JPS6237521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetizing yoke for a permanent magnet.

For magnetizing a permanent magnet, a magnetizing yoke corresponding to the desired number of poles is usually used. Recently, multi-pole magnetized disk-shaped permanent magnets have been widely used for speed control of small motors, and the number of poles is increasing in order to improve control accuracy. Therefore, multi-pole magnetized yokes are increasingly required to be precise, strong, and have a long life.

That is, as shown in FIGS. 1 and 2, in the conventional magnetizing yoke, grooves are dug in the inner surface of the yoke 1 of a circular ring made of soft iron at regular intervals along the circumference in the axial direction of the circular ring, and enamel, etc. After half-embedding the conductive wire 2 with a circular cross-section and insulating it, the inner peripheral surface of the yoke 1 is cut into a perfect circle as shown in Figs. 3 and 4 to ensure dimensional accuracy and magnetization. By shortening the distance to object 3, the magnetic properties were kept strong. However, this magnetizing yoke does not allow the object to be magnetized to
The inner surface of the yoke is subject to severe abrasion due to the insertion and removal of the conductor 2, and electromagnetic resistance increases due to abrasion of the conductor 2, resulting in frequent disconnections. In addition, since a part of the conductor is cut when processing the inner peripheral surface, the cross-sectional area of the conductor becomes smaller, which leads to a decrease in the current flowing.
Another drawback was that the number of lines of magnetic force generated was reduced. Furthermore, since the cross section of the conducting wire is circular, it is not possible to embed the conductive wire at a pitch smaller than its diameter, and it also has the disadvantage that it is not possible to have a large number of poles.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate these drawbacks and provide a highly accurate magnetizing yoke that can withstand long-term use without failures such as wire breakage, and can be strongly magnetized regardless of the increase in the number of poles.

In the present invention, a conducting wire 2 or 2' having a circular or approximately elliptical cross-sectional shape according to magnetization design specifications is pushed into a groove 4 of a pre-processed soft iron yoke 1'.
The upper surface of the conducting wire 2 or 2' is positioned below the surface connecting both shoulders of the groove 4 shown in FIG. 5, that is, inside the groove 4. The grooves 4 are provided on the inner circumferential surface of the annular yoke 1' in the annular axis direction, and are arranged at regular intervals along the circumference. Thereafter, the inner circumferential surface of the yoke 1' is cut into a predetermined size and shape. At this time, the conducting wire 2 or 2' is always placed below the inner peripheral surface of the yoke 1, that is, inside the groove 4, as shown in FIGS. 6 and 7.

The conducting wire may be of any material with good electrical conductivity, such as copper, silver, gold, or aluminum.The conducting wire may also be insulated with enameled wire coated in advance, or with insulating varnish adhered to the inner surface of the groove in advance. A treatment may be performed by pouring an agent to both bond and insulate the conductor wire. Further, the elliptical conducting wire 2' can be easily obtained by rolling a circular conducting wire with a metal roll or the like to give it a substantially elliptical shape.

In this way, the cross-sectional area of the conductor does not decrease during the yoke manufacturing process, and the conductor does not wear out due to the insertion and removal of magnetized objects, so the conductor can withstand long-term use without disconnection due to the large current of magnetization. . In addition, when the number of poles is extremely large, the pitch becomes narrow and the magnetizing current is insufficient for a circular conductor, and the desired strength of magnetization may not be achieved. Since it is used by arranging it in the radial direction of the long-diameter yoke, a large cross-sectional area can be obtained, a predetermined current can be flowed easily, and magnetization with a desired strength can be achieved.

Example 1 When magnetizing 76 poles on the outer periphery of a disk with a diameter of 20 mm and a thickness of 3 mm in a nylon 6 plastic magnet filled with barium ferrite powder, an outer diameter of 70
A groove with an opening of 0.5 mm and a depth of 0.95 mm is machined to a pitch of 0.84 mm on the inner peripheral surface of the yoke made of soft iron with an inner diameter of 20.2 mm.
It was rolled into a substantially elliptical cross-sectional shape of 0.46 mm and press-fitted into the groove. After that, the inner peripheral surface of the yoke is ground and the diameter
It was set to 20.24mm. The surface Gauss of the 76-pole magnet thus magnetized was approximately 700 Gauss. Additionally, 100,000 magnets were magnetized using this yoke, and it is still in use.

Example 2 When making a multi-polar magnet with the same dimensions as Example 1 except that the number of magnetic poles was 100, the width of the groove of the magnetizing yoke was 0.32 mm, the depth was 0.7 mm, the pitch was 0.636 mm, and the pitch was 0.46 mm. A copper wire having a diameter of 0.6 mm was rolled and deformed to have a major axis of 0.6 mm and a minor axis of 0.3 mm, and was press-fitted into the groove. still,
At this time, an epoxy adhesive was applied to the groove in advance, and after the conductor was press-fitted, it was heated and cured to complete the magnetizing yoke. The surface Gauss of the disc magnet magnetized with this material was approximately 300 Gauss. Additionally, this magnetizing yoke has been used to magnetize 120,000 pieces, and it still withstands use.

Comparative Example When making a 76-pole magnet similar to Example 1, copper wire with a diameter of 0.68 mm was wired with a width of 0.69 mm and a depth of 0.69 mm using the conventional method.
A magnetizing yoke was completed in the same manner as in Example 1 except for embedding it in the grooves machined to 0.69 mm and pitch 0.84 mm.

As a result of magnetization with this material, the surface Gauss is approximately 600
Gauss, and breakage occurred when the number of magnetized magnets was approximately 10,000.

As shown in the examples, the magnetizing yoke according to the present invention can withstand continuous long-term use without failures such as wire breakage, and greatly contributes to improving work efficiency and stabilizing quality. In addition, since the cross-sectional area of the conducting wire can be increased, even when magnetizing a large number of poles, it is possible to conduct electricity without reducing the current, and it can be magnetized strongly, making it possible to create multi-pole permanent magnets that are more precise and stronger than conventional magnets. What has become possible has greatly contributed to the rapid changes in technology and the progress of industry.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the state of embedding the conductor wire by the conventional method, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a cross-sectional view showing the finished state of the magnetizing yoke by the conventional method, and Fig. 4 The figure is an enlarged view of the main part of Fig. 3 showing the relative position with respect to the magnetized object during magnetization, Fig. 5 is a sectional view showing the magnetizing yoke according to the present invention, and Fig. 6 is the main part of Fig. 5. The enlarged view, FIG. 7, is an enlarged view of the main part of FIG. 5 when an elliptical cross-section conducting wire is used. 1 and 1' are yokes, 2 and 2' are conducting wires, 3 is a magnetized object, and 4 is a groove.

Claims (1)

[Scope of Claims] 1. Grooves in the axial direction of the annular ring are provided at regular intervals along the circumference on the inner peripheral surface of the yoke of the annular ring, and a conducting wire is embedded in each groove deeper than the surface connecting both shoulders of the groove, A method for manufacturing a magnetized yoke, characterized in that the inner circumferential surface of the yoke is cut to a predetermined dimension without cutting the conducting wire. 2. The method of manufacturing a magnetized yoke according to claim 1, wherein the conductive wire has a substantially elliptical cross-sectional shape, and its major axis is arranged in the radial direction of the yoke.