip

Abstract

The high-temperature superconducting tape defect detection device comprises a liquid nitrogen tank and a lifter connected below the bottom of the liquid nitrogen tank, a pay-off wheel and a take-up wheel are arranged on the two opposite sides of the liquid nitrogen tank respectively, and an inverted trapezoidal guide wheel set is arranged between the pay-off wheel and the take-up wheel. A high-temperature superconducting strip is released by the pay-off wheel, is guided downwards by the guide wheel set and then is withdrawn upwards by the take-up wheel, four sets of crimping assemblies are arranged on the material supporting base at intervals in the advancing direction of the high-temperature superconducting strip, and the interiors of the two sets of crimping assemblies close to the outside are jointly connected with a current source through wires capable of making contact with the high-temperature superconducting strip. And the inner part is connected with a voltage source. The critical current value of the high-temperature superconducting long belt is measured by adopting a crimping type four-lead method, so that the internal damage position of the belt is intuitively reflected, accurate searching is facilitated, meanwhile, the surface of the belt is prevented from being polluted, the interior of the belt is prevented from being damaged, the detected long belt can be used for the second time or subjected to a surface enhancement process, the detection efficiency is improved, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of performance detection of high-temperature superconducting materials, and particularly relates to a defect detection device for high-temperature superconducting tapes. The present invention also relates to a defect detection method for high-temperature superconducting tapes. Background Art

[0002] With the continuous development of technology, mankind has put forward higher requirements for related fields such as power systems, magnets, and motors, which has promoted the rapid development of high-temperature superconducting materials. Currently, commercial high-temperature superconducting materials are mainly composed of Bi-2223 and YBCO.

[0003] The Bi-2223 high-temperature superconducting tape is prepared by the powder-in-tube (PIT) process. The current transmission in the tape is mainly completed by the Bi-2223 phase grains formed after heat treatment and growing along the rolling direction. The YBCO high-temperature superconducting tape, also known as a coated conductor, is prepared by a multi-layer coating process, and its current-carrying core mainly relies on the YBCO coating. However, the Bi-2223 phase and the YBCO coating have low self-strength and are easily damaged by external forces. Moreover, the strength of their outer sheath materials and substrate materials (silver / silver alloy) is low, and the tape is prone to damage under the action of internal stress.

[0004] Before the high-temperature superconducting tape is used, it is necessary to detect the current-carrying performance of the entire tape. The welding four-lead method is used to measure the current-carrying performance of the long tape. After the measurement, a large number of solder joints remain on the tape surface, resulting in the long tape being unable to be used again or the need for a surface strengthening process for the tape; the magnetic measurement method cannot directly reflect the critical current value of the tape, and there is a certain error in evaluating the critical current value at the defect position of the tape. Summary of the Invention

[0005] The purpose of the present invention is to provide a defect detection device for high-temperature superconducting tapes, which solves the problems that the existing detection methods are prone to damage the tape and cannot directly reflect the defect position.

[0006] Another purpose of the present invention is to provide a defect detection method for high-temperature superconducting tapes.

[0007] The first technical solution adopted by the present invention is: a defect detection device for high-temperature superconducting tapes, including a liquid nitrogen tank. An elevator is connected below the bottom of the liquid nitrogen tank. Pay-off reels and take-up reels are respectively arranged on opposite sides of the liquid nitrogen tank. A trapezoidal inverted guide wheel group is arranged corresponding to the liquid nitrogen tank between the pay-off reel and the take-up reel. The high-temperature superconducting tape is released from the pay-off reel, guided downward by the guide wheel group, and then taken back by the take-up reel upward. A material supporting base is arranged at the bottom of the guide wheel group. Four groups of pressing components are arranged at intervals along the advancing direction of the high-temperature superconducting tape on the material supporting base. The two outer pressing components are commonly connected to a current source through wires that can contact the high-temperature superconducting tape, and the two inner pressing components are commonly connected to a voltage source through wires that can contact the high-temperature superconducting tape.

[0008] The first technical solution of the present invention is further characterized in that The guiding wheel set includes two upper guiding wheels whose tops are at the same height as the wire pay-off wheel and the wire take-up wheel. Between the two upper guiding wheels, there are two lower guiding wheels whose bottoms are at the same height as the centers of the four groups of crimping components.

[0009] The crimping component includes two crimping blocks facing each other up and down. The two crimping blocks are arranged at intervals and are jointly connected with an opener on one side in the advancing direction of the high-temperature superconducting tape.

[0010] Connectors are connected to the wires between the two outermost groups of crimping components at both ends of the current source. The wires between the connectors and the current source are all current leads, and the wires between the connectors and the two outermost groups of crimping components are all metal braided wires.

[0011] Connectors are connected to the wires between the two innermost groups of crimping components at both ends of the voltage source. The wires between the connectors and the voltage source are all voltage leads, and the wires between the connectors and the two innermost groups of crimping components are all metal braided wires.

[0012] A heating device is arranged between the guiding wheel set and the wire take-up wheel, and a lift is connected below the bottom of the heating device.

[0013] Tensioners are arranged on one side of the wire pay-off wheel and the wire take-up wheel respectively.

[0014] The second technical solution adopted by the present invention is: a method for detecting defects in high-temperature superconducting tapes, including the following steps: Step 1: Wind the high-temperature superconducting tape on the wire pay-off wheel. After the traction wire at the head of the tape is guided downward through the guiding wheel set, it is placed flat in the four groups of crimping components in an open state above the material supporting base, and then the tape is taken up to the wire take-up wheel through the guiding wheel set for upward guiding; Step 2: Apply tension to the tape through the tensioners on the wire pay-off wheel and the wire take-up wheel to keep it in a straightened state; Step 3: Fill the liquid nitrogen tank with liquid nitrogen, and raise the liquid nitrogen tank through the lift until the horizontal section at the bottom of the tape is completely immersed in the liquid nitrogen; Step 4: Close the four groups of crimping components so that the wires connected to the current source and the voltage source in the crimping components are all in contact with the tape; Step 5: Start the voltage source and set the quench voltage standard value, then start the current source. When the current output by the current source reaches the set quench voltage standard value of the voltage source, record the critical current value of the current source; Step 6: Open the four groups of crimping components, start the wire pay-off reel and the wire take-up reel, and stop when the strip between the two inner groups of crimping components travels outside the two inner groups of crimping components. Repeat Step 4 and Step 5 until the strip inspection is completed. If the change range of the critical current value recorded during the strip travel exceeds the preset range, it is determined that there is a defect point in the strip between the two inner groups of crimping components at the corresponding moment.

[0015] The beneficial effects of the present invention are as follows: The high-temperature superconducting strip defect detection device and detection method of the present invention use the crimping four-lead method to measure the critical current value of the high-temperature superconducting long strip, so as to intuitively reflect the internal damage position of the strip, which is convenient for accurate searching. At the same time, it avoids contaminating the strip surface and damaging the strip interior. The long strip after detection can be reused or undergo a surface enhancement process, improving the detection efficiency and reducing the manufacturing cost. Brief Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the high-temperature superconducting strip defect detection device of the present invention; Figure 2 is a front view schematic diagram of the position of the crimping component in the high-temperature superconducting strip defect detection device of the present invention; Figure 3 is a side view schematic diagram of the position of the crimping component in the high-temperature superconducting strip defect detection device of the present invention.

[0017] In the figure, 1. Liquid nitrogen tank, 2. Lift, 3. Wire pay-off reel, 4. Wire take-up reel, 5. High-temperature superconducting strip, 6. Material support base, 7. Crimping component, 8. Current source, 9. Voltage source, 10. Upper guide wheel, 11. Lower guide wheel, 12. Connector, 13. Current lead, 14. Metal braid, 15. Voltage lead, 16. Heating device; 71. Crimping block, 72. Opener. Detailed Embodiments

[0018] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0019] Embodiment 1 The present invention provides a high-temperature superconducting strip defect detection device, as Figure 1 shown, including a liquid nitrogen tank 1, the inside of which uses high-density polyurethane foam as a lining material, having excellent heat insulation and low-temperature resistance. A lift 2 is connected below the bottom of the liquid nitrogen tank 1, and a wire pay-off reel 3 and a wire take-up reel 4 are respectively arranged on the opposite sides of the liquid nitrogen tank 1, and a tensioner is arranged on one side of each of the wire pay-off reel 3 and the wire take-up reel 4.

[0020] A trapezoid-shaped guide wheel group is arranged corresponding to the liquid nitrogen tank 1 between the wire pay-off reel 3 and the wire take-up reel 4. The guide wheel group includes two upper guide wheels 10 at the top whose heights are the same as those of the wire pay-off reel 3 and the wire take-up reel 4. Two lower guide wheels 11 are arranged between the two upper guide wheels 10. The four guide wheels are located at the four points of an isosceles trapezoid. After being released from the wire pay-off reel 3, the high-temperature superconducting tape 5 is downward-guided through the upper part of the left upper guide wheel 10 and then introduced into the lower part of the left lower guide wheel 11. Then it horizontally passes through the centers of the four groups of crimping assemblies 7 and enters the lower part of the right lower guide wheel 11, and then is upward-introduced into the upper part of the right upper guide wheel 10 and is taken back by the wire take-up reel 4.

[0021] A material supporting base 6 is arranged at the bottom of the guide wheel group. Four groups of crimping assemblies 7 are arranged at intervals on the material supporting base 6 along the advancing direction of the high-temperature superconducting tape 5. The centers of the four groups of crimping assemblies 7 and the two lower guide wheels 11 are at the same height. In the two outer groups of crimping assemblies 7, a current source 8 is commonly connected through wires that can contact the high-temperature superconducting tape 5. In the two inner groups of crimping assemblies 7, a voltage source 9 is commonly connected through wires that can contact the high-temperature superconducting tape 5.

[0022] Embodiment 2 The present invention provides a high-temperature superconducting tape defect detection device. On the basis of Embodiment 1, as Figure 2 and Figure 3 shown, the crimping assembly 7 preferably includes two crimping blocks 71 facing each other up and down. The two crimping blocks 71 are arranged at intervals and are commonly connected with a switch 72 on one side in the advancing direction of the high-temperature superconducting tape 5, and an electric push rod can be used.

[0023] Connectors 12 are connected to the wires between the two outer groups of crimping assemblies 7 at both ends of the current source 8. The wires between the connectors 12 and the current source 8 are all current leads 13, and the wires between the connectors 12 and the two outer groups of crimping assemblies 7 are all metal braided wires 14; Connectors 12 are connected to the wires between the two inner groups of crimping assemblies 7 at both ends of the voltage source 9. The wires between the connectors 12 and the voltage source 9 are all voltage leads 15, and the wires between the connectors 12 and the two inner groups of crimping assemblies 7 are all metal braided wires 14. The above metal braided wires 14 are all made of pure Cu, pure Ag or tinned pure Cu braided wires.

[0024] Embodiment 3 The present invention provides a high-temperature superconducting tape defect detection device, which uses the crimping four-lead method to measure the critical current value of the high-temperature superconducting long tape, so as to intuitively reflect the internal damage position of the tape, facilitate accurate search, and at the same time avoid polluting the tape surface and damaging the tape interior. The long tape after detection can be reused or subjected to a surface enhancement process, improving the detection efficiency and reducing the manufacturing cost. It also has the following advantages: 1) Before the strip test, the metal braided wire 14 does not come into contact with the strip, avoiding stress damage inside the strip caused by different thermal expansion coefficients among various materials after entering liquid nitrogen.

[0025] 2) By applying a constant horizontal tension to the strip between the pay-off and take-up reels, the measurement accuracy of the strip can be improved.

[0026] 3) The liquid nitrogen tank 1 can be lifted up and down according to the detection requirements, avoiding liquid nitrogen leakage when the strip is immersed in liquid nitrogen for a long time due to unexpected situations.

[0027] 4) The input of the strip current signal and the acquisition of the voltage signal are both completed after flatly pressing the strip from above and below through the crimping assembly 7. The opening and closing between the upper and lower crimping blocks 71 are controllable. Flat pressing from above and below can reduce the damage and contamination to the internal structure of the strip. The metal braided wire 14 contacts the strip surface between the strip surface and the crimping block 71. One end of the metal braided wire 14 is connected to the current / voltage lead, and the other end is open. Since the larger the contact area between the test element and the strip, the greater the resistance generated when the superconducting performance decreases and the greater the impact on the determination of quench, the smaller contact area between the metal braided wire 14 and the strip surface can improve the measurement accuracy.

[0028] Example 4 The present invention provides a high-temperature superconducting strip defect detection device. On the basis of Example 1, a heating device 16 is provided between the right upper guide wheel 10 and the take-up reel 4. A lifter 2 is connected below the bottom of the heating device 16. The heating device 16 can adopt a hot air blower to dry the strip leaving the liquid nitrogen.

[0029] Example 5 The present invention also provides a high-temperature superconducting strip defect detection method, including the following steps: Step 1: Wind a 100m Bi-2223 high-temperature superconducting strip 5 on the pay-off reel 3. After the traction wire at the head of the strip is guided downward through the guide wheel group, it is placed flat in the four groups of crimping assemblies 7 in an open state above the material supporting base 6, and then the strip is taken up to the take-up reel 4 through the guide wheel group for upward guidance; Step 2: Apply tension to the strip through the tensioners on the pay-off reel 3 and the take-up reel 4 to keep it in a straightened state; Step 3: Fill the liquid nitrogen tank 1 with liquid nitrogen, and raise the liquid nitrogen tank 1 through the lifter 2 until the horizontal section at the bottom of the strip is completely immersed in liquid nitrogen; raise and start the heating device 16 to heat the strip leaving the liquid nitrogen in a timely manner; Step 4: Close the four groups of crimping assemblies 7 so that the wires connected to the current source 8 and the voltage source 9 in the crimping assemblies 7 are all in contact with the strip; Step 5: Start the voltage source 9. At this time, since the strip is in a superconducting state, the reading on the voltage source 9 should be relatively small. After checking and meeting the requirements, set the quench voltage standard value of the voltage source 9 according to the quench determination standard of 1 cm = 1 μV for the high-temperature superconducting strip. For example, if the length of the strip between the two crimping components 7 at both ends of the voltage source 9 is 2 m, the quench voltage standard value of the voltage source 9 at this time is 200 μV.

[0030] Then start the current source 8. During the process of increasing the current, the reading of the voltage source 9 fluctuates slightly and is close to unchanged. When the current output by the current source 8 approaches the critical current, that is, when the strip is close to quenching, the reading of the voltage source 9 rises rapidly. When the reading of the voltage source 9 reaches the set quench voltage standard value of 200 μV, record the current value of the current source 8 at this time, which is the critical current value. Step 6: Open the four groups of crimping components 7, start the pay-off reel 3 and the take-up reel 4, and stop when the strip between the two inner crimping components 7 travels outside the two inner crimping components 7. Repeat Step 4 and Step 5 until the strip detection is completed. If the change range of the recorded critical current value during the strip travel exceeds the preset range, it is determined that there is a defect point in the strip between the two inner crimping components 7 at the corresponding moment.

[0031] Example 6 The present invention also provides a method for detecting defects in high-temperature superconducting strips. Using the detection method shown in Example 5, the data results of the current source 8 are statistically shown in Table 1 below: Table 1 Critical current value statistics

[0032] The results show that a significant decrease in the critical current value occurs at the strip section number (2 m) 14 of the strip, indicating that there is a defect point in the middle of this 2 m strip.

Claims

1. A high-temperature superconducting tape defect detection device, characterized in that: The invention comprises a liquid nitrogen tank (1), wherein a lift (2) is connected to the bottom of the liquid nitrogen tank (1), a pay-off wheel (3) and a take-up wheel (4) are respectively arranged on opposite sides of the liquid nitrogen tank (1), and an inverted trapezoidal guide wheel group is arranged between the pay-off wheel (3) and the take-up wheel (4) corresponding to the liquid nitrogen tank (1). After the high-temperature superconducting tape (5) is paid out by the pay-off wheel (3), it is guided downward by the guide wheel group and then taken up by the take-up wheel (4). A support base (6) is arranged at the bottom of the guide wheel group, and four groups of crimping assemblies (7) are arranged on the support base (6) at intervals along the direction of travel of the high-temperature superconducting tape (5). The two outer groups of crimping assemblies (7) are connected to a current source (8) through a wire that can contact the high-temperature superconducting tape (5), and the two inner groups of crimping assemblies (7) are connected to a voltage source (9) through a wire that can contact the high-temperature superconducting tape (5).

2. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: The guide wheel assembly comprises two upper guide wheels (10) whose top ends are located at the same height as the pay-off wheel (3) and the take-up wheel (4), and two lower guide wheels (11) whose bottom ends are located at the same height as the centers of the four crimping assemblies (7) are arranged between the two upper guide wheels (10).

3. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: The crimping assembly (7) comprises two crimping blocks (71) facing each other vertically, the two crimping blocks (71) being arranged at an interval and being commonly connected to an opener and closer (72) on one side of the traveling direction of the high-temperature superconducting tape (5).

4. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: Connectors (12) are connected to the wires between the two ends of the current source (8) and the two outer groups of crimping assemblies (7), the wires between the connector (12) and the current source (8) are current leads (13), and the wires between the connector (12) and the two outer groups of crimping assemblies (7) are metal braided wires (14).

5. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: Connectors (12) are connected to the wires between the two ends of the voltage source (9) and the two inner groups of crimping assemblies (7); the wires between the connector (12) and the voltage source (9) are voltage leads (15); and the wires between the connector (12) and the two inner groups of crimping assemblies (7) are metal braided wires (14).

6. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: A heating device (16) is provided between the guide wheel group and the take-up wheel (4), and a lift (2) is connected below the bottom of the heating device (16).

7. The high temperature superconducting tape defect detection device according to claim 1, characterized in that: A tensioner is provided on one side of the pay-off wheel (3) and the take-up wheel (4).

8. A method for detecting defects in a high-temperature superconducting tape using the high-temperature superconducting tape defect detection device according to claim 1, characterized in that: The steps include: Step 1, winding a high-temperature superconducting tape (5) onto a pay-off wheel (3), guiding the traction wire at the head of the tape downward through a guide wheel group, and then placing the tape flat in four sets of crimping assemblies (7) in an open state above a support base (6), and then guiding the tape upward through the guide wheel group to be collected onto a take-up wheel (4); Step 2: applying tension to the strip through the tensioners on the pay-off wheel (3) and the take-up wheel (4) to keep the strip in a straightened state; Step 3, fill the liquid nitrogen tank (1) with liquid nitrogen, and raise the liquid nitrogen tank (1) by means of a lift (2) until the horizontal section at the bottom of the strip is completely submerged in the liquid nitrogen; Step 4, closing the four groups of crimping assemblies (7) so that the wires in the crimping assemblies (7) connected to the current source (8) and the voltage source (9) are all in contact with the strip; Step 5, starting the voltage source (9) and setting a quench voltage standard value, then starting the current source (8), when the current source (8) outputs a current to the voltage source (9) that reaches the set quench voltage standard value, recording the critical current value of the current source (8); Step 6, open the four groups of crimping assemblies (7), start the pay-off wheel (3) and the take-up wheel (4), so that the strip between the two inner groups of crimping assemblies (7) moves to the outside of the two inner groups of crimping assemblies (7) and then stops, and repeat steps 4 and 5 until the strip inspection is completed. If the change range of the critical current value recorded during the strip movement exceeds a preset range, it is determined that there is a defective point in the strip between the two inner groups of crimping assemblies (7) at the corresponding moment.

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