JP2010039447A - Magnetic roller and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of not being able to cope with the higher speed and higher image quality of a recent full-color machine since high magnetic flux density cannot be secured inexpensively in a conventional cylindrical magnet roller due to the securing of the high magnetic flux density by using an expensive rare earth based magnet block and the imbedding of the same in a groove in the axial direction of the cylindrical magnet. <P>SOLUTION: The cylindrical magnet which is formed by molding a mixture mainly composed of ferromagnetic powder and a resin binder has the cylindrical magnet imbedded with a plurality of numbers of magnet pieces that are repulsed magnetically from each other in an indention in an outer periphery section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnet roller used in an electrophotographic copying machine, a facsimile machine, a laser printer, and the like, and a manufacturing method thereof.

Conventionally, as a cylindrical or columnar magnet roller using a mixture mainly composed of a ferromagnetic powder and a resin binder, (1) a magnetic roll is formed by magnetic field orientation molding of a multipolar cylindrical or columnar plastic magnet. When manufacturing, by using a magnetic field orientation mold in which the yoke material is arranged at an angle arrangement different from the desired magnetic pole peak angle arrangement of the molded body, it can have a peak angle arrangement that hardly deviates from the desired value, Further, a magnet roller (Patent Document 1) capable of remarkably improving the yield as a product after assembly, or (2) a developing pole of a magnet roll formed in a cylindrical shape by dispersing magnetic powder in a polymer compound In a developing roller in which a groove-shaped storage portion is provided in a portion corresponding to To provide a developing roller having a small magnetic flux density deviation in the axial direction and a high magnetic flux density by injection molding using a molding die having a gate extending over the entire length and arranging a rare earth magnet block in the storage portion. There has been proposed a magnet roller (Patent Document 2).
JP 02-267907 A JP 2002-328532 A

  However, in Patent Document 1, since the gap between adjacent poles becomes narrow particularly in the case of a five-pole configuration, it is difficult to apply a high magnetic field to the development pole (main pole), and as a result, the development pole (main pole). In some cases, it may be difficult to increase the magnetic flux density, and it may not be possible to adapt to the recent full color, high image quality, and high speed.

  In Patent Document 2, a high magnetic flux density can be achieved by using a rare earth magnet block injection-molded on the developing electrode (main electrode). However, injection molding is less productive than extrusion molding, and rare earth Since magnetic powder is used, it becomes very expensive.

  For this reason, it is possible to increase the magnetic flux density of the developing pole (main pole) that can adapt to the recent full color, high image quality, and high speed, and there is a need for a magnet roller that is highly productive and low in cost. .

  The present invention relates to a cylindrical magnet formed by molding a mixture mainly composed of a ferromagnetic powder and a resin binder, wherein the cylindrical magnet embeds a plurality of magnet pieces that magnetically repel each other in a concave portion on an outer peripheral portion. Magnet roller.

  The present invention also provides a cylindrical magnet formed of a mixture mainly composed of a ferromagnetic powder and a resin binder. The cylindrical magnet having a concave portion on the outer peripheral portion and a hollow central portion is simultaneously oriented and magnetized. This is a method for manufacturing a magnet roller in which a magnet piece is embedded in the concave portion after molding and a shaft is inserted into the hollow portion of a cylindrical magnet.

  Moreover, this invention is a manufacturing method of the magnet roller which carried out the orientation magnetization shaping | molding of only the remaining poles except the recessed part of the outer peripheral part of the said cylindrical magnet.

  Moreover, this invention is a manufacturing method of the magnet roller whose magnet piece embed | buried in the recessed part of the outer peripheral part of the said cylindrical magnet is a several magnet piece which mutually repels magnetically.

  According to the present invention, it is possible to increase the magnetic flux density of the developing electrode (main electrode) at low cost, and it can be applied to full color, high image quality, and high speed.

  Next, the magnet roller of the present invention and the manufacturing method thereof will be described in detail with examples.

  The present invention relates to a cylindrical magnet formed by molding a mixture mainly composed of a ferromagnetic powder and a resin binder, wherein the cylindrical magnet embeds a plurality of magnet pieces that magnetically repel each other in a concave portion on an outer peripheral portion. Magnet roller.

  The present invention also provides a cylindrical magnet formed of a mixture mainly composed of a ferromagnetic powder and a resin binder. The cylindrical magnet having a concave portion on the outer peripheral portion and a hollow central portion is simultaneously oriented and magnetized. This is a method for manufacturing a magnet roller in which a magnet piece is embedded in the concave portion after molding and a shaft is inserted into the hollow portion of a cylindrical magnet.

  In the present invention, a mixture mainly composed of ferromagnetic powder and a resin binder is melt-kneaded to form a pellet. The pellets are melted and extruded using the molding apparatus (extrusion mold) shown in FIG. 1, and at the same time, a magnetic field of 240 K · A / m to 1200 K · A / m is applied to each yoke for orientation magnetization. Thus, a cylindrical magnet having a recess as shown in FIG. 2 is obtained.

  Further, the magnet piece embedded in the concave portion is made into a molten state and extruded using the molding apparatus (extrusion die) shown in FIG. 3 and at the same time a magnetic field of 240 K · A / m to 2400 K · A / m. Is applied and orientation magnetized to obtain a magnet piece as shown in FIG. Alternatively, at the same time as injection molding using the molding apparatus (injection mold) shown in FIG. 5 or FIG. 6, a magnetic field of 240 K · A / m to 2400 K · A / m is applied and orientation magnetization is performed, and FIG. A magnet piece as shown in FIG.

  Any one of the magnet pieces (FIGS. 4, 7, and 8) obtained above is embedded in a concave portion of a cylindrical magnet and fixed with an adhesive or the like, and a metal shaft (SUM22) is placed in the hollow portion of the cylindrical magnet. SUS303, etc.) or a resin shaft (phenolic resin, epoxy resin, polyamide resin, melamine resin, etc.) is inserted into a predetermined position to form a magnet roller as shown in FIG.

  In the present invention, even if the cylindrical magnet and the magnet piece to be embedded are the same magnet material, the main pole magnetic flux density of the magnet roller obtained above is the conventional molding apparatus (extrusion die) as shown in FIG. It becomes higher than the main pole magnetic flux density of the magnet roller extruded by using. This is because, in the conventional molding apparatus as shown in FIG. 10, for example, if the five-pole configuration is used, the gap between the adjacent poles becomes narrow, so that a high magnetic field cannot be applied to the portion corresponding to the main pole, and as a result Although the pole magnetic flux density is lowered, in the present invention, only the portion corresponding to the main pole can be formed with a high magnetic field, and as a result, the magnetic flux density of the main pole can be improved. And magnetic pole density other than a recessed part can also improve the magnetic flux density of each magnetic pole by carrying out orientation magnetization shaping | molding simultaneously with shaping | molding.

  In addition, compared to the conventional type in which the magnet piece is bonded to the outer peripheral portion of the shaft, the man-hour for extruding the magnet piece for each magnetic pole and the man-hour for bonding the molded magnet piece to the shaft are high, resulting in high cost. However, since the cylindrical magnet forms four magnetic poles by one molding and then embeds a separately molded magnet piece in the recess, a magnet roller can be formed with a small number of man-hours, and the cost is reduced.

  Furthermore, since a high magnetic flux density is possible without using an expensive rare earth magnet block, the cost is low.

  In the magnet roller of the present invention, the magnet piece embedded in the recess may be a plurality of magnet pieces that repel each other magnetically, and the manufacturing method is not particularly limited, but the cylindrical magnet is molded. A production method in which orientation magnetization molding is performed simultaneously is preferable.

  The magnet piece embedded in the recess is extruded using the molding apparatus (extrusion mold) shown in FIGS. 11A and 11B, and at the same time, a magnetic field of 240 K · A / m to 2400 K · A / m is applied. Then, two magnet pieces as shown in FIGS. 12A and 12B are obtained by orientation magnetization. The two magnet pieces obtained above are bonded together so as to be magnetically repelled from each other as shown in FIG. 13, and the bonded magnet block is embedded in the recess and fixed with an adhesive or the like. A metal shaft or a resin shaft is inserted into the hollow portion at a predetermined position to form a magnet roller as shown in FIG. Note that FIGS. 12A and 12B may be formed by injection molding.

  Further, in order to avoid workability degradation due to magnetic repulsion when bonding (a) and (b) in FIG. 12, either one of the magnet pieces may be demagnetized in advance and magnetized after bonding. .

  In the present invention, even if the cylindrical magnet and the embedded magnet piece are made of the same magnet material, the main pole magnetic flux density of the magnet roller formed by embedding two magnet pieces that repel each other magnetically is the conventional magnet roller. Higher than the main pole magnetic flux density. This is because the two magnet pieces embedded magnetically repel each other and the magnetic flux converges, resulting in a high magnetic flux density. As described above, the magnetic pole adjacent to the embedded magnetic pole (two magnet pieces) is also oriented and magnetized simultaneously with molding by the manufacturing method in which the cylindrical magnet is oriented and magnetized at the same time as molding. Can assist the magnetic flux density of the magnetic pole embedded therein, so that the magnetic flux density can be further improved.

  Further, the present invention is a magnet roller obtained by subjecting only the remaining poles to orientation magnetization molding except for the concave portion of the outer peripheral portion of the cylindrical magnet.

  Using the molding apparatus (extrusion mold) shown in FIG. 15, the magnetic field applied in the extrusion mold is obtained by orientation-magnetizing only the remaining poles (in this case, four poles) except for the concave portion of the cylindrical magnet. Is improved (240 K · A / m to 1600 K · A / m), and as a result, the magnetic flux density of the magnetic poles other than the concave portion (main pole portion) is improved. Then, the magnet piece to which (a) and (b) of FIG. 12 are bonded is embedded in the concave portion and fixed with an adhesive or the like, and a metal shaft or a resin shaft is placed in a predetermined position in the hollow portion of the cylindrical magnet. And a magnet roller as shown in FIG. 16 is formed.

  In the present invention, even if the cylindrical magnet and the magnet piece to be embedded are the same magnet material, the magnetic flux density of each magnetic pole of the cylindrical magnet (excluding the concave portion) obtained above is the same as the magnetic pole of the conventional cylindrical magnet. Further, when two magnet pieces using magnetic repulsion are embedded in the recess, the main pole magnetic flux density is further improved.

  In the above invention, the following ferromagnetic powder and resin binder can be used as the magnet material.

  Examples of the ferromagnetic powder include anisotropic ferrite magnetic powder having a chemical formula represented by MO.nFe2O3 (n is a natural number). As M in the formula, one type or two or more types such as Sr, Ba or lead can be appropriately selected and used.

  Further, as the ferromagnetic powder, anisotropic ferrite magnetic powder, isotropic ferrite magnetic powder, anisotropic rare earth magnetic powder (for example, SmFeN system), isotropic rare earth magnetic powder (for example, NeFeB system) are used alone or in two types. You may mix and use the above. What is necessary is just to select suitably by the required magnetic flux density. Among them, a ferromagnetic powder selected from anisotropic ferrite magnetic powder, isotropic ferrite magnetic powder, and magnetic powder in which ferrite magnetic powder and rare earth magnetic powder are mixed is preferable from the viewpoint of low cost.

  As the resin binder, ethylene ethyl acrylate resin, polyamide resin, polystyrene resin, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), EVA (ethylene-vinyl acetate copolymer), EVOH (ethylene) -Vinyl alcohol copolymer) and PVC (polyvinyl chloride) or one or more, or thermosetting epoxy resin, phenol resin, urea resin, melamine resin, furan resin, unsaturated polyester resin, polyimide resin, etc. One kind or two or more kinds of resins can be mixed and used.

  The content of the single magnetic powder or mixed magnetic powder shown above is preferably in the range of 50 to 95% by weight. If the content of the single magnetic powder or the mixed magnetic powder is less than 50% by weight, the magnetic properties of the magnet piece are lowered due to the lack of magnetic powder, making it difficult to obtain a desired magnetic force, and the content is 95% by weight. If it exceeds 1, the resin binder becomes insufficient and the moldability may be impaired.

  As additives, magnetic powder surface treatment agents such as silane and titanate coupling agents, polystyrene and fluorine lubricants that improve fluidity, stabilizers, plasticizers, or flame retardants are added. .

  In the present specification, a magnet roller composed of five magnetic poles is mainly described. However, the present invention is not limited to a five-pole magnet roller. That is, the number of magnet pieces may be selected according to the desired magnetic flux density and magnetic field distribution, and the number of magnetic poles and the magnetic pole position may be set as appropriate.

  Furthermore, in the present invention, it is mainly explained that the cylindrical magnet is formed by extrusion molding. However, the cylindrical magnet may be molded by injection molding or compression molding.

Example 1
As a magnet material, 10% by weight (including lubricant and stabilizer) of ethylene ethyl acrylate resin (Nihon Unicar PES210) as a resin binder, anisotropic strontium ferrite (SrO · 6Fe ₂ O ₃ ) powder as a ferromagnetic powder 90% by weight (NF-350, manufactured by Nippon Valve Industry Co., Ltd.) was mixed, melted and kneaded into pellets. The pellets are melted and a magnetic field of 240 K · A / m to 1200 K · A / m is applied to each yoke (five) simultaneously with extrusion using the molding apparatus (extrusion die) shown in FIG. Then, the magnet was oriented and magnetized to form a cylindrical magnet having a recess as shown in FIG.

  In addition, the same pellets as described above were oriented and magnetized while applying a magnetic field of 2400 K · A / m simultaneously with extrusion using the molding apparatus (extrusion die) shown in FIG. 3, and one magnet piece (N1 pole) Was molded.

  A SUM22 shaft is inserted into the hollow portion of the cylindrical magnet having the concave portion obtained above, and the magnet piece (N1 pole: main pole) is embedded in the concave portion. A magnet roller was formed by fixing with an adhesive.

  Here, the outer diameter of the magnet was φ16 mm, the magnet length was 320 mm, the outer diameter of the shaft was 6 mm, the shaft length was 370 mm, and the cylindrical magnet and the shaft were fixed with a cyanoacrylate-based instantaneous adhesive.

  The magnetic flux density of the obtained magnet roller was determined by the following method. While supporting the shafts at both ends of the magnet roller and rotating the magnet roller, a probe (Bell magnetic flux density sensor) is set at a position 9 mm away from the center of the magnet roller (on the sleeve), and circumferential magnetic flux is measured with a gauss meter. Density values were measured.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

（実施例２）
図５に示す成形装置（射出金型）を用いて、印加磁場を２４００Ｋ・Ａ／ｍとし、図７のマグネットピースを成形し、これを凹部を有する円筒状マグネットの凹部に埋設する以外はすべて実施例１と同様に行った。

(Example 2)
Using the molding apparatus (injection mold) shown in FIG. 5, the applied magnetic field is 2400 K · A / m, the magnet piece of FIG. 7 is molded, and this is embedded in the recess of the cylindrical magnet having the recess. The same operation as in Example 1 was performed.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

(Example 3)
Using the molding apparatus (injection mold) shown in FIG. 6, the applied magnetic field is set to 2400 K · A / m, the magnet piece of FIG. 8 is molded, and this is embedded in the recess of the cylindrical magnet having the recess. The same operation as in Example 1 was performed.
Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

Example 4
Using the molding apparatus (extrusion die) shown in FIGS. 11A and 11B, the applied magnetic field is 2400 K · A / m, and the two magnet pieces shown in FIGS. 12A and 12B are molded. Then, all of the operations were performed in the same manner as in Example 1 except that the magnet pieces were bonded together as shown in FIG. 13 to form a magnet block, and the magnet block was embedded in a concave portion of a cylindrical magnet having a concave portion.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

(Example 5)
Using the molding apparatus (extrusion die) shown in FIG. 1, a cylindrical magnet having a recess is formed without applying a magnetic field, and the magnet is magnetized at each magnetic pole position after molding to form a cylindrical magnet. Were all carried out in the same manner as in Example 4.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

(Example 6)
Using the molding device (extrusion die) shown in FIG. 15, the concave portion of the cylindrical magnet is removed, and only four poles are oriented and magnetized, and (a) and (b) of FIG. The same procedure as in Example 1 was performed except that the magnet block was embedded in a concave portion of a cylindrical magnet having a concave portion.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

(Comparative Example 1)
Using the molding apparatus (extrusion die) shown in FIG. 1, a cylindrical magnet having a recess is formed without applying a magnetic field, and the magnet is magnetized at each magnetic pole position after molding to form a cylindrical magnet. Were all carried out in the same manner as in Example 1.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

(Comparative Example 2)
Except for forming a 5-pole cylindrical magnet that does not have a recess and does not have a magnet piece embedded in the recess, using the molding apparatus (extrusion die) shown in FIG. went.

  Table 1 shows the measurement result of the peak magnetic flux density value of each magnetic pole.

  Comparing Examples 1-6 and Comparative Examples 1-2, the magnetic flux density of the example is higher than that of the comparative example, and in particular, the magnetic force of the N1 pole (main pole) is higher. It can be adapted to.

  Moreover, when Examples 1-6 are compared, what embedded the magnetic block which bonded the magnetically repulsive magnet piece of Examples 4 and 6 of N1 pole (main pole) compared with Examples 1-3. It can be seen that the magnetic flux density is high, which is optimal for increasing the speed and image quality of full-color machines. In Example 6, the magnetic flux density of the N1 pole (main pole) is slightly lower than that of Example 4, but the peak magnetic flux density values of the other magnetic poles are all higher than those of Example 4, and the developer transportability is high. It turns out to be stable.

Cylindrical magnet forming device (mold) Cylindrical magnet Magnet piece molding machine (extrusion mold) Magnet piece (perspective view) Magnet piece molding machine (injection mold) Another magnet piece molding machine (injection mold) Magnet piece (perspective view) Another magnet piece (perspective view) Magnet roller of the present invention (perspective view) Conventional cylindrical magnet forming equipment (mold) Another magnet piece molding device (extrusion mold) Another magnet piece perspective view Magnet block Another magnet roller of the present invention (perspective view) Another cylindrical magnet forming device (mold) Another magnet roller of the present invention (perspective view)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical magnet 2 Hollow part 3 Yoke (magnetic body)
4 Non-magnetic material 5 Concave portion 6 Magnet piece 7 Magnetic particle orientation magnetization direction 8 Excitation source 9 Yoke 10 Shaft

Claims (4)

  In a cylindrical magnet formed by molding a mixture mainly composed of ferromagnetic powder and resin binder, the cylindrical magnet has embedded therein a plurality of magnet pieces that magnetically repel each other in the concave portion of the outer peripheral portion. Magnetic roller characterized by   In a cylindrical magnet formed of a mixture mainly composed of a ferromagnetic powder and a resin binder, a cylindrical magnet having a concave portion on the outer peripheral portion and a hollow center portion is simultaneously formed by orientation magnetization molding, and after molding, A magnet roller manufacturing method comprising embedding a magnet piece in a recess and inserting a shaft into a hollow portion of a cylindrical magnet.   3. The method of manufacturing a magnet roller according to claim 2, wherein only the remaining poles are orientationally magnetized except for the concave portion of the outer peripheral portion of the cylindrical magnet.   4. The method of manufacturing a magnet roller according to claim 2, wherein the magnet piece embedded in the concave portion of the outer peripheral portion of the cylindrical magnet is a plurality of magnet pieces that repel each other magnetically.

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