JP2007072207A - Bearing member for image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing member for an image forming device which has enhanced the acccuracy of the rotation of an axis that is to be supported, and restrain the generation of abnormal sounds. <P>SOLUTION: A resin part 4 of the bearing member 2 is injection-molded with an electroformed part 3 formed by electroforming as an insert part, and the bearing surface is composed in such a manner that an axis 34a of a pickup roller 34 is supported rotatably by the inner peripheral surface 3a of the electroformed part 3. In the same way, a resin part 14 of the bearing member 12 is injection-molded with an electroformed part 13, formed by electroforming being an insert part, and the bearing surface is constituted, in such a manner that the axis 35a of a separation roller 35 is supported rotatably by the inner peripheral surface 13a of the electroformed part 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides, for example, a roll-shaped rotating body equipped in an image forming apparatus such as a copying machine (digital PPC, color PPC, etc.), a printer (color LBP, color LED, ink jet printer, etc.), a facsimile, or a composite machine thereof. The present invention relates to a bearing member to be supported.

  The image forming apparatus includes, for example, a photosensitive drum that forms an electrostatic latent image on an outer peripheral surface thereof by exposure, and a developing device roller that develops the electrostatic latent image by attaching a developer to the photosensitive drum by an electric action. (Development roller), a transfer roller for transferring the developed image to the sheet, a fixing roller for fixing the transferred image to the output paper, and the like, and picking up a sheet stored in a sheet storage unit such as a paper feed cassette A large number of roll-shaped rotating bodies such as a pick-up roller that performs pick-up and a registration roller that supplies a picked-up sheet between both members in synchronization with the rotation of the photosensitive drum or transfer roller are provided.

These roll-shaped rotators are rotatably supported by bearing members mounted on the image forming apparatus main body side (fixed side), and are connected to other drive shafts via power transmission means (gears, etc.) In many cases, the drive shaft is configured to rotate with the drive rotation of the drive shaft (see, for example, Patent Document 1). At this time, for example, a sliding bearing is known as a bearing to be used (see, for example, Patent Document 2).
JP-A-8-123194 Japanese Unexamined Patent Publication No. 7-125860

  Incidentally, in recent years, there has been an increasing demand for noise reduction of the image forming apparatus reflecting the improvement of the use environment and the user satisfaction. In response to this request, each component of the image forming apparatus, for example, a bearing that supports a roll-shaped rotating body involved in the sheet feeding and discharging process, is required to have high rotational accuracy from the viewpoint of suppressing vibration during use. The

  However, in conventional bearings (for example, sliding bearings), it is difficult to improve the rotational accuracy more than ever since it is difficult to perform high-precision machining of the inner peripheral surface serving as a bearing surface. Also, considering the current bearing surface accuracy, a large bearing gap must be taken at the design stage. In this case, when the roll-shaped rotator rotates, the rotation shaft of the roll-shaped rotator generates shaft runout with the bearing member, and the distance between the shaft and the drive shaft is not constant. For this reason, for example, the meshing of the gears connecting the two shafts may be deteriorated, and an abnormal noise such as a gear squeal may be generated.

  In addition, the roll-shaped rotating body involved in the sheet feeding / discharging process often conveys plain paper or thick paper in contact, and in this case, generation of paper dust or the like cannot be avoided. Therefore, depending on the size of the bearing gap, paper dust may enter the bearing gap and cause wear on the bearing surface. This type of wear is not preferable because it may cause a decrease in rotational accuracy.

  An object of the present invention is to provide a bearing member for an image forming apparatus in which the rotation accuracy of a shaft to be supported is increased and generation of abnormal noise is suppressed.

  In order to solve the above problems, the present invention provides a sheet feeding process for supplying a sheet picked up from a sheet storage unit to an image forming unit, or discharging a sheet for discharging a sheet having an image formed on the surface by the image forming unit. Supporting a roll-shaped rotating body involved in a paper process, characterized in that a bearing surface for supporting the roll-shaped rotating body is formed on the inner peripheral surface of an electroformed part formed by electroforming. Provided is a bearing member for an image forming apparatus.

  As described above, the present invention is characterized in that the bearing surface of the bearing member for supporting the roll-shaped rotating body is constituted by the inner peripheral surface of the electroformed part formed by electroforming. . Here, electroforming is a technology for forming metal layers by electrodeposition (electrolytic deposition) of metal ions on the master surface. Due to the characteristics of electroforming, the surface shape of the master is extremely on the inner surface of the electroformed part. Is transferred to a very fine level with high accuracy. Therefore, if the surface accuracy of the master is increased and the inner peripheral surface of the electroformed part is used as a bearing surface, a bearing surface having high surface accuracy can be obtained at low cost without performing special post-processing, Thereby, high rotation accuracy can be obtained between the roll-shaped rotating bodies to be supported. Therefore, vibration can be reduced between the roll-shaped rotating body and the bearing member that supports the rotating body, and generation of abnormal noise can be suppressed. In addition, when the rotating shaft of the roll-shaped rotating body is connected to the drive shaft via a gear, the distance between the shaft and the drive shaft is kept constant, and a good gear meshing state is established between the two shafts. As a result, such gear noise is reduced.

  In addition, according to the above configuration, since the inner diameter dimension of the bearing member (bearing surface) can be set in advance so that the gap (bearing gap) between the outer periphery of the roll-shaped rotating body is small, It is possible to avoid as much as possible that the paper dust generated due to the sliding friction enters the bearing gap. Accordingly, it is possible to suppress the wear of the bearing surface due to the mixing of paper dust and to smoothly perform the paper supply / discharge by the roll-shaped rotating body over a long period of time.

  The diameter gap between the bearing surface constituted by the inner peripheral surface of the electroformed part and the outer peripheral surface of the roll-shaped rotating body facing this is preferably 5 μm or less, and more preferably 2 μm or less. With the electroforming according to the present invention, the inner peripheral surface of the electroformed part serving as the bearing surface can be finished with high accuracy, so that high rotational accuracy can be obtained even when the diameter gap is 5 μm or less. . Further, if the diameter gap (bearing gap) is within the above range, it is possible to reliably prevent paper dust and the like generated by sliding friction between the sheet and the roll-shaped rotating body from entering the diameter gap.

  The bearing member configured as described above can be used as a bearing for a roller related to a sheet feeding / discharging process, and when the roll-shaped rotating body is, for example, a pickup roller that picks up a sheet from a sheet storage portion, the bearing for the pickup roller It can be suitably used as a member.

  In addition, when the roll-shaped rotating body is a registration roller for positioning an image formed on a sheet by an image forming unit, for example, the bearing member is preferably used as a bearing member for the registration roller. be able to.

  The bearing member for an image forming apparatus described above can be suitably used as a bearing unit for an image forming apparatus including the bearing member and a roll-shaped rotating body.

  As described above, according to the present invention, it is possible to provide a bearing member for an image forming apparatus in which the rotation accuracy of the shaft to be supported is increased and the generation of abnormal noise is suppressed.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram conceptually showing an image forming process and a sheet feeding / discharging process of an image forming apparatus according to an embodiment of the present invention. In the figure, reference numeral 20 denotes a laser exposure type quadruple tandem image forming unit, which is used by being incorporated in an image forming apparatus such as a laser printer. The image forming unit 20 includes a plurality (four) of photosensitive drums 21, a plurality of developing devices 22 arranged around each photosensitive drum 21, a transfer electrode 23 arranged downstream of the developing device 22, And a fixing unit 24. In the figure, reference numeral 25 denotes a paper feed unit that supplies the sheet 26 to the image forming unit 20, and 27 denotes a paper discharge unit that discharges the sheet 26 on which the image is formed on the surface by the image forming unit 20 to the outside of the apparatus. .

  First, the image forming unit 20 will be described in detail. The four photosensitive drums 21 are arranged in parallel along the longitudinal direction of the transfer belt 29 supported by a plurality of support rollers 28. Around each photosensitive drum 21, a charging electrode 30 for charging the outer peripheral surface of the photosensitive drum 21 is provided. On the downstream side in the rotation direction of the charging electrode 30, a plurality of single color signals obtained by color separation of input image information. An exposure device 31 for forming an electrostatic latent image by exposing each photosensitive drum 21 with a laser beam for each color is provided. Further, on the downstream side in the rotation direction of the exposure device 31, a developing roller 32 that performs development with the developer (toner) of each color described above, and a developing device 22 that includes the developing roller 32 are disposed, and on the downstream side, a transfer electrode. 23 is arranged. Of course, instead of the transfer electrode 23, for example, although not shown, a transfer roller provided with a voltage applying means may be used.

  When an electronic image is input by an image input unit (not shown), the outer peripheral surface of the photosensitive drum 21 rotating in the direction of the arrow is charged to a constant voltage by the charging electrode 30. Next, each photosensitive drum 21 is irradiated with laser light of each color {yellow (Y), magenta (M), cyan (C), black (BK)} obtained by color separation of the input image from the exposure device 31, and electrostatic for each color. A latent image is formed on the surface of the photosensitive drum 21. Each color image having a charge of opposite polarity is attached to the electrostatic latent image by the developing roller 32 of the developing device 22 to form each visible image (developed image) on the photosensitive drum 21.

  Next, the paper feeding unit 25 will be described in detail. The sheet feeding unit 25 includes a sheet storage unit 33, a pickup roller 34 positioned on the upper end side of the sheet storage unit 33, a pair of separation rollers 35 and 35 disposed on the downstream side of the pickup roller 34, a conveyance roller 36, 36, and registration rollers 37 and 37.

  One or a plurality of sheets 26 sent out from the sheet storage portion 33 by the pickup roller 34 are separated into one sheet by separation rollers 35 and 35. The separated sheet 26 is conveyed in the conveyance paths 38a and 38b by the conveyance rollers 36 and 36, and is guided to the registration rollers 37 and 37 located on the downstream side. Then, after adjusting the posture by abutting the leading end of the sheet 26 against the sandwiched portion (also referred to as a two-ply portion) of the resist rollers 37 and 37 in the stopped state, the resist roller is aligned with the photosensitive drum 21 and the transfer belt 29 in timing. By rotating the rollers 37, the sheet 26 is sent out in a state of being electrostatically attracted onto the transfer belt 29, and is conveyed in the direction of the arrow in the figure.

  The sheet 26 adsorbed on the transfer belt 29 is sequentially conveyed to a position (transfer portion) between each photosensitive drum 21 and the transfer electrode 23 by the movement of the transfer belt 29, and the visible image on the photosensitive drum 21 is transferred. It is transferred onto the sheet 26 by the load of the reverse polarity voltage of the electrode 23. Thereafter, the sheet 26 released from the electrostatic adsorption state with the transfer belt 29 by a separation electrode (not shown) is conveyed to the fixing unit 24, and the toner image is fixed on the sheet surface by heating and pressing by the fixing roller 39 and the pressure roller 40. To do. As a result, a color electrophotographic image in which the visible images of four colors of yellow, magenta, cyan, and black are superimposed on the sheet 26 is obtained. Thereafter, the sheet 26 is conveyed to a paper discharge unit 27 located on the downstream side of the fixing unit 24 and is discharged to the outside of the image forming apparatus by paper discharge rollers 41 and 41 provided in the paper discharge unit 27.

  Hereinafter, a bearing mechanism when the bearing member (for an image forming apparatus) according to the present invention is used to support the rotation of the pickup roller 34 provided in the paper feeding unit 25 will be described.

  FIG. 2 is a partial cross-sectional view schematically showing a drive mechanism related to the pickup roller 34 and one (upper side in FIG. 1) separation roller 35. In the drawing, a shaft 34 a of a pickup roller 34 has a roll portion 34 b at the center in the axial direction, and both ends in the axial direction are inserted into the inner circumferences of the bearing members 2 and 2. Similarly, the shaft 35 a of one separation roller 35 has a roll portion 35 b at the center in the axial direction, and both ends in the axial direction are inserted into the inner circumferences of the bearing members 12 and 12. The bearing members 2 and 12 on one end side (upper side) are both fixed to the first fixed side member 42, and the two bearing members 2 and 12 on the other end side (lower side) are both connected to the second fixed side member 43. Fixed.

  Gears 44a and 44b are mounted on both ends of the shaft 34a of the pickup roller 34, respectively. The gear 44a on one end side (upper side in FIG. 2) meshes with the gear 46 of the drive shaft 45 disposed in parallel with the shaft 34a, and the gear 44b on the other end side is similarly connected to the other end side of the shaft 35a ( It meshes with a gear 47 mounted on the lower side in FIG. Then, by rotating the drive shaft 45 by driving a drive source (such as a motor) (not shown), the rotational force from the drive shaft 45 is transmitted to the shaft 34a via the gears 46 and 44a. The bearing members 2 and 2 are rotatably supported. Further, the rotational force is transmitted to the shaft 35a of one separation roller 35 through the gear 44b attached to the other end side of the shaft 34a and the gear 47 meshing with the gear 44b. 12 is rotatably supported. In this case, the bearing unit 1 is composed of the bearing member 2 and the pickup roller 34 having the shaft 34 a that is rotatably supported by the bearing member 2. Further, the bearing unit 11 is configured by the bearing member 12 and the separation roller 35 having a shaft 35 a rotatably supported by the bearing member 12.

  As shown in FIG. 2, the bearing member 2 includes an electroformed part 3 and a resin part 4 obtained by molding the electroformed part 3 as an insert part, and is manufactured through the following steps, for example. In addition, although the manufacturing process of the bearing member 2 is described below, the bearing member 12 can be manufactured through the same process.

  The bearing member 2 includes a step of masking the outer surface of the master shaft 5 used in electroforming with an insulating material, a step of electroforming the masked master shaft 5 to form the electroformed portion 3, The cast member 3 and the master shaft 5 are used as insert parts, and the bearing member 2 is formed through a process of molding (insert molding) and a process of separating the electroformed part 3 and the master shaft 5 in this order.

  The master shaft 5 serving as a molding base of the electroformed portion 3 is formed of, for example, stainless steel in a perfect cross-sectional outline and a uniform diameter in the axial direction. The material of the master shaft 5 can be arbitrarily selected from metals and non-metals as long as it has a masking property, conductivity, and chemical resistance, such as a chromium alloy or a nickel alloy, in addition to stainless steel. It is.

  The master shaft 5 may be a solid shaft in which a hollow shaft or a hollow portion is filled with resin in addition to the peeled shaft (solid shaft). Further, the accuracy of the outer peripheral surface of the master shaft 5 directly affects the surface accuracy of the inner peripheral surface 3a of the electroformed part 3 serving as a bearing surface, so it is desirable that the master shaft 5 be finished as high as possible.

  As shown in FIG. 3, masking is performed on the outer surface of the master shaft 5 except for the region where the electroformed part 3 is to be formed. As the covering material for forming the masking portion 6, a material having insulating properties and corrosion resistance against the electrolyte solution is selectively used.

  In the electroforming process, the master shaft 5 is immersed in an electrolyte solution containing metal ions such as Ni and Cu, and the target metal is removed from the outer surface of the master shaft 5 except for the masking portion 6 by energizing the electrolyte solution. This is performed by electrolytic deposition on the exposed area of the outer peripheral surface 5a. The electrolyte solution may contain a sliding material such as PTFE or carbon, or a stress relaxation material such as saccharin, if necessary. In this embodiment, PTFE particles are used as a sliding material that is contained in an electrolyte solution. The kind of the deposited metal is appropriately selected according to required characteristics such as hardness required for the bearing surface of the bearing or resistance to lubricating oil (oil resistance).

  Through the above steps, as shown in FIG. 4, an electroformed shaft 7 in which a thin cylindrical electroformed portion 3 is formed in a region other than the masking portion 6 on the outer periphery of the master shaft 5 is manufactured. In this case, the above-mentioned PTFE particles are dispersed in the electroformed part 3 formed by precipitation, and a part thereof is present on the inner peripheral surface 3a serving as a bearing surface. If the thickness of the electroformed part 3 is too thin, it leads to a decrease in the durability of the bearing surface (inner peripheral surface 3a), and if it is too thick, the peelability from the master shaft 5 may be reduced. The optimum thickness is set in accordance with the bearing performance, bearing size, application, etc., for example, in the range of 5 μm to 200 μm.

  The electroformed shaft 7 manufactured through the above steps is supplied and arranged as an insert part in a mold for insert-molding the bearing member 2.

  FIG. 5 conceptually shows an insert molding process of the bearing member 2, and a mold including the movable mold 8 and the fixed mold 9 is provided with a runner 10 a, a gate 10 b, and a cavity 10 c. In this embodiment, the gate 10b is a point-like gate, and a plurality of gates 10b are provided at positions corresponding to one end surface in the axial direction of the resin portion 4 to be molded and at equal intervals in the circumferential direction of the molding die (fixed die 9). Locations (for example, 3 locations) are formed.

  In the mold configured as described above, the movable mold 8 is brought close to the fixed mold 9 and clamped while the electroformed shaft 7 is positioned and arranged. Next, with the mold clamped, molten resin P is injected and filled into the cavity 10c through the spool (not shown), the runner 10a, and the gate 10b, and the resin portion 4 is integrated with the electroformed shaft 7. Mold.

  Examples of the resin material include crystalline resins such as liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyacetal (POM), polyamide (PA), or polyphenylsulfone (PPSU). Amorphous resins such as polyethersulfone (PES), polyetherimide (PEI), and polyamideimide (PAI) can be used as the base resin. In addition, for example, from the viewpoint of preventing electromagnetic noise, it is possible to use a material obtained by blending a conductive filler typified by carbon fiber, SUS powder or the like with the above resin. Of course, these are merely examples, and a resin material suitable for the application and use environment of the bearing can be arbitrarily selected. For example, it is also possible to use a material in which a reinforcing material (regardless of shape) is blended with the resin aiming at improving the strength and dimensional stability of the resin portion 4.

  After the mold opening, the molded product in which the master shaft 5, the electroformed part 3, and the resin part 4 are integrated is removed from the molds 8 and 9. This molded product is separated into a bearing member 2 (see FIG. 2) composed of the electroformed portion 3 and the resin portion 4 and the master shaft 5 in a subsequent separation step.

  In the separation step, for example, the inner peripheral surface 3 a of the electroformed part 3 is peeled off from the outer peripheral surface 5 a of the master shaft 5 by applying an impact to the master shaft 5 or the electroformed part 3. Thereby, the master shaft 5 is pulled out from the bearing member 2 (electroformed part 3), and the bearing member 2 as a finished product is obtained.

  As the separating means for the electroformed part 3, in addition to the above means, for example, a method in which the electroformed part 3 and the master shaft 5 are heated (or cooled), and a difference in thermal expansion is generated between them, or A means using both means (impact and heating) in combination can be used.

  The bearing member 2 formed as described above is fixed to the first fixed-side member 42 shown in FIG. 2, and a shaft 34a separate from the extracted master shaft 5 is inserted into the inner periphery of the fixed bearing member 2. As a result, the bearing unit 1 shown in FIG. 2 is completed. Moreover, the bearing unit 11 shown in FIG. 2 is completed by fixing the bearing member 12 formed in the same manner to the first fixed side member 42 and inserting the shaft 35a into the inner periphery of the fixed bearing member 12. . Similarly, the bearing units 1 and 11 are formed for the bearing members 2 and 12 fixed to the second fixed side member 43.

  Thus, the electroformed part 3 constituting the bearing member 2 is formed by electrodeposition (electrolytic deposition) of metal ions in the electrolyte solution on the outer peripheral surface 5 a of the master shaft 5. The inner peripheral surface 3a is a surface to which the shape of the outer peripheral surface 5a of the master shaft 5 is transferred with high accuracy on the order of microns due to the characteristics of electroforming. Therefore, if the master shaft 5 with improved surface accuracy of the outer peripheral surface 5a is used, the inner peripheral surface (bearing surface) 3a having high surface accuracy can be manufactured at low cost without performing post-processing particularly for increasing the surface accuracy. Obtainable. For the same reason, the inner peripheral surface 13a of the electroformed part 13 in the bearing member 12 can be formed with high accuracy and low cost.

  Therefore, if such inner peripheral surfaces 3a and 13a are used as the bearing surfaces of the bearing members 2 and 12, respectively, high rotational accuracy can be obtained between the outer peripheral surfaces of the shafts 34a and 35a. Further, in the case of the bearing member 2 having high bearing surface accuracy, the diameter dimensions of the inner peripheral surfaces (bearing surfaces) 3a and 13a are set so that the diameter clearance (radial bearing clearance) between the shaft 34a is as small as possible. can do. As a result, the shaft runout during use can be reduced, and the distance between the pickup roller 34 and the drive shaft 45 connected to the pickup roller 34 via the gears 44a and 46 can be kept constant. Therefore, it is possible to maintain good meshing between the gears 44a and 46 and reduce the squealing of these gears 44a and 46.

  In particular, in the case of the pickup roller 34, when the sheet 26 is picked up from the sheet accommodating portion 33, the torque characteristic is important. As described above, the use of the bearing member 2 with improved rotation accuracy can be used. It is possible to reliably and smoothly pick up the seat 26 while minimizing torque fluctuations at the time.

  In this embodiment, since the bearing member 12 including the electroformed portion 13 is used not only for the pickup roller 34 but also for the separation roller 35, vibration of the separation roller 35 during use can be suppressed. it can. Further, the meshing of the gear 47 of the separation roller 35 and the gear 44b of the pickup roller 34 meshing with the separation roller 35 is kept good, and the noise of the gears 47 and 44b can be reduced.

  Further, as described above, by reducing the diameter gap (radial bearing gap) between the bearing surface of the bearing member 2 (the inner peripheral surface 3a of the electroformed part 3) and the outer peripheral surface of the shaft 34a as much as possible, It is possible to minimize the wear of the inside of the bearing by preventing the paper dust generated by sliding with the rollers 34 and 35 from entering the gap as much as possible. Specifically, since the paper dust diameter is usually 50 μm or more, the inner diameter dimension of the electroformed part 3 is set so that the radial bearing gap is 5 μm or less in terms of the diameter gap, so that the paper dust is more reliably obtained. It is possible to prevent dust from entering.

  Moreover, in this embodiment, since the electrolytic solution containing PTFE particles was used for the electroforming of the electroformed part 3, PTFE particles are formed on the inner peripheral surface 3a of the electroformed part 3 as a finished product. It becomes a distributed state. Therefore, the friction characteristic with respect to the shaft 34a and the wear resistance characteristic can be improved, and the deterioration of the rotation accuracy due to the aging of the image forming apparatus can be minimized.

  Further, this embodiment is characterized in that the bearing member 2 is formed by molding using the electroformed part 3 as an insert part. According to this configuration, since the thickness of the electroformed part 3 serving as the insert part can be made as thin as possible as long as the inner peripheral surface 3a can function as a bearing surface, other mold parts excluding the electroformed part 3 By adjusting the size of the resin portion 4 (here, the resin portion 4), the entire bearing unit 1 can be downsized compared to the conventional product.

  In addition, by integrally molding the electroformed part 3 as an insert part, the assembly process of the electroformed part 3 and the resin part 4 can be simplified, and the bearing member with improved assembly accuracy between the members 3 and 4 can be obtained. 2 can be obtained.

  Further, by forming all the portions of the bearing member 2 except the electroformed portion 3 with the resin portion 4, it is possible to greatly reduce the material cost of the bearing member 2.

  Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and can be applied to other forms.

  In the bearing member 2 according to the present invention, most of the outer diameter side excluding the electroformed part 3 is formed of a resin or metal mold part. For example, the first fixed side member 42 shown in FIG. It is also possible to integrally mold with the same material as the mold parts 2 and 12 (resin parts 4 and 14 in the figure). Of course, the second fixed side member 43 can be integrated with the bearing members 2 and 12 in the same manner. In this case, for example, although not shown in the drawings, the resin parts 4 and 14 and the first fixed side member 42 are integrally molded with resin using the electroformed parts 3 and 13 as insert parts, so that the bearing members 2 and 12 and Since the formation of the fixed side member 42 and the assembly of the bearing members 2 and 12 and the fixed side member 42 are performed in a single step, the work process can be simplified.

  Further, in the above embodiment, the case where the present invention is applied to the bearings for the pickup roller 34 and the separation roller 35 has been illustrated, but the present invention is not limited to this, and is involved in the paper supply / discharge process of the image forming apparatus. The present invention can also be applied to other roll-shaped rotating bodies, for example, bearings that rotatably support registration rollers 37 and 37 for positioning a toner image formed on the sheet 26 by the image forming unit 20.

  In this case, although not shown in the drawings, by configuring the bearing surface of the registration roller 37 with the inner peripheral surface of the electroformed part formed by electroforming, the rotational accuracy is improved as in the above embodiment, It is possible to suppress abnormal noise and prevent paper dust from entering the bearing gap. Further, since the registration roller 37 controls the image forming position on the sheet 26 by the image forming unit 20, the rotation accuracy is important. However, by increasing the rotation accuracy as described above, such an image can be obtained. Can be positioned with high accuracy.

  Of course, in addition to the registration roller 37, the present invention includes, for example, a conveyance roller 36, 36 that conveys the picked-up sheet 26 to the registration rollers 37, 37 and a paper discharge unit 27. As long as it is a roll-like rotator that is involved in the paper supply / discharge process of the image forming apparatus, such as the discharge rollers 41, 41 that discharge the toner image-formed sheet 26 to the outside of the apparatus, these roll-like rotators are supported. Can be widely applied to bearings.

  In the above embodiment, the bearing member 2 according to the present invention is a radial bearing in which the bearing surface is formed by the perfectly circular inner peripheral surface 3a of the electroformed part 3 and has a constant axial diameter between the shaft 34a. Although a so-called perfect circle bearing in which a gap is formed has been described, other forms may be adopted.

Aiming to improve moment resistance, reduce loss torque, etc.
The inner peripheral surface 3a of the electroformed part 3 is formed with a plurality of axially spaced bearing surfaces and an intermediate clearance portion located between the bearing surfaces and having an inner diameter dimension larger than the bearing surface. Can do.

  Further, as a bearing other than the above-mentioned perfect circle bearing, for example, illustration is omitted, but a fluid dynamic pressure action is generated in a bearing gap between the inner peripheral surface 3a of the electroformed part 3 and the outer peripheral surface of the shaft 34a opposed thereto. Therefore, a so-called dynamic pressure bearing provided with a dynamic pressure generating portion can be configured.

  Specifically, a so-called step bearing in which a plurality of axial grooves are formed on either the inner peripheral surface 3a or the outer peripheral surface of the shaft 34a can be configured.

  Alternatively, a plurality of arcuate surfaces are arranged continuously in the circumferential direction on either one of the inner circumferential surface 3a and the outer circumferential surface of the shaft 34a, and a wedge-shaped diameter is formed between the other surface facing in the radial direction. A so-called multi-arc bearing in which a directional gap (bearing gap) is formed can be configured.

  Alternatively, a dynamic pressure bearing in which a plurality of inclined grooves (so-called dynamic pressure grooves) are arranged in a herringbone shape on either the inner peripheral surface 3a or the outer peripheral surface of the shaft 34a can be configured.

  In any case, when the bearing gap is filled with a fluid, the structure (for example, the lubricating oil) inside the bearing does not leak to the outside of the bearing, for example, the electroformed part 3 constituting the radial bearing gap. It is preferable to form a seal space for holding the fluid inside at the axial end.

FIG. 3 is a cross-sectional view conceptually showing an image forming process and a paper supply / discharge process of the image forming apparatus according to the embodiment of the present disclosure. It is the schematic of the drive mechanism containing the bearing unit for pick-up rollers. It is a perspective view of the master axis | shaft which formed the nonelectroconductive masking part. It is a perspective view of the electroformed shaft in which the electroformed part was formed. It is a figure which shows notionally the injection molding process of the resin part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Bearing unit 2, 12 Bearing member 3, 13 Electroformed part 3a, 13a Inner peripheral surface (bearing surface)
4, 14 Resin section 5 Master shaft 10c Cavity 20 Image forming section 21 Photosensitive drum 22 Developing device 23 Transfer electrode 24 Fixing section 25 Paper feed section 26 Sheet 27 Paper discharge section 34 Pickup roller 35 Separating roller 36 Conveying roller 37 Registration roller 41 Discharge Paper rollers 44a, 44b, 46, 47 Gear 45 Drive shaft

Claims (5)

Supports a roll-like rotating body involved in a sheet feeding process for supplying a sheet picked up from the sheet storage unit to the image forming unit, or a sheet discharging process for discharging a sheet having an image formed on the surface by the image forming unit A bearing member for an image forming apparatus,
A bearing member for an image forming apparatus, wherein a bearing surface for supporting a roll-shaped rotating body is formed on an inner peripheral surface of an electroformed part formed by electroforming.   The bearing member for an image forming apparatus according to claim 1, wherein a diameter gap between a bearing surface constituted by an inner peripheral surface of the electroformed part and an outer peripheral surface of the roll-shaped rotating body facing the inner peripheral surface is 5 μm or less.   The bearing member for an image forming apparatus according to claim 1, wherein the roll-shaped rotating body is a pickup roller that picks up a sheet from the sheet storage portion.   The bearing member for an image forming apparatus according to claim 1, wherein the roll-shaped rotating body is a registration roller for positioning an image formed on the sheet by the image forming unit.   5. A bearing unit for an image forming apparatus, comprising the bearing member for an image forming apparatus according to claim 1 and a roll-shaped rotating body.

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