JP2014240928A - Manufacturing method of developer carrier, developer carrier, developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the limitation of the dimension of necessary clearance with an image carrier without causing a deterioration in accuracy to suppress vibration during rotation.SOLUTION: A developer carrier 115 according to the present invention includes a cylindrical member 132 that is rotatably arranged, and flange members 135 and 136 that are press-fit to ends 132b and 132f located in the axial direction of the cylindrical member, and further includes a bent shaped part 132d that is arranged on at least one ends located in the axial direction of the cylindrical member and has the outer diameter smaller than that of a body part located between the ends.

Description

  The present invention relates to a method of manufacturing a developer carrier used in a copying machine, a facsimile machine, a printer, a multi-function machine equipped with a plurality of mechanisms, and a developer carrier, a developing device, a process cartridge, and an image formation using the developer carrier. It relates to the device.

As one of the rotating bodies used in the image forming apparatus, there is a developer carrier that supplies a developer to an image carrier that is a counter member. The developer carrying member includes a non-rotating magnet roller, a cylindrical member made of a non-magnetic material so as to cover the outer peripheral surface of the magnet roller, and an end portion positioned in the axial direction of the cylindrical member. It has a flange member to be mounted.
As a method for fixing the flange member to the cylindrical member as the rotating body, there is a method in which the flange member is press-fitted inside the openings located at both ends of the sleeve. Since this method is easy as a process, it has been widely used in the past. However, in the fixing method, the cylindrical member needs to be set up a plurality of times by finishing the outer diameter and the inner diameter, and it is difficult to improve the deflection accuracy. In particular, when the rotating body is a developer carrier, there is a problem that density unevenness occurs in the circumferential direction of the image.
Therefore, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-133180), the magnet roller is covered with a cylindrical member (sleeve) made of a nonmagnetic material that is disposed to face the image carrier and is driven to rotate. A developer carrier that is rotatably supported by the shaft portion of the magnet roller with flange members provided at both ends of the sleeve, and the flange member is fitted and attached to the outer peripheral surface of the end portion of the sleeve with respect to the outer peripheral surface of the sleeve. Is disclosed. According to this, it is possible to omit high-accuracy machining of the sleeve inner circumferential surface when fitting on the sleeve inner circumferential surface, and to reduce the component machining cost while maintaining the component machining accuracy.
Japanese Patent Laid-Open No. 6-280855 discloses a cylindrical member having an end engaging member at least at one end of a cylinder (sleeve), and the end engaging member is fitted to the outside of the cylinder. A cylindrical member is disclosed that includes a fitting portion and is fitted to the end portion of the cylinder by the fitting portion, and the end portion of the cylinder is bent and joined into the notch portion of the engaging member. Yes. In the configuration of Patent Document 2, the outer diameter of the end portion is formed smaller than that of the body portion by forming the body portion of the sleeve in multiple layers and the end portions located at both ends in one layer. Thus, even when the flange member is fitted to the outer peripheral surface of the end portion of the sleeve, the outer diameter of the flange does not protrude outwardly from the outer diameter of the sleeve body portion.

In the developer carrier described in Patent Document 1, after the flange is fitted to the sleeve, the outer diameter of the flange becomes larger than the outer diameter of the sleeve, and the difference between the outer diameters of the developer carrier and the image carrier is larger. It is difficult to reduce the clearance (development gap). The clearance generally needs to be about 0.1 to 1.0 mm, and if it is larger than that, the image density is lowered. In addition, when the flange thickness is reduced to reduce the clearance, the rigidity of the developer carrying member is lowered and deformed, and the shake accuracy is deteriorated, which causes uneven image density. There are difficult challenges.
In the cylindrical member described in Patent Document 2, the outer diameter of the end portion is made smaller than that of the cylindrical body portion by forming the cylindrical body portion in multiple layers and the end portion of the cylinder in one layer. If multiple layers of films are formed on the part, the film thickness deviations are accumulated, so that the accuracy of the parts of the sleeve is lowered. Furthermore, since the thickness of the end portion is thin, there is a problem that the rigidity after fitting is also lowered.
The present invention reduces the restriction on the required clearance dimension with the opposing member, and suppresses uneven density and insufficient density of the image due to deterioration in shake accuracy during rotation after press-fitting the cylindrical member and the flange member. And its purpose.

  In order to achieve the above object, a developer carrier according to the present invention includes a cylindrical member that is rotatably arranged and a flange member that is press-fitted into an end portion of the cylindrical member that is positioned in the axial direction. It is characterized by having a curved portion having an outer diameter smaller than that of the body portion positioned between the end portions on at least one side of the end portions positioned in the axial direction of the shaped member.

  According to the present invention, the flange member is bent because at least one end of the end portion positioned in the axial direction of the cylindrical member has the bent shape portion whose outer diameter is smaller than that of the body portion positioned between the end portions. After press-fitting into the shape part, the length that the outer peripheral surface of the flange member protrudes outside the barrel part of the cylindrical member is reduced, reducing the restriction on the clearance dimension between the developer carrier and the image carrier as the opposing member can do. In addition, unlike the conventional developer carrier that press-fits the flange member inside the cylindrical member, the cylindrical member can be finished from the outside of the cylindrical member, eliminating the recombination work during processing, The body part and the press-fitting part of the member can be processed with high accuracy. For this reason, image density unevenness and density deficiency due to rotational shake can be suppressed without causing deterioration in shake accuracy during rotation after the press-fitting of the cylindrical member and the flange member.

1 is a front view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of a developing device according to an embodiment of the present invention. Sectional drawing which follows the III-III line in FIG. FIG. 3 is a cross-sectional view showing the configuration of the developer carrier and the clearance between the image carrier and the developer carrier according to the present invention. It is a figure which shows the structure of the flange with which a developing agent carrier is equipped, (a) is sectional drawing, (b) is a figure which shows the structure inside the flange seen from the axial direction. Sectional drawing which shows the edge part structure of the sleeve with which a developing agent carrier is equipped. FIG. 2 shows the assembled state of the flange and sleeve of the developer carrier, (a) is a cross-sectional view showing a state in which a bearing is mounted on the sleeve, and (b) starts to mount the sleeve on the bent portion of the flange. Sectional drawing which shows a state, (c) is sectional drawing which shows the mounting completion state of a sleeve with a flange. (A) is a cross-sectional view showing a first embodiment of the flange, (b) is a cross-sectional view showing the first embodiment of the sleeve, and (c) is a developer carrier and an image carrier according to the first embodiment. The partial expanded sectional view which shows the arrangement | positioning relationship with a body. Explanatory drawing of the shake | deflection precision of the developer carrier which concerns on a 1st Example. FIG. 10 is a partial enlarged cross-sectional view illustrating a positional relationship between a configuration of a developer carrier and an image carrier according to a second embodiment. FIG. 10 is a partial enlarged cross-sectional view illustrating a positional relationship between a configuration of a developer carrier and an image carrier according to a third embodiment. FIG. 10 is a partial enlarged cross-sectional view illustrating a positional relationship between a configuration of a developer carrier and an image carrier according to a fourth embodiment. The comparative example 1 is shown, (a) is sectional drawing which shows the structure of the flange which concerns on the comparative example 1, (b) is sectional drawing which shows the structure of the sleeve which concerns on the comparative example 1, (c) is comparative example 1. FIG. 3 is a partial enlarged cross-sectional view showing the positional relationship between the developer carrier and the image carrier. FIGS. 2A and 2B show Comparative Examples 2 and 3, in which FIG. 1A is a cross-sectional view showing a configuration of a flange according to Comparative Examples 2 and 3, FIG. 2B is a cross-sectional view showing a configuration of a sleeve according to Comparative Examples 2 and 3; ) Is a partial enlarged cross-sectional view showing the positional relationship between the developer carrier and the image carrier according to Comparative Examples 2 and 3. FIG. FIG. 5 is a process diagram showing an example of a method for producing a developer carrier according to the present invention. Process drawing which shows another example of the manufacturing method of the developer carrier which concerns on this invention.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. Note that, in each drawing, each embodiment, and example, the same member or a member having the same function is basically denoted by the same reference numeral, and redundant description is appropriately omitted.

FIG. 1 is a schematic configuration diagram of a configuration of an image forming apparatus according to an embodiment of the present invention as viewed from the front. FIG. 2 is a sectional view of the developing device mounted on the image forming apparatus shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG.
An image forming apparatus 101 that uses an electrophotographic method uses yellow (Y), magenta (M), cyan (C), and black (K) images, that is, color images, as recording paper 107 as a single transfer material. (Shown in FIG. 1). The units corresponding to the colors of yellow, magenta, cyan, and black are indicated by adding Y, M, C, and K at the end of the reference numerals.
As shown in FIG. 1, the image forming apparatus 101 includes an apparatus main body 102, a paper feed unit 103, a registration roller pair 110, a transfer unit 104, a fixing unit 105, and a plurality of laser writing units 122Y, 122M, and 122C. , 122K and a plurality of process cartridges 106Y, 106M, 106C, 106K.

The apparatus main body 102 is formed in a box shape, for example, and is installed on a floor or the like. The apparatus main body 102 includes a paper feed unit 103, a registration roller pair 110, a transfer unit 104, a fixing unit 105, a plurality of laser writing units 122Y, 122M, 122C, and 122K, and a plurality of process cartridges 106Y, 106M, and 106C. 106K.
A plurality of paper feed units 103 are provided in the lower part of the apparatus main body 102. The paper feed unit 103 includes a paper feed cassette 123 that can accommodate the above-described recording paper 107 in a stacked manner and can be taken in and out of the apparatus main body 102, and a paper feed roller 124. The paper feed roller 124 is pressed against the uppermost recording paper 107 in the paper feed cassette 123. The paper feed roller 124 is configured to transfer the above-described uppermost recording paper 107 to a transfer belt 129 (to be described later) of the transfer unit 104 and a photosensitive drum 108 as an image carrier to be described later of the process cartridges 106Y, 106M, 106C, and 106K. Send out in between.

  The registration roller pair 110 is provided in a conveyance path of the recording paper 107 conveyed from the paper supply unit 103 to the transfer unit 104, and includes a pair of rollers 110a and 110b. The registration roller pair 110 sandwiches the recording sheet 107 between the pair of rollers 110a and 110b, and at a timing at which the sandwiched recording sheet 107 can be superimposed on the toner image, the transfer unit 104 and the process cartridges 106Y, 106M, 106C, and 106K. Send out in between.

The transfer unit 104 is provided above the paper feed unit 103. The transfer unit 104 includes a driving roller 127, a driven roller 128, a conveyance belt 129, and transfer rollers 130Y, 130M, 130C, and 130K. The drive roller 127 is disposed on the downstream side in the conveyance direction of the recording paper 107 and is driven to rotate by a motor or the like as a drive source. The driven roller 128 is rotatably supported by the apparatus main body 102 and is disposed on the upstream side in the conveyance direction of the recording paper 107. The conveyor belt 129 is formed in an endless annular shape and is stretched over both the driving roller 127 and the driven roller 128 described above. The conveyance belt 129 circulates (endless travel) around the driving roller 127 and the driven roller 128 described above in the counterclockwise direction in the drawing as the driving roller 127 is rotationally driven.
The transfer rollers 130Y, 130M, 130C, and 130K sandwich the conveyance belt 129 and the recording paper 107 on the conveyance belt 129 between the photosensitive drums 108 included in the process cartridges 106Y, 106M, 106C, and 106K, respectively. In the transfer unit 104, the transfer rollers 130Y, 130M, 130C, and 130K press the recording paper 107 delivered from the paper supply unit 103 against the outer peripheral surface 108a of the photosensitive drum 108 of each process cartridge 106Y, 106M, 106C, and 106K. Then, the toner image on the photosensitive drum 108 is transferred to the recording paper 107. The transfer unit 104 sends the recording paper 107 onto which the toner image is transferred toward the fixing unit 105.

The fixing unit 105 is provided downstream of the transfer unit 104 in the conveyance direction of the recording paper 107, and includes a pair of rollers 105a and 105b that sandwich the recording paper 107 therebetween. The fixing unit 105 presses and heats the recording paper 107 sent out from the transfer unit 104 between the pair of rollers 105a and 105b, thereby recording the toner image transferred from the photosensitive drum 108 onto the recording paper 107. Fix to paper 107.
The laser writing units 122Y, 122M, 122C, and 122K are attached to the upper part of the apparatus main body 102, respectively. The laser writing units 122Y, 122M, 122C, and 122K correspond to one process cartridge 106Y, 106M, 106C, and 106K, respectively. The laser writing units 122Y, 122M, 122C, and 122K irradiate the outer peripheral surface 108a of the photosensitive drum 108 that is uniformly charged by the charging rollers 109 described later of the process cartridges 106Y, 106M, 106C, and 106K with laser light. An electrostatic latent image is formed.

The process cartridges 106Y, 106M, 106C, and 106K are provided between the transfer unit 104 and the laser writing units 122Y, 122M, 122C, and 122K, respectively. The process cartridges 106Y, 106M, 106C, and 106K are detachable from the apparatus main body 102. The process cartridges 106Y, 106M, 106C, and 106K are arranged in parallel along the conveyance direction of the recording paper 107.
As shown in FIG. 2, the process cartridges 106Y, 106M, 106C, and 106K include a cartridge case 111, a charging roller 109 as a charging device, a photosensitive drum (also referred to as an image carrier) 108, and a cleaning device as a cleaning device. A blade 112 and a developing device 113 are provided. Therefore, the image forming apparatus 101 includes at least a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113.
The cartridge case 111 is detachably attached to the apparatus main body 102 and accommodates a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113. The charging roller 109 uniformly charges the outer peripheral surface 108 a of the photosensitive drum 108. The photosensitive drum 108 is a rotating body of the developing device 113 which will be described later, and is arranged with a clearance (development gap) from a developing roller 115 serving as a developer carrier. The photosensitive drum 108 is formed in a columnar shape or a cylindrical shape that is rotatable around an axis. An electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 108 by the corresponding laser writing units 122Y, 122M, 122C, and 122K.
The photoreceptor drum 108 is developed on the electrostatic latent image formed on the outer peripheral surface by adsorbing the toner, and the toner image thus obtained is transferred to the recording paper 107 positioned between the conveyance belt 129. To do. The cleaning blade 112 removes the transfer residual toner remaining on the outer peripheral surface 108 a of the photosensitive drum 108 after transferring the toner image to the recording paper 107.

As shown in FIG. 2, the developing device 113 includes at least a developer supply unit 114, a case 125, a developing roller 115 as a developer carrier, and a doctor blade 116 as a regulating member.
The developer supply unit 114 includes a storage tank 117 and a pair of stirring screws 118 as stirring members. The storage tank 117 is formed in a box shape having a length substantially equal to that of the photosensitive drum 108. Further, a partition wall 119 extending along the longitudinal direction of the storage tank 117 is provided in the storage tank 117. The partition wall 119 partitions the storage tank 117 into a first space 120 and a second space 121. Moreover, both ends of the first space 120 and the second space 121 communicate with each other.
The storage tank 117 stores the developer 126 in both the first space 120 and the second space 121. The developer 126 includes toner and a magnetic carrier (also referred to as magnetic powder). The toner is appropriately supplied to one end portion of the first space 120 on the side away from the developing roller 115 in the first space 120 and the second space 121. The toner is spherical fine particles produced by an emulsion polymerization method or a suspension polymerization method. The toner may be obtained by pulverizing a lump composed of a synthetic resin in which various dyes or pigments are mixed and dispersed. The average particle diameter of the toner is 3 μm or more and 7 μm or less. The toner may be formed by pulverization or the like. The magnetic carrier is accommodated in both the first space 120 and the second space 121. The average particle size of the magnetic carrier is 20 μm or more and 50 μm or less.

The stirring screw 118 is accommodated in each of the first space 120 and the second space 121. The longitudinal direction of the stirring screw 118 is parallel to the longitudinal directions of the storage tank 117, the developing roller 115, and the photosensitive drum 108. The agitating screw 118 is provided so as to be rotatable around an axis, and rotates around the axis to agitate the toner and the magnetic carrier and convey the developer 126 along the axis.
In the illustrated example, the stirring screw 118 in the first space 120 conveys the developer 126 from one end to the other end described above. The agitation screw 118 in the second space 121 conveys the developer 126 from the other end toward the one end.
According to the above-described configuration, the developer supply unit 114 conveys the toner supplied to one end of the first space 120 to the other end while stirring with the magnetic carrier, and from the other end to the second space. The other end of 121 is conveyed. The developer supply unit 114 agitates the toner and the magnetic carrier in the second space 121 and supplies them to the outer peripheral surface of the developing roller 115 while conveying the toner in the axial direction.
The case 125 is formed in a box shape, is attached to the storage tank 117 of the developer supply unit 114 described above, and covers the developing roller 115 and the like together with the storage tank 117. In addition, an opening 125 a is provided in a portion of the case 125 that faces the photosensitive drum 108.

The developing roller 115 is formed in a cylindrical shape, and is provided between the second space 121 and the photosensitive drum 108 and in the vicinity of the opening 125a described above. The developing roller 115 is parallel to both the photosensitive drum 108 and the storage tank 117. The developing roller 115 is arranged with a space (development gap) from the photosensitive drum 108. A space between the developing roller 115 and the photosensitive drum 108 forms a developing region 131 in which the toner of the developer 126 is attracted to the photosensitive drum 108 and the electrostatic latent image is developed to obtain a toner image. In the developing area 131, the developing roller 115 and the photosensitive drum 108 face each other.
As shown in FIG. 3, the developing roller 115 includes a shaft 134, a cylindrical magnet roller (also referred to as a magnet body) 133, a developing sleeve 132 as a cylindrical member that covers the outer peripheral surface 133 a of the magnet roller 133, a flange, It has flanges 135 and 136 as members. The shaft 134 has a longitudinal direction parallel to the longitudinal direction of the photosensitive drum 108, and is fixed to the case 125 without rotating. The flange 135 is attached and fixed to one end 132b of the developing sleeve 132 by a fitting method described later, and the flange 136 is attached and fixed by being press-fitted into the other end 132f of the developing sleeve 132. .

The magnet roller 133 is made of a magnetic material and is formed in a cylindrical shape, and a plurality of fixed magnetic poles (not shown) are attached in the circumferential direction. The magnet roller 133 is fixed to the outer periphery of the shaft 134 without rotating around the shaft center.
The fixed magnetic pole is a long and rod-shaped magnet, and is attached to the magnet roller 133. The fixed magnetic pole extends along the longitudinal direction of the magnet roller 133, that is, the developing roller 115, and is provided over the entire length of the magnet roller 133. The magnet roller 133 having the above-described configuration is accommodated (enclosed) in the developing sleeve 132.
One fixed magnetic pole is opposed to the stirring screw 118 shown in FIG. The one fixed magnetic pole forms a pumping magnetic pole, and generates a magnetic force on the outer peripheral surface 132 A of the developing sleeve 132, that is, the outer peripheral surface of the developing roller 115, and the developer 126 in the second space 121 of the storage tank 117. Is adsorbed to the outer peripheral surface of the developing sleeve 132.
The other fixed magnetic pole is opposed to the photosensitive drum 108 described above. This fixed magnetic pole forms a developing magnetic pole, and generates a magnetic force on the developing sleeve 132, that is, the outer peripheral surface of the developing roller 115, thereby forming a magnetic field between the developing sleeve 132 and the photosensitive drum 108. The fixed magnetic pole forms a magnetic brush by the magnetic field, so that the toner of the developer 126 adsorbed on the outer peripheral surface 132A of the developing sleeve 132 is delivered to the photosensitive drum 108.
At least one fixed magnetic pole is provided between the pumping magnetic pole and the developing magnetic pole. The at least one fixed magnetic pole generates a magnetic force on the outer peripheral surface 132A of the developing sleeve 132, that is, the outer peripheral surface of the developing roller 115, and conveys the developer 126 before development toward the photosensitive drum 108 and develops it. The used developer 126 is conveyed from the photosensitive drum 108 into the storage tank 117.
When the developer 126 adsorbs the developer 126 to the outer peripheral surface 132A of the developing sleeve 132, a plurality of magnetic carriers of the developer 126 are overlapped along the lines of magnetic force generated by the fixed magnetic pole, and the outer peripheral surface of the developing sleeve 132 is fixed. Stand on top. As described above, a state in which a plurality of magnetic carriers are stacked on the outer circumferential surface 132A of the developing sleeve 132 along the lines of magnetic force is called standing on the outer circumferential surface 132A of the developing sleeve 132. As a result, the toner described above is adsorbed to the magnetic carrier. That is, the developing sleeve 132 attracts the developer 126 to the outer peripheral surface by the magnetic force of the magnet roller 133.

As shown in FIG. 3, the developing sleeve 132 is formed in a cylindrical shape. The developing sleeve 132 includes (accommodates) a magnet roller 133 and is provided so as to be rotatable around the axis of the shaft 134. The developing sleeve 132 is rotationally driven so that the inner peripheral surface thereof is sequentially opposed to the fixed magnetic pole. The developing sleeve 132 is made of a nonmagnetic material such as aluminum alloy, brass, stainless steel (SUS), or conductive resin. The developing sleeve 132 is roughened on its outer peripheral surface.
Aluminum alloys are excellent in terms of workability and lightness. When an aluminum alloy is used, it is preferable to use A6063, A5056, and A3003. When using SUS, it is preferable to use SUS303, SUS304, and SUS316. In the illustrated example, the developing sleeve 132 is made of an aluminum alloy. The outer diameter of the developing sleeve 132 is desirably about 14 mm to 30 mm. The length of the developing sleeve 132 in the axial direction is preferably about 300 mm to 350 mm.

  As shown in FIG. 2, the doctor blade 116 is provided at the end of the developing device 113 near the photosensitive drum 108. The doctor blade 116 is attached to the case 125 described above with a space from the outer peripheral surface 132 </ b> A of the developing sleeve 132. The doctor blade 116 scrapes the developer 126 on the outer peripheral surface 132A of the developing sleeve 132 exceeding the desired thickness into the storage tank 117, and the developer on the outer peripheral surface of the developing sleeve 132 conveyed to the developing region 131. 126 to the desired thickness.

In the developing device 113 configured as described above, the developer and the magnetic carrier are sufficiently stirred by the developer supply unit 114, and the stirred developer 126 is attracted to the outer peripheral surface 132A of the developing sleeve 132 by the fixed magnetic pole. The developing device 113 conveys the developer 126 adsorbed by a plurality of fixed magnetic poles toward the developing region 131 as the developing sleeve 132 rotates. The developing device 113 adsorbs the developer 126 having a desired thickness by the doctor blade 116 to the photosensitive drum 108. In this way, the developing device 113 carries the developer 126 on the developing roller 115, transports it to the developing area 131, develops the electrostatic latent image on the photosensitive drum 108, and forms a toner image.
The developing device 113 releases the developed developer 126 toward the storage tank 117. The developed developer 126 stored in the storage tank 117 is sufficiently stirred again with the other developer 126 in the second space 121 to develop the electrostatic latent image on the photosensitive drum 108. Used. When the toner concentration sensor described later detects that the concentration of toner supplied to the photosensitive drum 108 is lowered by the developer supply unit 114, for example, the developing device 113 causes the developing roller to rotate the stirring screw 118 to rotate the toner. It goes out to 115.

The image forming apparatus 101 having the above-described configuration forms an image on the recording paper 107 as described below.
First, the image forming apparatus 101 rotationally drives the photosensitive drum 108, and uniformly charges the outer peripheral surface 108 a of the photosensitive drum 108 to −700 V by the charging roller 109. The outer peripheral surface 108a of the photosensitive drum 108 is irradiated with laser light to expose the photosensitive drum 108, the image portion is attenuated to -150V, and an electrostatic latent image is formed on the outer peripheral surface 108a of the photosensitive drum 108. Form. When the electrostatic latent image is positioned in the developing area 131, a developing bias voltage of −550 V is applied to the electrostatic latent image, and the developer 126 adsorbed on the outer peripheral surface 132A of the developing sleeve 132 of the developing device 113 is absorbed. The electrostatic latent image is developed by being attracted to the outer peripheral surface 108 a of the photosensitive drum 108, and a toner image is formed on the outer peripheral surface of the photosensitive drum 108.
In the image forming apparatus 101, the recording sheet 107 conveyed by the sheet feeding roller 124 of the sheet feeding unit 103 is transferred between the photosensitive drum 108 of the process cartridges 106 Y, 106 M, 106 C, and 106 K and the conveying belt 129 of the transfer unit 104. The toner image formed on the outer peripheral surface of the photoconductive drum 108 is transferred to the recording paper 107 at a position therebetween. The image forming apparatus 101 uses a fixing unit 105 to fix the toner image on the recording paper 107. Thus, the image forming apparatus 101 forms a color image on the recording paper 107.

  On the other hand, the toner remaining on the photosensitive drum 108 without being transferred is collected by the cleaning blade 112. The photosensitive drum 108 from which the residual toner has been removed is initialized by a static elimination lamp (not shown) and used for the next image forming process.

  In the image forming apparatus 101 described above, process control is performed in order to suppress image quality fluctuations due to environmental fluctuations and temporal fluctuations. Specifically, first, the developing ability in the developing device 113 is detected. For example, an image of a certain toner pattern is formed on the photosensitive drum 108 under a condition where the developing bias voltage is constant, the image density is detected by an optical sensor (not shown), and the developing ability is grasped from the density change. Then, the image quality can be kept constant by changing the target value of the toner density so that the developing ability becomes a predetermined target developing ability. For example, when the image density of the toner pattern detected by the optical sensor is lower than the target development density, a CPU as a control means (not shown) drives a motor that rotationally drives the stirring screw 118 so as to increase the toner density. Control the circuit. On the other hand, when the image density of the toner pattern detected by the optical sensor is higher than the target development density, the CPU controls the above-described motor drive circuit so as to lower the toner density. Here, the toner density is detected by a toner density sensor (not shown). It should be noted that the image density of the toner pattern formed on the photosensitive drum 108 may vary somewhat due to the influence of the image density cycle unevenness caused by the developing sleeve 132.

As shown in FIG. 3, the developing roller 115 is coupled by attaching a flange 135 and a flange 136 to end portions 132 b and 132 fb as opening edges located in the axial direction of the developing sleeve 132. Flange 135 is the drive side and flange 136 is the passive side.
The flange 135 is a reference when the developing roller 115 is rotationally driven in the developing device. Depending on the relative positional relationship between the flange 135 and the developing sleeve 132, when the developing roller 115 is rotated, vibration occurs and uneven rotation of the developing sleeve 132 occurs, and a toner pattern formed on the photosensitive drum 108 is generated. The image density may cause periodic unevenness due to rotational unevenness of the developing sleeve 132.

As a general method of connecting the flange and the developing sleeve, the first method is “sliding fitting of the flange + caulking of the developing sleeve”, the second method is “sliding fitting of the flange + adhesive”, and third. As the method, “shrink fit” is known, and as the fourth method, “flange press fitting” is known. The coupling between the flange and the developing sleeve requires not only a relative positional relationship but also a coupling strength. Therefore, each coupling method has advantages and disadvantages with respect to the accuracy of the positional relationship and the coupling strength.
In the first method “sliding fitting of flange + crimping of developing sleeve”, the positional relation accuracy is secured by sliding fitting, and the coupling strength is secured by caulking the developing sleeve. Although this method is very advantageous in terms of preventing the flange from coming off, the developing sleeve is deformed after the flange is inserted, so that an increase in assembly man-hours and a large amount of caulking of the developing sleeve are required to ensure secure coupling. As a result, there are cases in which the influence of multiple parts also affects the fluctuation of the developing sleeve alone.
In the second method “sliding fitting and adhesive of flange” and the first method, the positional accuracy is ensured by sliding fitting. The bonding strength is ensured by using an adhesive, and there is no influence such as deformation of the developing sleeve unlike the first method. However, it is difficult to apply the adhesive uniformly, and it is difficult to ensure the same bonding strength throughout the insertion portion. Further, since the adhesive sticks out, it is not very desirable to use it as the developing roller 115 for transporting the developer.
In the “shrink fit” of the third method, the bonding strength is ensured by shrink fitting, that is, with the developing sleeve heated and expanded, by inserting a flange and being sandwiched by the cooled developing sleeve. In this method, since the developing sleeve is in an expanded state when the flange is inserted, it is difficult to ensure the positional relationship accuracy.
In the fourth method, “Flange press-fitting”, the fitting of the flange and the developing sleeve is press-fitted so that the positional accuracy is worse than that of the sliding fitting, but the coupling strength is higher than that of the sliding fitting. Secured. This bond strength is generally inferior to shrink fit. However, as a problem that can be said in common with the first to fourth methods, since the outer diameter processing of the developing sleeve and the inner diameter processing of the end portion are performed over two steps, it is said that there is a limit to increasing the processing accuracy. There is a point that a dedicated tool for machining the inner diameter is required, and the time required for the secondary machining becomes longer.
As described above, there are merits and demerits of securing the positional relationship accuracy and the coupling strength by the coupling method of the flange and the developing sleeve. However, in recent years, there has been a desire for both positional accuracy and coupling strength.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-133180), as a method of fixing the flange to the developing sleeve in manufacturing the developing roller, the flange is fitted to the outer peripheral surface of the developing sleeve, thereby fitting on the inner peripheral surface of the sleeve. In this case, the high-precision machining of the inner peripheral surface of the sleeve is omitted, and the component machining cost is reduced while maintaining the component machining accuracy. However, in the method of Patent Document 1, after the flange is fitted to the developing sleeve, the outer diameter of the flange becomes larger than the outer diameter of the sleeve, and the outer peripheral surface of the developing roller and the outer periphery of the photosensitive drum are larger than the outer diameter difference. It is impossible to reduce the clearance with the surface. This clearance forms the development region 131 referred to in the present application and is called a development gap, and generally needs to be about 0.1 to 1.0 mm as a predetermined range. When the development gap is larger than the predetermined range, the image density is lowered due to insufficient toner supply from the developing roller to the electrostatic latent image on the photosensitive drum. Further, if the thickness of the flange fitted to the outer peripheral surface of the developing sleeve is reduced in order to reduce the clearance (development gap), the rigidity of the developing roller itself is lowered and the deformation becomes easy. Insufficient rigidity of the developing roller itself leads to deterioration of shake accuracy, resulting in uneven density of the image. For this reason, it is difficult to ensure both image density and image density unevenness.

Therefore, in the present embodiment, while ensuring processing accuracy and rigidity, at the same time, by eliminating the restriction on the clearance dimension (development gap) between the developing roller 115 and the photosensitive drum 108, both ensuring image density and reducing image density unevenness are achieved. A developing roller 115 is proposed that enables the above.
FIG. 4 shows a basic configuration of the developing roller 115 according to this embodiment. In FIG. 4, a clearance (development gap) is formed between the outer peripheral surface of the developing roller 115 (the outer peripheral surface 132A of the developing sleeve 132) and the outer peripheral surface 108a of the photosensitive drum 108. The length of this clearance is A. The clearance length between the outer peripheral surface 135a1 as the outer peripheral portion of the large-diameter portion 135a of the flange 135 and the outer peripheral surface 108a of the photosensitive drum 108 is B. When A> B, when the developing roller 115 is brought closer to the photosensitive drum 108, the outer peripheral surface 135a1 of the flange 135 is contacted before the outer peripheral surface 132A of the developing sleeve 132 contacts the outer peripheral surface 108a of the photosensitive drum 108. Is in contact with the outer peripheral surface 108a of the photosensitive drum 108, it is difficult to reduce the clearance A.
Next, the configuration of the flange 135 will be described with reference to FIGS. 5 (a) and 5 (b). The flange 135 according to the present embodiment includes a cylindrical large-diameter portion 135a and a shaft portion 135b disposed on the same axis as this. A driving gear (not shown) is integrally attached to the shaft portion 135b. When a rotational driving force is input to the driving gear, the document roller 115 is rotationally driven. An annular circular groove 135c and a center hole 135d are formed on the inner surface of the large diameter portion 135a by machining so as to be on the same axis as the large diameter portion 135a and the shaft portion 135b. Of these, the flange press-fit portion 135e that is press-fitted into the developing sleeve 135 is formed as the outer peripheral side surface of the circular groove 135c. The center hole 135d is for mounting and holding a bearing 137 for rotatably supporting the shaft 134 described above. In this embodiment, the bearing 137 is press-fitted and attached to the center hole 135d.

  Here, as an example of the processing of the flange 135, there is a method of cutting off the base after cutting out the entire outer shape with one side of a metal round bar as a material chucked (held) by a machine tool such as a lathe. It is done. Since this method is a one-chuck processing, it is possible to perform processing while maintaining the deflection accuracy of the circular groove 135c having the large-diameter portion 135a, the shaft portion 135b, the center hole 135d, and the press-fit portion 135e.

Next, the configuration of the developing sleeve 132 will be described with reference to FIG. The developing sleeve 132 is a bent portion formed at an end portion 132b, 132f positioned in the axial direction, a body portion 132a having the same diameter at a portion between the end portions 132b, 132f, and an end portion 132b on one side. And a shape portion 132d. In the present embodiment, the end portion 132f is formed to have the same diameter as that of the body portion 132a, and the outer surface 132c of the end portion 132b is formed to have a smaller diameter than the body portion 132a. The bending angle θ is basically a right angle when the bending angle of the bent shape portion 132d that is a diameter changing portion from the body portion 132a to the end portion 132b is θ. In the present embodiment, the bending angle θ is an angle between the outer peripheral surface 132c of the end portion 132b and the end surface 132e of the end portion 132b that is continuous with the outer peripheral surface 132c and the body portion 132a and is orthogonal to the axis.
In this embodiment, the bent portion 132d is formed only at one end 132b of the developing sleeve 132, but the bent portion 132d is also formed on the end 132f side, and the developing sleeve 132 has both ends thereof. It is good also as a structure which has a curved shape part 132d.

Next, an embodiment of a method for manufacturing the developing roller 115 will be described.
In this manufacturing method, the bent end portion 132d is formed by forming the end portion 132b on one side located in the axial direction of the developing sleeve 132 into a small diameter portion 132g having an outer diameter smaller than that of the body portion 132a. The end forming step shown, the surface processing step shown in FIG. 15B for processing the surface 132c of at least the small diameter portion 132g formed in the end forming step into a predetermined dimension, and the small diameter portion processed in the surface processing step The mounting process shown in FIG. 15C is performed by press-fitting the flange 135 to 132g.

  In the end forming step shown in FIG. 15A, the metal pipe 190 that is the material of the developing sleeve 132 is drawn by the drawing device 200. The drawing machine 200 includes a chuck member 201 that holds the metal pipe 190 and is movable in the axial direction, and a drawing member 202 that is disposed so as to face the end 190a of the metal pipe 190. While holding at 201, the chuck member 201 is moved in the direction of the arrow, and the end 190a of the metal pipe 190 is pressed against the drawing member 202 to perform drawing, thereby reducing the outer diameter of the end of the metal pipe 190. By this drawing process, a small diameter portion 132g and a bent shape portion 132d are formed at the end portion 190a. Here, drawing is performed on one end 190a of the metal pipe 190, but drawing may also be performed on the other end located on the opposite side of the end 190a. Examples of the material of the metal pipe 190 include stainless steel, aluminum alloy, brass, and resin.

In the surface machining step shown in FIG. 15 (b), the inner surfaces of both ends of the drawn metal pipe 190 are held by holding means 203A and 203B, and finished by cutting by the cutting device 204, and the small diameter portion 132g is formed. The entire surface 190a of the metal pipe 190 is processed into a predetermined dimension and finished.
Further, here, in order to improve the rising of the developer 126 after the end of the cutting process or the grinding process, the surface 190a of the metal pipe 190 is processed such as grooving or roughening to form the developing sleeve 132. In the surface processing step shown in FIG. 15 (b), processing may be finished to a predetermined dimension by polishing processing by a polishing device (not shown) instead of cutting processing by the cutting device 204. In the present embodiment, the developing sleeve is processed so that the deflection accuracy with respect to the rotation center line is in the range of 5 to 10 μm.

In the case of a general developing sleeve, the press-fitting surface with the flange is the inner periphery of the sleeve. Therefore, after finishing the outer peripheral surface, changing the setup and chucking the outer peripheral surface of the sleeve, the inner press-fitting surface In addition to machining, a tool for inner machining is required. For this reason, it takes time to perform the setup change, and the deflection accuracy between the outer peripheral surface and the press-fit portion is lowered.
However, in the developing sleeve 132 according to the present embodiment, since the surface processing step that is the secondary processing can be performed from the outside of the developing sleeve 132, the end portion 132b passes through the body portion 132a without using an inner processing tool. Processing can be performed continuously over the end portion 132f, so that the processing time can be shortened, and a reduction in runout accuracy between the outer peripheral surface and the press-fit portion can be suppressed.

In the mounting process shown in FIG. 15C, the bearing 137 is inserted into the flange center hole 135d as shown in FIG. 7A. After the insertion, as shown in FIG. 7B, the flange press-fit portion 135e and the outer peripheral surface 132c that becomes the press-fit portion of the sleeve end portion 132b are fitted. Subsequently, as shown in FIG. 7C, the front end surface 135f of the flange press-fit portion 135e is abutted to the end surface 132e of the bent shape portion 132d of the developing sleeve 132. At this time, since the flange outer peripheral surface 135a1 does not protrude outside the sleeve body portion 132a, the clearance A (see FIG. 4) between the developing roller 115 and the photosensitive drum 108 can be made sufficiently small.
In this embodiment, as shown in FIGS. 4 and 15C, a flange 136 having a bearing 137 mounted and fixed in the center is press-fitted into the end opening of the developing sleeve 132 on the end 132f side. As the accuracy of the developing roller 115 at the end of the mounting process, the developing sleeve 132 and the flanges 135 and 136 are assembled so that the deflection accuracy with respect to the rotation center line is in the range of 10 to 20 μm.
For this reason, it is not necessary to reduce the thickness of the end portion 132b of the developing sleeve 132, and the lack of rigidity of the developing roller 115 itself is eliminated, so that the deflection accuracy is improved. As a result, a sufficient image density of the developing roller 115 can be secured, and at the same time, image density unevenness due to deterioration of shake accuracy due to deformation can be prevented. Further, since the processing accuracy of the developing sleeve 132 is also good, the developing roller 115 capable of reducing image density unevenness, the developing device 113, the process cartridge 106 (Y, M, C, K), and the image forming apparatus provided with the developing roller 115 101 can be provided.

Next, another embodiment of the method for manufacturing the developing roller 115 will be described.
This manufacturing method is shown in FIG. 16A in which a curved portion 132d is formed by making one end 132b side in the axial direction of the developing sleeve 132 a small diameter portion 132g having an outer diameter smaller than that of the body portion 132a. An end forming step shown in FIG. 16B, a surface processing step shown in FIG. 16B for processing the surface 132c of the small diameter portion 132g formed in at least the end forming step into a predetermined dimension, and a small diameter portion processed in the surface processing step. The mounting process shown in FIG. 16 (c) is performed by press-fitting the flange 135 to 132g.
The difference from the manufacturing method described in FIG. 15 is that the end portion forming step is a casting step, and the entire sleeve including the end portion is formed by casting. The other surface processing steps shown in FIG. 16 (b) and the mounting step shown in FIG. 16 (c) are basically the same as the steps shown in FIGS. 15 (b) and 15 (c). Here, the description will focus on the end forming step as the casting step shown in FIG.
In the end forming step shown in FIG. 16A, a metal material as a material of the developing sleeve 132 is melted in a melting furnace, and the shape of the developing sleeve 132 is previously formed as the space portion 307 from the upper die 301 and the lower die 302. The casting mold 300 is poured from the pouring port 303. In consideration of productivity, it is desirable to form a plurality of developing sleeves into one casting mold 300 and cast it instead of casting one developing sleeve with one casting mold 300. In this case, the space portion 307 having the shape of the developing sleeve is preferably communicated with the runner 304. The metal material used for casting is limited to materials having a relatively low melting point such as aluminum alloy, brass, and resin, and it is difficult to apply stainless steel. In consideration of taking out a casting (hereinafter referred to as “casting sleeve”) 305 from the casting mold 300, it is difficult to provide the bent portions at both ends of the sleeve. Note that the developing sleeve 132 in this embodiment is made of an aluminum alloy and the bent portion 132d is an end portion 132b on one side, and therefore can be molded by casting.
In the surface processing step shown in FIG. 16B, the inner surfaces of both ends of the casting sleeve 305 formed by casting are held by holding means 203A and 203B, and runner marks, burrs, and pouring gate marks are formed by cutting with the cutting device 204. At the same time as cutting, a finishing process is performed in which the entire outer peripheral surface 305a of the casting sleeve 305 including the small diameter portion 132g is processed into a predetermined dimension. Of course, you may finish by grinding instead of cutting. After finishing, in order to improve the rising of the developer 126, the surface 305a of the casting sleeve 305 is subjected to processing such as grooving or roughening to form the developing sleeve 132. In the present embodiment, the developing sleeve is processed so that the deflection accuracy with respect to the rotation center line is in the range of 5 to 10 μm.

In the mounting step shown in FIG. 16C, the bearing 137 is inserted into the flange center hole 135d as shown in FIG. 7A. After the insertion, as shown in FIG. 7 (b), the flange press-fit portion 135e and the outer peripheral surface 132c serving as the press-fit portion of the sleeve end portion 132b are fitted, and as shown in FIG. 7 (c), the flange press-fit portion 135e. The front end surface 135f of the developing sleeve 132 is abutted to the end surface 132e of the bent shape portion 132d of the developing sleeve 132. At this time, since the flange outer peripheral surface 135a does not protrude beyond the sleeve body portion 132a, the clearance A (see FIG. 4) between the developing roller 115 and the photosensitive drum 108 can be made sufficiently small. Further, as shown in FIGS. 4 and 16C, a flange 136 fitted with a bearing 137 is press-fitted into the end portion of the developing sleeve 132 on the end portion 132f side. As the accuracy of the developing roller 115 at the end of the mounting process, the developing sleeve 132 and the flanges 135 and 136 are assembled so that the deflection accuracy with respect to the rotation center is in the range of 10 to 20 μm.
For this reason, it is not necessary to reduce the thickness of the end portion 132b of the developing sleeve 132, and the lack of rigidity of the developing roller 115 itself is eliminated, so that the deflection accuracy is improved. As a result, a sufficient image density of the developing roller 115 can be secured, and at the same time, image density unevenness due to deterioration of shake accuracy due to deformation can be prevented. Further, since the processing accuracy of the developing sleeve 132 is also good, the developing roller 115 capable of reducing image density unevenness, the developing device 113, the process cartridge 106 (Y, M, C, K), and the image forming apparatus provided with the developing roller 115 101 can be provided.

  In the image forming apparatus 101 shown in FIG. 1, each of the process cartridges 106Y, 106M, 106C, and 106K includes a cartridge case 111, a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113. However, the process cartridges 106Y, 106M, 106C, and 106K according to the present embodiment need only include at least the developing device 113, and do not necessarily include the cartridge case 111, the charging roller 109, the photosensitive drum 108, and the cleaning blade 112. May be. In the above-described embodiment, the image forming apparatus 101 has been described as the process cartridges 106Y, 106M, 106C, and 106K that are detachable from the apparatus main body 102. However, the image forming apparatus 101 according to the present embodiment only needs to include the developing device 113 and may not necessarily include the process cartridges 106Y, 106M, 106C, and 106K.

  Next, the inventors of the present invention created the developing roller 115 shown in the following Examples 1 to 4 using the developing sleeve 132 and the flanges 135 and 136 molded by the above-described manufacturing method. Since the conventional method of press-fitting the flange 136 into the end portion 132f of the developing sleeve 132 is adopted as in the prior art, the relationship between the developing sleeve 132 and the flange 135 will be mainly described here.

  In Example 1 shown in FIGS. 8A, 8B, and 8C, the flange 135 is made of stainless steel, and the developing sleeve 132 is made of an aluminum alloy. As shown in FIG. 8 (a), the flange 135 has a configuration in which the outer diameter C of the flange large-diameter portion 135a is 26 mm in diameter, the outer diameter D of the flange press-in portion 135e is 24 mm (tolerance ± 0.01 mm), and the flange press-in portion. The length E in the axial direction of 135e was 6 mm. The developing sleeve 132 is configured such that the outer diameter G of the body portion 132a is 25 mm in diameter, and the outer diameter F of the sleeve press-fitting portion (the outer peripheral surface of the end portion 132b) 132c is 24 mm in diameter (tolerance +0.05 to +0.03 mm). The developing roller 115 was assembled by setting the length H of the sleeve press-fitting portion 132c in the axial direction to 7 mm, the thickness I of the barrel portion 132a, and the thickness J of the sleeve end portion 132b to the same thickness of 0.75 mm.

Next, using the image forming apparatus of a commercially available printer IPSIO SP C320 (manufactured by Ricoh Co., Ltd.), the developing roller 115 of Example 1 is mounted on the image forming apparatus, and the photosensitive drum 108 is charged to −820 V and developed. A bias voltage of −350 V was applied, and a cyan single-component polymerized toner (average particle diameter of 6 μm) was used to output an A4 vertical size whole surface solid image, and the image density (ID) and image density unevenness were evaluated. The image density was measured by “X-Lite” manufactured by AMTEC, and the image density unevenness was evaluated by visual recognition of an evaluator. Evaluation criteria are shown below. ○ is an allowable range, and x is outside the allowable range.
○: Image density is sufficient (ID 1.3 or more) and image density unevenness is not visually recognized. ×: Image density is insufficient (less than ID 1.3) or image density unevenness is visually recognized.
In Example 1, a good (◯) image having an image density of ID1.35 and no density unevenness was obtained. Further, as shown in FIG. 9, the deflection accuracy with respect to the rotation center line was 10 μm or less, the torque resistance was 4 Nm or more, and the clearance A between the developing roller 115 and the photosensitive drum 108 was 0.5 mm. And in the manufacture under these conditions, the yield rate and the non-defective rate of torque resistance were both 100%.

In the second embodiment shown in FIG. 10, the outer diameter C of the flange large-diameter portion 135a is 24 mm in diameter, the outer diameter D of the flange press-fit portion 135c is 22 mm (tolerance ± 0.01 mm), and the outer diameter F of the sleeve press-fit portion 132c is the diameter. The developing roller 115 was assembled in the same manner as in Example 1 except for 22 mm (tolerance +0.05 to +0.03), and image density (ID) and image density unevenness were evaluated under the same conditions as in Example 1. .
In Example 2, a good (◯) image with an image density of ID 1.40 and no visible image density unevenness was obtained. The deflection accuracy with respect to the rotation center line was 10 μm or less, the torque resistance was 4 Nm or more, and the clearance A between the developing roller 115 and the photosensitive drum 108 was 0.5 mm. And in the manufacture under these conditions, the yield rate and the non-defective rate of torque resistance were both 100%.

In Example 3 shown in FIG. 11, the thickness I of the body 132a of the developing sleeve 132 is set to 0.75 mm, and the thickness J of the sleeve end 132b is set to 1.5 mm. The developing roller 115 was assembled in the same manner as in Example 2, and image density (ID) and image density unevenness were evaluated under the same conditions as in Example 2.
In Example 3, a good (◯) image having an image density of ID 1.45 and no visible image density unevenness was obtained. The deflection accuracy with respect to the rotation center line was 10 μm or less, the torque resistance was 5 Nm or more, and the clearance A between the developing roller 115 and the photosensitive drum 108 was 0.5 mm. And in the manufacture under these conditions, the yield rate and the non-defective rate of torque resistance were both 100%.

In Example 4 shown in FIG. 12, the length E in the axial direction of the flange press-fit portion 135c is set to 7.5 mm, and other conditions are assembled in the same manner as in Example 3 and the developing roller 115 is assembled. The image density (ID) and the image density unevenness were evaluated under the following conditions.
In Example 4, the image density was 1.50 or more, and a good (◯) image in which density unevenness was not visually recognized was obtained. Further, even when continuously used, the developer 126 did not collect in the press-fitting portions of the flange 135 and the developing sleeve 132. The deflection accuracy with respect to the rotation center line was 10 μm or less, the torque resistance was 5 Nm or more, and the clearance A between the developing roller 115 and the photosensitive drum 108 was 0.5 mm. In the production under these conditions, both the accuracy of runout and the non-defective product of torque resistance were 100%.

[Comparative Example 1]
13 (a), 13 (b), and 13 (c) show Comparative Example 1. FIG. In Comparative Example 1, the developing roller 115 ′ is manufactured by press-fitting the flange 135 ′ shown in FIG. 13A inside the end 132b ′ of the well-known developing sleeve 132 ′ shown in FIG. 13B. It is. The material of the flange 135 ′ was stainless steel, and the material of the developing sleeve 132 ′ was aluminum alloy. In the flange 135 ′, the outer diameter C ′ of the outer peripheral surface 135a1 ′ of the flange large diameter portion 135a ′ is 23.5 mm (tolerance +0.05 to +0.03 mm). The developing sleeve 132 ′ has an inner diameter F ′ of the sleeve press-fit portion 132c ′ of 23.5 mm (tolerance ± 0.01 mm), a length E ′ of the flange press-fit portion 132c ′ in the axial direction of 6 mm, and a barrel portion 132a ′. The outer diameter G ′ is 25 mm in diameter, the length H ′ in the axial direction of the sleeve press-fit portion 132c ′ is 7 mm, the wall thickness I ′ of the barrel portion 132a ′ is 0.75 mm, and the wall thickness J ′ of the sleeve press-fit portion 132c ′ is It was 0.65 mm.

The developing roller 115 ′ was assembled using the developing sleeve 132 ′ and the flange 135 ′ having such a configuration, and image density (ID) and image density unevenness were evaluated under the same conditions as in Example 1.
In Comparative Example 1, the image density ID is 1.33 and the torque resistance is 3.5 Nm, which satisfies the standard. However, the deflection accuracy of the sleeve press-fit portion 132c ′ and the sleeve body portion 132a ′ is poor, and the rotation center line of the assembled developing roller 115 ′ In some cases, the deflection accuracy was poor (20 μm or more). In this developing roller 115 ′, the occurrence of an abnormal image having unevenness in image density in the circumferential direction was killed and became defective (×).
The non-defective product rate of runout accuracy with respect to the rotation center line of the developing roller 115 ′ obtained under the conditions of Comparative Example 1 was 96%, and the non-torque resistant product rate was 98%.

[Comparative Example 2]
14 (a), 4 (b), and 14 (c) show Comparative Example 2. FIG. In Comparative Example 2, the developing roller 115 "of Patent Document 1 was manufactured. The flange 135 was made of stainless steel, and the developing sleeve 132" was made of an aluminum alloy. The flange 135 has an outer diameter C of the flange large-diameter portion 135a of 27 mm, an inner diameter D of the flange press-fit portion 135e of 25 mm (tolerance ± 0.01 mm), and a length E in the axial direction of the flange press-fit portion 135e of 6 mm. . The developing sleeve 132 ″ has an outer diameter G ″ of the barrel portion 132a ″ of 25 mm (tolerance +0.05 to +0.03 mm) and a wall thickness I ″ of the barrel portion 132a ″ of 0.75 mm.
The developing roller 115 ″ was assembled using the developing sleeve 132 ″ and the flange 135 having such a configuration, and image density (ID) and image density unevenness were evaluated under the same conditions as in Example 1.
In Comparative Example 2, although the torque resistance is 1.33 Nm and the image density unevenness satisfies the standard, the clearance A ″ between the developing roller 115 ″ and the photosensitive drum 108 shown in FIG. Was lowered to ID 1.10, and a product satisfying the standard could not be obtained.

[Comparative Example 3]
In Comparative Example 3, among the conditions of the developing roller 115 ″ of Comparative Example 2, only the outer diameter C of the flange large diameter portion 135a is changed to a diameter of 26 mm, and the developing roller 115 ″ is assembled. Image density (ID) discharge density unevenness was evaluated.
In Comparative Example 3, the clearance A ″ between the developing roller 115 ″ and the photosensitive drum 108 is 0.5 mm, the image density is ID1.33 and the standard is satisfied, but the torque resistance is not 2Nm, and the flange 135 and the development are not satisfied. The press-fitting portion of the sleeve 132 ″ was immediately deformed, the deflection accuracy with respect to the rotation center line of the developing roller 115 ″ deteriorated to 20 μm or more, and image density unevenness occurred.
The results of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

Comparative Example 1: Developing roller having a flange press-fitted inside a well-known sleeve Comparative Example 2: Part 1 described in JP-A-2007-133180
Comparative Example 3: Part 2 described in JP2007-133180A

  According to each of the above embodiments and examples, the outer diameter of the end portion 132b of the developing sleeve 132 on one side of the end portions 132b and 132f is smaller than that of the body portion 132a positioned between the end portions. Since the bent portion 132d is provided, after the flange 135 is press-fitted into the end portion 132b, the length of the flange outer peripheral surface 131a1 protruding outside the body portion 132a is reduced, and the clearance dimension between the developing roller 115 and the photosensitive drum 108 is reduced. The limit of A can be reduced. Further, unlike the conventional developing roller that press-fits inside the developing sleeve, the finishing process of the developing sleeve 132 is a one-chuck having only the outer diameter, so that the sleeve body and the press-fitting portion can be processed with high accuracy. Therefore, it is possible to suppress image density unevenness and density deficiency caused by rotation unevenness in the press-fitting of the developing sleeve 132 and the flange 135.

  Since the outer diameter G of the barrel 132 of the developing sleeve 132 is larger than the outer diameter C of the outer circumferential surface 135a1 of the flange 132, after the flange 132 is press-fitted into the end 132b of the developing sleeve 132, the outer circumferential surface 135a1 Since it is smaller than 132a, there is no restriction on the clearance dimension A between the developing roller 115 and the photosensitive drum 108, and image density unevenness and density deficiency caused by rotational unevenness in press-fitting of the developing sleeve 132 and the flange 135 are further suppressed. be able to.

  When the thickness J of the end portion 132b of the developing sleeve 132 having the bent portion 132d is thicker than the thickness I of the body portion 132a, even when the flange 135 and the end portion 132b of the developing sleeve 132 are press-fitted, even if the same press-fitting is performed. Since the wall thickness is increased, it is possible to increase the rigidity of the developing roller 115 after press-fitting the flange 135 and the end portion 132b of the developing sleeve 132. Further, since it is not necessary to increase the thickness of the entire developing sleeve 132, it is possible to avoid a decrease in magnetic force due to an increase in the thickness of the body portion 132a. For this reason, it is possible to further suppress image density unevenness and density deficiency resulting from rotation unevenness in the press-fit coupling of the developing sleeve 132 and the flange 135.

  The flange 135 has a press-fit portion 135c that is press-fitted into the end portion 132b of the developing sleeve 132. When the front end surface 135f of the press-fit portion 135c press-fits the flange 135 into the end portion 132b of the developing sleeve 132, the bent portion 132d. When the dimensions (lengths E and H) are set so as to abut against the end surface 132e, the flange 135 in which the gap between the front end surface 135f and the end surface 132e disappears press-fits with the end portion 132b of the developing sleeve 132. For this reason, the developer does not collect in this gap, and it is possible to prevent image density unevenness caused by the accumulated developer being ejected by the centrifugal force caused by the rotation of the developing sleeve 132. It is possible to further suppress image density unevenness and density deficiency caused by rotation unevenness in the press-fit coupling of 135.

  The developing device 113, the process cartridge 106 (Y, M, C, K), and the image forming apparatus 101 described in the above embodiment have no rotation unevenness, and are excellent in reducing the restriction of the clearance dimension A of the photosensitive drum 108. Since the developing roller 115 capable of setting a clear clearance dimension A is provided, it is possible to suppress image density unevenness and density deficiency resulting from rotational unevenness after the press-fit coupling of the developing sleeve 132 and the flange 135.

In the above-described embodiments and examples, the rotating member included in the image forming apparatus is exemplified by the developing roller 115 provided in the developing device 113, and is photosensitive as an opposing member that forms a clear rank facing the developing roller 115. Although the body drum 108 is illustrated, the application range of the present invention is not limited to the developing roller 115.
The scope of application of the present invention is to prevent unevenness in density and insufficient density of an image due to rotational shake without causing deterioration in shake accuracy during rotation after the press-fitting of the cylindrical member and the flange member. The present invention can be applied to a rotating body installed in a place that requires an appropriate clearance between them. Or it can apply to the rotary body installed in the location which requires an appropriate clearance only with the member which only opposes.
That is, another aspect of the present invention is a rotating body having a cylindrical member and a flange member attached to an end portion positioned in the axial direction of the cylindrical member, and positioned in the axial direction of the cylindrical member. It suffices that at least one side of the end portion to be bent has a bent portion whose outer diameter is smaller than that of the body portion positioned between the end portions.
The outer diameter of the barrel portion of the tubular member may be larger than the outer diameter of the outer peripheral portion of the flange member, and the thickness of the end portion of the tubular member having the bent shape portion may be set to the thickness of the barrel portion. It may be thicker than the thickness.
Or when the flange member press-fits the flange member into the end of the tubular member, the front end surface of the press-fitting portion of the flange may abut against the bent portion.
In response to this, it is possible to provide a rotating body capable of setting a favorable clearance dimension by reducing the limitation on the clearance dimension between the facing member and the rotating body. It is also possible to suppress image density unevenness and density deficiency resulting from rotation unevenness after the press-fitting of the cylindrical member and the flange member. Further, if the thickness of the end of the tubular member having the bent shape portion is thicker than the thickness of the barrel portion of the tubular member, even when the flange member and the end of the tubular member are press-fitted, the same press-fit is possible. Since the thickness is increased, it is possible to increase the rigidity of the rotating body after press-fitting between the flange member and the end of the cylindrical member.

DESCRIPTION OF SYMBOLS 101 Image forming apparatus 102 Main body 103 Paper feed unit 104 Transfer unit 105 Fixing unit 106Y Process cartridge (yellow)
106M Process Cardridge (Magenta)
106C Process Cardridge (Cyan)
106K process card ridge (black)
107 Recording paper 108 Photosensitive drum (image carrier, counter member)
109 Charging roller 110 Registration roller pair 111 Cartridge case 112 Cleaning blade 113 Developing device 114 Developer supply unit 115 Developing roller (developer carrier)
116 Doctor blade 117 Storage tank 118 Stirring screw 119 Partition wall 120 First space 121 Second space 122Y Laser writing unit (yellow)
122M Laser writing unit (magenta)
122C Laser writing unit (cyan)
122K laser writing unit (black)
123 Feeding cassette 124 Feeding roller 125 Case 126 Developer 127 Driving roller 128 Driven roller 129 Conveying belt 130Y Transfer roller (yellow)
130M transfer roller (magenta)
130C transfer roller (cyan)
130K transfer roller (black)
131 Development area 132 Development sleeve (cylindrical member, rotating body)
132a body part 132b, 132f end part 132c outer peripheral surface (press-fit surface)
132d Bent part 133 Magnet roller 133a Peripheral surface of magnet roller 134 Shaft 135 Flange member 135a Flange large diameter part 135a1 Flange member outer peripheral part 135b Flange shaft part 135c Flange circular groove 135d Flange center hole 135e Flange press-fitting part 135f Tip face 136 Flange 137 Bearing θ Bend angle A Clearance between developing roller and photoconductor drum B Clearance between flange and photoconductor drum C Outer diameter of outer peripheral surface of flange D Inner diameter of flange press-fit portion E Length of press-fit portion of flange F Outer diameter of sleeve press-fit portion G Sleeve body Outside diameter H Length of sleeve press-fit part I Thickness of sleeve body J Thickness of sleeve end

JP 2007-133180 A JP-A-6-280855

Claims (12)

A cylindrical member made of a non-magnetic material rotatably arranged;
Having a flange member press-fitted into an end located in the axial direction of the tubular member;
A developer carrier, comprising: a bent portion having an outer diameter smaller than that of a body portion positioned between the end portions on at least one side of end portions positioned in the axial direction of the cylindrical member.   The developer carrying member according to claim 1, wherein an outer diameter of a body portion of the cylindrical member is larger than an outer diameter of an outer peripheral portion of the flange member.   3. The developer carrying member according to claim 1, wherein a thickness of an end portion of the cylindrical member having the bent shape portion is thicker than a thickness of the barrel portion.   The flange member has a press-fit portion that is press-fitted into an end portion of the tubular member, and the bent surface portion of the press-fit portion is pressed when the flange member is press-fitted into the end portion of the tubular member. The developer carrying member according to claim 1, wherein the developer carrying member is abutted against the developer carrying member. It has a magnet roller that does not rotate,
5. The developer carrying member according to claim 1, wherein the cylindrical member is made of a non-magnetic material and is disposed so as to cover an outer peripheral surface of the magnet roller. In a developing device comprising a developer carrier having a cylindrical member that adsorbs developer on the outer surface,
A developing device comprising the developer carrying member according to any one of claims 1 to 5 as the developer carrying member. In a process cartridge having at least a developing device,
A process cartridge comprising the developing device according to claim 6 as the developing device. In an image forming apparatus having at least an image carrier, a charging device, and a developing device,
An image forming apparatus comprising the developing device according to claim 6 as the developing device. A method of manufacturing a developer carrier having a cylindrical member made of a nonmagnetic material rotatably arranged and a flange member press-fitted into an end portion of the cylindrical member positioned in the axial direction,
An end portion forming step for forming a bent portion by forming at least one side of the end portion positioned in the axial direction of the cylindrical member into a small diameter portion having an outer diameter smaller than that of the body portion positioned between the end portions;
A surface processing step of processing at least the surface of the small diameter portion formed in the end portion forming step into a predetermined dimension;
A method for manufacturing a developer carrying member, comprising: a mounting step of press-fitting and mounting the flange member on a small diameter portion processed in the surface processing step.   The method for manufacturing a developer carrying member according to claim 9, wherein the end portion forming step is a step of drawing an end portion of the cylindrical member with a drawing apparatus.   The method for manufacturing a developer carrying member according to claim 9, wherein the end forming step is a step of forming the end of the cylindrical member by casting.   The developer carrying member according to claim 9, wherein the surface processing step is a step of cutting or grinding the surface of the small diameter portion formed in the end portion forming step to a predetermined dimension. Manufacturing method.

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