JPH10288892A - Magnet roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the precision of a magnet roll and to reduce cost by fixing at least one of both end parts in the axial direction of a cylindrical magnet and a core shaft with a fastener for inhibiting their relative rotations. SOLUTION: The core shaft 5 is inserted into the center hole 4 of the cylindrical magnet 3. Then, this magnet 3 and the core shaft 5 are fixed by the fastener 17. This fastener 17 is provided with a locking part consisting of a pair of locking pieces 18 locked with the core shaft 5, to prevent rotation relative to the core shaft 5 and a sharp projection 19 biting the end face in the axial direction of the magnet 3. On the other hand, a pair of flat surfaces 20 which are extended in the axial direction of the core shaft 5 and in parallel with each other are formed on the periphery of the core shaft 5 and a pair of the locking pieces 18 of the fastener 17 are engaged with these flat surfaces 20, respectively. Moreover, the end parts of one of a pair of the locking pieces 18 are integrally connected with each other through a connecting part 21 and the end parts of the other of a pair of the locking pieces 18 are separated from each other to form the fastener 17 of one part piece.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylindrical sleeve made of a non-magnetic material, a cylindrical magnet provided inside the sleeve, and a cylindrical magnet inserted into a center hole of the cylindrical magnet. And a core shaft fixed to the sleeve, wherein the sleeve and the cylindrical magnet are relatively rotatably assembled.

[0002]

2. Description of the Related Art Magnet rolls of the above type are used in various technical fields. For example, electronic copiers,
2. Description of the Related Art In an image forming apparatus configured as a facsimile, a laser printer, or a multifunction peripheral having at least two of these functions, the surface of an image carrier made of a photoreceptor is uniformly charged to a predetermined polarity, and the surface thereof is charged. Is exposed to form an electrostatic latent image, the electrostatic latent image is visualized as a toner image by a developing device, the toner image is transferred to a transfer material, and a transfer residue adhered to the surface of the image carrier is transferred. The toner is removed by a cleaning device and the surface of the image carrier is cleaned. The magnet roll described at the beginning is used in a developing device and a cleaning device of such an image forming apparatus.

[0003] That is, this magnet roll is supported by a developer case of a developing device, at least one of a sleeve of the magnet roll and a cylindrical magnet is driven to rotate, and a powder carried on the surface of the sleeve by the magnetic force of the cylindrical magnet. A magnetic developer is transported, and the electrostatic latent image is converted into a toner image by the developer.

Further, a magnet roll is supported on a casing of a cleaning device for cleaning the surface of the image carrier, and at least one of a core shaft and a cylindrical magnet is driven to rotate to transfer untransferred toner adhering to the surface of the image carrier. Can be attracted to the sleeve surface and transported.

In an image forming apparatus of a type in which a toner image formed on the surface of a photoreceptor is primarily transferred onto the surface of an image carrier composed of an intermediate transfer member, and the toner image is transferred to a final transfer material, the intermediate transfer member is used. A magnet roll can be used in a cleaning device for cleaning the transfer residual toner on the surface.

Conventional methods for manufacturing such a magnet roll are roughly classified into the following three methods. A method in which a plurality of magnet pieces divided in the circumferential direction of a cylindrical magnet are prepared, and these are bonded to a core shaft. A method in which a core shaft is press-fitted into a center hole of a cylindrical magnet formed into a cylindrical shape to integrate them. A method of integrally molding the core shaft and magnet.

Here, if the above-described method is adopted, the magnet piece and the core shaft are joined using an adhesive, so that the adhesive protrudes from between the joining surfaces, and the adhesive must be cleaned. The work becomes very complicated. If the thickness of the adhesive at the time of bonding is not constant, the outer diameter of the completed cylindrical magnet varies, and the coaxiality between the cylindrical magnet and the core axis also varies. Thereby, the magnetic force distribution on the sleeve surface when the magnet roll is used becomes unstable. If such a magnet roll is used, for example, in a developing device, the image quality of the toner image formed on the surface of the image carrier deteriorates.

In the above-described method, when the core shaft is press-fitted into the center hole of the cylindrical magnet, the resistance becomes extremely large, so that the diameters of the core shaft and the cylindrical magnet slightly vary. Even just by insertion of the core shaft, the shape of the cylindrical magnet subjected to a large pressure varies. For example, the length of the cylindrical magnet after insertion of the core shaft,
The swelling in the radial direction varies, and a cylindrical magnet of a predetermined form may not be obtained. When such an inaccurate magnet roll is used in, for example, a developing device, a predetermined magnetic force distribution cannot be formed on the surface of the sleeve, and the image quality of the toner image is inevitably deteriorated.

Further, when the core shaft is pressed into the center hole of the cylindrical magnet, the surface of the cylindrical magnet is shaved, and when the shavings enter between the cylindrical magnet and the sleeve, the sleeve and the cylindrical magnet are smoothly opposed to each other. The rotation may be hindered, and the magnet roll may not be able to perform a predetermined function.

As described above, when the methods described in (1) and (2) are employed, a great deal of labor and cost are required to manufacture a magnet roll having a predetermined accuracy, and thus the manufacturing cost of the entire magnet roll is reduced. Rises.

As described above, in order to integrally form the core shaft portion and the magnet portion, an expensive mold having a complicated structure must be used, and the core shaft of the completed magnet roll is also expensive. Since it is made of a magnet material, the drawback that the manufacturing cost of the magnet roll increases is inevitable.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost magnet roll which can easily fix a core shaft and a cylindrical magnet and has high accuracy.

[0013]

According to the present invention, there is provided a magnet roll of the type described at the beginning, wherein at least one of the axial ends of the cylindrical magnet is connected to a core. A magnet roll characterized in that the shaft and the shaft are fixed by a stopper that inhibits relative rotation between the shaft and the shaft (claim 1).

In this case, the stopper has a locking portion which is locked to the core shaft so as not to rotate relative to the core shaft, and a sharp projection which is inserted into the axial end surface of the cylindrical magnet. Advantageously (claim 2).

Further, in the magnet roll according to the second aspect, a pair of flat surfaces parallel to each other extending in the axial direction of the core shaft are formed on the peripheral surface of the core shaft, and Advantageously, it is constituted by a pair of locking pieces that engage with each of the flat surfaces (claim 3).

Further, in the magnet roll according to the third aspect, one ends of the pair of locking pieces are integrally connected to each other via a connecting portion, and the other end of the pair of locking pieces. Are advantageously separated from one another (claim 4).

In the magnet roll according to the fourth aspect, the length of the pair of flat surfaces in the axial direction is set to be longer than the thickness of the stopper including the projection in the axial direction. Advantageously (claim 5).

Furthermore, in the magnet roll according to any one of the first to fifth aspects, it is particularly advantageous that the entirety of the stopper is made of a non-magnetic material.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an example of a magnet roll according to the present invention, and FIG. 2 is an enlarged sectional view taken along line II-II of FIG. The magnet roll 1 shown here has a cylindrical sleeve 2 made of a non-magnetic material, for example, aluminum.
And a cylindrical magnet 3 provided inside the sleeve 2, and a core shaft 5 inserted into the center hole 4 of the cylindrical magnet 3 and fixed to the cylindrical magnet 3. The core shaft 5 is made of, for example, a high-strength material such as a metal, and the cylindrical magnet 3 has a plurality of magnetic poles along the circumferential direction on its surface. FIG. 2 shows an example of the magnetized state with S and N representing its polarity.

A cylindrical first end member 8 is rotatably rotatable relative to the core shaft 5 via bearings 6 and 7 at one end of the core shaft 5 protruding outward in the axial direction of the cylindrical magnet 3. Are fitted, and one end of the sleeve 2 is fitted and fixed to the outer peripheral surface of the first end member 8.

The center of a second end member 9 having a circular outer peripheral surface is relatively opposed to the other end of the core shaft 5 projecting outward in the axial direction of the cylindrical magnet 3 via a bearing 10. The sleeve 2 is rotatably fitted, and the other end of the sleeve 2 is fitted and fixed to the outer peripheral surface of the second end member 9.

As described above, the sleeve 2 and the cylindrical magnet 3 are connected to the first and second end members 8, 9 and the bearings 6, 9, respectively.
It is relatively rotatably assembled via 7, 10. At this time, the core shaft 5, the cylindrical magnet 3, and the sleeve 2 are arranged concentrically and extend long in the axial direction of the core shaft 5.

The second end member 9 is integrally formed with a shaft portion 11 which is arranged concentrically with the core shaft 5 and extends in the axial direction. The sleeve 2 is provided on the outer end surface of the first end member 8.
1 for preventing foreign matter from entering the interior of the vehicle
2 are installed. The seal 12 is made of a soft material such as a fluororesin.

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 above-described mode. For example, when this magnet roll 1 is used in a developing device, one end of the core shaft 5 in the axial direction is supported by one side wall 14 of a developer case 13 of the developing device, as exemplified by a chain line in FIG. The shaft portion 11 is rotatably supported on the other side wall 15 via a bearing 15A, and the gear 16 is fixed to the shaft portion 11. The gear 16 meshes with a gear (not shown) on the image forming apparatus main body side, and the sleeve 2 and the first and second end members 8 and 9 are connected to the core shaft 5 via these gears by a motor (not shown). Core shaft 5
Is rotationally driven around the central axis of At this time, a powdery one-component developer or a two-component developer at least partially composed of a magnetic material is carried on the surface of the sleeve 2 by the magnetic force of the cylindrical magnet 3, and the circumference of the sleeve 2 is rotated by the rotation of the sleeve 2. Conveyed in the direction. With such a developer,
As described above, the electrostatic latent image formed on the surface of the image carrier is visualized as a toner image. The two-component developer is a developer obtained by mixing at least a toner and a carrier, and the developer containing no carrier is a one-component developer.

The core shaft 5 is rotatably supported with respect to the developer case 13, and the core shaft 5 and the cylindrical magnet 3 are rotationally driven by a motor via a gear (not shown), or the sleeve 2 and the cylindrical magnet 3 are rotated. The developer carried on the surface of the sleeve 2 can be conveyed by rotating both the magnets 3 in opposite directions.

Here, the core shaft 5 and the cylindrical magnet 3 are
These are integrally fixed to each other so as to rotate around the center axis of the core shaft 5. For this fixation, the above-described methods described above have been adopted,
According to these methods, the above-mentioned problems cannot be avoided.

Therefore, in the magnet roll 1 of this embodiment, at least one of the axial ends of the cylindrical magnet 3, in the illustrated example, both ends, and the core shaft 5, Stop 17, which prohibits relative rotation of
17. These stops 17,1
7 can be configured substantially the same except that they are arranged symmetrically with respect to each other. Therefore, in the following description, a method of assembling the components of the magnet roll 1 will be mainly described for the stopper 17 provided on the first end member 8 side. It will be clarified while explaining one example.

First, the core shaft 5 is inserted into the center hole 4 of the cylindrical magnet 3. At this time, the cylindrical magnet 3 and the core shaft 5
May be inserted in a slipped state, and there is no need to press-fit the core shaft 5 into the cylindrical magnet 3 using a press-fitting machine or apply an adhesive to them. Therefore, the core shaft 5 can be easily inserted into the cylindrical magnet 3.

Next, the cylindrical magnet 3 and the core shaft 5 are fixed by the stoppers 17,17. FIGS. 3 and 4 are views showing a state in which the cylindrical magnet 3 and the core shaft 5 are fixed by the stopper 17, and the stopper 17 is not rotated relative to the core shaft 5. It has a locking portion composed of a pair of locking pieces 18, 18 which are locked to the shaft 5, and a sharp projection 19 to be inserted into the axial end surface of the cylindrical magnet 3. It is desirable that a plurality of projections 19, especially three or more projections, be provided.

On the other hand, the core shaft 5 of this embodiment is constituted by a round shaft, and a pair of parallel flat surfaces 20, 20 extending in the axial direction of the core shaft 5 is formed on the peripheral surface of the core shaft 5. Are formed, and a stop 1 is provided on each of these flat surfaces 20, 20.
7 are engaged with each other. The locking portion of the stopper 17 is a pair of flat surfaces 2 formed on the core shaft 5.
0, 20 and a pair of locking pieces 18, 18, respectively.
It is composed of

Also, one ends of the pair of locking pieces 18, 18 are integrally connected to each other via a connecting portion 21,
The other ends of the pair of locking pieces 18, 18 are separated from each other, and a stopper 17 formed of a part is formed.

Further, the length L of the pair of flat surfaces 20, 20 formed on the core shaft 5 in the core axis direction is longer than the thickness T of the stopper 17 including the projection 19 in the core axis direction. Is set.

In order to fix the cylindrical magnet 3 and the core shaft 5 inserted therein by the stopper 17 configured as described above, first, a pair of locking pieces 18,
18 so as to engage with each flat surface of the core shaft 5,
The stopper 17 is engaged with the core shaft 5. That is, the stopper 17
The side where the pair of locking piece ends are separated from each other faces the core shaft 5, and then, as shown by an arrow A in FIG. 5, the core shaft 5 is fixed to the two locking pieces 18,
18, each flat surface 20 of which is inserted into each locking piece 18,
18 so as to engage with each other. At this time, each projection 19 of the stopper 17 faces the end face side of the cylindrical magnet 3.

As shown in FIG. 5, the distance D between the locking pieces 18, 18 of the stopper 17 before being assembled to the core shaft 5.
Is the distance d between the two flat surfaces 20, 20 of the core shaft 5 (FIG. 4)
Is set equal to or smaller than (D ≦
d), preferably, the interval D is set smaller than the interval d (D <d). Thus, when the stopper 17 is assembled to the core shaft 5 as described above, the locking pieces 18, 18 of the stopper 17 are pressed against the flat surfaces 20, 20 of the core shaft 5 without rattling.

After the stopper 17 is set on the core shaft 5 as described above, the stopper 17 is moved while the locking pieces 18, 18 of the stopper 17 are in sliding contact with the flat surfaces 20, 20 of the core shaft 5. , FIG.
As shown by arrow B, the cylindrical magnet 3 is slid in a direction approaching the cylindrical magnet 3 so that the sharp projection 19 of the stopper 17 is inserted into the axial end surface of the cylindrical magnet 3 (FIG. 3). At this time, while the stopper 17 is relatively moved with respect to the cylindrical magnet 3 using a pressurizing device such as an air cylinder (not shown), the projection 19 can be inserted into the cylindrical magnet 3. .

The stopper 17 on the side of the second end member 9 is also assembled to the core shaft 5 in exactly the same manner as described above, and then the stopper 17 slides on a pair of flat surfaces 20 formed on the core shaft 5. Then, the projection is inserted into the axial end face of the cylindrical magnet 3.

Thus, the core shaft 5 and the cylindrical magnet 3 can be fixed. At this time, since the projection 19 of the stopper 7 is fitted into the cylindrical magnet 3, the two are firmly fixedly connected to each other. In addition, since the locking pieces 18, 18 of the stopper 17 are pressed against the flat surfaces 20, 20 of the core shaft 5 without looseness, the core shaft 5 and the cylindrical magnet 3 are firmly fixed, and both of them are firmly fixed. Relative rotation and relative movement in the axial direction are prevented. Thus, the quality of the magnet roll 1 can be stabilized. When three or more projections 19 are provided on each stopper 17 as described above, the cylindrical magnet 3 and the core shaft 5 can be more firmly fixed.

As described above, after fixing the cylindrical magnet 3 and the core shaft 5 with the stoppers 17, 17, the cylindrical magnet 3 is inserted into the inside of the sleeve 2, and the first and second end members 8, 9, the magnet roll 1 is completed when the bearings 6, 7, 10, and the seal 12 are assembled as shown in FIG. The gear 16 is fixed to the magnet roll for use.

As described above, the magnet roll 1 of this embodiment
Since the axial end of the cylindrical magnet 3 and the core shaft 5 are fixed by the stopper 17, there is no need to press the core shaft 5 into the cylindrical magnet 3 or fix them with an adhesive. In addition, there is no need to form the core shaft 5 from a magnet material, and an expensive mold for forming a cylindrical magnet is not required. In this way, the core shaft and the cylindrical magnet can be easily fixed, and a highly accurate magnet roll can be manufactured at low cost.

The magnet roll 1 shown in FIG.
A slight gap G is provided between the cylindrical magnet 3 and each of the end members 8 and 9, and the end members 8 and 9 and the sleeve 2 are moved relative to the core shaft 5 and the cylindrical magnet 3 which are immovably fixed. It is configured to be able to move slightly in the direction.
With this configuration, it is possible to prevent the axial end face of the cylindrical magnet 3 from coming into contact with each of the end members 8 and 9 with a large force when the magnet roll 1 is operated, so that the driving torque of the sleeve 2 is unnecessarily increased. Can be blocked.

However, when such a configuration is adopted in a conventional magnet roll, when the axial end face of the cylindrical magnet comes into contact with each end member, the end face of the cylindrical magnet is scraped off by an external force received by the end member, The shavings enter between the sleeve and the cylindrical magnet,
The smooth relative rotation between the sleeve and the cylindrical magnet may be hindered. For this reason, it is necessary to provide a spacer on the axial end surface of the cylindrical magnet so that the cylindrical magnet does not come into direct contact with each end member to prevent the cylindrical magnet from being scraped off. The cost of the magnet roll increases accordingly.

However, according to the illustrated magnet roll 1, the stoppers 17, 17 function as the above-mentioned spacers, so that the axial end surfaces of the cylindrical magnet 3 can be fixed to each end member 8, without providing an independent spacer. 9 can be prevented from being cut off. Even when the magnet roll 1 is configured so that no gap is provided between the stoppers 17, 17 and the end members 8, 9, the above-described operation and effect can be obtained.

In the illustrated magnet roll 1, both ends of the cylindrical magnet 3 in the axial direction are the stoppers 1.
Since the cylindrical magnet 3 and the core shaft 5 are fixed to the core shaft 5 by 7 and 17, the cylindrical magnet 3 and the core shaft 5 can be further firmly fixed.

In addition, the stopper 17 is engaged with the core shaft 5 so that the stopper 17 does not rotate relative to the core shaft 5, and the sharp projection 19 is inserted into the axial end surface of the cylindrical magnet 3.
Therefore, the cylindrical magnet 3 and the core shaft 5 can be easily and firmly fixed by making the projection 19 into the cylindrical magnet, so that the quality of the magnet roll 1 can be stabilized and the cost can be reduced. Can be reduced.

A pair of flat surfaces 20, 20 extending in the axial direction of the core shaft 5 are formed on the peripheral surface of the core shaft 5. , The relative rotation between the cylindrical magnet 3 and the core shaft 5 can be reliably prevented, and these can be accurately fixed, and thus stable. It is possible to provide the magnet roll 1 having a reduced quality.

Further, a pair of locking pieces 18 of the stopper 17,
One end of the pair 18 is integrally connected to each other via a connecting portion 21 and the other ends of the pair of locking pieces 18 are separated from each other. When assembling, the stopper 17 can be moved in a direction orthogonal to the axial direction of the core shaft 5 and fitted to the core shaft 5. For this reason, the stopper 17 can be easily incorporated into the core shaft 5, and it is possible to easily cope with this when the installation is automated.

Since the length L of the pair of flat surfaces 20 in the axial direction is set to be longer than the thickness T of the stopper 17 including the projection 19 in the axial direction, the stopper is provided. After assembling the core 17 with the core shaft 5, the stopper 17 is surely slid toward the cylindrical magnet 3, so that the projection 19 can be inserted into the cylindrical magnet 3.
Thus, the work of fixing the cylindrical magnet 3 and the core shaft 5 can be reliably automated.

The stopper 17 must be made of a high-strength material such as a resin or a metal, and is preferably made of a non-magnetic material, for example, a non-magnetic stainless steel. Thus, the stopper 1
When the entirety of the magnet roll 7 is made of a non-magnetic material, the magnetic force distribution can be prevented from being disturbed in the axial end region of the sleeve 2 when the magnet roll 1 is used, and the quality of the magnet roll 1 is further improved. be able to.

The magnet roll according to the present invention can be widely used not only for the developing device of the image forming apparatus but also for the above-mentioned cleaning device and other mechanical devices.
The configuration of the stopper for fixing the core shaft and the cylindrical magnet is not limited to the magnet roll, and can be widely applied to a member having a cylindrical member and a core shaft inserted into the center hole thereof, for example, a roller. is there.

[0051]

According to the structure of the first aspect, the core shaft and the cylindrical magnet can be easily fixed, the accuracy of the magnet roll can be increased, and the cost can be reduced.

According to the second aspect of the present invention, since the sharp projections of the stopper enter the cylindrical magnet, the cylindrical magnet and the core shaft can be easily and firmly fixed, thereby improving the quality of the magnet roll. Costs can be reliably reduced.

According to the third aspect of the present invention, since the locking pieces of the stopper are engaged with the pair of flat surfaces of the core shaft, the relative rotation of the core shaft and the cylindrical magnet is reliably prevented. As a result, the quality of the magnet roll can be improved, and the cost can be reduced more reliably.

According to the configuration of the fourth aspect, the stopper can be easily assembled to the core shaft.

According to the fifth aspect of the present invention, after the stopper is assembled to the core shaft, the stopper is slid relative to the core shaft in the axial direction, so that the projection is securely fixed. It can be inserted into a cylindrical magnet.

According to the structure of the sixth aspect, there is no possibility that the magnetic properties of the magnet roll are impaired by the stopper, and the quality of the magnet roll can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a magnet roll.

FIG. 2 is an enlarged cross-sectional view taken along line II-II of FIG.

FIG. 3 is a partially enlarged view of FIG. 1 showing a state where a core shaft and a cylindrical magnet are fixed by a stopper.

FIG. 4 is a side view as viewed from the left in FIG. 3;

FIG. 5 is a view showing the stopper before being assembled to the core shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet roll 2 Sleeve 3 Cylindrical magnet 4 Center hole 5 Core shaft 17 Stopper 18 Locking piece 19 Projection 20 Flat surface 21 Connecting part L Length T Thickness

Claims (6)

[Claims] A cylindrical sleeve made of a non-magnetic material;
A cylindrical magnet provided inside the sleeve, and a core shaft inserted into a center hole of the cylindrical magnet and fixed to the cylindrical magnet, wherein the sleeve and the cylindrical magnet rotate relatively. In a magnet roll that is assembled as possible, at least one end of the axial ends of the cylindrical magnet and the core shaft are fixed by a stopper that prohibits relative rotation between the two. Magnet roll. 2. The stopper according to claim 1, wherein the stopper has a locking portion that is locked to the core shaft so as not to rotate relative to the core shaft, and a sharp projection that fits into the axial end surface of the cylindrical magnet. 2. The magnet roll according to 1. 3. A pair of flat surfaces parallel to each other extending in the axial direction of the core shaft are formed on a peripheral surface of the core shaft, and a pair of engaging members are provided so that the locking portion engages with each of the flat surfaces. 3. The magnet roll according to claim 2, wherein the magnet roll is constituted by a stop piece. 4. The pair of locking pieces according to claim 3, wherein one ends of the pair of locking pieces are integrally connected to each other via a connecting portion, and the other ends of the pair of locking pieces are separated from each other. Magnet roll. 5. The magnet roll according to claim 4, wherein the length of the pair of flat surfaces in the axial direction is set longer than the thickness of the stopper including the projection in the axial direction. 6. The magnet roll according to claim 1, wherein the entire stopper is made of a non-magnetic material.