JP2008241751A - Developing roller and developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller capable of preventing occurrence of powder or the like produced as a result of scraping a plastic magnet when firmly inserted along a metal core, and to provide a developing device that has the developing roller. <P>SOLUTION: A chamfer 6a1 of a first peripheral wall 6a has a chamfer angle θ. The outside diameter of the leading end of the chamfer 6a1 (i.e., the smallest outside diameter of the chamfer 6a1) D1 is smaller than the diameter of the through-hole 2a of the plastic magnet 2 (i.e., the inside diameter of a plastic magnet 2) D2. Accordingly, when the plastic magnet 2 is firmly inserted along the metal core 1, the internal circumferential wall of the through-hole 2a of the leading end of the plastic magnet 2 is prevented from being scraped by the first peripheral wall 6a of the metal core 1. Therefore, the metal core 1 is firmly inserted into the through-hole 2a of the plastic magnet 2 smoothly along the face of the chamfer 6a1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of a developing roller used in an electrophotographic process and a developing device having the same.

In the electrophotographic process, a developing roller used for two-component development in which a magnetic carrier and a non-magnetic toner are mixed in a developer forms a positioning surface 1a when being fixed to the apparatus side as shown in FIG. And a magnet roller 3 having a cylindrical plastic magnet magnet 2 press-fitted to the outer periphery of the cored bar 1 and a ring such as an E-ring for regulating the axial position of the cylindrical plastic magnet 2 with respect to the cored bar 1 A member 4, a nonmagnetic sleeve 5 that conveys developer in cooperation with the magnet roller 3, a driving flange 7 and a driven flange 8 that rotatably support the nonmagnetic sleeve 5 with respect to the metal core 1, and And a metal bearing 9 disposed between the flange and the metal core 1. Further, the drive flange 7 and the driven flange 8 are respectively joined to both ends of the nonmagnetic sleeve 5 by press fitting, and the drive flange is rotated by a drive motor (not shown) to rotate the nonmagnetic sleeve 5 to serve as a carrier. A developing roller for supplying a carried toner to a photoreceptor of an electrophotographic process is known. (For example, see Patent Document 1)
JP 2003-257730 A

In the one described in Patent Document 1, as shown in FIG. 10, a cylindrical plastic magnet 2 having an inner diameter smaller than the outer diameter of the core metal is press-fitted into the core metal 1 so that the plastic magnet 2 does not rotate on the core metal 1. So that they are connected. However, when the plastic magnet 2 is press-fitted onto the core 1, as shown in FIG. 11, as shown in FIG. 11, the circumferential wall of the groove 6 is inserted into the circumferential groove 6 that fits the ring member 4 that restricts the position of the plastic magnet 2 in the axial direction. The shavings 10 of the plastic magnet 2 scraped off in this step enter, and it is necessary to remove the shavings 10, which causes a problem that the efficiency of the work of assembling the plastic magnet 2 to the core 1 is reduced.
Furthermore, if the shavings are not sufficiently removed, the shavings 10 that are not removed fall out of the groove 6 during use of the developing roller, and are sandwiched between the magnet roller 3 and the developing sleeve 5, so that the developing sleeve 5 The problem that the rotational load increases is likely to occur.
The present invention has been made in consideration of the above circumstances, and a developing roller capable of suppressing the occurrence of scraping of the plastic magnet when the plastic magnet is press-fitted onto the core metal, and a developing device including the developing roller The purpose is to provide.

In order to solve the above-mentioned problem, the invention according to claim 1 is a rotation of a magnet roller having a plurality of fixed magnetic poles in the center and a developer containing a magnetic carrier and a non-magnetic toner outside the magnet roller. A developing roller comprising a developing sleeve made of a possible non-magnetic material, a driving flange for transmitting rotation to the end of the developing sleeve, and a driven flange for supporting the magnet roller, wherein the magnet roller press-fits a cylindrical plastic magnet The cored bar has a circumferential groove portion for mounting a ring member for regulating the axial position of the plastic magnet, and a chamfered portion that circulates on the circumferential wall surface on the side of the groove portion facing the press-fitting direction of the plastic magnet is formed. It is characterized by being.
According to a second aspect of the present invention, in the developing roller according to the first aspect, the chamfering angle of the chamfered portion is in the range of 5 degrees to 15 degrees, and the tip outer diameter of the chamfered portion is the cylindrical shape. It is characterized by being smaller than the inner diameter of the plastic magnet.
According to a third aspect of the present invention, in the developing roller according to the first or second aspect, the groove portion has a vertical wall that is connected to the chamfered portion and the bottom portion, and the height of the vertical wall is 0.15 mm or more. It is characterized by having.
According to a fourth aspect of the present invention, there is provided a developing roller, a case containing a developer containing the developing roller, a magnetic carrier, and a non-magnetic toner, and the toner of the developer is placed in the case. In the developing device in which the opening for supplying the photosensitive member to the photosensitive member is formed, the developing roller is the developing roller according to any one of claims 1 to 3.

  According to the present invention, the magnet roller has a circular groove portion in which a ring member that regulates an axial position of the plastic magnet is mounted on a core metal into which a cylindrical plastic magnet is press-fitted. Since a chamfered portion is formed on the peripheral wall surface on the side opposite to the press-fitting direction, a developing roller capable of suppressing the occurrence of scraping of the plastic magnet when the plastic magnet is press-fitted onto the core metal, and the developing roller Can be provided.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
In the present invention, when examining the cause of the phenomenon that the rotational load of the developing sleeve of the developing roller increases with the course of use, the shavings of the plastic magnet when the plastic magnet is press-fitted onto the metal core are developed sleeve. It was clarified that it contributed to the increase of rotational load. In other words, conventionally, even if shavings are generated when the plastic magnet is pressed onto the metal core, the shavings are removed by suction or the like. However, since the shavings are also a magnetic material, they are difficult to remove. In many cases, sufficient removal is not performed. It has been found that the shavings that are not removed fall off during use of the developing roller, and the shavings that fall off adhere to the surface of the magnet roller, increasing the rotational load on the developing sleeve.
In the present invention, as a result of further investigation based on this investigation, it is recognized that it is necessary to suppress the occurrence of scraping as much as possible, and the plastic of the groove portion that fits the ring member of the core metal that is likely to scrape. The inventors have found that it is possible to suppress the occurrence of shaving as much as possible by forming a chamfered portion that circulates on the peripheral wall surface on the side facing the press-fitting direction of the magnet, thereby completing the invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Example 1]
FIG. 1 is a diagram showing a schematic configuration of a developing roller according to an embodiment of the present invention, in which (A) is a side view of the developing roller, (B) is a sectional view, and (C) is a magnet used for the developing roller. FIG. 4 is a diagram showing magnetic characteristics of a roller 3. In FIG. 1, the same components as those of the conventional developing roller are denoted by the same reference numerals.
The developing roller according to the present embodiment has a plurality of fixed magnetic poles, for example, a magnet roller 3 having fixed magnetic poles 11a to 11e as shown in FIG. And a developing sleeve 5 made of a rotatable nonmagnetic material for conveying a developer containing nonmagnetic toner. The developing sleeve 5 is rotatable about a cored bar 1 through a bearing 9 such as a slide bearing by a driving flange 7 connected to a driving motor (not shown) and a driven flange 8 supporting the magnet roller 3 at its end. It is attached and is rotated at a predetermined rotational speed by the rotation of the drive motor.
The magnet roller 3 includes a plastic magnet 2 formed by extruding a cylindrical cored bar 1 and plastic mixed with magnetic powder into a cylindrical shape with magnetic poles oriented as shown in FIG. The cored bar 1 is formed with a concave circumferential groove 6 between both ends of the plastic magnet 2 and the bearing 9. By inserting a ring member 4 such as an E ring or C ring into the groove 6. The position of the plastic magnet 2 in the thrust direction (axial direction) is regulated.

Further, a positioning surface 1a which is a flat surface is formed at the left end of the cored bar 1, and the magnetic poles 11a to 11e of the cylindrical plastic magnet 2 are described below with reference to the positioning surface 1a. As shown in FIG. 2, the cored bar 1 is press-fitted into the through hole 2 a of the plastic magnet 2 from the direction of arrow A so that the predetermined positional relationship is established.
When the metal core 1 is press-fitted into the through hole 2a of the plastic magnet 2, the metal core 1 having an outer diameter D3 larger than the diameter D2 of the through hole 2a of the plastic magnet 2 is press-fitted. When the inner peripheral portion of the magnet 2 falls and the plastic magnet 2 is further press-fitted, the inner peripheral surface of the plastic magnet 2 is formed by the upright peripheral wall surface 6a on the side of the groove portion 6 facing the press-fitting direction (C direction) of the plastic magnet 2. In some cases, the plastic magnet 2 may be scraped off. In the present invention, the generation of shavings is suppressed as much as possible.
That is, as shown in FIG. 3 in which the portion B of FIG. 2 is enlarged, a groove portion 6 into which the ring member 4 is fitted is formed at the right end of the cored bar 1, and the press-fitting direction of the plastic magnet 2 (the direction of arrow C) A chamfered portion 6a1 in which the outer peripheral portion of the peripheral wall 6a is chamfered over the circumference is formed on the first peripheral wall 6a of the peripheral groove portion 6 on the opposite side to. Further, a standing peripheral wall portion 6a2 is formed so as to stand vertically from the bottom surface 6e of the groove portion 6 to the chamfered portion 6a1 with respect to the axial direction of the cored bar 1. On the other hand, on the side facing the first peripheral wall 6 a of the groove portion 6, there is a standing peripheral wall erected perpendicularly to the axial direction of the core metal 1 from the bottom surface 6 e of the groove portion 6 to the outer surface 1 b of the core metal 1. A second peripheral wall 6b is formed, and the ring member 4 is held in contact with the ring member 4 inserted into the groove portion 6 by the second peripheral wall 6b and the standing peripheral wall portion 6a2 of the first peripheral wall 6a. Yes.

  As shown in FIG. 4, the chamfered portion 6 a 1 of the first peripheral wall 6 a has a chamfer angle θ, and the outer diameter (minimum outer diameter of the chamfered portion 6 a 1) D1 of the chamfered portion 6 a 1 is the plastic magnet 2. The diameter of the through hole 2a (the inner diameter of the plastic magnet 2) D2 is smaller. Therefore, when the plastic magnet 2 is press-fitted into the cored bar 1, the inner periphery of the through hole 2a at the tip of the plastic magnet 2 is not scraped by the first peripheral wall 6a of the cored bar 1 and is chamfered on the chamfered portion 6a1. And smoothly press-fitted into the through-hole 2a of the plastic magnet 2. In this case, in order to securely hold the plastic magnet 2 on the metal core 1, the outer diameter D3 of the metal core 1 is formed larger than the inner diameter D2 of the plastic magnet 2, and the plastic magnet is formed on the outer surface 1b of the metal core 1. The inner peripheral surface of 2 is crimped.

The chamfering angle 6 of the chamfered portion 6a1 is effectively 5 degrees or more and 15 degrees or less. When the chamfered angle θ is smaller than 5 degrees, the minimum outer diameter D1 of the chamfered section 6a1 and the inner diameter D2 of the cylindrical plastic magnet 2 are reduced. The difference is reduced, and the plastic magnet 2 is scraped at the standing wall 6a2 or the outer peripheral edge of the groove 6 when the plastic magnet 2 is press-fitted, and the shavings 10 are easily clogged in the groove 6. On the other hand, when the angle is larger than 15 degrees, the shavings 10 are likely to occur due to the impact on the chamfered portion 6a1.
Further, the first peripheral wall 6a of the groove portion 6 requires the standing peripheral wall portion 6a2 in order to hold the ring member 4 in the groove portion 6. The height (step) of the standing peripheral wall portion 6a2 and the ring member 4 are required. The escape from the groove portion 6 will be described with reference to FIGS. FIG. 5 is a view showing the height (step) h of the vertical wall portion 6a2, and as is clear from FIG. 5, the height h is the distance from the bottom surface 6e of the groove 6 to the tip of the chamfered portion 6a1. . When the ring member 4 is inserted into the groove portion 6 and assembled as shown in FIG. 6, a thrust load is applied from the direction of the arrow E, and the load and the vertical wall portion 6a2 until the ring member 4 is released from the groove portion 6. The relationship with the height (step) h of the film was examined.

FIG. 7 shows that as a result, if the height (step) h of the vertical wall portion 6a2 is less than 0.1 mm, it is easy to escape with a thrust load of 100 N, and if the step h is 0.15 mm or more, 300 N or more. The ring member 4 to which no load is applied does not escape. Normally, it is practical if the ring member 4 can be prevented from escaping with a thrust load of 100 N or more. Therefore, it is sufficient that the step h is 0.15 mm or more. In FIG. 7, in the case of 0.2 mm or more, the ring member 4 was not detached even at the limit thrust load 550N of the measuring instrument, but the ring member 4 was deformed. From this result, it is clear that the level difference h of 0.15 mm or more is sufficient.
Incidentally, in this example, an elastomer resin material containing 91 wt% of Sr ferrite magnetic powder was used, and the cylindrical plastic magnet 2 having an outer diameter = 16 mm and an inner diameter D2 = 5.85 mm formed by extrusion molding was used. When press-fitting the cored bar 1 with Ni plating applied to the surface of a stainless steel (SUM) with an outer diameter D3 = 5.98 mm straight provided with a groove 6 for the E-ring nominal diameter 5, press-fit direction (C direction) A chamfered portion 6a1 having an angle of 10 degrees and a length of 1 mm was formed on the first peripheral wall 6a on the counter side. Similarly, a chamfering process 1c having an angle of 15 degrees and a length of 1 mm was performed on the tip to prevent the plastic magnet 2 from being scraped at the start of press-fitting. At this time, the outer diameter of the chamfered portion is 5.63 mm, which is smaller than the inner diameter of the cylindrical plastic magnet 2. Even when the plastic magnet 2 was press-fitted into the cored bar 1 formed in this way, no occurrence of scraping of the plastic magnet 2 into the groove 6 was observed.

As described above, in the developing roller according to the present embodiment, the chamfered portion 6a1 that circulates around the first peripheral wall 6a of the groove member insertion groove 6 of the core metal 1 is formed. When press-fitting, the plastic magnet 2 is prevented from being scraped by the first peripheral wall 6a, and the occurrence of scraping of the plastic magnet 2 can be suppressed.
In this embodiment, the case where the press-fitting direction of the plastic magnet 2 of the metal core 1 starts from the right end of the metal core 1 as shown in FIG. Since 6d in FIG. 2 is the first peripheral surface, a chamfered portion 6d1 and a standing peripheral wall portion 6d2 are formed on the peripheral surface 6d, respectively.

[Example 2]
FIG. 8 is a diagram showing a schematic configuration of a developing device according to an embodiment of the present invention. In the figure, 12 is a developing drum, and 13 is a drum-shaped photoconductor. The developing device of this embodiment includes a developing roller 12 and a case 17 that accommodates the developing roller 12. The developing roller 12 is fixed so that the nonmagnetic sleeve 5 is rotatable in the case 17 and the magnet roller 3 is fixed in the nonmagnetic sleeve 5 so as not to move relative to the case 17. The case 17 has an opening 14 at a position of a transfer magnetic pole (main pole) 11c facing the photoconductor 13 as an image carrier.
A magnetic carrier catcher 14 is provided inside the case 17 so that the magnetic carrier remaining on the photoreceptor 13 can be caught. Further, in the case 17, a developer containing a magnetic carrier and a nonmagnetic toner is accommodated, and an agitating member 15 for agitating the developer is provided. The developer supplied from the stirring member 15 is held on the surface of the developing sleeve 5 of the developing roller 12 by a magnetic field generated by the magnet roller 3 of the developing roller 12, and the amount of toner supplied to the photoreceptor 1 is regulated by the doctor blade 16. The toner is electrostatically supplied from the developing sleeve 5 to the electrostatic latent image on the photosensitive member 13 adjacent to the developing sleeve 5 through the opening 14 to form a toner image on the photosensitive member 13. The photoreceptor 13 on which the toner image is formed in this way transfers the toner image onto the recording paper P conveyed from the arrow Y direction.
In the present embodiment, the developing roller formed in the above-described first embodiment is used as the developing roller 12. Accordingly, as described above, the occurrence of the scraping of the plastic magnet 2 due to the insertion groove 6 of the ring member 4 of the metal core 1 is suppressed, and the rotational load of the developing sleeve 5 is increased due to the scraping associated with the use of the developing roller 12. Can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the developing roller of Example 1 by this invention, (A) is a side view of a developing roller, (B) is sectional drawing of a developing roller, (C) shows the orientation state of the magnetic pole of a magnet roller. FIG. It is a top view which shows the formation method of Example 1 by this invention. It is the enlarged plan view which expanded the B section of FIG. It is a top view of the metal core and the plastic magnet for demonstrating the relationship between the front-end | tip outer diameter of the chamfering part of the metal core of Example 1 by this invention, and the internal diameter of a plastic magnet. It is a top view of the core metal for demonstrating the level | step difference of the standing peripheral wall part of the core metal of Example 1 by this invention. It is the top view which inserted the ring member in the groove part of the metal core of Example 1 by this invention. It is a figure which shows the relationship between the level | step difference of the standing wall part of Example 1 by this invention, and a thrust load. It is sectional drawing which shows schematic structure of the image development apparatus of Example 2 by this invention. It is sectional drawing which shows schematic structure of the conventional developing roller. It is a top view which shows the formation method of the conventional magnet roller. It is a top view which shows the storage state of the shavings of the conventional magnet roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core metal, 2 Plastic magnet, 3 Magnet roller, 4 Ring member, 5 Developing sleeve, 6 Circulation groove part, 6a 1st surrounding wall, 6a1 Chamfering part, 6a2 Standing circumferential wall part, 7 Drive flange, 8 Driven flange, 9 Bearing, 10 shavings, 11a, 11b, 11c, 11d, 11e magnetic pole, 12 developing roller, 13 photoconductor, 17 case

Claims (4)

A magnet roller having a plurality of fixed magnetic poles in the center, a developing sleeve made of a rotatable nonmagnetic material that conveys a developer containing a magnetic carrier and nonmagnetic toner to the outside of the magnet roller, and an end of the developing sleeve In the developing roller comprising a drive flange that transmits rotation to and a driven flange that supports the magnet roller,
The magnet roller has a core groove into which a cylindrical plastic magnet is press-fitted, and has a circumferential groove portion for mounting a ring member that regulates the axial position of the plastic magnet, and faces the press-fitting direction of the plastic magnet in the groove portion. A developing roller characterized in that a chamfered portion is formed around the peripheral wall surface on the side to be developed. The developing roller according to claim 1, wherein
A developing roller, wherein a chamfering angle of the chamfered portion is in a range of 5 to 15 degrees, and an outer diameter of a tip of the chamfered portion is smaller than an inner diameter of the cylindrical plastic magnet. The developing roller according to claim 1 or 2,
The developing roller according to claim 1, wherein the groove portion has a vertical wall connected to the chamfered portion and the bottom portion, and the vertical wall has a height of 0.15 mm or more. A developing roller, and a case containing a developer containing the developing roller, a magnetic carrier, and a developer containing non-magnetic toner, and an opening through which the toner of the developer is supplied from the developing roller to the photosensitive member in the case In the developing device formed with
The developing device according to claim 1, wherein the developing roller is a developing roller according to claim 1.

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