JPH023992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnet roll for magnetic brush development used in electrophotographic copying machines and facsimile receivers.

Structure of the conventional example and its problems As shown in Fig. 1, the conventional magnet roll for magnetic brush development consists of integrally forming ferrite particles in a cylindrical shape around a shaft 1, going through a sintering process, and then polishing the outer periphery. Sintered ferrite magnet 2
It was constructed by rotatably incorporating it into a cylindrical sleeve 3. Further, as shown in FIG. 2, a sintered ferrite magnet 4 obtained by polishing and magnetizing a sintered anisotropic magnet into a square column is pasted radially on the outer periphery of a shaft 5 to form a cylindrical magnet. It was configured to be rotatably incorporated into a shaped sleeve 6. However, since both magnet rolls for magnetic brush development require a sintering process, the shrinkage rates of the sintered ferrite magnets 2 and 4 differ partially depending on the sintering conditions, making it difficult to obtain uniform dimensions. It was hot. Further, polishing is required as a post-process, but the sintered ferrite magnets 2 and 4 are brittle and easily damaged, which is a significant disadvantage in terms of yield. Furthermore, the magnetic brush developing magnet roll shown in Figure 1 is extremely heavy because it is an integral type with a specific gravity of 5.0 to 5.2, while the magnetic brush developing magnet roll shown in Figure 2 is
There is a limit to the shape of the sintered ferrite magnet 4, and the outer diameter is limited, making it impossible to obtain a small magnet.

In order to eliminate the above drawbacks, the Special Publication No. 56-51481
The method proposed in the publication will be briefly explained with reference to FIGS. 3 to 9. A composite of ferrite particles 7 subjected to magnetic anisotropy treatment and a medium 8 for bonding the ferrite particles 7 is passed between rotating rolls 9 to magnetically orient the ferrite particles 7 in the medium 8 in the rolling direction. As shown in the characteristic diagrams in Figure 4 a and b, the length direction
An anisotropic sheet magnet material 10 exhibiting ferromagnetism in the thickness direction _Y1 from _X1 is obtained. Then, the sheet magnet material 10 is laminated into a flat plate by the required thickness as shown in FIG. 5a.

Magnetic sheet laminate 1 laminated in this way
1 is placed on a lower mold 12 with fan-shaped grooves provided at regular intervals as shown in FIG. The wave-shaped magnet 14 is formed by molding. The wave-shaped magnet 14 thus formed is cut along the cutting line _C1 to obtain a fan-shaped magnetic pole 15, which is a magnetic block with a fan-shaped cross section. Note that the angle on the wide-angle side of this fan-shaped magnetic pole 15 is the forming angle.
Call it _R1 .

The fan-shaped magnetic pole 15 obtained in this way is
As shown in FIGS. 7 and 7, it is attached around the shaft 16 and the outer periphery is finished to form a cylindrical rolled magnet body 17. Then, as shown in FIG. 8, a magnetizing yoke 18 is brought into contact with the center of the circumference of each fan-shaped magnetic pole 15 to magnetize it, thereby obtaining a roll-shaped magnet having a high magnetic force.

In this case, in each fan-shaped magnetic pole 15, the magnetic field is applied to the circumferential center 15a of the magnetic pole 15 and the side surfaces 15b, 15c adjacent to the circumference.

In addition, at this time, the distance between adjacent magnetic poles is called interpolar angle R ₂ .

As shown in FIG. 9, the magnetic flux density of the forming angle R ₁ of the fan-shaped magnetic pole 15 obtained in this manner peaks at around 60 degrees and then rapidly decreases. This is because the problem is that the magnetic poles are formed into a fan shape, and if the magnetic orientation is less than 60 degrees, the magnetic orientation of adjacent magnetic poles will be sequentially arranged in the direction of cutting the sheet magnet material 10 of each magnetic pole at right angles. High magnetic force was obtained by increasing concentration, but as shown in Figure 10, magnetic pole 15
If the angle exceeds 60°, each sheet magnet material 10 rises slowly, resulting in a decrease in the efficiency of magnetic flux density.

OBJECTS OF THE INVENTION In view of the above drawbacks, the present invention provides a magnet roll for magnetic brush development that allows the angle of magnetic pole arrangement to be arbitrarily selected and that can obtain high magnetic force.

Structure of the Invention In order to achieve the above object, the present invention provides a magnetic pole having a magnetic field applied to the central part of the circumference and a side surface adjacent to the circumference, and a strong magnetic pole having a fan-shaped cross section and having a magnetic field in the circumferential direction. A columnar magnet is formed by bonding the magnetic material portions together such that the side surface of the magnetic pole and the side surface of the ferromagnetic material portion are in contact with each other.

Since a magnetic field exists in the circumferential direction of the cylindrical magnet due to the ferromagnetic portion, even when the angle between the poles is widened, the flow of magnetic flux is good and high magnetic force can be obtained.

DESCRIPTION OF EMBODIMENTS A magnet roll for magnetic brush development according to an embodiment of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 11, a composite of ferrite particles 19 that have been subjected to magnetic anisotropy treatment and a medium 20 that joins these ferrite particles 19 is passed between rotating rolls 21 to hold the ferrite particles in the medium 20. 19 is magnetically oriented in the rolling direction, and as shown in Fig. 12, the thickness direction perpendicular to the length X ₂ is
An anisotropic sheet magnet material 22 exhibiting ferromagnetism in Y ₂ is obtained.

Next, as shown in FIG. 13a, anisotropic sheet magnet materials 22 are laminated to a required thickness to obtain a magnet laminate 23a. Then, as shown in FIG. 13b, the magnet laminate 23a is attached with chevron-shaped protrusions 24a, 24b,
Press molding is performed using an upper mold 26 and a lower mold 27 having 25a and 25b. Then, as shown in FIG. 13c, a magnet laminate 23b whose cross section has a zigzag shape having apertures at regular intervals and is symmetrical about the axis is obtained. After that, a cutting line C ₂ corresponding to the narrowed part and the thickest part of the magnet laminate 23b is drawn.
Then, the wedge-shaped ferromagnetic material portion 28 is obtained.

In the wedge-shaped ferromagnetic material portion 28 obtained in this way, each anisotropic sheet magnetic material 22 is
They are arranged from the lower base 28a to the upper base 28b, and the magnetic field is applied almost parallel to the lower base 28a and the upper base 28b.

Next, as shown in FIGS. 14a and 14b, the anisotropic sheet magnet material 22 obtained using the apparatus shown in FIG.
The stacked magnet laminate 23a is placed on a lower mold 29 in which fan-shaped grooves are provided at regular intervals,
Press molding is performed using an upper die 30 having a trapezoidal shape taking into consideration the orientation of the material, to form a wave-shaped magnet 31 as shown in FIG. 14c. The thus formed wave-shaped magnet 14 is cut along the cutting line _C3 to obtain the fan-shaped magnetic pole 32 shown in FIGS. 14d and 14e. Note that the magnetic layer 23a of the magnetic pole 32 is formed in a concave shape, and the magnetic field is generated by the fan-shaped magnetic pole 3.
It spans the circumferential center portion 32a and side surfaces 32b and 32c of No. 2.

Then, as shown in FIG. 15, the wedge-shaped ferromagnetic portion 28 is formed into a fan shape, and the magnetic pole 32 and the ferromagnetic portion 28 are bonded side to side to form a cylindrical magnet 3.
form 3.

As a result, the flow of magnetic flux density between the magnetic poles 32 proceeds perpendicularly to the circumferential direction of the ferromagnetic material portion 28, representing the most effective flow of magnetic flux. Further, as shown in A shown in FIG. 16, the magnetic flux concentration force of the magnetic poles 32 on both sides of the magnetic pole 32 can significantly improve the magnetic force compared to the conventional type B when the interpolar angle R ₂ is 60° or more.

The cylindrical magnet 33 obtained in this way is
As shown in Figure 7, a cylindrical non-magnetic sleeve 34
By installing it rotatably inside the
A magnet roll for magnetic brush development in one embodiment of the present invention is obtained.

Note that, as shown in FIG. 15, the ferromagnetic portion 28 can also be manufactured by applying a magnetic field in the direction of arrow D, which corresponds to the circumferential direction, using a coil 36 during molding using a molding die 35. You can get the same effect as .

Effects of the Invention As described above, the present invention provides a ferromagnetic material having a magnetic field on one side or both sides of at least one pole among a plurality of magnetic poles in a cylindrical magnet in a circumferential direction substantially perpendicular to the magnetic field of the magnetic pole. By arranging the magnetic poles for conveying and pumping toner, developing, etc., the angle between the poles can be arbitrarily selected and high magnetic force can be obtained, which is of great industrial value.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views of a conventional magnetic brush developing magnet roll, Figure 3 is a process diagram showing the manufacturing process of a conventional sheet magnet, and Figures 4 a and b.
are characteristic diagrams of the same sheet-like magnet, Figures 5a to 5e.
6 and 7 are cross-sectional and perspective views of a cylindrical magnet using the same fan-shaped magnet, and FIG. 8 is a diagram showing the manufacturing process of a conventional fan-shaped magnet. FIG. 9 is a cross-sectional view of a cylindrical magnet, FIG. 9 is a characteristic diagram of fan-shaped magnetic poles forming the cylindrical magnet, FIG. 10 is a magnetic orientation diagram of the cylindrical magnet, and FIG. 11 is a magnetic diagram in an embodiment of the present invention. A process diagram showing the manufacturing process of a sheet-like magnet used in a magnet roll for brush development, FIGS. 12a and 12b are characteristic diagrams of a sheet-like magnet used in the magnet roll, and FIGS. 13a-
d is a process diagram showing the manufacturing process of the ferromagnetic material part constituting the magnet roll, FIGS.
The figure shows the magnetic orientation diagram of the cylindrical magnets that make up the magnet roll, Fig. 16 shows the magnetic pole characteristics of the cylindrical magnets that make up the magnet roll, Fig. 17 shows a cross-sectional view of the magnet roll, and Fig. 18 shows the magnetic pole characteristics of the cylindrical magnets that make up the magnet roll. It is a sectional view showing another manufacturing method of the ferromagnetic material part of the magnet roll. 28...Ferromagnetic material part, 32...Magnetic pole, 33...
Cylindrical magnet, 34...Sleeve.

Claims (1)

[Claims] 1. A magnetic pole having a fan-shaped cross section and having a magnetic field applied to the central part of the circumference and a side surface adjacent to the circumference, and a ferromagnetic material part having a fan-shaped cross section and having a magnetic field in the circumferential direction. For magnetic brush phenomenon, a cylindrical magnet formed by bonding the side surfaces of the magnetic pole and the side surface of the ferromagnetic material part in contact with each other is rotatably incorporated inside a cylindrical non-magnetic sleeve. magnet roll.