CN115728131A - Device for realizing continuous application of large-stress load at low temperature by using superconducting coil - Google Patents
Device for realizing continuous application of large-stress load at low temperature by using superconducting coil Download PDFInfo
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- CN115728131A CN115728131A CN202211519029.1A CN202211519029A CN115728131A CN 115728131 A CN115728131 A CN 115728131A CN 202211519029 A CN202211519029 A CN 202211519029A CN 115728131 A CN115728131 A CN 115728131A
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Abstract
The invention discloses a device for realizing continuous application of a large stress load at low temperature by utilizing a superconducting coil, wherein a base is connected with a shell, a circular boss is arranged in the middle of the base for limiting a lower round cake coil, a pressing plate is arranged above an upper round cake coil, a circular boss is arranged in the middle of the lower part of the pressing plate for limiting the upper round cake coil, the pressing plate is connected with a piston, and a top block is arranged above the piston, is in contact with a sample and applies pressure. The upper and lower pancake coils are made of NbTi superconducting wire and wound on a stainless steel skeleton in a wet winding or dry winding dipping mode. When the upper and lower disk coils are energized with reverse current to generate electromagnetic repulsion, the upper disk coil is pushed upwards and is transmitted to the top block through the pressing plate and the piston, so that pressure is applied to the sample. The invention can continuously apply large stress load to the test sample at low temperature by utilizing the electromagnetic repulsion force generated by the superconducting coil, has simple device principle, simple and convenient operation, large applied load range, good stability and high uniformity, and provides a novel low-temperature stress continuous loading device for stress dependency measurement of various types of superconducting cables and other critical performances.
Description
Technical Field
The invention relates to the field of stress dependence measurement of critical performance of a low-temperature superconducting conductor, in particular to a device for realizing continuous application of a large stress load at low temperature by utilizing a superconducting coil.
Background
In recent years, with the development of superconducting technology, superconducting materials with stable performance are required for particle accelerators and fusion magnets to obtain higher magnetic fields. Critical current (I) c ) Is one of the important properties for measuring the performance of the superconducting material, and the critical current is influenced by the temperature and the magnetic field. Currently, nbTi and Nb 3 Sn is still a main superconducting material for large-scale superconducting application, nbTi is a tough material and is easy to process, and many past magnets are made of NbTi, but the critical performance is poor, and a higher magnetic field is difficult to obtain. Nb 3 The critical properties of Sn are significantly higher than those of NbTi, so that in order to obtain a higher magnetic field, brittle Nb must be selected 3 Sn or a novel practical high temperature superconducting material (MgB) 2 Bi-2212, YBCO, etc.), but for technical as well as commercial reasons, new practical high temperature superconducting materials have not been put into use on a large scale. Therefore, nb must be chosen for higher field superconducting applications 3 Sn。
Nb 3 Sn superconducting wires are not monolithic structures but need to be embedded in common metal structures for higher mechanical properties and thermal stability. As technology evolves, different wire manufacturing techniques are used for production. At present, mainly used for producing commercial Nb 3 The manufacturing technique of the Sn superconducting wire material includes: bronze, PIT, RRP, and the like. All Nb 3 Sn must be heat-treated to react the internal material to form a superconducting phase, in order to avoid self-healingThe inductance is too large, and a superconducting cable formed by twisting a plurality of superconducting wires is generally adopted to develop a large superconducting magnet. For example, rutherford cables, which have a twisted structure and can realize complete superconducting wire transposition, are mostly used as accelerator magnets. The Rutherford cable has the advantages of high current density, good mechanical strength, compact winding structure and low coil circulation loss. Heat treated Nb 3 The critical performance of Sn is very sensitive to stress strain, and usually generates performance degradation under the influence of electromagnetic, mechanical and thermal stress under high field, so that Nb is necessary to be subjected to experimental means 3 And (3) continuously applying stress to the Sn material/conductor to simulate the stress state of the Sn material/conductor during operation, and evaluating the stress dependence of the critical performance of the Sn material/conductor.
At present, various measurement techniques are developed rapidly, and a plurality of pairs of Nb are emerged 3 The load applying method of the Sn Rutherford cable is limited by the structure size, cannot realize continuous stress loading at low temperature, is complicated in load applying process and is difficult to operate. The invention develops a device for realizing continuous application of a large stress load at low temperature by using the electromagnetic repulsion of a superconducting coil, which can apply Nb to Nb in a very low temperature (4.2K) environment 3 The Sn Rutherford cable test sample applies continuous wide-range load, and can accurately measure the load, so that the load application procedure is simplified, the test time is shortened, and the load loading range is enlarged. Meanwhile, the applied load is measured by the extensometer and the strain gauge together, so that the accuracy of load measurement is improved, and the measurement is Nb 3 Research on the critical performance degradation under transverse stress load of Sn rutherford cables provides a key infrastructure.
Disclosure of Invention
The purpose of the invention is: provides a device for realizing continuous application of large stress load at low temperature by using the electromagnetic repulsion of a superconducting coil, and the low-temperature electromagnetic continuous pressurizing device can apply Nb to Nb in the extremely low-temperature (4.2K) environment 3 The Sn Rutherford cable test sample continuously applies load, and the load can be accurately measured.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a device for realizing continuous application of large stress load at low temperature by utilizing a superconducting coil comprises:
the device comprises a base, an upper disc coil, a lower disc coil, a pressure plate, a shell, a piston, a top block, an extensometer and a strain gauge;
the upper circular cake coil and the lower circular cake coil are superconducting coils; the base is connected with the shell through bolts, a circular boss is arranged in the middle of the base to limit the lower cake coil, the pressing plate is placed above the upper cake coil, the circular boss is also arranged in the middle of the lower portion of the pressing plate to limit the upper cake coil, the pressing plate is connected with the piston through bolts, and the top block is placed above the piston and is in contact with the sample to apply pressure;
when the upper and lower disk coils are energized with reverse current to generate electromagnetic repulsion, the upper disk coil is pushed upwards and is transmitted to the top block through the pressing plate and the piston, so that pressure is continuously applied to the sample; the displacement variation of the pressure plate is detected by the extensometer, the strain quantities at two ends of the top block are detected by the strain gauges, the applied stress value on the sample is obtained by combining the input current of the lower cake coil and the dead weight of the upper cake coil, the pressure plate, the piston and the top block, and the uniformity of the applied stress is monitored in real time.
Furthermore, the base, the pressing plate, the shell and the top block are made of stainless steel.
Further, the base, the pressure plate, the shell and the top block are made of 304 stainless steel.
Further, the piston material is carbon fiber. Compared with stainless steel, the carbon fiber has smaller density and higher strength, and can maintain good strength in an extremely low temperature environment.
Furthermore, the upper and lower pancake coils are formed by winding NbTi superconducting wires on a stainless steel framework in a wet winding or dry winding dipping mode. The NbTi superconducting wire is in a superconducting state in a 4.2K extremely-low-temperature environment, has no heat loss and higher current-carrying capacity compared with a conventional resistance coil, and at the moment, reverse currents are conducted to the upper and lower disk coils to generate electromagnetic repulsion, the upper disk coil is jacked up, and pressure is upwards transmitted to the jacking block through the pressing plate and the piston.
Furthermore, the top block is made of 316 stainless steel and is subjected to fillet treatment so as to avoid the phenomenon of stress concentration in the process of applying pressure to the test sample.
Furthermore, the extensometer is arranged on a pin penetrating through the upper circular cake coil and used for measuring relative displacement generated by electromagnetic repulsion after the upper circular cake coil and the lower circular cake coil are electrified, the electromagnetic repulsion generated after the upper circular cake coil and the lower circular cake coil are electrified is obtained through calculation by combining with the electrified current, the gravity of the pressing plate, the piston and the ejector block is subtracted, and the pressure value applied to the surface of the sample is obtained.
Further, two strainometers are installed respectively in the both sides of kicking block, and after upper and lower cake coil led to reverse current and produced electromagnetic repulsion, will exert power through clamp plate, piston and transmit the kicking block to, and then exert test sample surface, can produce small deformation when the kicking block atress, thereby the strainometer calculates through the small deformation that measures the kicking block production and obtains the kicking block atress size, the size that test sample applyed the load promptly, judges the homogeneity of exerting pressure simultaneously.
Furthermore, the magnitude of the applied load of the test sample is obtained by adopting the modes of measuring and calculating the strain gauge and the extensometer respectively, and the load measurement precision and accuracy are provided.
The invention has the beneficial effects that: the invention can continuously apply large stress load to the test sample at low temperature by utilizing the electromagnetic repulsion force generated by the superconducting coil, has simple device principle, simple and convenient operation, large applied load range, good stability and high uniformity, and provides a novel low-temperature stress continuous loading device for stress dependency measurement of critical performance of various superconducting cables and the like.
Drawings
FIG. 1 is a structural diagram of a device for continuously applying a large stress load at a low temperature by using an electromagnetic repulsive force of a superconducting coil.
In the figure: 1-strain gauge, 2-top block, 3-shell, 4-piston, 5-extensometer, 6-pressure plate, 7-upper disk coil, 8-lower disk coil and 9-base.
Detailed Description
The present invention will be described in detail below with reference to the drawings and examples.
As shown in figure 1, the device for realizing continuous application of large stress load at low temperature by using the electromagnetic repulsion of the superconducting coil comprises a base 9, an upper disc coil 7, a lower disc coil 8, a pressure plate 6, a shell 3, a piston 4, a top block 2, a extensometer 5 and a strain gauge 1. Wherein, the material of base 9, clamp plate 6, shell 3 and kicking block 2 is the stainless steel, base 9 and 3 bolted connection of shell, have circular boss to carry on spacingly to lower cake coil 8 in the middle of base 9, clamp plate 6 is placed in last cake coil 7 top, have circular boss to carry on spacingly to last cake coil 7 in the middle of clamp plate 6 below, clamp plate 6 is with 4 bolted connection of piston, kicking block 2 is placed in 4 tops of piston, contacts and exerts pressure with the sample. The upper and lower pancake coils 7, 8 are made of NbTi superconducting wire and are wound on the stainless steel framework by wet winding or dry winding impregnation. When the upper and lower cake coils 7, 8 are energized with reverse currents to generate electromagnetic repulsion, the upper cake coil 7 is pushed upwards and is transmitted to the top block 2 through the pressing plate 6 and the piston 4, so that pressure is continuously applied to the sample. The displacement variable z of the pressing plate 6 is detected by the extensometer 5, the deformation quantity epsilon of two ends of the jacking block 2 is detected by the strain gauge 1, the stress value applied to the sample can be calculated by combining the current input into the superconducting coil and the dead weight of the upper pancake coil 7, the pressing plate 6, the piston 4 and the jacking block 2, and according to the formula:
σ＝∈×E
wherein σ is the stress generated by the top block 2 due to the repulsion force transmitted upwards by the piston 4, ∈ is the strain generated by the top block 2 measured by the strain gauge, and E is the elastic modulus of the top block 2 under the condition. The stress condition of the top block 2 generated in the interior under the stress condition can be calculated through the formula. Meanwhile, as the stressed condition of the top block 2 is only vertical upward force, the internal stress of the top block 2 is equal to the pressure intensity of the top block 2 generated by the thrust of the piston 4. And then the magnitude of the upward force can be calculated according to the area of the top block 2. The strain gauges on both sides of the top block 2 can monitor the uniformity of the applied stress in real time.
Then according to the formula:
wherein F is an upper pancake coil7. The electromagnetic repulsion force generated by electrifying the lower disk coil 8, wherein I is the current value of the upper disk coil 7 and the lower disk coil 8, and M is the current value of the upper disk coil 7 and the lower disk coil 8 12 Is the mutual inductance between the upper disc coil 7 and the lower disc coil 8, z is the displacement measured by the extensometer, m is the mass of the pressure plate 6 and the piston 4, and g is the gravity acceleration. The magnitude of the electromagnetic repulsion can be calculated according to the formula.
The base 9, the pressure plate 6, the shell 3 and the top block 2 are made of 304 stainless steel.
The carbon fiber material of the piston 4 has smaller density and higher strength compared with stainless steel, and can also keep good strength in an extremely low temperature environment.
The upper and lower pancake coils 7, 8 are made of NbTi superconducting wire and are wound on the stainless steel skeleton by adopting a wet winding or dry winding impregnation mode. The NbTi superconducting wire is in a superconducting state in a 4.2K extremely-low-temperature environment, has no heat loss and higher current-carrying capacity compared with a conventional resistance coil, and at the moment, reverse currents are conducted to the upper and lower disk coils 7 and 8 to generate electromagnetic repulsion, the upper disk coil 7 is jacked up, and pressure is upwards transmitted to the jacking block 2 through the pressing plate 6 and the piston 4.
The top block 2 is made of 316 stainless steel and is rounded to prevent stress concentration during the process of applying pressure to the test specimen.
The extensometer 5 is arranged on a pin penetrating through the upper cake coil 7 and used for measuring the relative displacement generated by the electromagnetic repulsion after the upper and lower cake coils 7 and 8 are electrified, the electromagnetic repulsion generated after the upper and lower cake coils 7 and 8 are electrified is obtained by calculation in combination with the electrified current, the gravity of the pressure plate 6, the piston 4 and the top block 2 is subtracted, and the pressure value applied to the surface of the sample is obtained.
Two strain gauges 1 are installed on two sides of the top block 2, and after the upper and lower disk coils 7 and 8 are electrified with reverse current to generate electromagnetic repulsion, force is transmitted to the top block 2 through the pressing plate 6 and the piston 4, and then applied to the surface of a test sample. When the top block 2 is stressed, the micro deformation is generated, the strain gauge 1 calculates and obtains the stress of the top block 2 by measuring the micro deformation generated by the top block, namely the load applied by the test sample, and simultaneously judges the uniformity of the applied pressure. The calculation formula is as follows:
σ＝∈×E
wherein σ is a stress generated by the top block 2 due to a repulsive force transmitted upward by the piston 4, ∈ is a strain generated by the top block 2 measured by the strain gauge, and E is an elastic modulus of the top block 2 under the condition. The stress condition generated inside the top block 2 under the stress condition can be calculated through a formula. Meanwhile, as the stressed condition of the ejector block is only vertical upward force, the internal stress of the ejector block 2 is equal to the pressure intensity of the ejector block 2 generated by the thrust of the piston 4. And then the magnitude of the upward force can be calculated according to the area of the top block 2. The strain gauges on two sides of the top block can monitor the uniformity of applied stress in real time.
According to the invention, on the basis of measuring the electromagnetic repulsion force F generated by electrifying the upper cake coil 7 and the lower cake coil 8, the stress on the top block 2 calculated by measuring the strain generated by the top block 2 due to the pressure by using the strain gauge 1 and the stress on the top block 2 calculated by measuring the upward micro displacement generated by the upper cake coil 7 due to the electromagnetic repulsion force F by using the extensometer 5 are combined to obtain the applied load of the test sample, so that the effect of mutually verifying the measurement accuracy to improve the load measurement precision and accuracy can be achieved.
Claims (8)
1. A device for realizing continuous application of large stress load at low temperature by utilizing a superconducting coil is characterized in that:
the device comprises a base, an upper disc coil, a lower disc coil, a pressure plate, a shell, a piston, a top block, an extensometer and a strain gauge;
the upper pancake coil and the lower pancake coil are superconducting coils; the base is connected with the shell through bolts, a circular boss is arranged in the middle of the base to limit the lower cake coil, the pressing plate is placed above the upper cake coil, the circular boss is also arranged in the middle of the lower portion of the pressing plate to limit the upper cake coil, the pressing plate is connected with the piston through bolts, and the top block is placed above the piston and is in contact with the sample to apply pressure;
when the upper and lower disk coils are energized with reverse current to generate electromagnetic repulsion, the upper disk coil is pushed upwards and is transmitted to the top block through the pressing plate and the piston, so that pressure is continuously applied to the sample; the displacement variation of the pressure plate is detected through the extensometer, the strain quantities at two ends of the top block are detected through the strain gauges, the applied stress value on the sample is obtained by combining the input current of the lower disc coil and the dead weight of the upper disc coil, the pressure plate, the piston and the top block, and the uniformity of the applied stress is monitored in real time.
2. The apparatus of claim 1 for continuous application of large stress loads at low temperatures using superconducting coils, wherein:
the base, the pressing plate, the shell and the top block are made of stainless steel.
3. The apparatus for continuously applying a large stress load at a low temperature using a superconducting coil according to claim 2, wherein:
the base, the pressure plate, the shell and the top block are made of 304 stainless steel.
4. The apparatus for continuously applying a large stress load at a low temperature using a superconducting coil according to claim 1, wherein:
the piston material is carbon fiber.
5. The apparatus for continuously applying a large stress load at a low temperature using a superconducting coil according to claim 1, wherein:
the upper and lower pancake coils are formed by winding NbTi superconducting wires on a stainless steel framework in a wet winding or dry winding dipping mode.
6. The apparatus for continuously applying a large stress load at a low temperature using a superconducting coil according to claim 1, wherein:
the top block is made of 316 stainless steel and is subjected to fillet treatment.
7. The apparatus for continuously applying a large stress load at a low temperature using a superconducting coil according to claim 1, wherein:
the extensometer is arranged on a pin penetrating through the upper disc coil and used for measuring relative displacement generated by electromagnetic repulsion after the upper disc coil and the lower disc coil are electrified, the electromagnetic repulsion generated after the upper disc coil and the lower disc coil are electrified is obtained through calculation by combining with the electrified current, the gravity of the pressing plate, the piston and the ejector block is reduced, and the pressure value applied to the surface of the sample is obtained.
8. The apparatus of claim 1 for continuous application of large stress loads at low temperatures using superconducting coils, wherein:
two strainometers are installed respectively in the both sides of kicking block, and after upper and lower cake coil led to reverse current and produced electromagnetic repulsion, will do all can transmit power to the kicking block through clamp plate, piston, and then apply test sample surface, can produce small deformation when the kicking block atress, thereby the strainometer calculates through the small deformation that measures the kicking block production and obtains the kicking block atress size, the size of test sample applied load promptly, the homogeneity of judging the pressure simultaneously.
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| CN202211519029.1A CN115728131A (en) | 2022-11-30 | 2022-11-30 | Device for realizing continuous application of large-stress load at low temperature by using superconducting coil |
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| CN202211519029.1A CN115728131A (en) | 2022-11-30 | 2022-11-30 | Device for realizing continuous application of large-stress load at low temperature by using superconducting coil |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117438174A (en) * | 2023-10-12 | 2024-01-23 | 中国科学院近代物理研究所 | Superconducting magnet prestress application device and processing method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117438174A (en) * | 2023-10-12 | 2024-01-23 | 中国科学院近代物理研究所 | Superconducting magnet prestress application device and processing method thereof |
| CN117438174B (en) * | 2023-10-12 | 2024-03-22 | 中国科学院近代物理研究所 | Superconducting magnet prestress application device and processing method thereof |
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