JP3102285B2 - High precision electromagnet core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron core of a multi-pole electromagnet which requires extremely high precision with respect to the center position of the magnetic poles facing each other.

[0002]

2. Description of the Related Art In accelerators such as linear accelerators (linacs), synchrotrons, and storage rings (storage rings) used in the fields of high energy physics, use of synchrotron radiation, and radiation cancer treatment, charged particles such as electrons,
Various electromagnets are used to control the behavior of positrons, ions, and the like. As a typical example,
Bending electromagnets (bending magnets, dipole electromagnets) that act as mirrors, quadrupole electromagnets (quadrupole magnets) that act as lenses, and hexapole electromagnets (sector pole magnets) that correct chromatic aberration of charged particles are known. I have.

[0003] Of these electromagnets, a normal deflection electromagnet except for a special one has two opposing magnetic pole faces formed in parallel, and the uniform range of the magnetic field is larger than the range required for controlling charged particles. Since it is made wider, the accuracy of the alignment of the centers of the opposing magnetic poles is set relatively low.

[0004] On the other hand, in general, in a multipolar electromagnet having more than a quadrupole electromagnet, the shape of the opposing magnetic pole faces is not a parallel plane, and the shape of each magnetic pole face is cylindrical, hyperbolic (quadrupole electromagnet), It takes a complicated shape to achieve the required magnetic field distribution, such as a curved surface (six-pole electromagnet) represented by a quadratic function and a combination thereof or a straight line connecting them.

[0005] As an example of a conventional multipole electromagnet, a core of a quadrupole electromagnet is shown in Figs. As shown in FIGS. 3 to 5, in the case of a conventional quadrupole electromagnet (multipole electromagnet), the facing magnetic pole faces are not parallel planes. In order to obtain a predetermined magnetic field distribution using such a quadrupole electromagnet, not only the shape of each magnetic pole 1 but also the interval between adjacent magnetic poles 1 and the magnetic pole center of the opposing magnetic poles 1 must be mechanically matched. Are the essential requirements. From the above, the processing and assembly accuracy is originally stipulated from the necessity of obtaining a predetermined magnetic field accuracy. However, in actuality, since there are machine processing errors and assembly errors, the Accuracy of about 0.1 mm (several tens of microns or less for high-precision ones) will be specified. In order to satisfy this accuracy, conventionally, as shown in FIGS. 3 to 5, a knock pin 5 or the like is used for positioning the magnetic pole 1 and the return yoke 2 at the time of assembly.
A bolt 4 or the like is used as a method of fixing the motor and the return yoke 2 (hereinafter referred to as “prior art 1”).

Further, another example of the iron core of the quadrupole electromagnet is shown in FIGS.
FIG. 6 to 8, in order to align and fix the magnetic pole 1 and the return yoke 2, the protrusion (male type) 1a of the magnetic pole 1 and the groove (female type) 2a of the return yoke 2 are fitted to each other. The magnetic pole 1 and the return yoke 2 can be fitted to each other, and a bolt 4 or the like is used as a method of fixing the fitted magnetic pole 1 and the return yoke 2 (hereinafter referred to as “prior art 2”). ).

The performance of the electromagnets shown in the prior arts 1 and 2 is confirmed by measuring the magnetic field.

The accuracy of the magnetic pole length (parallel to the traveling direction of the charged particles) of each magnetic pole 1 may be relatively coarse, and may be 0.5 mm.
Degree, and in some cases, up to the order of mm.

[0009]

In order to obtain the magnetic field distribution required in the multipole electromagnets as shown in the prior arts 1 and 2, the individual magnetic poles 1 are processed with high precision, and the magnetic poles 1 and the return yoke are formed. When assembling with 2, dowel pins 5
Alternatively, the center of the magnetic pole of the opposing magnetic pole is aligned by performing alignment using a fitting structure or the like. In this alignment, if the processing of the individual magnetic poles 1 is performed with high precision, the magnetic pole center lines of the opposing magnetic poles 1 coincide with each other, whereby the interval between the adjacent magnetic poles 1 is also maintained at a predetermined value. Will be.

The problem here is the alignment of the magnetic pole center lines of the opposing magnetic poles 1 during assembly. In the case of the prior art 1 using the knock pin 5 shown in FIGS. 3 to 5, holes for the knock pin 5 are separately formed in the magnetic pole 1 and the return yoke 2 in advance. Therefore, a processing error occurs in each of them. Further, when the knock pin 5 is used, pure iron or the like is used as a material of the magnetic pole 1 and the return yoke 2, while stainless steel or the like is used as a material of the knock pin 5 as a non-magnetic material. Due to the difference in hardness, galling and burning may occur during disassembly and assembly, and reproducibility of disassembly and assembly cannot be obtained. The size of the knock pin 5 is required to be as small and short as possible so as not to adversely affect the magnetic field distribution at the tip of the magnetic pole. Therefore, when the magnetic pole 1 and the return yoke 2 are fixed by the bolt 4 or the like, it is impossible. When a strong force is applied, the magnetic pole 1 may be bent and fixed without being able to withstand the force, and it is not sufficient as a reference for alignment.

On the other hand, the prior art 2 using the fitting structure shown in FIGS. The first
, The positional relationship between the magnetic pole center of the protrusion (male type for fitting) 1a of the magnetic pole 1 and the magnetic pole center of the groove (female type for fitting) 2a of the return yoke 2 is the same. It becomes indispensable, and very high precision is required at the time of processing each single item, so that the processing cost increases. Second
Means that the final finishing of the magnetic pole 1, especially the magnetic pole tip, is performed after the magnetic pole 1 and the return yoke 2 are assembled. In this case, the machining allowance is measured precisely by a three-dimensional coordinate measuring instrument or the like. Since the return yoke 2 and the magnetic pole 1 are integrally processed, the cost of the intermediate inspection is increased, and the processing machine needs to be one size larger than when the magnetic pole 1 and the return yoke 2 are individually processed. become,
Processing costs increase. Third, once the magnetic pole 1 and the return yoke 2 are assembled, and after the measurement of the final finishing allowance is completed, the magnetic pole 1 and the return yoke 2 are divided for finishing the magnetic pole portion. More processes,
This will increase costs.

In the case of an electromagnet, a magnetic field is measured after manufacturing to confirm its performance. However, in the prior arts 1 and 2, a predetermined magnetic field performance is obtained due to the above-mentioned problems in processing and assembly. May not be possible. In that case, in prior arts 1 and 2, there was no alternative but to rework the entire electromagnet core, in part or in the worst case.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-precision electromagnet core capable of solving the above-mentioned problems, quickly and surely aligning the center of the magnetic pole of the opposed magnetic pole, and reducing the number of working steps and processing costs. To provide.

[0014]

SUMMARY OF THE INVENTION The present invention is an iron core of an electromagnet capable of dividing a magnetic pole and a return yoke, and the return yoke is provided in a direction inclined at a predetermined angle with respect to a magnetic pole center line of the electromagnet. The magnetic pole is provided with a protrusion which can be fitted with a predetermined space in the groove provided in parallel with the magnetic pole center line, between the fitted protrusion and the groove. A wedge-shaped structure for adjusting the position of the magnetic pole and the return yoke is disposed in the space. Further, a groove may be provided on the magnetic pole, and a protrusion may be provided on the return yoke.The groove may be provided in parallel with the magnetic pole center line, and the protrusion may be inclined at a predetermined angle with respect to the magnetic pole center line. It may be provided.

[0015]

By assembling the return yoke and the magnetic poles, the magnetic field is measured, and the position of the magnetic poles is adjusted until a predetermined magnetic field accuracy is obtained, whereby an extremely accurate electromagnet can be manufactured. To adjust the magnetic pole position, the magnetic pole is temporarily fitted into the return yoke, a wedge-shaped structure is arranged in the space between the magnetic pole and the return yoke, and the wedge-shaped structure is moved by an external force to adjust the position of the magnetic pole. The magnetic pole is fixed by fixing the magnetic pole at the time when the magnetic pole center of the magnetic pole coincides with the magnetic pole center of the opposing magnetic pole attached in advance. Thereby, the magnetic pole centers of the magnetic poles facing each other can be matched with high accuracy.

[0016]

Next, the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an embodiment of an electromagnet core according to the present invention, in which only one magnetic pole and a return yoke portion to which the magnetic pole is attached in the case of a quadrupole electromagnet are shown. FIG. 2 and FIG.
FIG.

As shown in FIGS. 1 and 2, the magnetic pole 1 is provided with a fitting projection (male type) 1a parallel to the magnetic pole center line 7. On the other hand, the return yoke 2 is provided with a fitting groove (female type) 2a that can be fitted to the male type 1a in a direction inclined by a predetermined angle with respect to the magnetic pole center line 7. Further, wedge-shaped structures 10, 10 are provided in a space formed between the male mold 1a and the female mold 2a. The magnetic pole 1 fitted to the return yoke 2 causes the wedge-shaped structures 10, 10 arranged in the space to be moved by an external force in a direction indicated by an arrow 13 in FIG. 2 (in FIG. 2, and indicates a moving direction). By moving the arrow 1 in FIG.
The direction indicated by 4 (in FIG. 2, and indicates the moving direction)
Can be moved to The magnetic pole 1 is provided with a tap 12, and the return yoke 2 is provided with a stupid hole 11 in consideration of a position adjustment allowance of the magnetic pole 1. The hole 11 a above the stupid hole 11 is a hole having a larger inner diameter than the stupid hole 11.

The installation of the electromagnet core of this embodiment is performed in the following order. FIGS. 1 and 2 show an example in which a through bolt 8 is used as a method of fixing the magnetic pole 1 and the return yoke 2. The bolt 8 is adapted to be screwed into the tap 12. The outer diameter of the head 8a of the bolt 8 is smaller than the inner diameter of the hole 11a and larger than the inner diameter of the stupid hole 11. The magnetic pole 1 and the return yoke 2 are processed as described above, and one magnetic pole 1 is fitted and attached to the return yoke 2 to fix the magnetic pole 1 at a mechanically determined position. The magnetic pole facing the fixed magnetic pole 1 is attached to the return yoke 2 in the same manner, and coils are attached to both magnetic poles. At this time, the coil is energized, and the magnetic field is measured using a Hall element or the like. If a predetermined value is obtained according to the magnetic field measurement result, the center of the magnetic pole 1 coincides with the center of the magnetic pole of the opposite magnetic pole. At this point, if the magnetic pole 1 is fixed to the return yoke 2 by the through bolt 8, Opposing magnetic poles will be installed with high accuracy in terms of magnetic field performance. Similarly, other magnetic poles may be provided.

Although FIGS. 1 and 2 show an example in which the return yoke 2 is a flat plate, it goes without saying that the return yoke 2 itself may have any other shape.
Further, as means for fixing the magnetic pole 1 and the return yoke 2,
FIGS. 1 and 2 show an example in which the stupid hole 11 and the through bolt 8 are used, but these cannot be limited to the conditions of the present invention. Further, the sectional shapes of the male and female types shown in FIG. 1 and the positional relationship between the magnetic pole 1 and the return yoke 2 do not similarly restrict the conditions of the present invention.

Further, in the wedge-shaped structure shown in FIGS. 1 and 2, two magnets are not required for each magnetic pole, and the structure and the shape of the wedge can be adjusted so that the position of the magnetic pole can be adjusted. The invention is not particularly limited to a flat trapezoidal shape as described in the present embodiment. Furthermore, the assembly procedure shown here is only one embodiment of the present invention, and does not restrict the present invention with respect to other assembly procedures.

For example, in a quadrupole electromagnet frequently used in a circular accelerator such as a storage ring, it is required to reduce hexapole and dodecapole components other than the quadrupole component as much as possible.
In the case of using the electromagnet core of the present invention in such a case, if the inclination (inclination) of the fitting projection and the groove is set to 1/40 as an example, the pole piece is moved by 4 mm in the magnetic pole length direction. In order to adjust with a precision of 100 μm with respect to the opposing pole piece, the pole piece may be moved within a range of 1 mm in the direction of the magnetic pole.

[0023]

As described above, according to the present invention, it is possible to position the opposing magnetic poles based on the result of the magnetic field measurement, and to obtain an electromagnet core with high magnetic field performance. Thus, an industrially useful effect is obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing only one magnetic pole of a quadrupole electromagnet and a return yoke portion to which the magnetic pole is attached, according to an embodiment of the electromagnet core of the present invention.

FIG. 2 is an AA view of FIG. 1 showing only one magnetic pole of a quadrupole electromagnet and a return yoke portion to which the magnetic pole is attached, according to one embodiment of the electromagnet core of the present invention.

FIG. 3 is a front view showing an example of a conventional quadrupole electromagnet using a knock pin for positioning a magnetic pole and a return yoke.

FIG. 4 is a plan view showing an example of a conventional quadrupole electromagnet core using a knock pin for positioning a magnetic pole and a return yoke.

FIG. 5 is a view showing an example of a conventional quadrupole electromagnet core using a knock pin for positioning a magnetic pole and a return yoke.
FIG.

FIG. 6 is a front view showing another example of a conventional electromagnet core using a fitting structure in which grooves are vertically formed on the surfaces of the magnetic pole and the return yoke for positioning the magnetic pole and the return yoke.

FIG. 7 is a plan view showing another example of a conventional electromagnet core using a fitting structure in which grooves are vertically formed on the surfaces of the magnetic pole and the return yoke for positioning the magnetic pole and the return yoke.

FIG. 8C shows another example of a conventional electromagnet core using a fitting structure in which grooves are vertically formed on the surfaces of the magnetic pole and the return yoke for positioning the magnetic pole and the return yoke.
FIG.

[Explanation of symbols]

 1: magnetic pole 2: return yoke 3: coil 4: fixing bolt between magnetic pole and return yoke 5: knock pin 7: magnetic pole center line 8: through bolt 8a: head 9: through bolt for fixing return yokes 10: Wedge-like structure 11: Stupid hole considering magnetic pole position adjustment allowance 11a: Hole above stupid hole 12: Tap hole drilled in magnetic pole 13: Moving direction 14: Moving direction

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 7/06

Claims (3)

(57) [Claims] 1. An iron core of an electromagnet capable of dividing a magnetic pole and a return yoke, wherein the return yoke has a groove provided in a direction inclined at a predetermined angle with respect to a magnetic pole center line of the electromagnet. The groove is provided in parallel with the magnetic pole center line.The groove includes a protrusion that can be fitted with a predetermined space, and the space between the fitted protrusion and the groove has the magnetic pole and the groove. A high-precision electromagnet core comprising a wedge-shaped structure for adjusting the position of the return yoke. 2. The high-precision electromagnet core according to claim 1, wherein a groove is provided on the magnetic pole, and a protrusion is provided on the return yoke. 3. The high-precision electromagnet core according to claim 1, wherein the groove is provided in parallel with the magnetic pole center line, and the protrusion is provided in a direction inclined at a predetermined angle with respect to the magnetic pole center line.