JPH11149219A - Manufacturing method of magnet roller - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the insertion force in the case of manufacturing a magnet roller by press-fitting and fixing a core metal to a hollow cylindrical magnet and to suppress variation in the amount of shrinkage of the hollow cylindrical magnet caused by press-fitting. . SOLUTION: A volatile lubricant 17 is applied at room temperature only to the leading side of a press-fit side of a metal core 12 and the lubricant 1
Before the metal 7 completely evaporates, the core metal 12 is pressed into the hollow cylindrical magnet 11. After the press-fitting, the magnet 11 is heated to a temperature at which the magnet 11 does not deform, and the lubricant 17 is volatilized. The application of the lubricant is performed by immersing the head portion in a lubricant. As the magnet 11, a polyolefin-based elastomer resin, for example, an ethylene-ethyl acrylate copolymer is preferably used.

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 magnet roller.

[0002]

2. Description of the Related Art FIG. 2 shows a developing roller 10 which uses a two-component developer obtained by mixing a magnetic carrier and a non-magnetic toner as a developer among magnet rollers used in an electrophotographic process or the like. It has a structure. The developing roller 10 generally includes a magnet roller 13, a sleeve 14 made of a rotatable non-magnetic material, and a driving side flange 15.
And the driven side flange 16. Also,
The magnet roller 13 includes a hollow cylindrical magnet 11 (a hollow cylindrical plastic magnet or a hollow cylindrical rubber magnet) having a plurality of fixed magnetic poles, and a metal core 12 pressed into the inner peripheral surface thereof. General.

In such a two-component developing roller 10,
Magnetic properties (magnetic flux density) as shown in FIG. 3 are required. In most cases, a plastic magnet or a rubber magnet is used as a molding material, and injection molding or extrusion molding is performed while applying a magnetic field thereto. Magnetic field orientation molding is performed. Since this magnet is in a roller shape, multipolar orientation can be easily performed after molding, so that there is an advantage that production efficiency can be increased.

When the cylindrical (roller-shaped) magnet 11 having a multipolar orientation structure is manufactured by injection magnetic field molding, for example, a molding apparatus shown in FIG. 4 is used. That is, the molten resin is injected into a magnetic field orientation mold 52 having a magnetic field generating yoke 51 (permanent magnet or electromagnet) by a screw (not shown) in a cylinder 53, and after the molded product is cooled and solidified, Take out. In FIG. 4, reference numeral 55 denotes a shaft for forming a pipe hole for forming a hollow cylindrical magnet.

When the magnet 11 is manufactured by extrusion magnetic field molding, for example, as shown in FIGS. 5 and 6, a molten resin is supplied into a magnetic field orientation mold 62 by a screw 61, and a magnetic field is applied here. After being oriented (anisotropic) by this, it is extruded from the magnetic field orientation mold 62. In these figures, 63 is a cylinder, 64 is a nipple, 65 is an orientation die, 66 is a magnetic field generating coil, and 67 is a yoke.

The magnet roller 13 can be manufactured by a method of directly forming the magnet 11 on the outer peripheral surface of the core metal 12 or by inserting the core metal 12 into the magnet 11 (hereinafter sometimes referred to as a work). There is a way.
In the latter method, a resin (a plastic magnet or a rubber magnet) containing a magnetic material is extruded into a cylindrical shape, cut into a predetermined size, and then, as shown in FIG. Press into the inner peripheral surface to insert the core 12
To fix the magnet roller 13.

[0007]

However, conventionally, in the step of inserting the cored bar 12 into the inner peripheral surface of the work 11, there have been the following technical problems. In the case of a magnet roller in which the angle between the magnetic force distribution of the work and a specific portion (D cut or the like) on the core metal must be aligned, high precision is required for positioning the specific portion on the core metal with the work. .

[0008] The magnet roller may be rotated and used. In order to prevent the displacement between the work and the metal core due to the rotation, the core metal must have a withstand torque. A press-fitting or bonding step is required to obtain the torque resistance. However, in the case of bonding, since the torque resistance varies depending on the amount of the adhesive, strict control of the amount of the adhesive is required, and the structure of the bonding apparatus becomes complicated. In the case of press-fitting, the press-in allowance [(core diameter)-(workpiece inner diameter)] is set, but a large torque resistance is required to clear the conditions of use (number of rotations, frequency) and environmental tests of the magnet roller. In order to obtain the above, it is necessary to increase the press-fitting allowance. As a result, the insertion force at the time of press-fitting the core metal becomes large, and the device needs to be upsized. When the core is fixed to the inner peripheral surface of the work by press-fitting, when the core is inserted from one side of the work, the work 11 shrinks as shown in FIG. And the length accuracy cannot be ensured.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, that is, to reduce the core metal insertion force and to prevent the work shrinkage when the core metal is inserted from varying. Specifically, the inventions according to claims 1 to 6 provide a magnet roller with less variation in roller length. Another object of the present invention is to provide a magnet roller which has a small variation in roller length and has excellent torque resistance.

[0010]

The structure, operation and effect of the invention described in each claim will be described below. Claim 1
The invention described in (1) relates to a method of manufacturing a magnet roller having a magnetic field generating layer composed of a hollow cylindrical magnet (meaning a hollow cylindrical plastic magnet or a hollow cylindrical rubber magnet; the same applies hereinafter) around a metal core. A method for manufacturing a magnet roller, characterized in that a core metal coated with an agent is pressed into a hollow cylindrical magnet.

Specifically, for example, as shown in FIG. 1A, a desired lubricant 17 is applied to an appropriate portion of the outer peripheral surface of the cored bar 12 and then applied to the inner peripheral surface of the hollow cylindrical magnet 11. Press-fit. According to the manufacturing method of the first aspect, the core metal insertion force at the time of press-fitting can be reduced, and as shown in FIG. 1B, the shrinkage of the hollow cylindrical magnet 11 at the time of core metal insertion is prevented. It becomes possible. Therefore, it is possible to prevent the length of the magnet roller from varying.

According to a second aspect of the present invention, there is provided a method of manufacturing a magnet roller according to the first aspect, wherein a lubricant is applied to the core by dipping the core in a lubricant. According to this manufacturing method, when applying the lubricant to the core, the core is immersed in the lubricant and applied. Therefore, the lubricant is applied to the core in a short time, uniformly, and using only a simple tool. It becomes possible.

According to a third aspect of the present invention, there is provided a magnet roller according to the first or second aspect, wherein a lubricant is applied only to a leading side of the core when the core is pressed into the hollow cylindrical magnet. It is a manufacturing method. According to this manufacturing method, during or after the insertion of the core metal into the hollow cylindrical magnet, excess lubricant stays at the end of the hollow cylindrical magnet on the core metal insertion side, or the magnet roller is contaminated. Can be prevented.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a magnet roller having a magnetic field generating layer composed of a hollow cylindrical magnet around a core metal, wherein the inner cylindrical surface of the hollow cylindrical magnet is coated with a lubricant. A method for manufacturing a magnet roller, comprising press-fitting a cored bar. According to this manufacturing method, the core metal insertion force at the time of press fitting can be reduced, and it becomes possible to prevent the hollow cylindrical magnet from shrinking when the core metal is inserted. Therefore, it is possible to prevent the length of the magnet roller from varying.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a magnet roller according to the fourth aspect, wherein a lubricant is applied to an inner peripheral surface of the hollow cylindrical magnet by a spray method. According to this manufacturing method, it is possible to apply the lubricant to the inner peripheral surface of the hollow cylindrical magnet uniformly in a short time using only a simple tool.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a magnet roller according to the fourth or fifth aspect, wherein a lubricant is applied only to the core metal insertion side of the inner peripheral surface of the hollow cylindrical magnet. . According to this manufacturing method, during or after the insertion of the core into the hollow cylindrical magnet, excess lubricant stays at the end of the hollow cylindrical magnet on the side opposite to the side where the core is inserted, or stains the magnet roller. Can be prevented.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, a lubricant which is volatile at normal temperature is used, and the core is attached to the hollow cylindrical magnet before the lubricant is completely evaporated. A method for manufacturing a magnet roller, characterized by press-fitting gold. According to this manufacturing method, the core metal insertion force at the time of press-fitting is reduced, and it becomes possible to prevent the hollow cylindrical magnet from shrinking at the time of core metal insertion. It is possible to increase the frictional force and adhesion between gold and the hollow cylindrical magnet. Therefore, it is possible to obtain a magnet roller which has no variation in length and has excellent torque resistance.

The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein after the core metal is pressed into the hollow cylindrical magnet, the softening point of the plastic constituting the hollow cylindrical magnet or A method for manufacturing a magnet roller, characterized in that a lubricant is volatilized by heating at a temperature lower than a denaturation temperature of rubber constituting a hollow cylindrical magnet. According to this manufacturing method, the core metal insertion force at the time of press-fitting is reduced, it is possible to prevent the occurrence of shrinkage of the hollow cylindrical magnet at the time of core metal insertion, and the lubricant volatilizes after the core metal is inserted, It is possible to increase the frictional force and adhesion between the core metal and the hollow cylindrical magnet. In addition, since the heating is performed at a temperature lower than the softening point of the plastic forming the hollow cylindrical magnet or the denaturing temperature of the rubber, deformation, deterioration and change in magnetic properties of the hollow cylindrical magnet can be prevented. Therefore, it is possible to obtain a magnet roller that has no variation in length, has excellent torque resistance, and has little variation in deformation, deterioration, and magnetic characteristics.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a magnet roller according to any one of the first to eighth aspects, wherein the hollow cylindrical magnet is a hollow cylindrical plastic magnet made of an elastomer resin. It is. In this manufacturing method, the core metal is pressed into a hollow cylindrical plastic magnet made of an elastomer resin, whereby the core metal insertion force at the time of press-fitting is reduced due to the elasticity and flexibility of the elastomer. Shrinkage of the shaped magnet can be prevented from occurring.

Further, when the shape of the inner peripheral surface of the hollow cylindrical magnet is not symmetrical in the axial direction or the circumferential direction due to imperfections in the magnet molding, or the shape of the core metal due to imperfections in the production of the core metal. Is not symmetrical in the circumferential and axial directions, and the elasticity of the elastomer resin constituting the hollow cylindrical magnet can be obtained even when the metal core press-in allowance for the hollow cylindrical magnet is not constant in the circumferential or axial direction.・
Due to the flexibility, the inner peripheral surface of the hollow cylindrical magnet is brought into close contact with the core metal, and the frictional force and the adhesion between the core metal and the hollow cylindrical magnet can be increased. Therefore, it is possible to obtain a magnet roller which has no variation in length and has excellent torque resistance.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a magnet roller according to the ninth aspect, wherein the hollow cylindrical plastic magnet is made of a polyolefin elastomer resin. In this manufacturing method, the core metal insertion force at the time of press-fitting is reduced due to the elasticity and flexibility of the elastomer by press-fitting into a hollow cylindrical plastic magnet made of a polyolefin elastomer resin, and the hollow cylindrical shape at the time of inserting the core metal is used. It is possible to prevent the magnet from shrinking.

Further, when the inner peripheral surface shape of the hollow cylindrical magnet is not symmetrical in the axial direction or the circumferential direction due to imperfections in the magnet molding, or the shape of the core metal is imperfect due to imperfections in manufacturing the core metal. The elasticity and flexibility of the elastomer resin that composes the hollow cylindrical magnet, even when the core metal press-in allowance for the hollow cylindrical magnet is not constant in the circumferential or axial direction when it is not symmetrical in the circumferential and axial directions. Due to this, the inner peripheral surface of the hollow cylindrical magnet and the core metal adhere closely,
It is possible to increase the frictional force and adhesion between the core metal and the hollow cylindrical magnet. Therefore, it is possible to obtain a magnet roller which has no variation in length and has excellent torque resistance. Furthermore, polyolefin elastomers have strong resistance to various organic solvents and aqueous solvents,
Further, since the solubility in these solvents is low, the types of lubricants to be applied can be increased.

According to an eleventh aspect of the present invention, in the tenth aspect, the hollow cylindrical plastic magnet is ethylene-based.
A method for producing a magnet roller, comprising a ethyl acrylate copolymer. In this manufacturing method,
By inserting a core into a hollow cylindrical plastic magnet made of an ethylene-ethyl acrylate copolymer, the core metal insertion force at the time of press-fitting is reduced due to the elasticity and flexibility of the elastomer. Shrinkage of the shaped magnet can be prevented from occurring.

Further, when the inner peripheral surface shape of the hollow cylindrical magnet is not symmetrical in the axial direction or the circumferential direction due to imperfections in the magnet molding, or when the core metal shape is circular due to imperfections in manufacturing the core metal. Due to the elasticity and flexibility of the elastomer resin that composes the hollow cylindrical magnet, even when the core metal press-in allowance for the hollow cylindrical magnet is not constant in the circumferential or axial direction when it is not symmetrical in the circumferential and axial directions. The inner peripheral surface of the hollow cylindrical magnet and the core metal are in close contact with each other, and it is possible to increase the frictional force and adhesion between the core metal and the hollow cylindrical magnet. Therefore, it is possible to obtain a magnet roller which has no variation in length and has excellent torque resistance.

Further, the polyolefin-based elastomer has high resistance to immersion in various organic solvents and aqueous solvents, and has low solubility in these solvents, so that the type of lubricant to be applied can be increased. Among the polyolefin-based elastomers, ethylene-ethyl acrylate copolymer has flexibility over a wide temperature range and has high impact strength even at low temperatures, so to obtain a magnet roller with a large magnetic force, the hollow cylindrical magnet is made of magnetic material such as ferrite. Even when the powder is composed of 90 wt% of the powder and 10 wt% of the ethylene-ethyl acrylate copolymer, the hollow cylindrical magnet has the advantage of the hollow cylindrical magnet made of the above-mentioned elastomer.

According to a twelfth aspect of the present invention, in the eleventh aspect, strontium ferrite having a particle diameter of about 1 μm is used as the hollow cylindrical plastic magnet in a range of 90.5 to 9 μm.
An ethylene-ethyl acrylate copolymer containing 1.5 wt% (the total amount of strontium ferrite and ethylene-ethyl acrylate copolymer is 100
wt%), and the press-fitting margin of the core metal into the hollow cylindrical plastic magnet is set to 0.05 to 0.15 mm.

According to this manufacturing method, it is possible to obtain a magnet roller having a strong magnetic force and a high torque resistance and having a small variation in length. It consists of an ethylene-ethyl acrylate copolymer and strontium ferrite having a particle size of about 1 μm, and has a strontium ferrite content of 9%.
With a hollow cylindrical plastic magnet of 0.5 to 91.5 wt%, if the press-fitting allowance is in the range of 0.05 to 0.15 mm, both the insertion force at the time of press-fitting and the withstand torque of the magnet roller are within appropriate ranges. be able to. In the case of the hollow cylindrical plastic magnet, the press-fitting allowance is set at 0.1.
If it is smaller than 05 mm, the torque resistance is 20 N or less, which is insufficient for practical use. If the press-in allowance is larger than 0.15 mm, an insertion force of 2 kN or more is required for press-fitting even if a lubricant is used. In addition to an increase in the size of the device, problems such as bending of the cored bar due to the insertion force occur.

[0028]

EXAMPLE 1 (1) Material of hollow cylindrical magnet: 8.7 wt% of ethylene-ethyl acrylate copolymer, 91.3 wt% of strontium ferrite (2) Dimension of hollow cylindrical magnet: outer diameter φ14 mm,
Inner diameter φ5.88mm, length 310mm (3) Material of core metal: SUM22 (4) Dimension of core metal: φ5.98mm (press-fitting 0.1m
m) (5) Type of lubricant: G-6311FK (manufactured by Nippon Kogyo Oil Co., Ltd.) A core metal was pressed into a hollow cylindrical magnet under the above conditions (10
The results were as shown in the following [Table 1].

Comparative Example 1 The results of pressing a core metal into a hollow cylindrical magnet in the same manner as in Example 1 except that no lubricant was used are also shown in Table 1.

[0030]

[Table 1]

As described above, in Example 1, the insertion force was smaller than that of Comparative Example 1, and the anti-torque was hardly changed.
A magnet roller with a small change in length could be obtained.

[0032]

As apparent from the above description, the following effects can be obtained according to the present invention. (1) According to the first aspect of the present invention, in the method for manufacturing a magnet roller having a magnetic field generating layer composed of a hollow cylindrical magnet around a core metal, the core metal coated with a lubricant is pressed into the hollow cylindrical magnet. By doing so, it is possible to obtain a magnet roller with less variation in length.

(2) According to the second aspect of the present invention, the lubricant is applied to the core by dipping the core in the lubricant.
The lubricant can be uniformly applied to the metal core in a short time using only a simple tool.

(3) According to the third aspect of the present invention, the lubricant is applied only to the leading side of the core when the core is pressed into the hollow cylindrical magnet, thereby inserting the core into the hollow cylindrical magnet. At the time of or after insertion, it is possible to prevent a problem that an excessive lubricant stays at the end of the hollow cylindrical magnet on the core metal insertion side side or stains the magnet roller.

(4) In the method for manufacturing a magnet roller having a magnetic field generating layer composed of a hollow cylindrical magnet around a core metal according to the invention of claim 4, the inner peripheral surface of the hollow cylinder is coated with a lubricant. By press-fitting the core metal into the shaped magnet, it is possible to obtain a magnet roller with less variation in length.

(5) According to the fifth aspect of the present invention, the lubricant is applied to the inner peripheral surface of the hollow cylindrical magnet by a spray method, so that the lubricant is uniformly applied to the inner surface of the hollow cylindrical magnet in a short time. In addition, it is possible to apply using only a simple tool.

(6) According to the sixth aspect of the present invention, the lubricant is applied only to the core metal insertion side of the inner peripheral surface of the hollow cylindrical magnet, so that the core metal is inserted into the hollow cylindrical magnet or after insertion. Excessive lubricant can be prevented from staying at the end of the hollow cylindrical magnet opposite to the side where the metal core is inserted, and from soiling the magnet roller.

(7) According to the seventh aspect of the present invention, a lubricant which is volatile at normal temperature is used, and the core metal is pressed into the hollow cylindrical magnet before the lubricant is completely volatilized. And a magnet roller having excellent torque resistance can be obtained.

(8) In the invention according to the eighth aspect, after the core metal is press-fitted into the hollow cylindrical magnet, the hollow cylindrical magnet is replaced with the softening point of the plastic constituting the hollow cylindrical magnet or
By heating at a temperature lower than the denaturation temperature of rubber to volatilize the lubricant, it is possible to obtain a magnet roller that has no variation in length, has excellent torque resistance, and has little variation in deformation, deterioration, and magnetic properties. Become.

(9) According to the ninth aspect of the invention, the core metal is press-fitted into the hollow cylindrical plastic magnet made of an elastomer resin, so that there is no variation in length.
Moreover, a magnet roller having excellent torque resistance can be obtained.

(10) According to the tenth aspect of the invention, the core roller is press-fitted into a hollow cylindrical plastic magnet made of a polyolefin-based elastomer resin, so that there is no variation in length and the magnet roller has excellent torque resistance. Can be obtained. Further, the type of lubricant to be applied can be increased.

(11) According to the eleventh aspect of the present invention, the core metal is press-fitted into the hollow cylindrical plastic magnet made of the ethylene-ethyl acrylate copolymer, so that there is no variation in length and the torque resistance is excellent. Thus, it is possible to obtain a magnet roller that has a large size. Further, the type of lubricant to be applied can be increased.

(12) In the twelfth aspect of the present invention, the hollow cylindrical plastic magnet has a particle diameter of about 1 μm.
90.5 to 91.5 wt% of strontium ferrite
% Of ethylene-ethyl acrylate copolymer, and a strong magnetic force and torque resistance can be obtained by making the press-fitting margin of the core metal into this hollow cylindrical plastic magnet 0.05 to 0.15 mm. In addition, it is possible to obtain a magnet roller having a small variation in length.
Further, the insertion force at the time of press-fitting and the torque resistance of the magnet roller can be kept within appropriate ranges.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method of manufacturing a magnet roller according to the present invention.

FIG. 2 is a longitudinal sectional view of a magnet roller used for two-component development in an electrophotographic process.

FIG. 3 is an explanatory diagram of magnetic characteristics (magnetic flux density) of the magnet roller of FIG. 2;

FIG. 4 is a front view showing a main part structure of a conventional injection magnetic field forming apparatus.

FIG. 5 is a longitudinal sectional view showing a main part structure of a conventional extrusion magnetic field forming apparatus.

FIG. 6 is a right side view of FIG.

FIG. 7 is a diagram illustrating a conventional method of manufacturing a magnet roller and a problem thereof.

[Explanation of symbols]

 Reference Signs List 10 developing roller 11 hollow cylindrical magnet (work) 12 cored bar 13 magnet roller 14 sleeve 15 drive side flange 16 driven side flange 17 lubricant

 ──────────────────────────────────────────────────の Continuing on the front page (72) Tachi Tani Inventor Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (12)

[Claims] 1. Hollow cylindrical magnet (hollow cylindrical plastic magnet or hollow cylindrical rubber magnet)
A method of manufacturing a magnet roller having a magnetic field generating layer formed around a core metal, comprising press-fitting a core metal coated with a lubricant into a hollow cylindrical magnet. 2. The method according to claim 1, wherein the lubricant is applied to the core by dipping the core in a lubricant. 3. The method for manufacturing a magnet roller according to claim 1, wherein a lubricant is applied only to a leading side of the core when the core is pressed into the hollow cylindrical magnet. 4. A hollow cylindrical magnet (hollow cylindrical plastic magnet or hollow cylindrical rubber magnet)
A method for manufacturing a magnet roller having a magnetic field generating layer formed around a core metal, comprising press-fitting the core metal into a hollow cylindrical magnet coated with a lubricant on an inner peripheral surface. 5. The method according to claim 4, wherein a lubricant is applied to the inner peripheral surface of the hollow cylindrical magnet by a spray method. 6. The method for manufacturing a magnet roller according to claim 4, wherein the lubricant is applied only to the core metal insertion side of the inner peripheral surface of the hollow cylindrical magnet. 7. The method according to claim 1, wherein a lubricant that is volatile at room temperature is used, and the core metal is pressed into the hollow cylindrical magnet before the lubricant completely volatilizes. 3. The method for manufacturing a magnet roller according to item 1. 8. After the core is pressed into the hollow cylindrical magnet, the lubricant is heated at a temperature lower than the softening point of the plastic forming the hollow cylindrical magnet or the denaturing temperature of the rubber forming the hollow cylindrical magnet. The method for manufacturing a magnet roller according to any one of claims 1 to 7, further comprising: 9. The method of manufacturing a magnet roller according to claim 1, wherein the hollow cylindrical magnet is a hollow cylindrical plastic magnet made of an elastomer resin. 10. The method according to claim 9, wherein the hollow cylindrical plastic magnet is made of a polyolefin elastomer resin. 11. The method according to claim 10, wherein the hollow cylindrical plastic magnet is made of an ethylene-ethyl acrylate copolymer. 12. Strontium ferrite having a particle size of about 1 μm is used as a hollow cylindrical plastic magnet.
A material made of an ethylene-ethyl acrylate copolymer containing 0.5 to 91.5 wt% is used, and the press-in allowance of the core metal into the hollow cylindrical plastic magnet is 0.05 to 9%.
The method according to claim 11, wherein the thickness is set to 0.15 mm.