JPH0736372B2 - Method and apparatus for manufacturing long bonded magnet using moving sizing die - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a long plastic bond magnet, a manufacturing apparatus, and the like, and more specifically, a copying machine, a facsimile and a laser beam printer (LB).
P) and the like, the present invention relates to a method for manufacturing a magnet roll used in a developing device and a cleaning device by an electrophotographic method, a manufacturing device, and the like. More specifically, a manufacturing method and a manufacturing apparatus for a "multi-pole integrated magnet roll" in which the necessary number of magnetic poles are formed on the surface of one long plastic bond magnet by the polar anisotropic orientation method or the multi-pole magnetization. Etc.

[0002]

2. Description of the Related Art A magnetic field oriented extrusion method is suitable for producing long plastic bonded magnets as a highly productive method.
However, the fatal drawback of this is that the instantaneous cooling of the extrudate is not possible, so that the extrudate is deformed by magnetic stress while it exits the die and solidifies by cooling, and it is not easy to obtain a product in the desired shape. Since the magnetic field distribution near the die exit is different from the magnetic field distribution inside the die, the desired orientation state is disturbed, it is easy to obtain a bonded magnet with an undesired magnetic field pattern, and until it solidifies by cooling due to the demagnetizing field (self-destructive magnetic field). That is, the degree of grain orientation is lowered, and thus the magnetic properties are lowered. These phenomena are particularly remarkable in the manufacture of the multipole long magnet. Therefore, a lot of trial and error are required for the development of a new product, and it is impossible to make an inexpensive magnet roll having high magnetic characteristics capable of meeting the high image quality of electronic copiers, facsimiles and LBPs. , Etc. are occurring.

A basic method for solving such a problem is to cool and solidify the extrudate in a magnetic field which does not disturb the orientation (to cool the extrudate in the vicinity of or in contact with a soft magnetic material such as iron to eliminate the demagnetizing field). (Including solidification), which is already known per se (for example, JP-A-59-127).
823, JP-A-63-16608). The inventors of the present invention also disclosed in JP-A-62-273707 that a caterpillar (endless belt) -shaped soft magnetic material block and / or another permanent magnet block is formed until the extrudate comes out of a magnetic field orientation die and is cooled and solidified. We proposed a method to move the object in synchronization with the extrudate. However, this is difficult to apply to the manufacture of multi-pole cylindrical magnets.

On the other hand, in JP-A-60-182710, the resin magnet melt is not magnetically oriented in the die.
A method is disclosed in which the resin magnet melt is magnetically oriented while passing through a cooling and magnetic field orientation sizing die that is left stationary after the die. However, in this method, since the resin magnet melt is rapidly cooled and the viscosity increases,
Even though a magnetic field is applied, the degree of orientation of the magnetic particles does not increase, and the sizing die is stationary, so the friction between the wall and the extrudate hinders the orientation of the magnetic particles, As a result, there is a problem that a bonded magnet having high magnetic properties cannot be obtained.

[0005]

The present invention, which has been made to solve the above-mentioned fatal problem of magnetic field oriented extrusion, is a long bond made of a material in which ferromagnetic powder having magnetic anisotropy is dispersed and mixed in a plastic. When a magnet is produced by a magnetic field orientation extrusion method, the molten mixture is magnetically oriented in a die, the extrudate exiting the die is passed through a sizing die having a magnetic circuit structure, and the sizing die is extruded. The essence includes a process of moving the extrudate in the take-up direction to solidify by cooling, and thereafter, the sizing die releases the extrudate, is cooled, and is moved and returned to an initial standby position near the die.
The manufacturing apparatus for carrying out such a manufacturing method has the following structure.
Have a success. Ferromagnetic powder with magnetic anisotropy
Push out the bonded magnet material that is dispersed and mixed in the plastic
Heated and extruded from the extruder and the extruder
The bonded magnet material is press-fitted to magnetically orient the bonded magnet material.
Shaped magnetic field orientation die and sage with magnetic circuit structure
Is a die and is extruded from the magnetic field orientation die.
Received extrudate and mold the received extrudate
The mold itself moves in the take-up direction of the extrudate while holding it inside.
Cutting the sizing die and the extrudate after moving to the desired length
Cutter device for cutting and sizing the cut extrudate
While cooling the sizing mold and the means to separate from the mold
Means for returning to the standby position .

[0006]

The reason why the above problems can be solved by the present invention is as follows. First, since the extrudate is sandwiched between sizing dies and cooled and solidified, deformation during the cooling process can be prevented. Also, since the sizing die is provided with magnetic poles forming a magnetic circuit, the orientation of the extrudate does not deteriorate, and even if the orientation of the extrudate deteriorates immediately before entering the sizing die. Corrected in the sizing mold.
Furthermore, since this sizing die is moved in the take-up direction with the extrudate stored, the die wall and the extrudate do not rub,
Therefore, the alignment state is not disturbed.

The magnetic pole portion of the sizing die does not necessarily have to generate a magnetic field by itself. This is because the magnetic pole is also magnetized by the magnetic interaction with the extrudate to generate a magnetic field, which largely cancels the self-demagnetizing field of the extrudate and drastically reduces the magnetic factor of orientation disorder. In this case, the sizing die need not be provided with an excitation source.

Of course, it is desirable that the sizing die is provided with an excitation source so that the magnetic pole portion itself generates a magnetic field. This is because if so, the effect of correcting the alignment disorder is large. In the concrete implementation, the magnetic circuit in the sizing die is most commonly configured so that its magnetic field distribution is similar to that in the extrusion die, but if the desired magnetic field pattern is finally obtained. For example, the structure does not necessarily have to be similar. Further, since the magnetic field orientation is performed by both the extrusion die and the sizing die, the time for magnetic field orientation is extended. Further, an unfavorable orientation state inevitably caused by friction between the extrudate and the die wall for magnetic field orientation by magnetic field orientation in the sizing die for a certain period of time,
It corrects both the orientational disturbances that occur as the extrudate exits the die and is stored in the sizing die. Due to these effects, the magnetic characteristics of the long cylindrical magnet can be enhanced.

Although the main body magnet of the magnet roll has a substantially cylindrical cross section, it may have a cut surface for convenience of positioning and the like. Further, co-extrusion (insert extrusion) of the shaft and the resin magnet material is used to penetrate the shaft.

Since the extrudate just discharged from the die is in a low viscosity state, it tends to sag and curve due to its own weight in horizontal extrusion, so that the diameter becomes small and it may be difficult to store it in a sizing die. If the viscosity of the extrudate is increased, the sag is reduced, but the motion of the magnetic particles is restricted and the degree of orientation is lowered. Therefore, it is desirable to perform sizing while keeping the viscosity low. Therefore, it is better to extrude the extrudate in the vertical direction using a crosshead die or the like.

As the magnetic powder of the bonded magnet material, hexagonal ferrite, SmCo type alloy, NdFeB type alloy, Sm
FeN-based alloys and the like can be mentioned. Hexagonal ferrite (barium ferrite, strontium ferrite) is particularly preferable because it is inexpensive. Any plastic can be used as the binder as long as it can be extruded, and a typical binder is a mixture of polyvinyl chloride and polyvinyl acetate homo- or copolymer, chlorinated polyethylene, and a suitable plasticizer.

[0012]

EXAMPLES The details of the present invention will now be described based on specific examples carried out in order to confirm the effects of the present invention, but this does not limit the present invention in any way.

(Example 1)

[Table 1] A long cylindrical magnet having an outer diameter of 14φ, which penetrates a 6φ iron shaft (length: 250 mm), has four magnetic poles, and has a peak-to-peak angle of a radial component (hereinafter simply referred to as magnetic force) of surface magnetic flux density. Should be the "desired value" in Table 3 Anisotropic long cylindrical magnet (Magnet length 220m
m) was molded by the following procedure using pellets made from the formulations in Table 1. FIG. 1 shows a conceptual diagram of the apparatus configuration used in the manufacturing method, in which 1 is a long cylindrical magnet, 2 is a magnetic field orientation die, 3 is a magnetic field orientation magnetic pole, 4 is a sizing die, and 5 is a permanent magnet for excitation. A magnet and 6 are magnetic field generating yokes. The extruder and magnetic field orientation device are not shown. The arrow means the moving direction of the sizing die. The manufacturing process of the long cylindrical magnet by the apparatus will be described below.

(1) Rotating shaft portions 7a, 7a having reduced diameters at both ends
The shaft 7 (FIG. 2) having the above and the molten resin magnet material of Table 1 are coextruded by magnetic field orientation using a crosshead die. 15 between the shafts as shown in FIG.
mm rotating shaft portions 7a, 7a are butted against each other, and there are rotating shaft portions 7a, 7a with a reduced diameter having a total length of 30 mm. By fitting the socket 8 on the outside, the adjacent shafts are connected. Then, a large number of shafts are continuously supplied to the die while being connected in a line. (2) The extrudate is introduced into the sizing die 4 which is standing by in an open state at a temperature of 80 ° C. or less at a position at least several centimeters away from the die end surface. (Fig. 4) (3) When the magnet comes in place, the sizing die 4 is quickly closed. (FIG. 5) (4) The sizing die 4 is moved in the extrusion direction by a horizontal movement mechanism (not shown) at a speed of 2.5 m / min, which is approximately equal to the extrusion speed of the magnet. (FIG. 6) (5) When the magnet temperature becomes 90 ° C. or less and the magnet has a hardness such that it can be cut, the cutter unit 9 cuts the magnet portion at the socket position to obtain a magnet roll having a predetermined length. (Fig. 7) (6) Immediately after cutting, the upper side 4a of the sizing die 4 is picked up and opened (Fig. 8), the socket 8 is removed, and the rotary shaft portion 7 is removed.
After exposing a (FIG. 9), both ends of the shaft 7 are grasped, the magnet roll 10 is taken out, and the magnet roll 10 is stored in a pallet.
(Fig. 10) (7) The sizing die 4 is moved in a direction perpendicular to the take-up direction while keeping the upper side open, and is returned to the original position when set in a horizontal movement mechanism opposite to the take-up direction. . (Figure 11)

Although not shown, a plurality of sizing dies were used in order to improve the production efficiency, and SmCo rare earth magnets were used as the excitation sources for these sizing dies. Further, in the present example, natural cooling was sufficient for cooling the sizing die. The magnetomotive force applied to the electromagnet for magnetic field orientation is 9 for the N1 pole and S1 pole.
000A · T (ampere turn), N2 pole and S2 pole were 3000A · T. It was confirmed that the cross-sectional shape of the cylindrical magnet produced here was substantially a perfect circle and was hardly deformed. Table 2 shows the magnetic force and the degree of deformation (maximum diameter / minimum diameter) of each pole. Table 3 shows the angular intervals of the peak values of the magnetic force of each pole.

(Comparative Example) A magnet roll was prepared by magnetic field orientation co-extrusion using the same pellets and shafts as in the above example, but without using a sizing die. The cross-sectional shape of this was deformed into an angular shape with the magnetic pole portion protruding. Table 2 also shows the magnetic polarities and the degrees of deformation of the magnet rolls of this comparative example. Table 3 shows the angular intervals of the peak values of the magnetic force of each pole.

[0017]

[Table 2]

[0018]

[Table 3] As is clear from Tables 2 and 3, the long cylindrical magnet manufactured by the manufacturing method of the present invention is extremely excellent in that it has little deformation, the magnetic force is high, and the angle between magnetic forces does not deviate from the desired value.

[0019]

As described above, by using the moving sizing die, a long cylindrical magnet having a small deformation, a high magnetic force, and an angle between the magnetic forces hardly deviating from a desired value can be produced by an extrusion molding method with high productivity. Can be produced. Therefore, it is possible to contribute to higher performance and lower cost of the magnet roll for use in the electrophotographic method such as the electronic copying machine, the facsimile and the LBP.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an apparatus configuration used in a method for producing a long magnet using a moving sizing die.

FIG. 2 is an explanatory view showing external dimensions of a shaft used in an example of the present invention.

FIG. 3A is a perspective view showing a shaft and a socket, and FIG. 3B is a partial cross-sectional explanatory view showing a state in which the shaft is connected by a socket.

[Figure 4]

FIG. 11 is an explanatory view showing each step of the manufacturing method of the present invention.

[Explanation of symbols]

 1 Long Cylindrical Magnet 2 Magnetic Field Orienting Die 3 Magnetic Field Orienting Magnetic Pole 4 Sizing Die 5 Excitation Permanent Magnet 6 Magnetic Field Generating Yoke 7 Shaft 7a Rotating Shaft 8 Socket 9 Cutter Device 10 Magnet Roll

Claims (8)

[Claims] 1. A step of press-fitting a raw material obtained by dispersing and mixing a ferromagnetic powder having magnetic anisotropy into a plastic in an extruder in a state where the material is heated and melted to orient the magnetic field, and an extrudate discharged from the die. A step of storing in a sizing die having a magnetic circuit structure and moving it together with the die in the take-up direction, a step of cutting the extrudate into a desired length and separating the extrudate from the sizing die, and cooling the sizing die A method of manufacturing a long bonded magnet, characterized in that a series of steps of moving and returning to a standby position while repeating is repeated. 2. A sizing die having a magnetic pole having substantially the same structure as that of the magnetic field orientation die, and a permanent magnet and / or an electromagnet being appropriately provided as an excitation source is used. Manufacturing method of long bonded magnet. 3. The method for producing a long bond magnet according to claim 1, wherein the sizing die is composed of two or more separable partial dies. 4. A rod-shaped shaft material and a material in which a ferromagnetic powder having magnetic anisotropy is dispersed and mixed are mixed and coextruded in a magnetic field.
A method for producing the long bonded magnet described. 5. A rotary shaft portion having a diameter smaller than that of the shaft body is provided at both ends of the rod-shaped shaft member, the shaft is continuously arranged in the longitudinal direction, and the rotary shaft portion is located in a butted state between adjacent shaft bodies. 5. The manufacturing method according to claim 4, wherein the shafts are continuously supplied by connecting the rotary shafts with a socket having a length capable of completely containing the rotary shafts. 6. A ferromagnetic powder having magnetic anisotropy is added as a plastic.
Extrusion to extrude bond magnet materials dispersed and mixed in stick
Equipment and the heated and melted extruder extruded from the extruder.
And magnetic field orientation molding of bonded magnet material
Magnetic field orientation die and scidin with magnetic circuit structure
A die, extruded from the magnetic field orientation die
Receive the extrudate and place it in the mold
The mold itself moves in the pick-up direction of the extrudate while holding it
Cut the sizing die and the extrudate after transfer to the desired length.
Cutter device and sizing die for cut extrudate
And wait while cooling the sizing die.
A long bond magnet provided with means for moving and returning to the machine position.
Stone manufacturing equipment. 7. A sizing die having a magnetic pole having substantially the same structure as that of the magnetic field orientation die and using a permanent magnet and / or an electromagnet appropriately as an excitation source is used. Equipment for manufacturing long bonded magnets. 8. The manufacturing apparatus for a long bonded magnet according to claim 6, wherein the sizing die is composed of two or more separable partial dies.