JP2009003030A - Rolling device, manufacturing method for developing roller, developing roller, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling device and a manufacturing method by which a developing roller having excellent developing characteristic is obtained, the developing roller manufactured by the rolling device or the manufacturing method, and a reliable developing device equipped with the developing roller and an image forming apparatus. <P>SOLUTION: A die for rolling is equipped with a curved part 222 where a line segment linking the tops of respective projected lines 221 is curved to be projected so that a distance between the top of each projected line 221 and an axial line X<SB>1</SB>may become shorter and shorter from a center part side to respective end sides in the axial line X<SB>1</SB>direction as seen in section including the axial line X<SB>1</SB>, and the width of the curved part 222 in the axial line X<SB>1</SB>direction is larger than the double of a predetermined feed amount L<SB>1</SB>. When the distance between the top of the projected line 221 and the axial line X<SB>1</SB>is defined as r<SB>1</SB>and r<SB>2</SB>at two sections separated from each other by the predetermined feed amount L<SB>1</SB>in the axial line X<SB>1</SB>direction at least on one end side in the axial line X<SB>1</SB>direction of the curved part 222, ¾r<SB>1</SB>-r<SB>2</SB>¾ is 5 μm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling device, a developing roller manufacturing method, a developing roller, a developing device, and an image forming apparatus.

Image forming apparatuses such as printers, copiers, and facsimile machines that employ an electrophotographic method are applied to a recording medium such as paper by a series of image forming processes such as a charging process, an exposure process, a development process, a transfer process, and a fixing process. Then, an image made of toner is formed.
Such an image forming apparatus is provided with a developing device that visualizes an electrostatic latent image on a photoreceptor as a toner image. Such a developing device has a developing roller (developer carrying member) for carrying toner, and applies the toner from the developing roller to the photosensitive member, thereby visualizing the latent image on the photosensitive member as a toner image.

In general, the outer peripheral surface of the developing roller is roughened to form a fine uneven portion so that toner is easily carried.
As a method for forming such fine uneven portions, blasting is generally used, but it is proposed to use a rolling method in which a rolling die is pressed against a work to form the uneven portions. ing. Unlike the blasting process, the rolling method can form regular uneven portions (see, for example, Patent Document 1).
In the rolling method according to Patent Document 1, rolling (so-called through rolling) is performed while transferring a workpiece in the axial direction to a rolling die. That is, in Patent Document 1, when forming the concavo-convex portion, the rolling die and the workpiece are pressed while rotating relative to each other in a state where the axis of the rolling die is slightly inclined with respect to the axis of the workpiece.

Further, the rolling die used in such a rolling method has a roller shape, and a plurality of ridges extending in a direction inclined parallel to the circumferential direction and inclined with respect to the circumferential direction are formed on the outer circumferential surface thereof. Yes. And this rolling die was provided in the straight part in which the distance of the top part of each protruding item | line and the axis line of the rolling die was constant (an outer diameter is constant), and the one end side of the straight part It has a biting portion and a relief portion provided on the other end side of the straight portion.
The biting portion and the relief portion are tapered so that the distance between the top of each protrusion and the axis of the rolling die gradually decreases toward the outside. Thereby, the biting of the rolling die with respect to the workpiece is improved, and the transfer of the workpiece is stabilized.

  However, in the rolling method according to Patent Document 1, when the workpiece feed amount is increased, that is, when the inclination angle of the die is increased, streaks are formed along the workpiece circumferential direction for each feed cycle. For this reason, the formed concavo-convex part varies in the depth of the concave part and the height of the convex part. When a roller having such a concavo-convex portion is used as a developing roller, light and shade unevenness occurs.

JP 2005-254202 A

  SUMMARY OF THE INVENTION An object of the present invention is a rolling apparatus and manufacturing method capable of obtaining a developing roller having excellent development characteristics while improving productivity and reducing cost, and manufactured by such a rolling apparatus or manufacturing method. It is an object of the present invention to provide a developing roller, and a highly reliable developing device and image forming apparatus including the developing roller.

Such an object is achieved by the present invention described below.
The rolling device of the present invention is a roller-shaped die for rolling in which a plurality of ridges extending in a direction inclined parallel to the circumferential direction and extending in the circumferential direction are formed on the outer circumferential surface thereof, and
The rolling die is installed so that its axis is inclined at a predetermined inclination angle with respect to the axis of the workpiece having a cylindrical or columnar shape, and the rolling die is rotated around the axis on the outer peripheral surface of the workpiece. by pressing while the feeding means for relatively moving with respect to the rolling die at the workpiece prescribed feeding amount L ₁ in accordance with the predetermined tilt angle per one rotation of the workpiece in the axial direction With
By the pressing of the outer peripheral surface of the workpiece and the outer peripheral surface of the rolling die, a groove is formed so as to be inclined with respect to the circumferential direction of the workpiece by the convex ridges,
When the rolling die is viewed in a cross-section including the axis, the distance between the top of each ridge and the axis gradually decreases from the center side to the end side in the axial direction. A line segment connecting the tops of the ridges is provided with a curved portion curved in a convex shape,
The width in the axial direction of the bending portion is larger than twice said predetermined feeding amount L _1, and said predetermined feeding amount L ₁ axially separated from each other in at least one end in the axial direction of the bending portion When r ₁ and r ₂ are distances between the tops of the respective convex ridges and the axis of the rolling die at the two portions, | r ₁ −r ₂ | is 5 μm or less. It is characterized by that.

  Accordingly, the curved portion has a width that can stably guide the workpiece while preventing the corner portion from being formed on the processed surface of the rolling die. Therefore, it is possible to form the uneven portion on the outer peripheral surface of the workpiece while preventing the generation of streaks at each workpiece feeding period due to the corner portion. As a result, it is possible to suppress variations in the depth of the concave portion and the height of the convex portion of the uneven portion obtained. Therefore, when a developing roller is manufactured using such a rolling device, a developing roller having excellent developing characteristics can be obtained. In addition, even if the workpiece feed rate is increased, streaks can be prevented at each workpiece feed cycle, which improves productivity and lowers costs while maintaining good development characteristics. A developing roller can be obtained.

In the rolling apparatus according to the present invention, it is preferable that | r ₁ −r ₂ |
As a result, it is possible to prevent the occurrence of streaks while making the running stability of the workpiece extremely excellent.
In the rolling device of the present invention, it is preferable that | r ₁ −r ₂ | is 5 μm or less on each end side in the axial direction of the bending portion.
Thereby, generation | occurrence | production of a streak can be prevented, making the protrusion of the ridge with respect to a workpiece | work excellent.

In the rolling apparatus of the present invention, r ₁ / r ₃ is preferably 5 to 20 when the radius of the workpiece is r ₃ .
Thus, by suppressing the inclination angle of the rolling die while the conveyance of the workpiece and are stable, it is possible to increase the feeding amount L ₁ of the work. Therefore, it is possible to obtain a high-quality developing roller having excellent developing characteristics while improving productivity and reducing costs more reliably.

In the rolling apparatus of the present invention, the predetermined inclination angle is preferably 0.1 to 5 °.
Thereby, it is possible to reduce the cost while improving the developing characteristics of the developing roller.
In rolling apparatus of the present invention, the predetermined feed amount _{L 1} is preferably a 0.1 to 5 mm.
Thereby, it is possible to reduce the cost while improving the developing characteristics of the developing roller.

In the rolling apparatus of the present invention, a pair of the rolling dies are provided so as to narrow the work, and a plurality of first grooves are formed by the one rolling die and the other rolling die is formed. It is preferable that a plurality of second grooves intersecting the plurality of first grooves are formed by a building die.
Thereby, the uneven part suitable for a developing roller can be formed easily and reliably.

The method for producing a developing roller according to the present invention includes a step of preparing a cylindrical or columnar workpiece that is an object of rolling,
Forming a groove for carrying toner by pressing a rolling die while moving the outer peripheral surface of the workpiece relatively in the axial direction thereof,
The rolling die has a roller shape, and a plurality of ridges extending in a direction inclined parallel to the circumferential direction and inclined with respect to the circumferential direction are formed on the outer circumferential surface thereof,
When the rolling die is viewed in a cross-section including the axis, the distance between the top of each ridge and the axis gradually decreases from the center side to the end side in the axial direction. The line segment connecting the tops of the ridges is provided with a curved portion that is curved in a convex shape,
In the step of forming the groove, the rolling die is installed so that the axis is inclined at a predetermined inclination angle with respect to the axis of the workpiece, and the rolling die is arranged around the axis on the outer peripheral surface of the workpiece. in by pressing while rotating, while relatively moving the said workpiece with respect to rolling die in the axial direction to a predetermined in accordance with the predetermined tilt angle per one rotation of the workpiece feed amount L ₁ ,
By the pressing of the outer peripheral surface of the workpiece and the outer peripheral surface of the rolling die, a groove is formed so as to be inclined with respect to the circumferential direction of the workpiece by the convex ridges,
The width in the axial direction of the bending portion is larger than twice said predetermined feeding amount L _1, and said predetermined feeding amount L ₁ axially separated from each other in at least one end in the axial direction of the bending portion When r ₁ and r ₂ are distances between the tops of the respective convex ridges and the axis of the rolling die at the two portions, | r ₁ −r ₂ | is 5 μm or less. It is characterized by that.
As a result, a developing roller having excellent development characteristics can be obtained.

The developing roller of the present invention is manufactured by the developing roller manufacturing method of the present invention.
Thereby, a developing roller having excellent developing characteristics can be provided.
The developing device of the present invention includes the developing roller of the present invention.
Thereby, it is possible to provide a developing device having high reliability.
The image forming apparatus of the present invention includes the developing device of the present invention.
Thereby, an image forming apparatus having high reliability can be provided.

Hereinafter, preferred embodiments of a rolling device, a developing roller manufacturing method, a developing roller, a developing device, and an image forming apparatus of the present invention will be described with reference to the accompanying drawings.
1 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing a schematic configuration of a developing device provided in the image forming apparatus shown in FIG. It is. In the following description, the upper side in the figure is referred to as “upper” and the lower side is referred to as “lower”.

(Image forming device)
First, a laser beam printer (hereinafter simply referred to as “printer”) 10 as an example of an image forming apparatus will be described with reference to FIG.
As shown in FIG. 1, the printer 10 has a photoreceptor 20 that carries a latent image and rotates in the direction of the arrow in the figure, and along the rotation direction (clockwise), a charging unit 30, an exposure unit 40, and a development unit. 50, a primary transfer unit 60, an intermediate transfer body 70, and a cleaning unit 75 are arranged in this order. In addition, the printer 10 has a paper feed tray 92 that feeds a recording medium P1 such as paper at the lower part of FIG. 1, and the secondary from the paper feeding tray 92 toward the downstream in the transport direction of the recording medium P1. A transfer unit 80 and a fixing unit 90 are sequentially arranged.

The photoreceptor 20 has a cylindrical conductive substrate and a photosensitive layer formed on the outer peripheral surface thereof, and is rotatable around the axis in the arrow direction (clockwise direction) in FIG. The charging unit 30 is a device for uniformly charging the surface of the photoreceptor 20 by corona charging or the like.
The exposure unit 40 receives image information from a host computer such as a personal computer (not shown), and irradiates the uniformly charged photoconductor 20 with a laser beam in a desired pattern in accordance with the image information. This is an apparatus for carrying (forming) an electrostatic latent image (electrostatic latent image) on the outer peripheral surface.

  The developing unit 50 has four developing devices, a black developing device 51, a magenta developing device 52, a cyan developing device 53, and a yellow developing device 54, and selects these developing devices corresponding to the latent image on the photoconductor 20. In particular, the latent image is visualized as a toner image on the photoconductor 20. The black developing device 51 uses black (K) toner, the magenta developing device 52 uses magenta (M) toner, the cyan developing device 53 uses cyan (C) toner, and the yellow developing device 54 uses yellow (Y) toner. .

  The developing unit 50 in the present embodiment is rotatable so that the above-described four developing devices 51, 52, 53, and 54 can be selectively opposed to the photoreceptor 20 (in a predetermined order). . Specifically, in the developing unit 50, four developing devices 51, 52, 53, and 54 are respectively held by four holding portions 55a, 55b, 55c, and 55d of a holding body that can rotate around a shaft 50a. The rotation of the holder causes the developing devices 51, 52, 53, and 54 to selectively face the photoconductor 20 while maintaining their relative positional relationship. The detailed configuration of each developing device will be described later.

The primary transfer unit 60 is a device for transferring the toner image formed on the photoconductor 20 to the intermediate transfer body 70.
The intermediate transfer member 70 is composed of an endless belt, and is driven to rotate (circulate) in the direction of the arrow shown in FIG. On the intermediate transfer member 70, a toner image of at least one of black, magenta, cyan, and yellow is carried. For example, when a full-color image is formed, four color toner images of black, magenta, cyan, and yellow are sequentially formed. The toner images are transferred to form a full-color toner image.

The secondary transfer unit 80 is a device for transferring a single color or full color toner image formed on the intermediate transfer body 70 to a recording medium P1 such as paper, film, or cloth.
The fixing unit 90 is an apparatus for fixing the toner image as a permanent image by fusing the toner image on the recording medium P1 by heating and pressurizing the recording medium P1 that has received the transfer of the toner image.
The cleaning unit 75 has a rubber cleaning blade 76 that contacts the surface of the photoconductor 20 between the primary transfer unit 60 and the charging unit 30, and a toner image is transferred onto the intermediate transfer body 70 by the primary transfer unit 60. Then, the toner remaining on the photoreceptor 20 is scraped off and removed by the cleaning blade 76.

Next, the operation of the printer 10 configured as described above will be described.
First, in response to a command from a host computer (not shown), a developing roller 510 (see FIGS. 2 and 3) described later provided corresponding to the developing devices 51, 52, 53, and 54 of the photosensitive member 20 and the developing unit 50, Then, the intermediate transfer member 70 starts to rotate. The photoreceptor 20 is sequentially charged by the charging unit 30 by rotating.

The charged region on the photoconductor 20 reaches an exposure position facing the exposure unit 40 as the photoconductor 20 rotates, and the exposure unit 40 causes the latent image corresponding to the image information of the first color, for example, yellow Y. Is formed in the region.
The latent image formed on the photoconductor 20 reaches the development position as the photoconductor 20 rotates, and is developed with yellow toner by the yellow developing device 54. As a result, a yellow toner image is formed on the photoreceptor 20. At this time, in the developing unit 50, the yellow developing device 54 faces the photoconductor 20 at the developing position (see FIG. 1).

The yellow toner image formed on the photoconductor 20 reaches the primary transfer position as the photoconductor 20 rotates, and is transferred to the intermediate transfer body 70 by the primary transfer unit 60. Specifically, since the primary transfer unit 60 is applied with a primary transfer voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner, the primary transfer unit 60 is formed on the photoconductor 20 by the temporary transfer voltage. The yellow toner image is attracted to the intermediate transfer member 70. During this time, the secondary transfer unit 80 is separated from the intermediate transfer member 70.
The same processing as described above is repeatedly executed for the second color, the third color, and the fourth color, so that the toner images of the respective colors corresponding to the respective image signals are transferred onto the intermediate transfer body 70 in an overlapping manner. The As a result, a full-color toner image is formed on the intermediate transfer member 70.

On the other hand, the recording medium P 1 is conveyed from the paper feed tray 92 to the secondary transfer unit 80 by the paper feed roller 94 and the registration roller 96.
The full-color toner image formed on the intermediate transfer member 70 reaches the secondary transfer position where the secondary transfer unit 80 is disposed as the intermediate transfer member 70 rotates, and is transferred to the recording medium P1 by the secondary transfer unit 80. Is done. Specifically, since the secondary transfer unit 80 is pressed against the intermediate transfer body 70 and a secondary transfer voltage (secondary transfer bias) is applied, the secondary transfer voltage is applied onto the intermediate transfer body 70 by the secondary transfer voltage. The formed full-color toner image is attracted and transferred to the recording medium P1 interposed between the intermediate transfer body 70 and the secondary transfer unit 80.

The full-color toner image transferred to the recording medium P1 is heated and pressed by the fixing unit 90 and fused onto the recording medium P1, thereby obtaining a fixed toner image.
On the other hand, after the primary transfer position has passed, the photoreceptor 20 is prepared for charging to form the next latent image by scraping off the toner adhering to the surface thereof by the cleaning blade 76 of the cleaning unit 75. The toner scraped off is collected by a residual toner collecting unit (not shown) in the cleaning unit 75.

(Developer)
Next, the developing devices 51, 52, 53, and 54 of the developing unit 50 will be described in detail. Since these devices have almost the same configuration, the yellow developing device 54 will be described as a representative based on FIG. To do.
A yellow developing device 54 shown in FIG. 2 includes a housing 540 that accommodates toner T, which is yellow toner, a developing roller 510 that is a toner carrier, a toner supply roller 550 that supplies toner T to the developing roller 510, and a developing roller. And a regulating blade 560 for regulating the layer thickness of the toner T carried on 510.

  The housing 540 stores the toner T in a storage portion 530 formed as an internal space thereof. In the housing 540, the toner supply roller 550 and the developing roller 510 are supported so as to be able to rotate in pressure contact with each other at an opening formed in the lower portion of the housing portion 530 and in the vicinity thereof. A regulating blade 560 is attached to the housing 540 and is in pressure contact with the developing roller 510. Further, a seal member 520 for preventing leakage of toner from between the housing 540 and the developing roller 510 in the opening is attached to the housing 540.

The developing roller 510 holds (carryes) the toner T on the outer peripheral portion, and applies the held toner T to the photoconductor 20 (that is, conveys the held toner T to a developing position facing the photoconductor 20). To do). Further, the developing roller 510 is a cylindrical object that can rotate around an axis, and in this embodiment, rotates in a direction opposite to the rotation direction of the photoconductor 20.
In this embodiment, the developing roller 510 and the photoconductor 20 face each other in a non-contact state with a minute gap during development by the yellow developing device 54. Then, by applying an alternating electric field between the developing roller 510 and the photosensitive member 20 (hereinafter, this state is referred to as “electric field applying state”), the toner T is caused to fly from the developing roller 510 to the photosensitive member 20, The latent image on the photoconductor 20 is developed.

  The toner supply roller 550 supplies the toner T stored in the storage unit 530 to the developing roller 510. The toner supply roller 550 is made of polyurethane foam or the like, and is pressed against the developing roller 510 in an elastically deformed state. In the present embodiment, the toner supply roller 550 rotates in the direction opposite to the rotation direction of the developing roller 510. The toner supply roller 550 not only has a function of supplying the toner T stored in the storage unit 530 to the developing roller 510, but also peels off the toner T remaining on the developing roller 510 after the development from the developing roller 510. It also has a function.

The regulating blade 560 regulates the layer thickness of the toner T carried on the developing roller 510, and applies a charge to the toner T carried on the developing roller 510 by frictional charging at the time of regulation. This regulating blade 560 also functions as a seal member on the upstream side of the developing position in the rotation direction of the developing roller 510. The regulating blade 560 includes a rubber portion 560a as a contact member that is contacted along the axial direction of the developing roller 510, and a rubber support portion 560b as a support member that supports the rubber portion 560a. . The rubber part 560a is made of silicon rubber, urethane rubber or the like as a main material, and the rubber support part 560b also has a function of urging the rubber part 560a toward the developing roller 510. A sheet-like thin plate having elasticity) is used. One end of the rubber support portion 560 b is fixed to the blade support metal plate 562. The blade support metal plate 562 is attached to the housing 540, and the seal member 520 is also attached to the housing 540. Further, with the developing roller 510 attached, the rubber portion 560a is pressed against the developing roller 510 by the elastic force due to the bending of the rubber support portion 560b.
In the present embodiment, a blade back member 570 is provided on the side opposite to the developing roller 510 side of the regulating blade 560 to prevent the toner T from entering between the rubber support portion 560b and the housing 540. The rubber portion 560a is pressed against the developing roller 510, and the rubber portion 560a is pressed against the developing roller 510.

In this embodiment, the free end portion of the regulating blade 560, that is, the end portion opposite to the side supported by the blade support metal plate 562, is not contacted with the developing roller 510 at the end edge. It is in contact with the developing roller 510 at a slightly separated site. The regulating blade 560 is disposed so that the tip thereof faces the upstream side in the rotation direction of the developing roller 510, and is in a so-called counter contact.
The configuration, operation, and effects of the developing devices 51, 52, and 53 of the developing unit 50 are the same as those of the developing device 54.

(Development roller)
Next, the developing roller 510 of the present invention will be described in detail with reference to FIGS.
3 is a plan view showing a schematic configuration of the developing roller provided in the developing device shown in FIG. 2, FIG. 4 is an enlarged plan view of a groove formed in the developing roller shown in FIG. 3, and FIG. It is an AA sectional view taken on the line.

As shown in FIG. 3, the developing roller 510 protrudes from both ends of the main body 300 along the columnar main body 300 and the rotation axis (center axis) X of the main body 300, and is reduced in diameter from the outer diameter of the main body 300. And a pair of reduced diameter portions 310.
The main body 300 of the developing roller 510 is mainly composed of a metal material such as aluminum, stainless steel, or iron. Thereby, when the groove | channel 2 mentioned later is formed in the outer peripheral part 301 of the main body 300 (developing roller 510), for example by rolling (transfer method), the said groove | channel 2 can be formed easily and reliably. Further, the toner T can be efficiently charged by conveying the toner T on the outer peripheral portion 301 of the main body 300.

In the present embodiment, as shown in FIG. 5, the main body 300 includes a metal tube 511 configured using a metal material as a main material, and nickel plating, chrome plating, etc. provided so as to cover the outer peripheral surface of the metal tube 511. And the surface layer 512. Note that the surface layer 512 can be omitted.
The outer diameter (diameter) of the main body 300 is not particularly limited, but is preferably 10 to 30 mm, for example, and more preferably 15 to 20 mm.

  As shown in FIG. 3, a groove 2 into which toner T particles enter is formed in the outer peripheral portion 301 of the main body 300. The groove 2 includes a plurality of first grooves 21 that are substantially parallel to each other and a plurality of second grooves 22 that intersect the first grooves 21 (substantially orthogonal in the present embodiment) and are substantially parallel to each other. It is configured. That is, in the outer peripheral portion 301, the plurality of first grooves 21 and the plurality of second grooves 22 are formed in a lattice shape. Therefore, the convex portion 3 is formed in a region surrounded by a pair of first grooves 21 adjacent to each other and a pair of second grooves 22 adjacent to each other. The top portion 31 of the convex portion 3 forms a flat surface.

As shown in FIG. 3, the first groove 21 is formed in a spiral shape along the outer peripheral portion 301. In other words, the first groove 21 extends in a direction inclined with respect to the circumferential direction of the outer peripheral portion 301.
Further, as shown in FIG. 5, the first groove 21 has a substantially trapezoidal cross-sectional shape. The configuration of the second groove 22 is the same as the configuration of the first groove 21 except that the extending direction is different as described above. For convenience of explanation, FIG. 4 schematically shows the first groove 21 and the second groove 22.

Since such grooves 2 are regular and uniform, it is possible to carry a uniform and optimum amount of toner T on the developing roller 510, and the rolling property (rolling) of the toner on the outer peripheral surface of the developing roller 510. (Ease) can also be made uniform. As a result, it is possible to prevent poor local charging and conveyance of the toner and to exhibit excellent development characteristics.
Further, unlike those obtained by blasting, the groove 2 (uneven portion) has excellent mechanical strength because the width of the tip of the protruding portion 3 is relatively large. In particular, since the groove 2 is obtained by a rolling process using a rolling die as described later, the strength of the pressed portion is improved, and the groove 2 is obtained by a process such as cutting. In comparison, it has excellent mechanical strength. The developing roller 510 having such a groove 2 can exhibit excellent durability even when it is slid by the regulating blade 560 and the toner supply roller 550 as described above. Therefore, such a developing roller 510 can be suitably used in a developing device that uses dry one-component non-magnetic toner. Further, since the width of the tip (top portion 31) of the convex portion 3 is relatively large, there is little change in shape even when worn, and it is possible to prevent development characteristics from deteriorating sharply due to wear, resulting in excellent development characteristics over a long period of time. It can be demonstrated.

The width of each of the first groove 21 and the second groove 22 is larger than the average particle diameter of the toner T. Thereby, the toner T can be reliably carried (held) in the formed groove 2.
In particular, when the width (maximum width) of each of the first grooves 21 and the second grooves 22 is A and the average particle diameter of the toner T (developer) is d, A / d is: It is preferable that it is 2-20, and it is more preferable that A / d is 4-10. As a result, the developing roller 510 can carry the toner T (developer) in the groove 2 in a uniform and optimal amount. On the other hand, if A / d is less than the lower limit value, depending on the shape of the groove 2 and the arrangement of the protrusions 3, the toner does not enter the groove 2 and the rolling property deteriorates, resulting in poor charging. Even if the toner T enters the groove, it tends to stay in the groove 2 and cause filming. On the other hand, when A / d exceeds the upper limit, depending on the shape of the groove 2 and the arrangement of the convex portion 3, the amount of toner carried on the developing roller 510 is small, resulting in poor conveyance, or toner on the convex portion 3. There are cases where the chance of contact decreases, the rolling property deteriorates, and charging failure occurs.

Further, when the depth of each of the first grooves 21 and each of the second grooves 22 is D and the average particle diameter of the toner T (developer) is d, D / d is 0.5-2. It is preferable that it is 0.9 to 1.3. As a result, the obtained developing roller 510 can carry the toner T in the groove 2 in a uniform and optimum amount. On the other hand, if D / d is less than the lower limit, depending on the shape of the groove 2 and the like, it is difficult to be caught on the convex portion 3, the rolling property of the toner T is deteriorated, and charging failure tends to occur. On the other hand, when D / d exceeds the upper limit value, depending on the shape of the groove 2 or the like, the toner in the groove 2 may not come into contact with either the developing roller 510 or the regulating blade 560, and charging failure may occur.
Here, the specific range of the average particle size of the toner T is preferably, for example, 1 to 10 μm, and more preferably 1 to 7 μm. When the toner T having such an average particle size is used, the toner T is not stacked and accommodated in the groove 2, and smoothly rolls on the outer peripheral portion 301. Charged.

(Development roller manufacturing method)
Next, an example of a method for manufacturing the developing roller 510 will be described as an example of a method for manufacturing the developing roller according to the present invention with reference to FIGS.
6 is a diagram for explaining a developing roller manufacturing method according to an embodiment of the present invention, and FIG. 7 is a schematic configuration of a rolling device that forms grooves on the outer peripheral surface of the substrate in the manufacturing method shown in FIG. FIG. 8 is an enlarged side view of the rolling device shown in FIG. 7, FIG. 9 is a partial enlarged cross-sectional view of a rolling die provided in the rolling device shown in FIG. 7, and FIG. FIG. 10 is a partially enlarged view for explaining an example of the protrusions of the rolling die shown in FIG. 9.
The manufacturing method of the developing roller 510 includes [1] preparing a work to be the developing roller 510 and [2] forming a groove 2 on the outer peripheral surface of the base material.

Hereinafter, each process will be described in detail.
[1] Step of Preparing Substrate First, as shown in FIG. 6A, a workpiece 400 to be the developing roller 510 is prepared.
The work 400 is to be the developing roller 510, and has a cylindrical main body 401 and a pair that protrudes from both ends of the main body 401 along the central axis of the main body 401 and has a diameter smaller than the outer diameter of the main body 401. And a reduced diameter portion 410.
Thereafter, if necessary, the outer peripheral surface of the workpiece 400 is ground using centerless polishing or the like so that the axis of the main body 401 of the workpiece 400 matches the axis of the reduced diameter portion 410.

[2] Step of Forming Groove Next, as shown in FIG. 6B, the groove 2 is formed on the outer peripheral surface of the main body 401 of the workpiece 400.
Hereinafter, the formation of the groove 2 will be described in detail with reference to FIGS.
In forming the groove 2, for example, a rolling device 200 as shown in FIG. 7 is used.

The rolling device 200 shown in FIG. 7 performs rolling by a so-called through rolling (step rolling) method. Such a rolling device 200 includes a base 210 that supports the workpiece 400 from below, a first rolling die 220 that presses the workpiece 400 on the base 210 from both sides, and a second rolling die. And a die 230 (a pair of rolling dies).
The base 210 supports the workpiece 400 so as to be rotatable about its axis X.

The first rolling die 220 and the second rolling die 230 are each pressed against the outer peripheral surface of the workpiece 400, which is an object to be rolled, thereby forming a groove 2 for carrying toner. This is a rolling die.
Each of the first rolling die 220 and the second rolling die 230 has a roller shape and is rotatable around each axis.

Such a first rolling die 220 is supported by the feeding means 240 fixed to the base 210 described above in a state where the axis X ₁ is slightly inclined with respect to the axis X of the workpiece 400. together are driven to rotate about the axis X _1. Similarly, the second rolling die 230 is supported by the feeding means 250 fixed to the base 210 in a state where the axis X ₂ is slightly inclined with respect to the axis X of the workpiece 400. together are driven to rotate about the axis X _2.

These feed means 240 and 250, so as to maintain the axis X the position and orientation of the axes X ₁ and axis X ₂ constant, and is supported relative to base 210 by a support means (not shown).
More specifically, as shown in FIG. 7, the first rolling die 220 is installed such that its axis X ₁ is inclined at an inclination angle θ with respect to the axis X of the workpiece 400. The first rolling die 220 is rotatable around its axis X _1.

On the other hand, the second rolling die 230 is installed such that its axis X ₂ is inclined at an inclination angle θ on the side opposite to the axis X _{1 of} the first rolling die 220 with respect to the axis X of the workpiece 400. Has been. Then, the second rolling die 230 is rotatable around its axis X _2.
The first rolling die 220 is formed with a plurality of ridges (convex portions) 221 for forming the plurality of first grooves 21 as shown in FIG. The plurality of ridges 221 extend in a direction that is parallel to each other at an interval of a pitch p ₁ and that is inclined with respect to the circumferential direction.

On the other hand, the second rolling die 230 is formed with a plurality of ridges (convex portions) 231 for forming the plurality of second grooves 22. A plurality of ridges 231 extend in a direction inclined with respect to parallel and circumferential directions spaced at a pitch p _2.
When the first rolling die 220 and the second rolling die 230 are rotated in opposite directions while pressing the workpiece 400 from both sides, the workpiece 400 is moved as shown by arrows in FIG. Processing with the first rolling die 220 and the second rolling die 230 is performed while being conveyed in the axial direction.
At that time, relative movement with respect to the first rolling die 220 and the second rolling die 230 feeding amount L ₁ given per revolution of the workpiece 400 workpiece 400 in the axial direction X (transporting) Is done. The feeding amount L ₁ are those corresponding to the inclination angle θ as described above.

By using such a pair of rolling dies (the first rolling die 220 and the second rolling die 230), the groove 2 as described above is formed by one rolling die. Compared to the above, the groove 2 suitable for the developing roller 510 can be formed easily and reliably.
That is, since the formation of the first groove 21 and the formation of the second groove 22 are performed using separate rolling dies, it is only necessary to provide a plurality of protrusions parallel to each other on each rolling die. Thus, the shape of the rolling die can be simplified, and the groove 2 can be easily formed.

The constituent materials of the first rolling die 220 and the second rolling die 230 are not particularly limited, but materials harder than the workpiece 400, such as SKD, SKH, and SLD, are available. Preferably used.
Further, the pitch p ₁ between the ridges 221 and the pitch p ₂ between the ridges 231 are not particularly limited, but are preferably 50 to 150 μm, and more preferably 50 to 100 μm. In the present embodiment, the pitch _{p 2} is equal to the pitch _{p 1.} Note that the pitch p ₁ and the pitch p ₂ may be different from each other depending on the shape of the groove 2 and the like.

Hereinafter, the first rolling die 220 will be described in detail. The second rolling die 230 is the same as the first rolling die 220, and therefore the description thereof is omitted.
As described above, the first rolling die 220 as described above has a roller shape, and has a plurality of protrusions extending on the outer peripheral surface thereof in parallel to each other at an interval and in a direction inclined with respect to the circumferential direction. A strip 221 is formed.

As shown in FIG. 9, such first rolling die 220, when viewed in cross section including the axis X _1, each toward the central portion in the axial direction X ₁ to each end side as the distance between the top and the axis X ₁ of the ridges 221 is gradually reduced, and a curved portion 222 which line is convexly curved at a predetermined radius of curvature connecting the top portions of Kakutotsujo 221. In the following, the distance between the top of each ridge 221 and the axis X is also referred to as “radius”.

Here, the curved portion 222, when viewed in cross-section containing the axis X _1, as a line segment connecting the top portions of the ridges 221, and symmetric with respect to a line segment passing through the orthogonal and centered on the axis X ₁ Is formed.
Such central portion and around in the axial direction X ₁ of the curved portion 222, a change in the distance between the top and the axis X ₁ of Kakutotsujo 221 less, functions as a main processing surface.

Further, both end portions in the axial direction X ₁ of the curved portion 222, respectively, the change is large in the distance between the top and the axis X ₁ of the ridges 221 than near the center, the main guide for the workpiece 400 good (The right end portion functions as a biting portion in FIG. 9, and the left end portion functions as a relief portion in FIG. 9).
The degree of the convex curvature in the cross section as described above of the curved portion 222 is particularly as long as it satisfies the condition of the step L ₂ as described later (that is, the condition of r ₁ -r ₂ ). Although not limited, the radius of curvature is preferably 20 to 150 mm, more preferably 60 to 150 mm. Thereby, even if the inclination angle θ slightly varies, the rolling can be performed stably.

Such curved portion 222 has a relationship is optimized configuration of the feeding amount L ₁ as described above. Hereinafter, the configuration of the curved portion 222 on the relationship between the feed amount L _1. In the following, the configuration on the escape portion side of the bending portion 222 will be mainly described. The configuration on the biting portion side of the bending portion 222 is the same as the configuration on the escape portion side of the bending portion 222. Description is omitted.

In the bending portion 222, the width W in the direction of the axis of the bending portion 222 (that is, the axis X _{1 of} the first rolling die 220) is larger than twice the feed amount L ₁ , and the bending portion 22. each of the axes X ₁ of the top and rolling die 220 of each ridge 221 at two sites that during a predetermined feeding amount L ₁ separating the axis X ₁ directions at each end side in the axial direction X ₁ When r ₁ and r ₂ are distances (radius) between | r ₁ −r ₂ | (step L ₂ shown in FIG. 9) is 5 μm or less.

By optimizing the relationship between the width W and the radius of curvature of the feeding amount L ₁ of the thus bent portion 222, while preventing the corner portion on the processed surface of the first rolling die 220 is formed The curved portion 222 has a width W that can stably guide the workpiece 400.
Therefore, the groove 2 (first) is formed on the outer peripheral surface of the work 400 while preventing the occurrence of streaks (hereinafter also simply referred to as “streaks”) due to the corners as described above. 1 groove 21) can be formed. As a result, variations in the depth of the obtained groove 2 and the height of the convex portion 3 can be suppressed.

Therefore, when the developing roller 510 is manufactured using such a rolling device 200, the developing roller 510 having excellent developing characteristics can be obtained. Further, since the occurrence of the streaks of each feeding cycle of the workpiece 400 be larger the feeding amount L ₁ of the workpiece 400 can be prevented, while reducing the cost by improving the productivity, excellent developing characteristics It is possible to obtain a developing roller 510 having good quality. In addition, the width of the curved portion 222 can be reduced, and the first rolling die 220 and the second rolling die 230 can be reduced in size. In this respect as well, cost reduction can be achieved.

In particular, the relief portion, i.e., at the end of the downstream side of the workpiece 400 in the curved portion 222 has a larger portion of the width than the feeding amount _{L 1,} and, in that part _| r 1 _-r 2 _|, that step _{L 2} is 5μm or less. Therefore, the generation of streaks can be prevented while making the running stability of the workpiece 400 extremely excellent. In particular, by optimizing the relationship between the feed amount L ₁ to the width and radius of curvature described above the relief portion, can effectively prevent the occurrence of streaks, the effect of the present invention becomes remarkable.

Further, chamfer, i.e., even at the end of the upstream side in the transport direction of the workpiece 400 in the curved portion 222 has a larger portion of the width than the feeding amount L _1, and, in that part | r ₁ -r ₂ |, That is, the step L ₂ is 5 μm or less. Therefore, the occurrence of streaks can be prevented while the biting of the ridges 221 on the workpiece 400 is excellent.
Here, the level difference L ₂ (that is, | r ₁ −r ₂ |) is not particularly limited as long as it is larger than 0 and not larger than 5 μm, but it is about 1 to 4.5 μm for reasons such as dice manufacturing limitations. Is preferred.

Further, when the radius of the workpiece 400 is r ₃ , r ₁ / r ₃ is preferably 5 to 20, and more preferably 7 to 15. Thus, it is possible to suppress the inclination angle θ of the first rolling die 220 while the conveyance of the workpiece 400 as stable, to increase the feeding amount L ₁ of the workpiece 400. Therefore, it is possible to obtain the high-quality developing roller 510 having excellent developing characteristics while improving the productivity and reducing the cost more reliably.

On the other hand, if r ₁ / r ₃ is less than the lower limit value, the feed amount L ₁ is reduced, and the formation of each first groove 21 is performed with a small number of pressings by each projection 221. Depending on the width of the one rolling die 220 in the axial direction, the constituent material of the workpiece 400, and the like, the dimensional accuracy of the formed groove 2 and the convex portion 3 may be deteriorated, or the first rolling die 220 may be worn. May be significantly faster. On the other hand, when r ₁ / r ₃ exceeds the upper limit, the size and cost of the first rolling die 220 are increased.

Further, the inclination angle θ of the axis _{X 1} of the first rolling die 220 relative to the axis X of the workpiece 400, is preferably from 0.1 to 5 °, that is 0.5 to 1.5 ° More preferred. Thereby, it is possible to reduce the cost while improving the developing characteristics of the developing roller 510.
In contrast, or cause the inclination angle θ is less than the lower limit, or cause a reduction in productivity becomes small feed amount L _1, the size and cost of the first rolling die 220 To do. On the other hand, when the inclination angle θ exceeds the upper limit value, the running stability of the workpiece 400 is lowered, the running stability of the workpiece 400 is lowered, and the dimensional accuracy of the formed groove 2 or convex portion 3 is deteriorated. Sometimes.

The feed amount _{L 1} of the workpiece 400 with respect to the first rolling die 220 is preferably from 0.1 to 5 mm, preferably from 0.5 to 1.5 mm. Thereby, it is possible to reduce the cost while improving the developing characteristics of the developing roller 510.
In contrast, when the feeding amount L ₁ is less than the lower limit, it leads to a decrease in productivity, as a result, which leads to higher cost of the development roller 510. On the other hand, when the feeding amount L ₁ exceeds the upper limit value, or cause the size and cost of the first rolling die 220, reduced running stability of the workpiece 400, a groove 2 Ya formed The dimensional accuracy of the convex part 3 may deteriorate.

The width W of the curved portion 222 is twice larger than the feeding amount L ₁ as described above, and is not particularly limited as long as it results in a step L ₂ as described above, is 5~50mm Is preferable, and it is more preferable that it is 10-30 mm.
Here, the height of the ridges 221 in the central portion in the axial direction _{X 1} of the curved portion 222 and _{D 1,} the height of the ridges 221 at ends in the axial direction _{X 1} of the curved portion 222 and the _{D 2} when, the height D ₁ and height D ₂ may be different even in the same.

Moreover, as shown in FIG. 10, the height of each protruding item | line 221 may gradually reduce toward the edge part side from the center part side of the bending part 222, and as shown in FIG. The height of each ridge 221 from the center side to the end side may be substantially constant.
As described above, rolling apparatus 200 according to the present invention, since the optimized in relation to the feed amount L ₁ of the width and radius of curvature of the curved portion 222, while achieving a cost reduction by improving the productivity, A high-quality developing roller 510 having excellent developing characteristics can be obtained.

After forming the groove | channel 2 using the rolling die | dye as mentioned above, the plating process is given to the surface as needed. Thereby, the mechanical strength of the groove 2 obtained can be further improved.
The plating method is not particularly limited, but electroless Ni—P plating, electroplating, hard chrome plating, or the like can be suitably used.
The plating thickness is preferably about 2 to 10 μm.

As described above, the developing roller 510 can be manufactured.
Such a developing roller 510 has excellent developing characteristics. Further, the developing unit (developing device) 50 and the printer (image forming apparatus) 10 including such a developing roller 510 have high reliability.
As described above, the rolling device, the developing roller manufacturing method, the developing roller, the developing device, and the image forming apparatus of the present invention have been described with respect to the illustrated embodiments. However, the present invention is not limited thereto, and Each component can be replaced with any component that can exhibit the same function. Moreover, arbitrary components may be added.

In the above-described embodiment, the configuration in which both end portions of the bending portion 222 in the axial direction are optimized in relation to the feed amount L ₁ has been described. However, at least one end portion of the bending portion 222 in the axial direction is described. of it may be optimized in relation to the feed amount L ₁ configuration.
Further, the bending portion 222, when viewed in cross-section containing the axis X _1, line segment connecting the top portions of the ridges 221, to a line segment passing through the orthogonal and centered on the axis X ₁ may be asymmetric .

Next, specific examples of the present invention will be described.
1. Production of developing roller (Example 1)
<1> First, a roller-shaped workpiece composed of a carbon steel pipe STKM11A for machine structure was prepared. Here, as the workpiece, a workpiece having a reduced diameter portion provided at both ends of a cylindrical main body having a length of 314.5 mm and a diameter of 18 mm (radius r ₃ = 9 mm) was used.

<2> Next, grooves as shown in FIGS. 4, 5, and 10 were formed on the outer peripheral surface of the workpiece by a rolling method using a rolling device as shown in FIGS.
Here, main conditions, such as a dimension of each rolling die of the used rolling apparatus, and an inclination angle, are as follows.
<Conditions for rolling equipment>
・ Maximum outer diameter of rolling die: 150 mm
・ Inclination angle θ of rolling die: 0.5 °
-Feed amount L ₁ : 0.5 mm
・ Width W of curved portion: 25 mm
-Curvature radius of curvature: 200mm
Step difference L ₂ (= | r ₁ −r ₂ |): 0.6 μm
-Pitch pitches p ₁ and p ₂ : 80 μm
・ Inclination angle with respect to the circumferential direction of each ridge: 45 °
・ Rotation speed of rolling die: 150rpm
Here, the curved portion was formed so that the line segment connecting the tops of the ridges was symmetric with respect to the line segment orthogonal to the axis and passing through the center when viewed in a cross section including the axis.
Moreover, main conditions, such as a dimension and an angle of each part of the formed groove | channel, are as follows.

<Conditions for each part of the groove>
・ The depth of the first groove and the second groove: 5 μm
・ An intersection angle between the first groove and the second groove: 90 °
・ Pitch p of first groove and second groove: 80 μm
First groove / second groove width A: 55 μm

<3> Next, a surface layer was formed on the outer peripheral surface of the steel pipe according to the following formation conditions.
<Surface layer formation conditions>
-Formation method: Electroless plating method-Composition: Ni-P (P content: 10 wt%)
・ Average thickness: 5μm
The developing roller was manufactured as described above.

(Examples 2 to 10)
A developing roller was produced in the same manner as in Example 1 except that the conditions of the rolling die were as shown in Table 1.
(Comparative Examples 1-6)
A developing roller was produced in the same manner as in Example 1 except that the conditions of the rolling die were as shown in Table 1.

2. Evaluation The surface of the developing roller of each Example and each Comparative Example was visually observed, and each developing roller was incorporated into a printer (manufactured by Epson, LP-9000C), and an image with a printing rate of 50% was recorded on a recording paper (Fuji Xerox Co., Ltd.). Printed on high-quality paper (J paper), and the printed state was observed with the naked eye, and the surface state (generation of streaks) and the printed state (occurrence of unevenness) of the developing roller were evaluated as shown below. The evaluation results are shown in Table 1.
As the toner, a spherical toner having a polyester resin composition having an average particle diameter of 6.5 μm was used.

<Developer roller surface condition>
A: No streak was observed at all.
○: Slight streaks were observed.
X: A streak was remarkably recognized.
<Printing status>
A: No unevenness was observed at all.
◯: Slight unevenness was observed, but at a level where there was no problem in actual use.
X: Unevenness was noticeable.

As apparent from Table 1, in Examples 1 to 10 of the present invention, both the surface state and the printing state of the developing roller were extremely excellent.
On the other hand, in the developing roller of each comparative example, streaks were generated on the surface of the developing roller, and the printing state was inferior to that of Examples 1-10.

1 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a schematic configuration of a developing device provided in the image forming apparatus illustrated in FIG. 1. It is a top view which shows schematic structure of the developing roller with which the developing device shown in FIG. 2 was equipped. FIG. 4 is an enlarged plan view of a groove formed in the developing roller shown in FIG. 3. It is the sectional view on the AA line in FIG. It is a figure for demonstrating an example of the process of the manufacturing method of the developing roller shown in FIG. It is a perspective view which shows schematic structure of the rolling apparatus which forms a groove | channel in the outer peripheral surface of a base material in the manufacturing method shown in FIG. It is an enlarged side view of the rolling apparatus shown in FIG. It is the elements on larger scale of the rolling die with which the rolling apparatus shown in FIG. 7 was equipped. It is the elements on larger scale for demonstrating an example of the convex line of the rolling die shown in FIG. It is the elements on larger scale for demonstrating the other example of the protruding item | line of the rolling die shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Printer 2 ... Groove 21 ... 1st groove 211 ... Side surface 212 ... Bottom 22 ... 2nd groove 20 ... Photoconductor 200 ... Rolling device 210 ... Base 220 ... First 1 rolling die 222... Curved portion 230... 2nd rolling die 240 and 250... Feeding means 3 .. convex portion 31 .. top portion 221 and 231. ... Main body 301 ... Outer peripheral part 310, 410 ... Reduced diameter part 320 ... Groove forming part 40 ... Exposure unit 400 ... Workpiece 401 ... Main body 50 ... Developing unit 50a ... Shaft 51 ... Black developing device 52 …… Magenta developing device 53 …… Cyan developing device 54 …… Yellow developing device 55a to 55d …… Holding portion 510 …… Developing roller 511 …… Metal tube 512 …… Surface layer 520 …… Seal member 530 ... Housing 540... Housing 550... Toner supply roller 560... Restricting blade 560 a... Rubber part 560 b... Rubber supporting part 562 ... Blade supporting sheet metal 570. Intermediate transfer body 75 …… Cleaning unit 76 …… Cleaning blade 80 …… Secondary transfer unit 90 …… Fixing unit 92 …… Feed tray 94 …… Feeding roller 96 …… Registration roller P1 …… Recording medium T …… Toner X, X ₁ , X ₂ ...... Axis

Claims (11)

A rolling die in which a plurality of protrusions extending in a direction that is in a roller shape and is parallel to each other and spaced apart from each other and inclined in the circumferential direction are formed;
The rolling die is installed so that its axis is inclined at a predetermined inclination angle with respect to the axis of the workpiece having a cylindrical or columnar shape, and the rolling die is rotated around the axis on the outer peripheral surface of the workpiece. by pressing while the feeding means for relatively moving with respect to the rolling die at the workpiece prescribed feeding amount L ₁ in accordance with the predetermined tilt angle per one rotation of the workpiece in the axial direction With
By the pressing of the outer peripheral surface of the workpiece and the outer peripheral surface of the rolling die, a groove is formed so as to be inclined with respect to the circumferential direction of the workpiece by the convex ridges,
When the rolling die is viewed in a cross-section including the axis, the distance between the top of each ridge and the axis gradually decreases from the center side to the end side in the axial direction. A line segment connecting the tops of the ridges is provided with a curved portion curved in a convex shape,
The width in the axial direction of the bending portion is larger than twice said predetermined feeding amount L _1, and said predetermined feeding amount L ₁ axially separated from each other in at least one end in the axial direction of the bending portion When r ₁ and r ₂ are distances between the tops of the respective convex ridges and the axis of the rolling die at the two portions, | r ₁ −r ₂ | is 5 μm or less. A rolling device characterized by that. _2. The rolling device according to claim ₁ , wherein | r ₁ −r ₂ | is 5 μm or less at least on the end side of the curved portion on the downstream side in the conveyance direction of the workpiece. 3. The rolling device according to claim ₂ , wherein | r ₁ −r ₂ | is 5 μm or less on each end side in the axial direction of the curved portion. The rolling device according to claim ₁ , wherein r ₁ / r ₃ is 5 to 20 when the radius of the workpiece is r ₃ .   The rolling device according to any one of claims 1 to 4, wherein the predetermined inclination angle is 0.1 to 5 °. The predetermined feeding amount _{L 1} is rolling apparatus according to any one of the claims 1 to 0.1 to 5 mm 5.   A pair of the rolling dies are provided so as to narrow the work, and a plurality of first grooves are formed by the one rolling die, and the plurality of first dies are formed by the other rolling die. The rolling device according to any one of claims 1 to 6, wherein the rolling device is configured to form a plurality of second grooves intersecting one groove. A step of preparing a cylindrical or columnar workpiece which is an object of rolling processing;
Forming a groove for carrying toner by pressing a rolling die while moving the outer peripheral surface of the workpiece relatively in the axial direction thereof,
The rolling die has a roller shape, and a plurality of ridges extending in a direction inclined parallel to the circumferential direction and inclined with respect to the circumferential direction are formed on the outer circumferential surface thereof,
When the rolling die is viewed in a cross-section including the axis, the distance between the top of each ridge and the axis gradually decreases from the center side to the end side in the axial direction. The line segment connecting the tops of the ridges is provided with a curved portion that is curved in a convex shape,
In the step of forming the groove, the rolling die is installed so that the axis is inclined at a predetermined inclination angle with respect to the axis of the workpiece, and the rolling die is arranged around the axis on the outer peripheral surface of the workpiece. in by pressing while rotating, while relatively moving the said workpiece with respect to rolling die in the axial direction to a predetermined in accordance with the predetermined tilt angle per one rotation of the workpiece feed amount L ₁ ,
By the pressing of the outer peripheral surface of the workpiece and the outer peripheral surface of the rolling die, a groove is formed so as to be inclined with respect to the circumferential direction of the workpiece by the convex ridges,
The width in the axial direction of the bending portion is larger than twice said predetermined feeding amount L _1, and said predetermined feeding amount L ₁ axially separated from each other in at least one end in the axial direction of the bending portion When r ₁ and r ₂ are distances between the tops of the respective convex ridges and the axis of the rolling die at the two portions, | r ₁ −r ₂ | is 5 μm or less. A method for producing a developing roller.   A developing roller manufactured by the method for manufacturing a developing roller according to claim 8.   A developing device comprising the developing roller according to claim 9.   An image forming apparatus comprising the developing device according to claim 10.

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