JPH03102810A - Manufacture of magnet roll and molding apparatus used therefor - Google Patents

Abstract

PURPOSE:To provide a magnet roll having 'intermediate pole' of substantially 0G near the intermediate of the same polarity poles by employing a magnetic field orienting mold in which a yoke member having no exciting coil is arranged between yokes having exciting coils. CONSTITUTION:A magnetic flux excited by the exciting coils of poles is transmitted to the yoke 1 to form a molding magnetic field in a molding cavity 2. A yoke 6 having no exciting coil between the same polarity poles becomes an escaping path of the magnetic flux from yokes 1a, 1b having both adjacent exciting coils, and an 'intermediate pole' is newly formed. Since the magnetic flux passed to the yoke 6 is connected to the outer frame for performing the role of an outer yoke through a nonmangetic material, it actually becomes a stop, and a large quantity of magnetic flux is not passed. Accordingly, 'the intermediate pole' formed in the cavity 2 becomes very small. Thus, the 'intermediate pole' can be generated at the intermediate part of the adjacent equal polarity poles only by the exciting coils of the same number as that of desired poles.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a magnet roll used in developing devices and cleaning devices of electronic copying machines, printers, etc., and a molding device used therein. be. [Prior art and problems] Plastic magnets have a lower content of magnetic material than sintered magnets, so to obtain high magnetic properties, it is necessary to orient anisotropic magnetic particles in a specific direction. There is. Usually, the particles are oriented so that the entire magnet is magnetized in one direction. However, in manufacturing integrated multipole magnets, in order to obtain as high a surface magnetic force as possible, a polar anisotropic orientation method (orienting magnetic particles in the direction of the magnetic flux lines emitted by a die or mold with multiple magnetic field generating poles) is used to create magnets. (method of applying multiple magnetic poles on the same surface)
is known to be effective. Furthermore, it is known that in recent full-color copying machines and the like, it is desirable to have a magnet roll that has adjacent magnetic poles of the same polarity and has a magnetic flux density of substantially OG near the middle. In the conventional polar anisotropic orientation molding method, as shown in FIG. Molding cavity (
2), and an external frame (5) made of magnetic material on the outer periphery.
A molding device equipped with That is, it has been common knowledge that among the yokes for generating an alignment magnetic field, the yokes directly appearing in the molding cavity should be arranged in the molded body for the desired number of magnetic poles. However, with this method, as is clear from the magnetic flux density pattern in FIG. 6, it is extremely difficult to obtain a magnet roll whose magnetic flux density is substantially OG near the middle of the same magnetic poles. A method to solve this problem is to provide a relatively small "intermediate magnetic pole" in the middle of the magnetic poles of the same polarity on the surface of the magnet roll, so that the magnetic flux density can be effectively reduced to OG on the sleeve surface slightly away from the surface. It is known that it is possible to
683). In order to manufacture such a magnet roll, it is conceivable to add more excitation coils to the conventional excitation coils for the number of magnetic poles, but this would inevitably result in a complicated structure. Moreover, when there are many magnetic poles, it is impossible to add one more pole in the middle.

[Means for solving problems]

In view of this situation, the present inventors have developed a structure by using a yoke that does not have an excitation coil in order to obtain an "intermediate magnetic pole" in the middle of the same magnetic poles. j[In order to avoid 9fi and also to prevent the "intermediate magnetic pole" from becoming too large, the external frame that holds the excitation coil is generally made of a magnetic material and serves as a yoke for passing magnetic flux for the excitation coil. By paying attention to the fact that
The inventors have found that the above problem can be solved and have perfected the present invention. That is, the first aspect of the present invention is that when manufacturing a magnet roll having multiple magnetic poles having at least one pair of adjacent same poles in the circumferential direction by orienting or shaping a cylindrical or cylindrical plastic magnet in a magnetic field, A second aspect of the present invention provides a method for manufacturing a magnet roll, characterized in that a mold for magnetic field orientation is used, in which a yoke member having no excitation coil is arranged between yokes having excitation coils corresponding to the same magnetic poles. In a magnetic field orientation molding device equipped with a cylindrical or cylindrical molding cavity portion that is surrounded by a yoke made of a magnetic material and a part between poles made of a non-magnetic material, adjacent same polarity Each of these devices is a device for a magnet roll, characterized in that a yoke having no excitation coil is disposed in the middle of a yoke having an excitation coil corresponding to the magnetic poles.

An explanation will be given based on a drawing showing an example of a device used in the present invention. In Figures 1 and 2, the molding device is an excitation coil (3).
It consists of a yoke (1) having an excitation coil behind it, a yoke (6) without an excitation coil, and an external frame (5). In Fig. 1, the external frame (5) is made of non-magnetic material (5a).
In addition, in Fig. 2, the external frame (5
) consists of a magnetic material and a non-magnetic material part, and the excitation coil (
The yoke (1) having the magnetic material (3) is connected to the magnetic material (5b), and the yoke (6) having no excitation coil is connected to the non-magnetic material (5a). (7) is a die.

FIG. 3 shows another example of the molding apparatus of the present invention, which has a configuration in which the external frame (5) in FIGS. 1 and 2 is not provided. The magnetic materials used in the present invention include SS4L, SIO
Examples include C, S25C, and SUS410. Examples of non-magnetic materials include austenitic stainless steel such as StJS304, copper beryllium alloy, and high manganese steel. There are no particular restrictions on the magnetic powder used in the present invention,
Examples include hexagonal ferrite, samarium-cobalt alloy, neodymium-iron monoboron alloy, and the like.

The synthetic resin used in the present invention is not particularly limited, and includes, for example, polyvinyl chloride, polyethylene, chlorinated polyethylene, polypropylene, boria ξ-d, polyester, polycarbonate, polyphenylene sulfide, acrylic resin, and the like. The molding method of the present invention can be applied to injection molding, extrusion molding, compression molding, etc., but injection molding in particular produces a molded product with good dimensional accuracy, while extrusion molding produces a molded product with uniform magnetic force in the longitudinal direction. Good results. [Effect] By preparing as shown in Figures 1 to 3 above, the seventh
As shown in the figure, the magnetic flux excited by the excitation coil (not shown) of each magnetic pole is transmitted through the yoke (1) and forms a shaped magnetic field as shown by the arrow in a certain shaped cavity (2). The yoke (6) that does not have an excitation coil between the magnetic poles of the same polarity becomes a loophole for the magnetic flux from the yokes (1a) and (1b) that have excitation coils on both sides, and a new magnetic pole ("intermediate magnetic pole") is formed. ．． The magnetic flux that has escaped to the yoke (6) becomes a virtual dead end because the yoke (6) is connected to the external frame that serves as an external yoke via a non-magnetic material, and a large amount of magnetic flux cannot escape. become. Therefore, the "intermediate magnetic pole J" formed in the molding cavity (2) becomes very small.Thereby, only the same number of excitation coils as the desired number of magnetic poles are needed to fill the intermediate part of the adjacent same-polarity magnetic poles. ``It is possible to generate an intermediate magnetic pole J, and as shown in Figure 4,
It is possible to obtain a magnet roll having a magnetic force pattern such that the "intermediate magnetic pole" has a magnetic flux density substantially OG at the sleeve surface position.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited thereto. Example hexagonal ferrite (GP330, manufactured by Toda Kogyo ■) 90.
0% by weight vinyl chloride resin (s 1001. Manufactured by Kanebuchi Chemical Industry ■)
7.0% by weight DOP 2.8% by weight Tribase 0.1% by weight Lead stearate
0. 1% by weight of the above formulation was mixed using a high-speed rotary blade stirrer and then kneaded to produce pellets. Using this pellet, we performed magnetically oriented extrusion molding into a cylindrical shape. The apparatus shown in FIG. 1 was used.

SS41 was used as the magnetic material for the yoke, and SUS304 was used as the non-magnetic material for the interpolar part and the outer frame, and the diameter of the molding cavity formed from these was 20φ. A 6φ core was placed in the center of the die. A magnet roll was obtained by inserting and gluing an iron shaft with a diameter of 6φ into the cylindrical molded body obtained as described above.
Table 1 shows the values of the magnetic flux density at each magnetic pole of the obtained magnet roll and the position between the same magnetic poles. Comparative Example In the example, the same operation was carried out except that the apparatus shown in FIG. 5, in which the yokes and excitation coils were arranged in the same number of yokes as the desired number of magnetic poles of the magnet roll, was used. The results are shown in Table 2.

Table 1 Table 2 [Effects of the Invention] As explained above, the magnetic field oriented molding method and molding apparatus of the present invention can be performed by using the same number of excitation coils as the desired number of magnetic poles of the magnet roll without adding any further excitation coils. ,
It is possible to provide a magnet roll having a substantially OG "intermediate magnetic pole" near the middle of the same magnetic poles.

[Brief explanation of drawings]

1, 2 and 3 are schematic cross-sectional views showing embodiments of the magnetic field orientation forming apparatus of the present invention, FIG. 4 is a magnetic flux density pattern of a magnet roll obtained by the apparatus of the present invention, and FIG. 5 6 is a schematic cross-sectional view showing a conventional magnetic field orientation molding device, FIG. 6 is a magnetic flux density pattern of a magnet roll obtained by the conventional device, and FIG. 7 is an enlarged view of a molding cavity portion in the device of the present invention. DESCRIPTION OF SYMBOLS 1... Yoke 2 having an excitation coil... Molded cavity 3... Excitation coil 4... Inter-pole portion 5... External frame 5a... Non-magnetic material 5b... Magnetic material 6...・Yoke 7 without excitation coil...Dice Figure 5 Figure 6 Flash speed φ 2 Figure 7

Claims (4)

[Claims] 1. When manufacturing a magnet roll with multiple magnetic poles having at least one pair of adjacent same poles in the circumferential direction by magnetic field orientation molding of a cylindrical or cylindrical plastic magnet, an excitation coil corresponding to the adjacent same poles is provided. A method for manufacturing a magnet roll, comprising using a magnetic field orientation mold in which a yoke member having no excitation coil is arranged between yokes. 2. It has an external frame for holding the excitation coil,
2. The manufacturing method according to claim 1, wherein a magnetically oriented mold is used in which a yoke having no excitation coil is connected to the frame via a gap or a non-magnetic material. 3. In a magnetic field orientation molding device equipped with a cylindrical or cylindrical molding cavity defined by a yoke made of a magnetic material disposed around the periphery and an interpolar part made of a non-magnetic material, a A forming device for a magnetic roll, characterized in that a yoke having no excitation coil is disposed in the middle of a yoke having a corresponding excitation coil. 4. Equipped with an external frame to hold the excitation coil,
4. The molding apparatus according to claim 3, wherein the yoke having no excitation coil is connected to the frame via a gap or a non-magnetic material.