JPH04139706A - Magnet roll and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a magnet roll which can produce copies of an excellent picture quality by making the magnetic field distribution of its main pole asymmetrical with respect to a peak intensity value within the range from the peak intensity value to the half of the peak intensity value in the magnetic field distribution. CONSTITUTION:A vacant space section 4 is formed around a center core 3 made of a nonmagnetic substance and die yoke sections 1 made of a ferromagnetic substance and interpole sections 2 made of a nonmagnetic substance are alternately arranged on the outside of the section 4. The 1a, 1b, and 1c in the figure respectively represent magnetism leading paths for forming main pole, the first adjacent pole, and the second adjacent pole. In addition, the 5 in the figure represents a projecting section formed to the magnetism leading path for forming the first adjacent pole and protrudes toward the path 1a. The projecting section is formed toward the adjacent magnetism leading path on the inner surface side of the metallic mold, namely, near the leading end of the magnetism leading path.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic roll used in a developing device or a cleaning device in an electronic copying machine, a laser printer, etc., and a method for manufacturing the same, and more specifically relates to a method for producing a magnetic roll used in a developing device or a cleaning device in an electronic copying machine or a laser printer. The present invention relates to an integrally molded magnet roll and a manufacturing method thereof.

[Conventional technology]

Conventional magnet rolls include an adhesive type in which multiple magnets are bonded together along a shaft, as shown in Figure 7, and an adhesive type in which a plurality of magnets are bonded together along a shaft, and an oriented type in which the orientation direction of magnetic particles is focused on the magnetic pole surface on the surface of the integrally molded magnet roll. There is a multi-pole integrated type, which is created by magnetizing a plurality of magnetic poles using a polar anisotropic orientation method.

[Problem to be solved by the invention]

By the way, in order to obtain good copy image quality, it is necessary that the magnetic field pattern of at least one pole or its peak position be asymmetrical in the circumferential direction distribution diagram of the radial magnetic field component of the entire magnet roll. be.

The adhesive type allows each magnet to be bonded to be individually magnetized, so there is a high degree of freedom in the magnetic field pattern, and it is easy to obtain an asymmetrical magnetic field pattern, making it suitable for manufacturing high-performance magnetic rolls. ing. However, on the other hand, it is difficult to bond a plurality of elongated magnets together over their entire lengths with high precision, resulting in an increase in manufacturing costs. On the other hand, the extremely anisotropically oriented type has the advantage of reducing manufacturing costs because it does not require bonding. Due to the magnetic circuit of the mold used to mold the mold, the circumferential magnetic field pattern of each magnetic pole becomes almost symmetrical with respect to its peak, making it impossible to obtain an asymmetrical pattern. More specifically, although the bottom of the magnetic field pattern (near the baseline of the magnetic field pattern) can be asymmetrical, in the region where the magnetic field strength is 1/2 of the peak value from the peak value position, the magnetic field pattern (Currently, only magnetic rolls with inferior copy quality could be obtained.

As a means to solve this problem, a method has been disclosed in which the symmetry of the magnetic field pattern is disrupted by providing recesses, protrusions, or 7-shaped grooves in the longitudinal direction on the surface of the magnet roll (Japanese Patent Application Laid-Open No. 63-11111).
-5371, JP-A-63-7604).

However, it is not possible to provide recesses, protrusions, 7-shaped grooves, etc. in post-processing.
In addition, if the magnet roll is formed using a mold that has a structure for forming concave portions, convex portions, and 7-shaped grooves, post-processing will be unnecessary, but it will not be possible to optimize the design of the mold or die. Another problem is that it takes a lot of time to manufacture, and the magnetic pattern changes due to wear of the mold.

The present invention has been made in view of the current situation, and is extremely unique in that an asymmetrical magnetic field pattern can be obtained by integral molding and even without providing recesses, protrusions, 7-shaped grooves, etc. on the surface of the magnet roll. The purpose is to provide a universal magnetic roll that does not require post-processing, does not require the use of complicated molds, and has a stable magnetic pattern even if the mold wears out. It is an object of the present invention to provide a magnetic roll that can provide good copy image quality.

[Means for solving problems]

In order to solve the above problem, the present inventors developed a structure of a mold used when forming a magnet roll using the polar anisotropic magnetic field orientation method, as shown in Figure 2. Among the yokes, if the structure is such that the tip width of the yoke corresponding to the magnet roll magnetic pole that is to form an asymmetrical magnetic field pattern has a different value from the tip width of the yoke adjacent to the yoke, there are concave portions, convex portions, It has been found that it is possible to produce an integrally molded magnet roll with an asymmetrical magnetic field pattern without providing grooves, etc. However, in this method, the magnetic roll magnetic pole corresponding to the wide yoke, i.e. The magnetic field pattern generated by the magnetic poles inevitably becomes wider and the peak value becomes low (as a result, there are cases where the magnetic roll cannot meet the various required performances.

As a result of intensive research to solve this problem, the present inventors found that of the two magnetic poles adjacent to the magnetic pole (hereinafter referred to as the main pole) that should have an asymmetric pattern, the side where the pattern of the main pole is steeper. (hereinafter referred to as the first adjacent pole,
The other adjacent pole will be referred to as the second adjacent pole)
The present invention was achieved by discovering that the magnetic guiding path for forming the magnetic guiding path may have a structure in which a protrusion toward the adjacent magnetic guiding path is provided near the tip thereof. The shape of the protruding part of the magnetic guiding path may be designed according to the desired asymmetry and the magnetic field strength of the magnetic pole, and the protruding direction of the protruding part in the first adjacent pole forming magnetic guiding path is It is also possible to direct it to the magnetic guiding path for forming the main pole, or to the magnetic guiding path located on the opposite side to the magnetic guiding path for forming the main pole.

A magnet roll made by such a method has a distribution waveform in the circumferential pattern of the radial magnetic field component within a range from the peak value of the magnetic field of the main pole until the strength becomes at least 1/2, with the peak value sandwiched between the peak values. The main pole is substantially asymmetrical, and the outer periphery of the region including the main pole and at least one of the two adjacent magnetic poles is substantially a part of a circular arc.

[For production]

By forming the protrusion near the tip of the magnetic conduction path for forming the first adjacent pole, the first adjacent pole magnetic field pattern of the magnet roll is not made excessively wide (therefore, without lowering its peak value), and the main pole is The magnetic field pattern can be made asymmetrical, and a magnet roll suitable for obtaining good copied images can be provided.

It is presumed that this effect is produced for the following reasons.

First, if a yoke with a wide tip without a protrusion is used, almost uniform magnetic flux will enter the molten resin magnet from the entire tip surface, and the magnetic poles will be oriented and magnetized almost evenly, resulting in a wide It is thought that a magnetic field pattern is formed.

On the other hand, even if the tip width is the same, if the protrusion structure is used, a part of the magnetic flux will not enter the molten resin magnet roll, but will go to the main pole magnetic conduction path via this protrusion.

Therefore, the magnetic flux that enters the resin magnet is not uniform, and the amount of magnetic flux that enters from the overhang is small. Therefore, the magnetic properties of the area facing the magnetic guide path protrusion of the magnet are low,
The main pole pattern can be made asymmetrical without excessively widening the pattern of the first adjacent pole.

〔Example〕

Next, details of the present invention will be explained based on illustrated embodiments.

The magnetic material powder used in the present invention may be any material that can be molded into a resin magnet, and examples thereof include magnetic materials such as hexagonal ferrite, samarium-cobalt alloy neodymium-iron-boron system, and the like. Further, there are no particular limitations on the synthetic resin, and examples thereof include vinyl chloride, polyethylene, chlorinated polyethylene, polypropylene, polyamide, polyester, polycarbonate, polyphenylene sulfide, acrylic resin, methacrylic resin, etc., and can be appropriately selected according to desire. .

FIG. 1 shows an embodiment of the molding die used in the present invention, which has a core 3 made of a non-magnetic material at the center, and a gap 4 which becomes a magnetic roll molding space is formed outside the core 3. Further, a die yoke portion 1 made of a ferromagnetic material is arranged outside the gap portion 4 with a pole gap portion 2 made of a non-magnetic material interposed therebetween. What is shown as 1a in the figure is the magnetic guide path for forming the main pole, and 1b in the figure is the magnetic guide path for forming the first adjacent pole,
The IC is a magnetic guide path for forming a second adjacent pole. Further, in the figure, reference numeral 5 denotes an overhang portion formed on the first adjacent pole forming magnetic guide path, and the overhang portion 5 is configured to protrude toward the main pole forming magnetic guide path 1a. The projecting portion may protrude toward the adjacent magnetic conduction path on the inner surface of the mold, that is, near the tip of the magnetic conduction path (for example, it may have a shape as shown in Fig. 3 or Fig. 4). Furthermore, as shown in FIG. 5, the projecting portion 5 can be directed toward the second adjacent pole forming magnetic guiding path 1c, which is the magnetic guiding path on the opposite side to the main pole forming magnetic guiding path 1a. A prominent configuration is also possible.

Hereinafter, the present invention will be explained in more detail based on specific examples, but the present invention is not limited thereto.

Example Hexagonal ferrite 90% by weight (Product name: GP330, manufactured by Toda Kogyo ■) Vinyl chloride resin
7.0% by weight (Product name: 5100I
, manufactured by Kanebuchi Chemical Industry Co., Ltd.) DOP
2.8 weight 96 tribase 0
．． 1% by weight lead stearate 0.1% by weight Using pellets made from the above formulation, diameter 14φ,
A magnetic roll having three magnetic poles and the following value as the peak-to-peak angle of the radial magnetic field component was formed by magnetically oriented extrusion molding.

/5-N1=115°C /Nl-N2=120°C/N2-S=125°C The main pole is the S pole, and the N1 pole side of the pattern is made steeper. To achieve this, we used the die shown in Figure 1 to magnetically couple each magnetic conduction path to an electromagnet provided for each yoke, and connected the excitation coil for the S pole to 10,000 AT (ampere turns) for the N1 and N2 poles. 3000A for excitation coil
Extrusion molding was carried out while passing a direct current equivalent to T. In addition, as a comparative example, extrusion molding was carried out using the die shown in FIG. 2 under the same conditions. The die shown in FIG. 2 has the same magnetic conductive path for forming the S pole and the magnetic guiding path for forming the N2 pole as in FIG.
In addition, the width of the part of the Nll shadow forming magnetic guide path facing the outer surface of the magnet roll is the same as that in Figure 1, but it is made wider up to the outer diameter of the die, and the overhanging part is eliminated. is different from that in Fig. 1.

The radial magnetic field components of the two magnet rolls obtained (
The distribution of the absolute value of N2) with respect to the rotation angle is shown in FIG. The solid line shows the distribution when the die shown in FIG. 1 is used, and the broken line shows the distribution when the die shown in FIG. 2 is used. In order to conveniently quantify the degree of asymmetry of the pattern of the S pole, which is the main pole, the following parameters will be used. That is, the ratio of the distance from the intersection of the perpendicular line drawn from the peak to the baseline and the horizontal line indicating half the height of the peak value to both ends of the pattern, that is, in FIG. ! ,,! ! , C1,≦12)/! /
/I is the degree of asymmetry A, S, D (Asymmetric
gree). When two magnet rolls were evaluated using this degree of asymmetry, both received an A rating.

It was found that S and D were 1.9, indicating that the asymmetric structure was sufficiently achieved. However, in the comparative example, the Nl electrode pattern was too wide and the peak value was too low, making it unsuitable for use as a magnet roll.

On the other hand, it was confirmed that in the magnet roll made by the method of the present invention, the distribution range of the magnetic field pattern of the N1 pole is narrowed, and a high peak value can be achieved.

In addition, in the above-mentioned embodiment, the shape of the outer peripheral portion was symmetrical only with a circular cross section, but the magnet roll of the present invention has a symmetrical shape.
Other shapes may be used as long as at least the region from the main pole to the first adjacent pole constitutes a part of the circular arc on the outer periphery of the magnet roll, for example, other than the region from the main pole to the first adjacent pole. This also includes those with a flat cut surface on the outer circumferential surface for purposes such as positioning.

Further, as the magnetic field orientation molding means, not only extrusion molding but also injection molding, compression molding, etc. can be selected as necessary.

〔effect〕

According to the present invention, it is possible to make the magnetic field distribution of the main pole asymmetrical with respect to the peak value in the range from a peak of only 4 degrees to a strength of 172 degrees of the peak value, and a good result is obtained. A magnetic roll that can achieve copy image quality can be obtained. In addition, the magnetic roll obtained by the present invention not only has an asymmetrical magnetic field distribution at the main pole, but also has a magnetic field pattern that spreads over a wide range or has a lower level at the adjacent pole located on the side where the magnetic field distribution is desired to be steeper. There is no problem, and the basic function as a magnetic roll is not impaired. Moreover, a magnet roll with such excellent properties can be made by integral molding, and it also has recesses and grooves on the surface of the magnet roll.
There is no need for post-processing such as forming protrusions or V-shaped grooves.
In addition to being excellent in mass production, there is no fear of changes in characteristics due to mold wear.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a die used in the method of the present invention, Fig. 2 is a sectional view showing an example of a conventional die, and Figs. 3 to 5 are sectional views showing an example of a die used in the method of the present invention. FIG. 6 is a sectional view of another embodiment of the radial magnetic field (H) of the magnet roll formed using the die shown in FIGS.
l) Pattern: Figure 7 is an example of a conventional magnetic roll. 1: Dice yoke part, 1a: Main pole forming magnetic guide path, lb:
1st adjacent pole forming magnetic guide path, 1C: 2nd adjacent pole forming magnetic guide path, 2; interpolar portion, 3: core, 4: gap portion, 5: overhang portion. (Fig. (Fig. Tsukui)) Fig. 1.

Claims (5)

[Claims] (1) In the circumferential pattern of the radial magnetic field component, the intensity is at least 1/2 from the peak value of the magnetic field of any main pole.
The distribution waveform within the range up to is substantially asymmetrical across the peak value, and the outer periphery of the region including from the main pole to at least one of the two adjacent magnetic poles is substantially A resin-bonded, integrally molded magnet roll that is magnetized by polar anisotropic orientation that is part of a circular arc. (2) A claim that in the circumferential pattern of the radial magnetic field component, the distribution waveform within the range from the peak value of the magnetic field of any main pole until the intensity becomes 1/3 is substantially asymmetrical with the peak value in between. The magnetic roll according to item 1. (3) In the circumferential pattern of the radial magnetic field component, the intensity is at least 1/2 from the peak value of the magnetic field of any main pole.
The distribution waveform within the range up to is substantially asymmetrical across the peak value, and the outer periphery of the region including from the main pole to at least one of the two adjacent magnetic poles is substantially In the molding of a resin-bonded integrally molded magnet roll that is magnetized by polar anisotropic orientation that is part of a circular arc, the magnetic field pattern of the main pole is located on the side where the magnetic field pattern of the main pole is steeper among the two magnetic poles adjacent to the main pole. A method for manufacturing a magnet roll, characterized in that a molding die is used in which a protrusion is formed near the tip of a magnetic guide path for forming a magnetic pole, and a protrusion toward an adjacent magnetic guide path for forming a magnetic pole. (4) The method for manufacturing a magnet roll according to claim 3, wherein the protrusion formed near the tip of the magnetic guide path is directed toward the magnetic guide path for forming the main pole. (5) The method of manufacturing a magnet roll according to claim 3, wherein the protruding portion formed near the tip of the magnetic guide path is directed toward the magnetic guide path that exists on the opposite side to the side where the main pole forming magnetic guide path exists.