KR20230128671A - tie rod for supercunducting magnets - Google Patents

Abstract

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

Description

Tie rod for superconducting magnets}

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

In general, a material whose electrical resistance is zero below a certain temperature is called a superconductor. Such superconductors are classified into low-temperature superconductors and high-temperature superconductors according to the size of the transition temperature.

A low-temperature superconductor refers to a material that becomes a superconductor at a temperature of about 4K. Since it is processed in the form of a wire, it is easily wound into a coil and used for a superconducting magnet.

In contrast, a high-temperature superconductor refers to a material that becomes a superconductor even at a temperature of 30K or more, and is processed into a tape form, so that it cannot be wound in the form of an electromagnet like the low-temperature superconductor, so that a plurality of coils in the form of a pancake or double pancake are formed. layered and used.

In this regard, Patent Document 1, 'Superconducting Magnet and Superconducting Magnet Manufacturing Method' has been proposed.

1 is 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 consists of

The connecting member 23 is composed of a connecting rod and a nut, and fixes the plurality of superconducting plates to maintain a stacked state.

However, the superconducting magnet is manufactured in a room temperature environment and used in a cryogenic environment. In this case, a thermal contraction phenomenon in which a volume is reduced due to a temperature change occurs.

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

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

In order to solve the above problems, the connecting member 23 should be formed in consideration of the contraction length of the superconducting plate 1 . That is, the contraction length of the connection member 23 and the superconducting plate 1 is the same, or the contraction length of the connection member 23 is longer than the contraction length of the superconducting plate 1, but the connection member 23 ) and the superconducting plate 1 should not be damaged.

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

KR 10-1311459 B1

An object of the present invention is to stably fix the superconducting coil by adjusting the contraction length of the tie rod to be less than the total contraction length of the superconducting coil through a tie rod formed of two or more parts having different thermal contraction coefficients, thereby preventing the quench phenomenon, An object of the present invention is to provide a tie rod for a superconducting magnet that prevents a superconducting coil and a tie rod from being deformed or damaged by compressive stress and thermal stress caused by a difference in contraction length.

A 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 than other parts. At this time, the heat shrinkage 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 formed of two or more of aluminum, stainless steel, copper, and G-10, in which the first part and the second part are molded together and shrink-fitted.

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

According to an embodiment of the present invention, the quench phenomenon is prevented by stably fixing the superconducting coil by adjusting the contraction length of the tie rod to be less than the total contraction length of the superconducting coil through a tie rod formed of two or more parts having different thermal contraction coefficients. and prevent deformation or damage of the superconducting coil and the tie rod due to compressive stress and thermal stress generated due to the difference in contraction length.

1 is a perspective view of a superconducting magnet according to the prior art;
2 is a view showing an example of heat shrinkage of a superconducting magnet according to the prior art.
3 is a perspective view of a superconducting magnet including a tie rod according to an embodiment of the present invention.
4 is an exploded perspective view of a tie rod according to an embodiment of the present invention;
5 is a view 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 accompanying drawings, it will be described in detail so that those skilled in the art can easily carry out the present invention. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the accompanying drawings.

3 is 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 wire or may have a form in which a plurality of pancakes or double pancakes are stacked. Alternatively, as in the prior art, a plurality of superconducting plates may be stacked.

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 an area larger than that of the superconducting coil 100 and are respectively positioned above and below the superconducting coil 100 . In addition, a plurality of coupling holes spaced apart from each other are formed in the edge regions of the upper and lower plates 210 and 220 .

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

The tie rod 230 according to an embodiment of the present invention is formed by coupling a plurality of parts coaxially, and a portion of each part positioned at both ends is directed to the top of the top plate 210 and the bottom of the bottom plate 220. penetrated In addition, threads are formed on the outer circumferential surface of each part located at both ends.

The nuts 240 are respectively located on the upper part of the upper plate 210 and the lower part of the lower plate 220, and are coupled with the tie rods 230 to fix the upper and lower plates 210 and 220 so as not to be 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.

4 is 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 shrinkage coefficient than 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 shrinkage coefficient of the first part 231 is equal to that of the second part 232. greater than the heat shrinkage coefficient.

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 may be formed by including any two or more of non-magnetic materials.

The diameter of each part is formed to be the same, but the height is formed differently according to the thermal 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 a height direction so as to be molded to each other.

In detail, both 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 coupled with the first part 231 .

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

After the first and second parts 231 and 232 are molded together, they are shrink-fitted.

According to another embodiment of the present invention, the first and second parts 231 and 232 are formed with a screw thread on the inside of the depressed surface and formed on the outside of the protruding surface, so that the first and second parts 231 and 232 are screwed together

5 is a view 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, since the contraction length of the tie rod 230 is greater than the contraction length of the superconducting coil 100, the upper and lower surfaces of the superconducting coil 100 come into surface contact with the upper and lower plates 210 and 220.

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

Alternatively, when the contraction length of the tie rod 230 is longer than the contraction 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 contraction length. is generated and the superconducting coil 100 is fixed.

The contraction 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

is the contraction length,

is the initial length,

is the current length,

is the thermal 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 means the length from the lower end of the upper plate 210 to the upper end of the lower plate 220, and is the same as the initial length of the superconducting coil 100.

That is, the contraction length of the tie rod 230 is determined by the heat contraction coefficient of the material forming each part. In addition, the contraction length of the tie rod 230 is determined in consideration of the compressive stress generated in the superconducting coil 100 due to the difference in contraction length and the yield strength of the superconducting coil 100 . Accordingly, the contraction 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.

In addition, compressive stress is generated in the superconducting coil 100 and thermal stress is generated in the tie rod 230 in proportion to the contraction 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

is the material elastic modulus.

That is, the contraction length of the tie rod 230 is a range in which the tie rod 230 is not deformed or damaged by the thermal stress in consideration of the thermal stress generated in the tie rod 230 and the yield strength of the tie rod 230. is determined within

Looking at the superconducting magnet including the connecting member 23 according to the prior art shown in FIGS. 1 and 2, since the connecting member 23 is formed of a single material, the contraction length of the connecting member 23 is the superconducting coil 100 It is not easy to adjust to be more than the contraction length of

In detail, according to Equation 1, the initial length of the connecting member 23 is equal to the initial length of the superconducting coil 100. Therefore, in order to adjust the contraction 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 adjust the contraction 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 coupling the first part 231 and the second part 232, but the first part 231 is more heat-shrinkable than the second part 232. coefficient is large. That is, the contraction length of the first part 231 is longer than that of the second part 232 .

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

At this time, the contraction length can be easily adjusted by changing the material 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 the material of the tie rod 230 are 0.4% and 0.3%, respectively, between 77K and 300K. 0.32% and 1%.

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

That is, in the present invention, one or more of the number of parts, the initial length and initial diameter of each part, or the material of each part is changed in order to adjust the contraction length of the tie rod 230 . 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: first part
232: second part
240: nut

Claims (5)

In a tie rod for a superconducting magnet connecting between upper and lower plates respectively located above and below the superconducting coil to fix the superconducting coil,
The tie rod,
A tie rod for a superconducting magnet formed by combining a plurality of parts, wherein at least one part has a different heat shrinkage coefficient than other parts. According to claim 1,
The tie rod,
The heat shrinkage 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,
The tie rod for a superconducting magnet in which the first part is provided between the second parts. According to claim 2,
The total contraction length of the superconducting coil is,
A tie rod for a superconducting magnet, characterized in that less than the sum of the contraction lengths of the first part and the second part. According to claim 3,
The tie rod,
A tie rod for a superconducting magnet, characterized in that the first part and the second part are molded together and shrink-fitted. According to claim 4,
The tie rod,
A tie rod for a superconducting magnet, characterized in that it is formed of at least two of aluminum, stainless steel, copper, and G-10.

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