JP3502534B2 - Manufacturing method of magnet roll - 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 magnet roll.

[0002]

2. Description of the Related Art A cylindrical sleeve made of a non-magnetic material,
A magnet having a plurality of magnetic poles arranged inside the sleeve and arranged in the circumferential direction, and a magnet that is fitted and fixed inside each end of the sleeve in the axial direction and is rotatably assembled to the magnet. A magnet roll having a pair of end members formed therein is conventionally well known, and such a magnet roll is used in various technical fields. For example, in an image forming apparatus configured as an electronic copying machine, a facsimile machine, a laser printer, or a composite machine having at least these two functions, the surface of an image carrier made of a photoconductor is made uniform in a predetermined polarity. The surface of the image bearing member is charged with electricity, the surface thereof is imagewise exposed to form an electrostatic latent image, the electrostatic latent image is visualized as a toner image by a developing device, and the toner image is transferred onto a transfer material. The transfer residual toner adhering to the surface is removed by a cleaning device to clean the surface of the image carrier, and the magnet roll of the above type is used in the developing device and the cleaning device of such an image forming apparatus.

That is, this magnet roll is supported by a developer case of a developing device, at least one of a sleeve and a magnet of the magnet roll is rotationally driven, and powdery magnetic development is carried on the surface of the sleeve by the magnetic force of the magnet. The developer is conveyed, and the electrostatic latent image is converted into a toner image by the developer. The magnet roll in this case is generally called a developing roller.

Further, a magnet roll is supported in a casing of a cleaning device for cleaning the surface of the image bearing member, and at least one of the sleeve and the magnet is rotationally driven,
It is also possible to attract the transfer residual toner adhering to the surface of the image bearing member to the surface of the sleeve by magnetic force and convey the toner.
The magnet roll in this case is called a cleaning roller or the like.

Further, in the image forming apparatus of the type in which the toner image formed on the surface of the photoconductor is primarily transferred to the surface of the image carrier which is an intermediate transfer member, and the toner image is transferred to the final transfer material, the intermediate transfer is performed. A magnet roll may be used as a cleaning device for cleaning the transfer residual toner on the body surface.

As described above, in the magnet roll used in various technical fields, it is necessary to firmly fix the sleeve and the end members so that the sleeve and the end members do not separate during the operation. That is, when a large torque is applied to the magnet roll during the use of the magnet roll, the coupling between the sleeve and the end member is broken, and the two rotate relative to each other so that the sleeve idles, or the end member and the sleeve. Must be prevented from slipping out in the axial direction.

The torque when a large external force acts on the magnet roll to break the coupling between the sleeve and the end member and both start rotating relative to each other is called torque resistance, and the end member slips out of the sleeve in the axial direction. If the force at that time is called pull-out strength, the sleeve and the end member must be firmly fixed so that high torque resistance and high pull-out strength can be obtained.

For this reason, conventionally, the sleeve and each end member were fixed by the adhesive, but according to this method, the adhesive may adhere to the surface of the sleeve during the fixing work. In this case, Since the adhered adhesive must be wiped off with a chemical or the like, the work becomes complicated. Further, the adhesive strength of the adhesive may decrease with time or changes in the environment.

In order to eliminate such a defect, there has been proposed a method of plastically deforming the axial end portion of the sleeve to fix the sleeve and the end member. However, this method also has a limit in increasing the bonding strength between the sleeve and the end member. Also, a claw protruding outward is formed at each end of the sleeve in the axial direction, the claw is plastically deformed, and the claws formed in the end members are engaged to fix the sleeve and the end members. Although a method of doing so is also known, if the claw is formed on the sleeve and the locking groove is formed on each end member, the overall shape becomes complicated, and eventually the manufacturing cost of the magnet roll increases.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a magnet roll which eliminates the above-mentioned drawbacks of the prior art and which is simple and low-cost and which can obtain high torque resistance and high pull-out strength. .

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a cylindrical sleeve made of a non-magnetic material,
A magnet having a plurality of magnetic poles arranged inside the sleeve and arranged in the circumferential direction, and a magnet that is fitted and fixed inside each end of the sleeve in the axial direction and is rotatably assembled to the magnet. A magnet roll having a pair of end members formed on the outer peripheral surface of at least one end member, the taper surface tapering toward the outer end surface of the end member farthest from the center of the magnet roll axial direction. In the method for manufacturing a magnet roll in which the taper surface is formed with concave and convex portions, the end member having the taper surface is fitted inside the axial end portion of the sleeve. , Which has a form corresponding to the tapered surface, and which pushes the axial end of the sleeve into which the end member with the tapered surface is fitted against the molding surface with the convex portion formed on the surface. Give proposes a method for manufacturing a magnet roller, characterized in that plastic deformation along the sleeve tapered surface (claim 1).

At this time, when the end portion of the sleeve is plastically deformed, the convex portion formed on the surface of the molding surface is composed of a plurality of ridges extending parallel to the concave portions of the end member. Is advantageous (claim 2).

Further, in the method of manufacturing a magnet roll according to claim 1, when the end portion of the sleeve is plastically deformed, the convex portion formed on the surface of the molding surface is a knurled portion formed on the end member. Advantageously, it comprises a plurality of ridges which intersect at an angle of more than 0 ° with respect to the recesses of (3).

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing an example of a magnet roll according to the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. The magnet roll 1 shown here is a cylindrical sleeve 2 made of a non-magnetic material such as aluminum.
And the magnet 3 arranged inside the sleeve 2.
And a pair of end members 4 and 5 which are fitted and fixed inside the respective end portions of the sleeve 2 in the axial direction (longitudinal direction). These end members 4 and 5 are also generally called flanges or flange members.

In the illustrated example, the magnet 3 is formed in a cylindrical shape, and a round rod-shaped core shaft 8 is inserted and fixed in the center hole 7 of the magnet 3. The magnet 3 has a plurality of magnetic poles arranged in the circumferential direction thereof, and FIG. 2 shows an example of the magnetized state with S and N indicating its polarity. The magnet 3 is configured as, for example, a plastic magnet or a rubber magnet, and the core shaft 8 is configured by a high strength material such as metal. Magnet 3 and core shaft 8
It is also possible to integrally form and and both of them are made of a magnet material.

The magnet 3 is wholly disposed inside the sleeve 2, and one end of a core shaft 8 protruding outward in the axial direction of the magnet 3 is fitted with a bearing 9 to the core shaft 8 concerned.
One end member 4 is fitted so as to be relatively rotatable with respect to. The end member 4 is also formed in a substantially cylindrical shape, the core shaft 8 penetrates through the center hole thereof, and one end of the sleeve 2 in the axial direction is fitted and fixed to the outer peripheral surface of the end member 4 as described later. There is.

Similarly, the other end of the core shaft 8 projecting outward in the axial direction of the magnet 3 is relatively rotatably fitted to the center of the other end member 5 via a bearing 10. The end member 5 is also formed in a substantially cylindrical shape, and the other axial end portion of the sleeve 2 is fitted and fixed to the outer peripheral surface of the end member 5 as described later. The end members 4 and 5 are located inside the respective end portions in the axial direction of the sleeve 2 and are firmly fixed to the respective end portions.

As described above, the pair of end members 4, 5
Is relatively rotatably assembled to the magnet 3 around its central axis. The sleeve 2 and the pair of end members 4 and 5 which are integrally fixed to each other include a bearing 9,
It is assembled so as to be relatively rotatable with respect to the magnet 3 via the core 10 and the core shaft 8. The core shaft 8, the magnet 3, the pair of end members 4, 5 and the sleeve 2 are concentrically arranged, and these extend in the axial direction to form the magnet roll 1.

The other end member 5 has a round rod-shaped shaft portion 11 which is concentric with the core shaft 8 and projects outward in the axial direction thereof, and the outer end surface of the one end member 4 has the sleeve 2 of the sleeve 2. A sealing material 12 made of a soft material is attached inside to prevent foreign matter or toner described later from entering.

The magnet roll 1 configured as described above is assembled in, for example, a developing device or a cleaning device of an image forming apparatus, and is used in the mode described above.
The magnet roll 1 of this example is configured to be used as a developing roller in a developing device.

That is, as illustrated by a chain line in FIG.
One end portion in the axial direction of the core shaft 8 to which the magnet 3 is fixedly fixed is attached to one side wall 14 of the developer case 13 of the developing device.
The shaft portion 11 is rotatably supported by the other side wall 15 via a bearing 16, and the gear 17 is fixed to the shaft portion 11. The gear 17 meshes with a gear (not shown) on the image forming apparatus main body side, and a motor (also not shown) similarly causes the sleeve 2 to pass through these gears.
Both end members 4 and 5 are rotationally driven with respect to the core shaft 8 around the center axis of the core shaft 8. At this time, a powdery two-component developer, at least a part of which is made of a magnetic material, is carried on the surface of the sleeve 2 by the magnetic force of the magnet 3, and is conveyed in the circumferential direction by the rotation of the sleeve 2. With the developer, as described above, the electrostatic latent image formed on the surface of the image carrier is visualized as a toner image. Similarly, it is also possible to carry and convey a one-component developer, and thereby an electrostatic latent image can be visualized. The two-component developer is a developer formed by mixing at least a toner and a carrier, and the developer containing no carrier is a one-component developer. Generally, the carrier is composed of a magnetic material, and the toner is composed of an insulating toner.

The sleeve 2 and both end members 4, 5 are fixedly fixed to the developer case 13, and the core shaft 8 is rotatably supported with respect to the developer case 13. The core shaft 8 and the magnet 3 are shown in the drawing. Alternatively, the developer carried on the surface of the sleeve 2 can be conveyed by rotationally driving it by a motor through a gear that is not provided, or by rotationally driving both the sleeve 2 and the magnet 3 in opposite directions.

When the sleeve 2 is rotationally driven from the side of the other end member 5 on the right side as shown in FIG. 1, this end member 5 serves to transmit the rotation to the sleeve 2, so that the drive side is generally used. Also called a flange, the end member 5 is
It is often made of a non-magnetic material having excellent wear resistance, such as aluminum. The one end member 4 also has a function of holding the magnet 3 in the sleeve 2, and is generally called a driven side flange. Such end member 4
Is often made of a resin molded product for weight reduction and cost reduction. When the magnet roll is used as a developing roller as shown in FIG. 1, since a bias voltage is generally applied to the sleeve 2 via the end member 5, the sleeve 2 and the end member 5 are made of a conductive material. Composed.

The structure itself of the magnet roll described above is the same as that of the conventional magnet roll. In such a magnet roll, the sleeve 2 and the end members 4 and 5 need to be firmly fixed so as not to separate from each other by an external force or the like applied during the operation. That is, the sleeve 2 and the respective end members 4, 5 are prevented from relatively rotating about their axes, and the respective end members 4, 5 are pulled out outward in the axial direction with respect to the sleeve 2. Need to be blocked.

A large external force acts on the magnet roll 1 to break the coupling between the sleeve 2 and the end members 4 and 5, and the torque at which the two start relative rotation, that is, the torque resistance, and the end members 4 and 5. It is necessary to firmly fix the sleeve 2 and the end members 4 and 5 so that the force of pulling out from the sleeve 2 in the axial direction thereof, that is, the pull-out strength can be increased.

As described above, since the end member 5, which is also called the drive side flange, serves to transmit the rotation to the sleeve 2, a large torque is applied, and therefore, the end member 5 and the sleeve 2 are particularly large. Torque resistance and high pull-out strength are required. The driven end member 4 also needs to be firmly fixed to the sleeve 2 so as not to slip out of the sleeve 2 in the axial direction thereof.

In order to meet such requirements, in the magnet roll 1 of this example, as shown in FIGS. 1 and 3 to 6, the outer peripheral surface of each end member 4, 5 is arranged in the axial direction of the magnet roll 1. The outer end face 21 of each end member 4, 5 in
22 taper surface (chamfered portion) 2 tapering gradually toward 22
3, 24 are respectively formed on the entire peripheral surface,
Moreover, each axial end portion of the sleeve 2 is plastically deformed along the entire circumference thereof along the tapered surfaces 23 and 24 of the end members 4 and 5, whereby each end portion of the sleeve 2 is
It is fixed to each of the end members 4 and 5. The end portions of the sleeve 2 are bent and deformed and fixed to the tapered surfaces 23 and 24 in a crushed state.

Further, in the embodiment shown in FIG. 1, the center of the magnet roll 1 in the axial direction X, that is, the portion that bisects the length of the magnet roll 1 is the center of the magnet roll axial direction as shown in FIG. When C is set, a portion D1 of the outer peripheral surface of each of the end members 4 and 5 close to the center C of the magnet roll in the axial direction contacts the inner peripheral surface of the sleeve 2 to maintain the accuracy of assembly with the sleeve 2. A portion D2 which constitutes a sleeve supporting surface, and is separated from the sleeve supporting surface D1 with respect to the center C of the magnet roll axial direction.
Is formed as tapered surfaces 23, 24 that taper toward the outer end surfaces 21, 22 of the end members 4, 5 farthest from the center C of the magnet roll axial direction. Moreover, the sleeve portion fitted to each tapered surface 23, 24 is fixed to each end member 4, 5 by being plastically deformed along the entire circumference thereof along the tapered surface 23, 24. Furthermore, the axial outer end surfaces 30 and 31 of the sleeve 2 are located closer to the magnet roll axial center C than the outer end surfaces 21 and 22 of the end members 4 and 5, respectively.

According to the above construction, the sleeve 2 and both end members 4, 5 can be fixed with high torque resistance and high pull-out strength. Moreover, the tapered surfaces 23, 24 are formed over the entire circumferences of the respective end members 4, 5, and the entire circumferences of the respective end portions of the sleeve 2 are plastically deformed along the tapered surfaces 23, 24. It can be simplified, for example, by a simple pressing device, each end of the sleeve 2 is bent and deformed,
This can be fixed to each end member 4, 5.

FIG. 7 shows an example of the pressing device. This pressing device has a die 25 and a knockout 26 slidably arranged in a center hole thereof, and a guide ring 27 is fixed to an end surface of the die 25. The die 25 has a molding surface 28 that is inclined at the same angle as the inclination angle θ (FIGS. 3 and 5) of the tapered surfaces 23 and 24 of the end members.

The sleeve 2 has a thickness t ₁ at each end in the axial direction slightly smaller than the thickness t ₂ at its central portion, and is already inside the thin end. The end member 4 assembled with the magnet 3 and the core shaft 8 is lightly press-fitted. At this time, due to the step at the boundary between the thin end portion of the sleeve 2 and the thick central portion, the end member 4 is
Positioned with respect to.

In this state, the sleeve 2 is fixed and the die 25
Is brought close to the sleeve 2, and the end face of the sleeve 2 is plastically deformed along the tapered surface 23 by the molding surface 28 thereof.
At this time, the knockout 26 has the outer end surface 21 of the end member 4.
It is pressed by and is escaped to the left in FIG. 7 against the biasing force of a spring (not shown).

The other end of the sleeve 2 is also plastically deformed in exactly the same manner, and the other end member 5 is fixed to the sleeve 2. Normally, both end members 4, 5 can be fixed to the sleeve 2 at the same time. Is used.

As described above, the tapered surfaces 23 and 24 are formed on the end members 4 and 5, respectively, and the sleeve 2 is plastically deformed along the tapered surfaces 23 and 24. Even if an external force is applied in the axial direction, the tapered surfaces 23, 24 of the end members 4, 5 and the plastically deformed sleeve portion are firmly engaged with each other, and the withdrawal is prevented. Large pull-out strength is guaranteed.

Similarly, even if a large torque is applied to the magnet roll 1, they do not relatively rotate due to the high coupling strength between the tapered surfaces 23 and 24 and the plastically deformed sleeve portion. High torque resistance is guaranteed.

Further, in the magnet roll 1 shown in FIG. 1, the axial outer end surfaces 30 and 31 of the sleeve 2 are located at the axial center C of the magnet roll rather than the outer end surfaces 21 and 22 of the end members 4 and 5, respectively. Since it is located on the side of
When the sleeve 2 is plastically deformed by the pressing device as shown in FIG.
The pressure per unit area of and becomes large, both are firmly fixed, and the above-mentioned pull-out strength and torque resistance can be effectively increased.

The outer end surfaces 30 and 31 of the sleeve 2 and the outer end surfaces 21 and 22 of the end members 4 and 5 are made to coincide with each other, or, as can be seen from FIG.
The end members 4 and 5 may be projected further outward than the outer end surfaces 21 and 22, but with such a configuration, when the sleeve 2 is plastically deformed by the pressing device, the tapered surface 24 shown in FIG. The force is concentrated on the pressure contact portion between the edge portion 24A and the sleeve 2, and the pressure per unit area between the entire surface of the tapered surface 24 and the sleeve 2 is reduced, and the coupling strength thereof may be somewhat reduced. The same applies to the side of the tapered surface 23.

Further, in the magnet roll 1 shown in FIG. 1, the taper surface 23 farther away from the center C than the sleeve supporting surface D1 closer to the center C of the end members 4 and 5 in the magnet roll axial direction. , 24, the sleeve 2 is plastically deformed, and the sleeve supporting surface D1 is not bent. Before pressing the sleeve 2, the inner peripheral surface of the sleeve 2 is fitted to the sleeve supporting surface D1 in a state of being in close contact with the sleeve supporting surface D1, and thereby the end members 4, 5 and the sleeve 2 are concentric with each other. The sex is maintained. Since the sleeve portion that is in close contact with the sleeve supporting surface D1 is not pressed, the close contact state between the sleeve supporting surface D1 and the sleeve portion that is not plastically deformed is maintained even after the sleeve 2 is plastically deformed. To be done. Therefore, even after the plastic deformation of the sleeve 2, the concentricity of the sleeve 2 and the end members 4 and 5 is maintained, and the assembling accuracy of both of them is improved.

As described above, the sleeve supporting surface D1 is a portion that contacts the inner peripheral surface of the sleeve 2 to maintain the accuracy of assembly with the sleeve 2, and the sleeve portion fitted to this portion should not be pressed. Thereby, the assembling accuracy of the sleeve 2 and the end members 4 and 5 after the press working can be improved. When such a magnet roll 1 is used in a developing device, it is possible to prevent a problem that the sleeve 2 rotates in a largely eccentric state or shakes greatly, and it is possible to form a high quality toner image on the photoconductor. In the illustrated example, the sleeve supporting surface D1 of each of the end members 4 and 5 is formed as a cylindrical surface parallel to the magnet roll axis direction X, but the surface D1 is inclined and the corresponding inclination is made. It is also possible to bring the inner peripheral surfaces of the sleeves into contact with each other and fit them together.

In this way, it is possible to obtain a magnet roll having a high coupling strength between the end members 4 and 5 and the sleeve 2 and having high accuracy.

Next, the advantages of the above-mentioned configuration and further advantageous configurations will be clarified while explaining an experimental example conducted by the present inventor.

In this experiment, A606 was used as the sleeve 2.
The extraction material of 3 was used. Its outer diameter is 16 mm and its wall thickness is t _2.
Is 0.75 mm, and the press-fitted end of the end member is additionally processed to have a wall thickness t ₁ of 0.35 mm. t ₁ / t ₂ is 0.
35 / 0.75 = 0.47, which is 0.5 or less. The one end member 4 is made of ABS containing glass fiber.
A molded resin is used, and the other end member 5 is
AHS made of Showa Aluminum, which is wear-resistant aluminum, was used.
The form of this magnet roll is as shown in FIG.

Further, as shown in FIG. 1, the length L of the plastically deformed sleeve portion in the sleeve axial direction is 1 mm, and the angle (taper angle) formed by the tapered surfaces 23 and 24 with respect to the axial direction of the magnet roll. θ is 15 °, 30
Five kinds of end members having angles of 45 °, 45 °, 60 ° and 75 ° were prepared. Using the end members 4 and 5 and the sleeve 2, the pressing force F of the pressing device shown in FIG. 7 was set to 3 MPa, and the sleeve 2 was fixed to the end members 4 and 5 as described above.

The torque resistance of the end member 5 and the sleeve 2 of each magnet roll thus obtained and the taper surface 2 thereof
FIG. 9 shows the relationship between the taper angle θ of 4 and the taper angle θ.

On the other hand, when a large number of magnet rolls were manufactured as described above and the details thereof were examined, it was found that each end of the sleeve 2 was pressed by a pressing device so as to be along the tapered surfaces 23 and 24 of the end members 4 and 5. When plastically deformed, it can be seen that due to the deformation, the sleeve surface portion near the bent sleeve end portion is slightly deformed so as to bulge outward in the radial direction of the sleeve as exaggeratedly shown in FIG. It was It was also clarified that the bulge of the outer diameter of the sleeve changes depending on the taper angle θ of the taper surface.

If such a bulge is formed on the sleeve 2 and this bulge becomes remarkable, the following problems occur. That is, as shown by a chain line in FIG. 1, the end regions of the sleeve 2 corresponding to the non-image regions on the photoreceptor are
In order to prevent the carrier of the developer from adhering to this and to more surely prevent the toner from entering the inside of the sleeve 2, thin resin seals 29 are brought into contact with each other. At that time, as shown in an exaggerated manner in FIG. 24, if the above-mentioned bulges are formed at each end of the sleeve 2, the seal 2
9 cannot adhere to the surface of the sleeve 2 and its sealing function deteriorates. Further, the seal 29 strongly hits the convex portion of the bulge of the sleeve 2, and the seal 29 is worn and deteriorated at an early stage. Therefore, it is necessary to minimize such a bulge of the sleeve.

The relationship between the bulge of the outer diameter of the sleeve and the taper angle θ of the taper surface obtained in this experimental example is as shown in FIG. The outer diameter change amount mm on the vertical axis of this graph indicates the difference between the outer diameter of the bulged portion of the sleeve and the predetermined outer diameter of the sleeve.

As can be seen from the graph of FIG. 10, the smaller the taper angle θ of the tapered surfaces 23 and 24, the smaller the change in the outer diameter of the sleeve, and the minimum when the taper angle θ is 30 °. According to a number of experiments conducted by actually loading each magnet roll into the developing device, if the taper angle θ is in the range of 25 ° to 35 °, the outer diameter change amount of the sleeve 2 can be suppressed to be small, and thus the seal can be reduced. It was confirmed that 29 functions could be exhibited without any problems.

On the other hand, it can be seen from the graph shown in FIG. 9 that the torque resistance can be maintained high if the taper angle θ is 60 ° or less. When the taper angle θ is 75 °, the angle θ of the molding surface 28 of the die 25 shown in FIG. 7 is close to a right angle. Therefore, the end portion of the sleeve 2 should be bent and deformed to a predetermined angle. However, the torque resistance is extremely small as can be seen from FIG. Further, when the taper angle θ is 15 °, the bending angle of the end portion of the sleeve also becomes small, so that it is clear that the pulling-out strength is lower than when the taper angle θ is in the range of 20 ° to 60 °. became. Thus, in order to obtain high torque resistance and high pull-out strength, it is desirable that the taper angle θ be in the range of 20 ° to 60 °.

From the above results, the tapered surfaces 23, 2
Angle θ formed by 4 with the axial direction of the magnet roll
Is set to a value in the range of 25 ° to 35 °, it is possible to construct an ideal magnet roll in which both the torque resistance and the pull-out strength are increased and the swelling of the sleeve is suppressed.

In the example shown in FIG. 1, the tapered surfaces 23 and 24 of the end members 4 and 5 are linear when viewed in their longitudinal sectional shape, but as shown in FIG. The tapered surfaces 23 and 24 may be formed as curved surfaces so that the sleeve 2 is plastically deformed along the curved surfaces.

Further, the tapered surfaces 23 and 24 are formed to have a constant taper angle θ, and as shown in FIG. 12, tapered surfaces 24a and 24b having different taper angles may be formed. . Further, as shown in FIG. 13, the tapered surface 24 may be composed of two curved portions 24c and 24d, or, as shown in FIG. 14, the curved portion 24e may be a tapered surface including a straight portion 24f.

Further, in each of the above-mentioned constitutions, as shown in FIGS. 15 and 16, each end member 4, 5 has a center C in the axial direction of the magnet roll rather than each taper surface 23, 24.
The outer peripheral surface 32 is further provided at a portion distant from (FIG. 1).
It is also possible to plastically deform the sleeve 2 along the outer peripheral surface 32 thereof. In the example of FIG. 15, the outer peripheral surface 32 is inclined in a direction in which the diameter increases toward the outer end surfaces 21 and 22 of the end members 4 and 5, and in the example shown in FIG. 16, the outer peripheral surface 32 is the magnet roll axis. It is formed on a cylindrical surface parallel to the direction.

Further, in each of the above-described configurations, as shown in FIGS. 1 and 7, the thickness t ₁ of the axial end portion of the sleeve 2 to which the end members 4 and 5 are fitted and fixed is equal to both end portions thereof. Although it is set to be smaller than the thickness t ₂ of the sleeve portion between the _two , if the thickness t ₁ is set to 1/2 or less of t _{2 and} the thickness of each end of the sleeve is made sufficiently small, the sleeve 2 When is plastically deformed by a pressing device, its end can be completely bent with a small force, and this can be firmly fixed to the tapered surfaces 23 and 24.

On the other hand, if the ratio t ₁ / t ₂ of the thicknesses t ₁ and t ₂ described above is larger than 0.5, it may be difficult for the pressing device to completely plastically deform the sleeve. Then, the coupling strength between the tapered surfaces 23 and 24 and the deformed sleeve portion tends to be weakened. Although the sleeve 2 can be plastically deformed by increasing the pressing force at the time of plastic deformation, when the sleeve 2 is processed with such a large pressure, the bulge shown in FIG. 23 easily occurs due to the influence at this time. As a result, the trouble described above with reference to FIG. 24 may occur. The thickness t ₁ of the axial end portion of the sleeve 2 to which the end members 4 and 5 are fitted and fixed is equal to ₁ of the thickness t ₂ of the sleeve portion between the both end portions.
By setting it to / 2 or less, it is possible to effectively suppress the occurrence of the above-mentioned bulge.

Further, in each of the above-mentioned configurations, as illustrated in FIG. 1, the length L in the sleeve axial direction of the sleeve portion which is plastically deformed and abuts against the end members 4 and 5, respectively, is set to 1 mm or more, for example, 2 mm. Then, the contact area between the sleeve portion that is plastically deformed and bent and the end members 4 and 5 is increased, and the joint strength between the both can be particularly increased. When the length L is smaller than 1 mm, both the pulling strength and the torque resistance are lower than when the length L is 1 mm or more. This has been confirmed by many experiments.

Further, in each of the above-mentioned constitutions, it is advantageous to form the knurls in which the unevenness is repeated in the circumferential direction on the outer peripheral surface portion of at least one of the end members 4, 5 with which the plastically deformed sleeve portion is fitted. . For example, as shown in FIG. 17, when the taper surface 24 is formed with knurls (jagged) 33 in which irregularities are repeated in the circumferential direction, and the end portion of the sleeve 2 is bent and engaged with the taper surface, Both can be more firmly coupled and the torque resistance can be further enhanced. This configuration can be applied to either one of the both end members 4 or 5, or both of them, but since a larger torque resistance is required for the end member 5 on the drive side that directly transmits the rotation to the sleeve 2, The end member 5 can be applied particularly advantageously.

As can be seen from FIG. 18 which is an enlarged view of one convex portion of the notch 33 shown in FIG. 17, when the width of the top surface of the notch of the notch 33 in the end member circumferential direction is d, this d
Is smaller, the engagement force between the tapered surface and the sleeve 2 can be increased. According to experiments, when the width d is set to 0.2 mm or less, the torque resistance can be particularly increased.

If the notches 33 shown in FIG. 17 are formed by knurls, for example, flat knurls, the notches having a predetermined shape can be easily obtained.

A taper surface 24 having a taper angle θ of 30 ° is formed on the end member 5 made of aluminum on the driving side, and the flat surface of the protrusion has a width d of 0.2 mm on the taper surface. 30 is formed by knurling, and the end portion of the sleeve 2 is plastically deformed by the pressing force F of 3 MPa using the pressing device shown in FIG. 7, and the end portion of the sleeve 2 is fixed to the end member 5. About 3 times (2.
A torque resistance of 4 to 2.6 N · m) was obtained.

On the other hand, the width d of the flat top surface of the protrusion is 0.8 mm.
When the end portion of the sleeve 2 and the end member 5 are fixed under the same conditions as described above, the torque resistance thereof is about 3/4 (1.8 N · m) when the width d is 0.2 mm. Fell. Thus, if the width d is 0.2 mm or less, the torque resistance can be particularly enhanced.

Further, in each of the configurations described above, when at least one groove extending in the circumferential direction is formed in the outer peripheral surface portion of at least one end member into which the plastically deformed sleeve portion fits, the plastically deformed sleeve is formed. The bonding strength between the portion and the end member can be further increased. For example, as shown in FIGS. 19 and 20, a groove 34 extending in the circumferential direction is formed in the tapered surface 24 of the end member 5. In this example, the above-described notch 33 and groove 34 are both formed on the tapered surface 24.

After the sleeve 2 is plastically deformed by the pressing device shown in FIG. 7 as described above, when the die 25 is retracted and separated from the sleeve 2, the force on the sleeve 2 is released, and at this time, the springback is performed. Therefore, the sleeve 2 may be loosened with respect to the end member. If such loosening is possible, a slight backlash between the end member and the sleeve 2 is likely to occur even if the torque resistance is not so low. If the magnet roll thus wobbled is used in the developing device, the toner image formed on the photoconductor may have uneven density.

On the other hand, when the groove 34 is formed as shown in FIGS. 19 and 20, when the sleeve 2 is plastically deformed, the sleeve engages so as to bite into the edge of the groove 34, and the two are joined. The strength is increased, and the above-mentioned springback can be prevented. Further, since the groove 34 is formed in the circumferential direction of the end member 5, when the end member 5 receives an external force in the axial direction in which the end member 5 is pulled out,
The edge of the groove 34 is tightly engaged with the sleeve 2 and is prevented from coming off.

In particular, as shown in FIG. 20, of the pair of side faces 35, 36 that define the groove 34 and face each other, the side face 35 on the side farther away from the outer end face 22 of the end member 5.
Since the angle θ1 formed by the tapered surface 34 is 90 ° or less, the upper edge of the side surface 35 is strongly engaged with the sleeve 2.
The pull-out strength and torque resistance can be effectively increased.

The above-mentioned structure of the groove 34 can be applied to at least one of the both end members 4 and 5, but can be particularly advantageously applied to the end member 5 which is required to have a high torque resistance.

By the way, as exemplified above, the cylindrical sleeve 2 made of a non-magnetic material, the magnet 3 arranged inside the sleeve 2 and having a plurality of magnetic poles arranged in the circumferential direction, and the sleeve 2 Of a pair of end members 4 and 5 which are respectively fitted and fixed inside respective axial end portions of the magnet, and which are rotatably assembled to the magnet, at least one of the end members. 4,
5, tapered surfaces 23, 24 tapering toward the outer end surfaces 21, 22 of the end member farthest from the center C in the axial direction of the magnet roll are formed.
The magnet roll having the crevices 33 in which the concavities and convexities are repeated on 3, 24 can be manufactured, for example, by the pressing device shown in FIG. 7 as described above.

In the method of manufacturing a magnet roll, even if the end members are formed with the knurls 33, if the molding surface 28 of the die 25 is formed into a flat surface, the end member has a hardness higher than that of the sleeve. When such a material, for example, wear-resistant aluminum, is not plastically deformed in the sleeve 2, the sleeve does not sufficiently dig into the concave portion of the crevice 33, and a large torque resistance may not be obtained. In order to obtain a large torque resistance, it is sufficient to increase the pressing force of the die 25 against the sleeve, but this may cause the sleeve 2 to be bent and deformed.

Therefore, as shown in FIG. 21, a convex portion 37 is formed on the molding surface 28 of the die 25, and the end member having the tapered surface is fitted to the axial end portion of the sleeve 2 as described above. Then, when the sleeve 2 is pressed by the molding surface 28 to be plastically deformed, the convex portion 37 is pressed against the sleeve 2 with a large force per unit area, so that the sleeve 2 is notched into the notch of the end member 5. It is possible to sufficiently dig into the recess, increase the bonding strength between the two, and prevent the above-described problems from occurring.

This manufacturing method is the same as the method for manufacturing a magnet roll described above in which at least one of the end members has a tapered surface on the outer peripheral surface, the end member having the tapered surface is placed inside the axial end of the sleeve. The sleeve is fitted and has a shape corresponding to the tapered surface, and the axial end of the sleeve in which the end member with the tapered surface is fitted is pressed against the molding surface with the convex portion formed on the surface. The sleeve is plastically deformed along the tapered surface.

At this time, as shown in FIG. 21, when the end portion of the sleeve is plastically deformed, the convex portion 37 formed on the surface of the molding surface 28 becomes the concave portion of the notch 33 formed on the end member 5. When the sleeve is formed, the concave portions of the crevice 33 and the convex portions 37 of the molding surface 28 can be aligned with each other when the sleeve 2 is formed.
The recesses of the crevice 33 can be effectively cut into each other, and the coupling strength between the sleeve 2 and the end member 5 can be further increased.

However, each concave portion of the notch 33 and the molding surface 28
It is not easy to match the respective convex portions 37 of the above, and a situation where they do not completely match occurs. Therefore, as shown in FIG. 22, when the end portion of the sleeve 2 is plastically deformed, the molding surface 28
When the convex portion 37 formed on the surface of the concave portion 33 is formed by a plurality of ridges intersecting with the concave portion of the notch 33 formed on the end member 5 at an angle greater than 0 °, the concave portion of the notch 33 is formed. Even if the convex portions 37 of the molding surface 28 are not aligned with each other, the sleeve can be firmly engaged with the notch 33 of the end member with a small force.

The examples shown in FIGS. 21 and 22 can be applied to the case where at least one of the end members 4 and 5 is fixed to the sleeve 2. However, the end member on the drive side which requires particularly high torque resistance is required. This is particularly advantageous when fixing the sleeve 5 and the sleeve 5.

The magnet roll according to the present invention can be widely used not only in the developing device of the image forming apparatus but also in the above-mentioned cleaning device and other mechanical devices.
Further, the idea of the present invention can be applied to general elements formed by fixing end members to a hollow pipe.

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

According to the method of manufacturing a magnet roll of the first aspect of the present invention, when the sleeve is plastically deformed, the sleeve can be eroded into the notched concave portion of the end member with a small force.

According to the method of manufacturing a magnet roll described in claims 2 and 3, it is possible to further ensure the action and effect exhibited by the manufacturing method of claim 1.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a magnet roll, in which a part thereof is broken away.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a view showing one end member alone.

FIG. 4 is a diagram viewed from the left side of FIG.

FIG. 5 is a view showing the other end member alone.

FIG. 6 is a view seen from the right side of FIG.

FIG. 7 is a cross-sectional view showing a state where the end portion of the sleeve is bent and deformed by the pressing device to fix the sleeve and the end member.

FIG. 8 is a cross-sectional view of a magnet roll in which an outer end surface of a sleeve projects outward from an outer end surface of an end member.

FIG. 9 is a graph showing the relationship between taper angle and torque resistance.

FIG. 10 is a graph showing the relationship between the taper angle and the amount of change in outer diameter.

FIG. 11 is a cross-sectional view showing another example of the end member.

FIG. 12 is a cross-sectional view showing still another example of the end member.

FIG. 13 is a cross-sectional view showing still another example of the end member.

FIG. 14 is a cross-sectional view showing still another example of the end member.

FIG. 15 is a cross-sectional view showing still another example of the end member.

FIG. 16 is a sectional view showing still another example of the end member.

FIG. 17 is a perspective view of an end member having a notch.

FIG. 18 is an enlarged view showing a convex portion of one notch.

FIG. 19 is a perspective view showing an example in which a groove is formed in an end member.

20 is a partial cross-sectional view of FIG.

FIG. 21 is a perspective view showing a molding surface on which a convex portion is formed.

FIG. 22 is a perspective view showing a molding surface on which a convex portion is formed.

FIG. 23 is a cross-sectional view showing a bulge formed on the sleeve.

FIG. 24 is a diagram illustrating a problem when the sleeve is bulged.

[Explanation of symbols]

1 magnet roll 2 sleeve 3 magnets 4 end members 5 end members 21 Outer face 22 Outer face 23 Tapered surface 24 Tapered surface 33 Cranial eyes 37 convex C center

─────────────────────────────────────────────────── ─── Continued Front Page (72) Makoto Nakamura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kyota Hizuka 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Kenichi Ishiguro 1-3-6 Nakamagome, Ota-ku, Tokyo Inside company Ricoh (72) Inventor Kenro Araki 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company (56) Reference JP-A-2-205874 (JP, A) JP-A-62-292918 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/09

Claims (3)

(57) [Claims] 1. A cylindrical sleeve made of a non-magnetic material,
A magnet having a plurality of magnetic poles arranged inside the sleeve and arranged in the circumferential direction, and a magnet that is fitted and fixed inside each end of the sleeve in the axial direction and is rotatably assembled to the magnet. A magnet roll having a pair of end members formed on the outer peripheral surface of at least one end member, the taper surface tapering toward the outer end surface of the end member farthest from the center of the magnet roll axial direction. In the method for manufacturing a magnet roll in which the taper surface is formed with knurls, the end member having the taper surface is fitted inside the axial end of the sleeve. , Which has a form corresponding to the tapered surface, and which pushes the axial end of the sleeve into which the end member with the tapered surface is fitted against the molding surface with the convex portion formed on the surface. A method for manufacturing a magnet roll, which is characterized in that the sleeve is plastically deformed along a tapered surface. 2. When the end portion of the sleeve is plastically deformed, the convex portion formed on the surface of the molding surface is composed of a plurality of ridges extending parallel to the concave portions of the end member. Item 2. A method for manufacturing a magnet roll according to Item 1. 3. When the end portion of the sleeve is plastically deformed, the convex portion formed on the surface of the molding surface intersects with the concave portion formed in the end member at an angle larger than 0 °. The method of manufacturing a magnet roll according to claim 1, which comprises a plurality of ridges.