JP2024049570A - Method for assembling a magnetic field generating device - Google Patents

Abstract

To provide a method for correctly and safety assembling a magnetic field generation device by Halbach array without increasing a size and using an assemble jig with a layout degree of freedom.SOLUTION: A method of assembling a magnetic field generation device 1, contains: a step of obtaining a plurality of adhesion bodies so that each of a plurality of permanent magnets 21a and 21b, respectively and a plurality of auxiliary yokes 22, respectively are adhered; a step of obtaining a plurality of magnetized adhesion bodies by magnetizing the plurality of adhesion bodies; a step of bolting each auxiliary yoke of each magnetized adhesion body positioned at a center of a magnet array and a back yoke 11 to fix each magnetized adhesion body with the back yoke; a step of bolting each auxiliary yoke of the other magnetized adhesion body adjacent to the magnetized adhesion body positioned at the center of the magnet array and the back yoke to fix the other magnetized adhesion body to the back yoke; and a step of bolting each auxiliary yoke of the other magnetized adhesion body adjacent to the other magnetized adhesion body and the back yoke to further fix the magnetized adhesion body to the back yoke.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for assembling a magnetic field generating device using a Halbach array.

The Halbach array of permanent magnets is an arrangement in which the magnetization direction of adjacent magnets in a magnet row is rotated by 90 degrees, and since the magnetic field can be concentrated on one main surface side of the magnet row, a strong magnetic field can be obtained by facing the magnets in the Halbach array to form a dual Halbach array. Halbach array magnetic field generators (magnetic circuits) are widely used in research fields such as synchrotron radiation and industrial fields such as linear motors, and are described in, for example, Patent Document 1.

While a magnetic field generator (magnetic circuit) using a Halbach array can generate a strong magnetic field, because magnets with magnetization directions differing by 90 degrees are arranged side by side, a force acts in the direction of rotation of the magnets as they are brought closer together, making it extremely difficult to arrange them precisely and glue them to the yoke. For this reason, when gluing, it is necessary to slide the magnets closer together while pressing them down with a jig.

Patent document 2 describes a method for assembling a magnet array in a Halbach array in which magnetized main pole magnets and auxiliary pole magnets are configured as a magnet unit, and adjacent auxiliary pole magnets in multiple magnet units are arranged so as to be spaced apart from each other and then glued together. In addition, patent document 3 describes the use of an assembly jig as a method for assembling a magnetic field generating device that uses magnetized magnets, although it is not a Halbach array.

JP 2007-19127 A JP 2016-163366 A JP 2000-51175 A

In the assembly method of Patent Document 2, multiple magnet units are formed by combining one main pole magnet and two interpole magnets, and then each magnet unit is fixed to a plate-shaped member, so the freedom of design of the magnetic field generator is small. Also, since each unit is spaced apart to facilitate assembly, the magnetic field generator inevitably becomes large. Furthermore, an assembly jig is required for assembly. Also, in the assembly method of Patent Document 3, a dedicated jig is made just for assembly, which is a factor in increasing costs. In the method using these jigs, the adhesive applied to the bonded surface is slid as if to scrape it off, so much of the adhesive is scraped off from the bonding surface, and there is a risk of insufficient adhesive strength.

The present invention aims to provide a method for assembling a magnetic field generator using a Halbach array, which allows for a high degree of freedom in the design of the magnet arrangement, does not increase the size, and can be assembled accurately without using an assembly jig.

The method for assembling a magnetic field generating device of the present invention is a method for assembling a magnetic field generating device having a magnet array in which a plurality of permanent magnets are arranged in a Halbach pattern and a back yoke on which the magnet array is arranged, and includes the steps of: bonding the plurality of permanent magnets to a plurality of auxiliary yokes to obtain a plurality of adhesive bodies; magnetizing the plurality of adhesive bodies in the magnetization easy direction of the permanent magnets to obtain a plurality of magnetized adhesive bodies; fixing the magnetized adhesive body to the back yoke by bolting the auxiliary yoke of the magnetized adhesive body located at the center of the magnet array and the back yoke; fixing the other magnetized adhesive body to the back yoke by bolting the auxiliary yoke of another magnetized adhesive body adjacent to the magnetized adhesive body located at the center of the magnet array fixed to the back yoke and the back yoke; fixing the still further magnetized adhesive body to the back yoke by bolting the auxiliary yoke of a further magnetized adhesive body adjacent to the other magnetized adhesive body fixed to the back yoke and the back yoke.

The auxiliary yoke and back yoke of the magnetized adhesive body located in the center of the magnet row are preferably bolted with a countersunk bolt, and the auxiliary yoke and back yoke of the other magnetized adhesive body and the further other magnetized adhesive body are preferably bolted with a cap bolt.

It is preferable that the bolt hole for the cap bolt has a clearance with respect to the bolt diameter.

It is preferable to have a pair of magnet arrays in which multiple permanent magnets are arranged in a Halbach pattern, a pair of back yokes in which the pair of magnet arrays are arranged, and a columnar member that magnetically couples the pair of back yokes.

The present invention provides a method for assembling a magnetic field generator using a Halbach array, which allows for a high degree of freedom in the design of the magnet arrangement, does not increase the size, and can be assembled accurately without using an assembly jig.

FIG. 2 is a perspective view of a magnetic field generating device produced by the assembly method of the present invention. FIG. 2 is a front view of a magnetic field generating device manufactured by the assembly method of the present invention. FIG. 2 is a side view of a magnetic field generating device produced by the assembly method of the present invention. 1A to 1C are diagrams illustrating an assembly procedure of the assembly method of the present invention. 1A to 1C are diagrams illustrating intermediate steps in the assembly method of the present invention. 1A to 1C are diagrams illustrating intermediate steps in the assembly method of the present invention. 1A to 1C are diagrams illustrating intermediate steps in the assembly method of the present invention. 1A to 1C are diagrams illustrating intermediate steps in the assembly method of the present invention. 11A to 11C are diagrams illustrating another example of an assembly method according to the present invention.

The following describes an embodiment of the present invention with reference to the drawings. FIG. 1 is a perspective view showing an example of a magnetic field generator produced by the assembly method of the present invention, FIG. 2 is a front view, and FIG. 3 is a side view. As shown in FIGS. 1 to 3, the magnetic field generator 1 has a pair of magnet rows 2a and 2b fixed to a plate-shaped back yoke 11, which are arranged facing each other with a gap (the distance between the magnet rows 2a and 2b is, for example, 8 to 15 cm) between them and a columnar member 12. The magnet rows 2a and 2b include permanent magnets 21a and 21b, and an auxiliary yoke 22. The permanent magnets 21a and 21b are anisotropic permanent magnets such as neodymium magnets, alnico magnets, ferrite magnets, and samarium cobalt magnets. The back yoke 11, the auxiliary yoke 22, and the columnar member 12 are made of magnetic materials such as iron.

Next, the magnetization direction of each permanent magnet in magnet rows 2a and 2b will be described with reference to Figure 2. Magnet rows 2a and 2b are arranged in an alternating fashion with main pole magnets 21a1 and 21b1 (the permanent magnets located in the center and the left and right ends in the figure) whose magnetization direction is perpendicular to one main surface (the surface on which the magnet rows are arranged) of back yoke 11, and auxiliary pole magnets 21a2 and 21b2 (permanent magnets sandwiched between the main pole magnets) whose magnetization direction is rotated 90° from the magnetization direction of main pole magnets 21a1 and 21b1 (parallel to one main surface).

The main pole magnets 21a1 and 21b1 located in the center have a magnetization direction facing upward in the figure, and the main pole magnets 21a1 and 21b1 are arranged so that their different magnetic pole faces face each other. The main pole magnets 21a1 and 21b1 located at the left and right ends in the figure have a magnetization direction facing downward in the figure, and the main pole magnets 21a1 and 21b1 are arranged so that their different magnetic pole faces face each other. Furthermore, the auxiliary pole magnets 21a2 of the magnet row 2a have a magnetization direction in a direction away from the main pole magnet 21a1 located in the center, and the auxiliary pole magnets 21b2 of the magnet row 2b have a magnetization direction in a direction approaching the main pole magnet 21a1 located in the center. Note that the magnetization direction of the auxiliary pole magnets 21a2 and 21b2 does not necessarily have to be rotated 90° from the orientation direction of the main pole magnets 21a1 and 21b1 depending on the design of the magnetic field generator 1, and may be in an oblique direction of, for example, 45°, 30°, etc.

By magnetically coupling a pair of magnet rows 2a and 2b, in which main pole magnets and interpole magnets having the above-mentioned magnetization directions are arranged, to the back yoke 11, the auxiliary yoke 22, and the columnar member 12, a strong magnetic field can be generated in the gap in which the pair of magnet rows 2a and 2b face each other. Note that the magnetization direction is the magnetization direction (from the south pole to the north pole) when an anisotropic permanent magnet manufactured by aligning (orienting) the magnetization easy direction in a specific direction is magnetized in the same direction as the magnetization easy direction. In other words, in an anisotropic permanent magnet, the magnetization easy direction (sometimes called the orientation direction) and the magnetization direction are basically the same direction.

The method of assembling the magnetic field generating device of the present invention will be described below with reference to Figures 4 to 8. Figure 4 is a diagram explaining how to form an adhesive body by adhering a magnet and an auxiliary yoke. The permanent magnet 21a1 and the auxiliary yoke 22 are rectangular parallelepipeds, and the auxiliary yoke 22 has two screw holes 23 on its upper surface in Figure 4. The screw holes 23 are provided at positions corresponding to the bolt holes 13 in Figure 15 described later. The upper surface of the permanent magnet 21a1 in Figure 4 and the lower surface of the auxiliary yoke 22 are used as adhesive surfaces, and are adhered with an adhesive such as an epoxy adhesive or an acrylic adhesive to form an adhesive body 24a1. Adhesive bodies 24a2, 24b1, and 24b2 are formed similarly for the other permanent magnets 21a2, 21b1, and 21b2. At this time, as described above, the main pole magnets 21a1 and 21b1 are arranged with the magnetization easy direction of the permanent magnet perpendicular to one main surface of the back yoke 11 (perpendicular to one main surface of the auxiliary yoke 22 in the figure), and the interpole magnets 21a2 and 21b2 are arranged with the magnetization easy direction of the permanent magnet parallel to one main surface of the back yoke 11 (parallel to one main surface of the auxiliary yoke 22 in the figure) before bonding. Next, the bonded bodies are magnetized. In the case of the main pole magnet bonded bodies 24a1 and 24b1, the magnetization is perpendicular to the bonding surface (one main surface of the auxiliary yoke 22) as shown in FIG. 4, and in the case of the interpole magnet bonded bodies 24a2 and 24b2, the magnetization is parallel to the bonding surface (one main surface of the auxiliary yoke 22). In other words, magnetization is performed after bonding. Hereinafter, the bonded body after magnetization is referred to as a magnetized bonded body. In this manner, a plurality of magnetized bonded bodies are prepared. That is, instead of a magnet unit that combines a main pole magnet and an auxiliary pole magnet as in Patent Document 2, the magnetized adhesive body of the main pole magnet and the magnetized adhesive body of the auxiliary pole magnet are prepared separately. This allows for greater freedom in designing the magnet arrangement.

Next, as shown in Figures 5 and 6, the magnetized adhesive 24a1 and the back yoke 11 are fixed with bolts. The magnetized adhesive 24a1 is placed in the center of the magnet array 2a and is fixed by the screw hole 23 drilled in the auxiliary yoke 22 with the flat head bolt 13 through the bolt hole 13h. The magnetized adhesive 24a1 is fixed by the flat head bolt, so it is accurately positioned.

Next, as shown in Figures 7 and 8, the magnetized adhesive 24a2 is fixed to the back yoke 11. As described above, the magnetized adhesive 24a2 (permanent magnet 21a2) has a magnetization direction rotated 90° relative to the adhesive 24a1 (permanent magnet 21a1), so as it approaches the magnetized adhesive 24a1, a force is applied in the direction of rotation, and it is difficult to adhere it with adhesive without using a jig. In the assembly method of the present invention, after the permanent magnet 21a2 is adhered to the auxiliary yoke 22 with a bolt hole, the magnetized magnetized adhesive 24a2 is pressed against the back yoke 11 and moved in the direction of the arrow (thick arrow) in the figure, and bolted with the cap bolt 14 through the bolt hole 14h. At this time, the bolt hole 14h has a slight clearance with respect to the cap bolt 14, and by bolting the magnetized adhesive 24a2 while moving it toward the magnetized adhesive 24a1, it is possible to accurately position it without any gap between the magnetized adhesive 24a1. Therefore, unlike Patent Document 2, there is no need to separate the units to facilitate assembly, and the magnetic field generating device does not become larger. Also, with the above assembly method, accurate positioning is possible without using a dedicated assembly jig. Furthermore, with the conventional method of gluing after magnetization, the magnet is moved in a direction that scrapes off the applied adhesive, which can cause the adhesive layer to become too thin and the adhesive strength to be insufficient. However, with the assembly method of the present invention, the adhesive body that has already been adhered with sufficient adhesive strength is bolted in place, so there is no shortage of strength.

Furthermore, as in magnet example 2a in FIG. 2, magnetized adhesive 24a1 and magnetized adhesive 24a2 are fixed in the same manner. As a result, by sequentially fixing the other magnetized adhesives using the position of the accurately positioned central magnetized adhesive 24a1 as a reference, all of the magnetized adhesives on the magnet row 2a side are accurately positioned and fixed. Note that in the above example, the central magnetized adhesive 24a1 is fixed with a flat head bolt 13, and the other magnetized adhesives are fixed with a cap bolt 14, but this is not limited to this. All may be flat head bolts 13 or cap bolts 14, or both may be used in combination. Also, bolts of other shapes may be used.

The opposing magnet array 2b is fixed in the same manner, and the magnetic circuit is completed by sandwiching the columnar member 12 between the two back yokes 11. The magnetized adhesives 24a1 to 24b2 may be covered with a side cover made of a non-magnetic material such as aluminum or stainless steel.

As shown in FIG. 9, a handle hole 25 can be provided on the front or back side of the auxiliary yoke 22, and a handle 26 can be inserted and fixed in place. The magnetized adhesive 24 can be moved using the handle 26 when fixing it to the back yoke 11, and the handle 26 can be removed after fixing. This avoids the risk of getting one's hand caught between the auxiliary yoke 22 and the back yoke 11, improving safety during assembly work.

The present invention has industrial applicability in that the Halbach array magnetic field generator has a high degree of freedom in the design of the magnet arrangement, and can be assembled accurately and safely without increasing the size of the magnetic field generator and without using assembly tools.

1. Magnetic field generator
11 Back Yoke
12 Pillar members
13 Flat head bolt
13h Bolt hole for countersunk bolt
14 Cap bolt
14h Bolt hole for cap bolt
2a Magnet array
2b Magnet array
21 Magnet
21a1 Main pole magnet
21a2 Interpolated magnet
21b1 Main pole magnet
21b2 Interpolated magnet
22 Auxiliary yoke
23 Screw holes
24 Adhesive
25 holes
26 Handle

Claims (4)

A method for assembling a magnetic field generating device having a magnet array in which a plurality of permanent magnets are arranged in a Halbach array and a back yoke in which the magnet array is arranged, comprising the steps of:
a step of bonding the plurality of permanent magnets and the plurality of auxiliary yokes to obtain a plurality of bonded bodies;
a step of magnetizing the plurality of adhesive bodies in the magnetization easy direction of a permanent magnet to obtain a plurality of magnetized adhesive bodies;
a step of fixing the magnetized adhesive to the back yoke by bolting an auxiliary yoke of the magnetized adhesive located at the center of the magnet array and the back yoke;
a step of fixing the other magnetized adhesive body to the back yoke by bolting an auxiliary yoke of the other magnetized adhesive body adjacent to the magnetized adhesive body located at the center of the magnet row fixed to the back yoke and the back yoke;
a step of fixing the still further magnetized adhesive body to the back yoke by bolting an auxiliary yoke of the still further magnetized adhesive body adjacent to the still further magnetized adhesive body fixed to the back yoke and the back yoke;
A method for assembling a magnetic field generating device, comprising: The method for assembling a magnetic field generator according to claim 1, characterized in that the auxiliary yoke and the back yoke of the magnetized adhesive body located in the center of the magnet row are bolted with flat head bolts, and the auxiliary yokes and the back yokes of the other magnetized adhesive bodies and the further other magnetized adhesive bodies are bolted with cap bolts. The method for assembling a magnetic field generating device according to claim 2, characterized in that the bolt holes for the cap bolts have a clearance with respect to the bolt diameter. The method for assembling the magnetic field generating device according to claim 1, characterized in that it has a pair of magnet arrays in which a plurality of permanent magnets are arranged in a Halbach pattern, a pair of back yokes in which the pair of magnet arrays are arranged, and a columnar member that magnetically couples the pair of back yokes.

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