KR102680346B1 - tie rod for supercunducting magnets - Google Patents

Abstract

The present invention relates to a tie rod for a superconducting magnet that secures a superconducting coil.
The present invention is formed by combining a plurality of parts, but at least one part has a different thermal contraction coefficient from the other parts. At this time, the heat contraction coefficient of the first part is greater than that of the second part, the second part is coupled to the upper plate and the lower plate, respectively, and the first part is provided between the second parts. In addition, the tie rod is made of any two or more of aluminum, stainless steel, copper, and G-10, in which the first part and the second part are joined and shrink-fitted together. Additionally, the total contracted length of the superconducting coil is less than or equal to the sum of the contracted lengths of the first part and the second part.
According to the present invention, the contraction length of the tie rod is adjusted to be less than the total contraction length of the superconducting coil through a tie rod formed of two or more parts with different thermal contraction coefficients, thereby preventing the quench phenomenon by stably fixing the superconducting coil. And prevents the superconducting coil and tie rod from being deformed or damaged by compressive stress and thermal stress caused by the difference in shrinkage length.

Description

Tie rod for superconducting magnets}

The present invention relates to a tie rod for a superconducting magnet that secures a superconducting coil.

In general, materials whose electrical resistance becomes 0 below a certain temperature are called superconductors. These superconductors are divided into low-temperature superconductors and high-temperature superconductors depending on the size of the transition temperature.

Low-temperature superconductors refer to materials that become superconductors at a temperature of about 4K. Since they are processed in the form of wires, they are easily wound into coils and used in superconducting magnets.

On the other hand, a high-temperature superconductor refers to a material that becomes a superconductor even at a temperature of 30K or higher. Since it is processed in the form of a tape, it cannot be wound in the form of an electromagnet like the low-temperature superconductor, so it has a plurality of coils in the form of a pancake or double pancake. It is used layered.

In this regard, Patent Document 1, ‘Superconducting magnet and method of manufacturing superconducting magnet,’ has been proposed.

Figure 1 shows a perspective view of a superconducting magnet according to the prior art. Looking at this, Patent Document 1 includes a plurality of superconducting plates 1 that are stacked, and a fixing member for fixing the plates, and the fixing member includes an upper plate 21, a lower plate 22, and a connecting member 23. It consists of

The connecting member 23 consists of a connecting rod and a nut, and secures the plurality of superconducting plates to maintain the stacked state.

However, the superconducting magnet is manufactured in a room temperature environment and used in a cryogenic environment, and at this time, a heat shrinkage phenomenon occurs in which the volume is reduced due to temperature changes.

Figure 2 shows a diagram showing an example of heat shrinkage of a superconducting magnet according to the prior art. Looking at this, the length contracted by heat shrinkage of the superconducting plate 1 and the connecting member 23 (hereinafter referred to as 'contraction length') is different, so that the superconducting plate 1 is in contact with the upper or lower plates 21 and 22. It doesn't work. As a result, the superconducting plate 1 is not stably fixed, resulting in a quench phenomenon in which the superconductivity phenomenon is broken and resistance rapidly increases when operating a system using a superconducting magnet.

Alternatively, when the shrinkage length of the superconducting plate 1 is shorter than the connecting member 23, a strong compressive force is applied to the superconducting plate 1 by the upper and lower plates 21 and 22, causing the superconducting plate 1 to deform or deform. It may be damaged. In addition, due to the difference in shrinkage length between the superconducting plate 1 and the connecting member 23, thermal stress may be generated inside the connecting member 23, causing the connecting member 23 to be deformed or damaged.

In order to solve the above-mentioned problems, the connecting member 23 must be formed in consideration of the shrinkage length of the superconducting plate 1. That is, the shrinkage length of the connection member 23 and the superconducting plate 1 is the same, or the shrinkage length of the connection member 23 is longer than the shrinkage length of the superconducting plate 1, but the connection member 23 is caused by thermal stress and compressive stress. ) and the superconducting plate (1) must be ensured not to be damaged.

However, the connecting member 23 is not only formed of a single material, but also, unlike the superconducting plate 1, is formed of a non-magnetic material, so it is easy to manufacture the connecting member 23 according to the contracted length of the superconducting plate 1. don't do it

KR 10-1311459 B1

The purpose of the present invention is to prevent the quench phenomenon by stably fixing the superconducting coil by adjusting the shrinkage length of the tie rod to be less than the total shrinkage length of the superconducting coil through a tie rod formed of two or more parts with different thermal contraction coefficients, To provide a tie rod for a superconducting magnet that prevents the superconducting coil and tie rod from being deformed or damaged by compressive stress and thermal stress caused by differences in shrinkage length.

The tie rod according to an embodiment of the present invention is formed by combining a plurality of parts, and at least one part has a different thermal contraction coefficient from the other parts. At this time, the heat contraction coefficient of the first part is greater than that of the second part, the second part is coupled to the upper plate and the lower plate, respectively, and the first part is provided between the second parts.

In addition, the tie rod is made of any two or more of aluminum, stainless steel, copper, and G-10, in which the first part and the second part are joined and shrink-fitted together.

Additionally, the total contracted length of the superconducting coil is less than or equal to the sum of the contracted lengths of the first part and the second part.

According to an embodiment of the present invention, the contraction length of the tie rod is adjusted to be less than the total contraction length of the superconducting coil through a tie rod formed of two or more parts with different thermal contraction coefficients, thereby stably fixing the superconducting coil to prevent the quench phenomenon. and prevents the superconducting coil and tie rod from being deformed or damaged due to compressive stress and thermal stress caused by the difference in shrinkage length.

1 is a perspective view of a superconducting magnet according to the prior art.
Figure 2 is a diagram showing an example of heat shrinkage of a superconducting magnet according to the prior art.
Figure 3 is a perspective view of a superconducting magnet including a tie rod according to an embodiment of the present invention.
Figure 4 is an exploded perspective view of a tie rod according to an embodiment of the present invention.
Figure 5 is a diagram showing an example of heat shrinkage of a superconducting magnet including a tie rod according to an embodiment of the present invention.

Hereinafter, with reference to the attached drawings, the present invention will be described in detail so that those skilled in the art can easily implement it. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and identical or similar components are given the same reference numerals throughout the specification. In addition, the attached drawings are only intended to facilitate understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings.

Figure 3 shows a perspective view of a superconducting magnet including a tie rod according to an embodiment of the present invention.

Looking at this, the superconducting magnet includes a superconducting coil 100 and a fixing member.

The superconducting coil 100 may be wound in the form of a line or may be a form in which a plurality of pancakes or double pancakes are stacked. Alternatively, it may be a form in which a plurality of superconducting plates are stacked, as in the prior art.

The fixing member includes an upper plate 210, a lower plate 220, a tie rod 230, and a nut 240.

The upper and lower plates 210 and 220 are formed with a larger area than the superconducting coil 100 and are located at the upper and lower parts of the superconducting coil 100, respectively. In addition, a plurality of coupling holes are formed in the edge areas of the upper and lower plates 210 and 220, spaced apart from each other.

The upper and lower plates 210 and 220 may be made of an insulating material that is electrically insulated from the superconducting coil 100, and may be made of, for example, a resin or plastic material.

The tie rod 230 according to an embodiment of the present invention is formed by combining a plurality of parts so as to form a coaxial axis, and a portion of each part located at both ends is located at the upper part of the upper plate 210 and the lower part of the lower plate 220. It penetrates. And threads are formed on the outer peripheral surface of each part located at both ends.

The nut 240 is located at the lower part of the upper and lower plates 220 of the upper plate 210, and is combined with the tie rod 230 to secure the upper and lower plates 210 and 220 from being removed. That is, the upper and lower plates 210 and 220 are fixed to stably contact the upper and lower surfaces of the superconducting coil.

Figure 4 shows an exploded perspective view of a tie rod according to an embodiment of the present invention.

Looking at this, the tie rod 230 is formed of two or more parts, and at least one part has a different heat contraction coefficient from the other parts. The thermal contraction coefficient means a negative thermal expansion coefficient.

According to an embodiment of the present invention, the tie rod 230 is formed of a first part 231 and a second part 232, and the heat contraction coefficient of the first part 231 is that of the second part 232. greater than the heat contraction coefficient.

And the second part 232 is coupled to the upper and lower plates 210 and 220, respectively, and the first part 231 is provided between the second parts 232.

The tie rod 230 may be formed of any two or more of aluminum, stainless steel, copper, and G-10. That is, it can be formed by including any two or more of the non-magnetic materials.

The diameter of each part is formed to be the same, but the height is formed differently depending on the heat contraction coefficient. That is, the first part 231 may be formed longer than the second part 232.

According to an embodiment of the present invention, the upper and lower surfaces of the first part 231 and the second part 232 are recessed or protruded in the height direction to form a shape that can be fitted with each other.

In detail, both the upper and lower surfaces of the first part 232 are recessed or protruded, and the second part 232 is recessed or protruded so as to be capable of being coupled to the first part 231.

Alternatively, one side of the first part 232 is depressed and the other side protrudes, and the second part 232 is formed in a form that can be combined with the first part 231.

And the first and second parts 231 and 232 are shrink-fitted after being joined.

According to another embodiment of the present invention, a screw thread is formed on the inside of the recessed side of the first and second parts 231 and 232, and a screw thread is also formed on the outside of the protruding side, so that the first and second parts 231 and 232 are are screwed together.

Figure 5 shows a diagram showing an example of heat shrinkage of a superconducting magnet including a tie rod according to an embodiment of the present invention.

Looking at this, the contracted length of the tie rod 230 is longer than the contracted length of the superconducting coil 100, so that the upper and lower surfaces of the superconducting coil 100 are in surface contact with the upper and lower plates 210 and 220.

When the contracted length of the tie rod 230 and the contracted length of the superconducting coil 100 are the same, frictional force is generated on the surface where the superconducting coil 100 and the upper and lower plates 210 and 220 contact, so that the superconducting coil 100 It is fixed.

Alternatively, when the contracted length of the tie rod 230 is longer than the contracted length of the superconducting coil 100, compressive stress is applied to the superconducting coil 100 in surface contact with the upper and lower plates 210 and 220 due to the difference in contracted length. This occurs and the superconducting coil 100 is fixed.

The shrinkage length is determined by Equation 1 below.

은 수축 길이,

은 초기 길이,

은 현재 길이,

는 열수축 계수,

은 초기 온도 및

는 현재 온도를 의미한다.remind

silver shrinkage length,

is the initial length,

is the current length,

is the heat contraction coefficient,

is the initial temperature and

means the current temperature.

According to an embodiment of the present invention, the initial length of the tie rod 230 refers to the length from the bottom of the upper plate 210 to the top of the lower plate 220, and is the same as the initial length of the superconducting coil 100.

That is, the shrinkage length of the tie rod 230 is determined by the thermal contraction coefficient of the material forming each part. In addition, the shrinkage length of the tie rod 230 is determined by considering the compressive stress generated in the superconducting coil 100 and the yield strength of the superconducting coil 100 due to the difference in shrinkage length. Accordingly, the contracted length of the tie rod 230 is determined within a range in which the superconducting coil 100 is not deformed or damaged by compressive stress.

And at the same time that compressive stress is generated in the superconducting coil 100, thermal stress is generated in the tie rod 230 in proportion to the contracted length due to contraction restraint.

The thermal stress is determined by Equation 2 below.

는 열응력 및

는 소재 탄성 계수를 의미한다.remind

is the thermal stress and

means the material elastic modulus.

That is, the shrinkage length of the tie rod 230 is within a range in which the tie rod 230 is not deformed or damaged by thermal stress, considering the thermal stress occurring in the tie rod 230 and the yield strength of the tie rod 230. It is decided within.

Looking at the superconducting magnet including the connecting member 23 according to the prior art shown in FIGS. 1 and 2, the connecting member 23 is formed of a single material, so the contracted length of the connecting member 23 is that of the superconducting coil 100. It is not easy to adjust it to exceed the contracted length of .

In detail, according to Equation 1, the initial length of the connecting member 23 is the same as the initial length of the superconducting coil 100. Therefore, in order to adjust the shrinkage length of the connecting member 23, the material of the connecting member 23 must be changed.

Therefore, since the superconducting coil 100 formed of a magnetic material may further include two or more materials such as a bonding material, it is not easy to control the shrinkage length with only a single material of the connecting member 23.

According to an embodiment of the present invention, the tie rod 230 is formed by coaxially combining a first part 231 and a second part 232, and the first part 231 is thermally contracted more than the second part 232. The coefficient is large. That is, the contracted length of the first part 231 is longer than the contracted length of the second part 232.

And the sum of the contracted lengths of one first part 231 and the two second parts 232 is greater than or equal to the total contracted length of the superconducting coil 100.

At this time, the shrinkage length can be easily adjusted by changing the materials of the first part 231 and the second part 232 or changing the initial length ratio of the first part 231 and the second part 232.

The heat shrinkage rates of aluminum, stainless steel, copper, and G-10 used as materials for the tie rod 230 are 0.4% and 0.3%, respectively, at 77K to 300K. 0.32% and 1%.

Therefore, the tie rod 230 is formed in consideration of the thermal contraction rate depending on the material of the superconducting coil 100.

That is, in order to adjust the contracted length of the tie rod 230, the present invention changes one or more of the number of parts, the initial length and initial diameter of each part, or the material of each part. At this time, in order to prevent the tie rod 230 and the superconducting coil 100 from being deformed or damaged, the tie rod 230 is formed by considering the yield strength of the tie rod 230 and the superconducting coil 100. .

The scope of the present invention should be construed as including all changes or modified forms derived based on the technical idea of the present invention in addition to the embodiments disclosed herein.

100: superconducting coil
210: upper plate
220: lower plate
230: tie rod
231: Part 1
232: Part 2
240: nut

Claims (5)

In the tie rod for a superconducting magnet, which connects between the upper and lower plates located at the upper and lower parts of the superconducting coil, respectively, for fixing the superconducting coil,
The tie rod is,
Two second parts respectively coupled to the upper plate and lower plate,
The first part provided between the two second parts is coaxially coupled to each other,
The first part has a higher heat contraction coefficient than the second part,
The sum of the contracted lengths of the first part and the two second parts is greater than the total contracted length of the superconducting coil,
A tie rod for a superconducting magnet, wherein the length of the first part is longer than the length of the second part, so that more shrinkage occurs in the central part of the tie rod.
delete delete delete According to claim 1,
The tie rod is,
A tie rod for superconducting magnets, characterized in that it is formed through a combination of two or more of aluminum, stainless steel, copper, and G-10.

Images