JP2012141548A - Method for manufacturing elastic body roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a desired roller form with high accuracy, stably and at a low cost without fluctuation in shape after polishing a number of rollers in production, while easily obtaining the desired roller form with high accuracy without labor such as dressing.SOLUTION: A manufacturing method, in which both ends of an elastic body roller with a cylindrical elastic layer formed around a ferroelectric core bar are rotatably supported and a cylindrical grindstone having a width larger than that of the elastic layer is pressed against the outer peripheral surface of the elastic body roller to polish this outer peripheral surface, includes performing the polishing while controlling deflection of the core bar by polishing while applying magnetic force to the core bar in the approach direction of the grindstone or in the opposite direction.

Description

  The present invention relates to a method for manufacturing an elastic roller used in an electrophotographic apparatus.

  Conventionally, methods of contact charging and contact transfer have been studied in a charging / transfer process of an electrophotographic apparatus. FIG. 1 is a diagram schematically showing the configuration of an electrophotographic apparatus having contact charging means and contact transfer means. Reference numeral 1 denotes an image holding member as a member to be charged, which is a drum type photosensitive member having a conductive support such as aluminum and at least a photoconductive layer on the outer peripheral surface thereof. A charging means 2 is in contact with the photosensitive member and uniformly charges the surface of the photosensitive member to a predetermined potential. The charging unit is pressed against the photosensitive member 1 by a predetermined pressing force using a pressing unit (not shown) such as a spring, and rotates following the rotation of the photosensitive member 1. Further, the photosensitive member 1 is contact-charged to a predetermined potential by applying a direct current and an alternating current or a direct current bias to the shaft body. That is, in order to obtain a good image, the charging unit 2 needs to be in uniform contact with the photoreceptor 1 and have good conductivity.

  Next, the surface of the photoreceptor 1 charged with a predetermined potential by the charging unit 2 is exposed to image information by exposure 3 output from an exposure unit (not shown) such as a laser or LED. As a result, an electrostatic latent image corresponding to the target image information is formed on the surface of the photoreceptor 1.

  Next, the latent image on the surface of the photoreceptor 1 is visualized as a toner image by the developing unit 4. This toner image is obtained by transferring the toner image on the surface of the photoreceptor 1 to the surface side of the transfer material 6 by charging the toner with the reverse polarity to the toner from the back of the transfer material 6 by the transfer member 5. The transfer material 6 that has received the transfer of the toner image is separated from the photoreceptor 1 and is fixed by applying heat and pressure by the fixing member 7. Further, the surface of the photosensitive member 1 after the toner image transfer is cleaned by the cleaning member 8 to remove the adhering matter such as residual toner at the time of transfer, and is repeatedly used for image formation. In FIG. 1, 9 denotes toner and 10 denotes a rotation axis.

  As shown in FIG. 2, the charging unit 2, the transfer member 5, the developing unit 4, and the like include a shaft body that is rotatably supported at least at both ends, and the elasticity of rubber provided on the outer peripheral surface of the shaft body. An elastic roller 101 composed of layers is used. The elastic roller 101 is required to ensure a stable contact state by bringing the roller surface into close contact with a photoconductor, an image carrier such as a transfer belt, paper, or the like. For this reason, the elastic layer of rubber is composed of a low-hardness elastic body formed into a solid or foam shape using a material such as rubber or elastomer.

  Various elastic rollers are used for the charging unit 2, the transfer member 5, the developing unit 4, and the like. For example, a straight elastic roller having the same outer diameter at the center and both ends in the axial direction, a crown-shaped elastic roller whose outer diameter gradually decreases from the center toward the end, and the like. Can do. Further, there can be mentioned an inverted crown-shaped elastic body roller whose outer diameter gradually increases from the central portion toward the end portion. The shape of the elastic roller is appropriately selected according to the purpose of the rubber roller to be used.

  On the other hand, an elastic roller used in an electrophotographic apparatus is required to have a processing accuracy of 1/100 mm in the outer diameter. This is because the dimensional accuracy such as the outer diameter and runout of the elastic roller affects the image characteristics. For example, a charging roller used in pressure contact with a photoconductor for an electrophotographic apparatus often employs a crown shape in order to uniformly charge the photoconductor. The principle of charging the photosensitive member by the charging roller is to discharge between gaps formed between the charging roller and the photosensitive member. Therefore, at this time, if the dimensional accuracy such as the outer diameter or the shake of the charging roller is low, uneven discharge may occur on the photosensitive member due to the non-uniformity of the gap between the charging roller and the photosensitive member. As a result, an image defect may occur, which may cause contamination with toner or external additives. Therefore, in order to make the width of the gap between the charging roller and the photosensitive member uniform, it is important to control the crown shape of the roller.

  For manufacturing such a roller, the raw material composition is extruded into a tube shape after being extruded into a tube shape, or rubber is coated on the core metal by extruding it simultaneously with the core metal using a cross head, and is removed by polishing or the like. A technique for obtaining a highly accurate roller by adjusting the diameter is used. As another method, a method using a mold is also known, but there are cases where the accuracy of the shape and the like is low at the mating portion of the mold, and it is not preferable from the viewpoint of cost.

  As a method of polishing a roller, a traverse method and a plunge method are known. The traverse method uses an abrasive wheel having a width smaller than the axial width of the rubber elastic layer of the rubber roller, and moves the abrasive wheel and the rubber roller relative to each other in the axial direction, thereby moving the outer peripheral surface of the roller in the entire axial direction. It is a method to polish over. The plunge method is a method in which a cylindrical polishing grindstone having a width equal to or larger than the axial width of the rubber elastic layer is used, and the entire length in the axial direction of the rubber elastic layer is brought into contact with the polishing grindstone for polishing. In this method, the polishing grindstone and the roller are fixed and polished without moving. This plunge type polishing process has the advantage that the entire width of the roller can be polished at once, and the processing time can be shortened compared to the traverse type polishing process.

  Further, when polishing the outer peripheral surface of the roller by plunge type polishing, a polishing grindstone having a shape that matches the desired shape of the roller has been used. For example, when a roller is finished in a crown shape, the polishing process is performed using a polishing grindstone previously formed into an inverted crown shape.

  However, when polishing is performed in a short time on an elastic roller having an elastic layer having a high hardness, when the plunge-shaped grindstone is pressed, the core metal or the elastic layer is bent and the shape of the elastic roller after polishing is In some cases, the desired shape was not achieved. Therefore, in order to make the elastic roller into a desired shape by polishing, it is necessary to calculate the shape of the grinding wheel to a shape different from the desired shape of the elastic roller by back-calculating the influence of the deflection of the core metal or elastic layer. was there. The shape of the grinding wheel can be adjusted by an operation of a dress for polishing and molding the surface of the grinding wheel with a diamond dresser or the like. However, finishing by this dressing work requires a lot of work time, which reduces the operating rate of the polishing machine. In addition, when a large number of polishings are performed, the cutting ability is reduced due to wear of the grinding wheel, etc., and the shape changes (specifically, if the crown shape is used, the crown amount increases). Was. Therefore, Patent Document 1 discloses a method of polishing by applying a backup roller to a workpiece to be polished.

JP-A-8-215999

  However, in the case of an elastic roller by the method described in Patent Document 1, when the backup roller comes into contact with the surface, the resistance is different when the surface has a surface roughness or conductivity, resulting in unevenness. It was. The present invention has been made to solve the problems described above. That is, when plunge polishing is performed, the desired shape can be stably produced without adjusting the crown shape of the elastic roller without time-consuming adjustment such as dressing and without bringing the member into contact with the surface of the elastic layer. Is to provide a method.

  Therefore, the present inventor has intensively studied to solve the above problems. As a result, it has been found that the crown shape can be changed by controlling the deflection of the core of the elastic roller during the polishing of the elastic roller by the magnetic force, and the present invention has been completed.

  That is, the present invention rotatably supports both ends of an elastic roller in which a cylindrical elastic layer is formed around a ferroelectric core bar, and presses a cylindrical grindstone wider than the elastic layer to In the manufacturing method for polishing, an elastic roller manufacturing method is characterized in that polishing is performed while applying a magnetic force to the metal core in the approaching direction of the grindstone or in the opposite direction.

  With the elastic roller manufacturing method of the present invention, a desired roller shape can be easily obtained with high accuracy and without trouble such as dressing, and a desired shape can be obtained with high accuracy without any variation in shape after polishing a large number of products during production. It can be manufactured stably at low cost. Further, it is possible to manufacture an elastic roller having uniform physical properties with no surface roughness or resistance unevenness.

Schematic diagram showing an example of an electron beam irradiation device The schematic diagram which shows an example of the elastic body roller obtained by this invention Schematic diagram of extruder Schematic diagram (top view) showing an example of a plunge type polishing machine Schematic diagram (top view, cross-sectional view) showing an example of a structure for applying a magnetic force to a roller held by a polishing machine Schematic diagram (top view, cross-sectional view) showing an example of a structure for applying a magnetic force to a roller held by a polishing machine Schematic diagram (top view, cross-sectional view) showing an example of a structure for applying a magnetic force to a roller held by a polishing machine Schematic diagram (top view, cross-sectional view) showing an example of a structure in which a roller held by a polishing machine is pressurized with a backup roller The schematic diagram showing the conventional example of the roller hold | maintained at the grinder. (Top view, sectional view) Schematic diagram showing an example of an apparatus for measuring the outer diameter shape of an elastic roller

  Hereinafter, the elastic roller according to the semi-invention will be described in more detail.

  First, as a method for forming an elastic roller having an elastic layer provided on a core metal, two cylindrical pieces that concentrically hold a shaft core metal are assembled in a cylindrical mold, and heated after injecting a rubber material. The material is cured by injection molding to form an elastic roller, after the rubber material is extruded into a tube shape, the core metal is covered with the tube-shaped rubber material, or the core metal and the rubber material are integrally extruded to form a cylindrical shape. There are extrusion molding, transfer molding, press molding and the like for molding the elastic roller, but there is no particular limitation. In view of shortening the manufacturing time, extrusion molding in which a rubber material is extruded integrally with a core and an elastic roller is formed is preferable. As for the heating method of the elastic roller, any method such as a hot stove, vulcanizing can, hot platen, far / near infrared, induction heating, etc. may be used, and further, it is pushed while rotating on a heated cylindrical or planar member. A hitting method may be used.

  Here, the schematic diagram of an extruder is shown in FIG. The extruder 31 includes a cross head 32. The crosshead can insert the core metal 34 fed from the core metal feed roller 33 from behind, and can simultaneously extrude the cylindrical rubber material simultaneously with the core metal. After the rubber material was formed in a cylindrical shape around the core, the end portion was cut and removed 35, and an unpolished elastic roller 36 was obtained through an appropriate vulcanization step.

  Next, a schematic configuration diagram of the plunge type polishing apparatus used in the present invention will be described in detail with reference to FIG. The polishing machine of the present invention is a plunge type cylindrical polishing machine for polishing the outer peripheral surface of an elastic roller having a shaft body and a rubber elastic layer on the outer peripheral surface of the shaft body. A grinding wheel and holding means are provided. The grinding wheel is rotatable and has a cylindrical shape. The holding means is configured to hold and rotate the elastic roller in the polishing machine so that the axial directions of the elastic roller and the grinding wheel are parallel to each other.

  FIG. 4 is a schematic view showing an example of a plunge type cylindrical polishing machine of the present invention. As shown in FIG. 4, the polishing machine can rotate while holding the elastic roller by the holding means. The elastic roller holding means has a headstock unit and a tailstock unit. The headstock unit includes a main bearing portion 41, a collet chuck 42a, a pulley and belt 43, and a work rotation motor 44 that integrally rotates the main shaft and the collet chuck 42a via the pulley and belt. Similarly, the tailstock unit includes a tailstock bearing 45, a collet chuck 42b, a pulley and belt 43, and a work rotation motor 44. Further, the tailstock unit includes a linear guide or the like (not shown) so as to be able to move forward and backward.

  A collet chuck 42a is attached to the tip of the main shaft, and the shaft body end portion 22 of the rubber roller 21 is held by the collet chuck 42a. The other shaft body end 22 is held by a collet chuck 42b after the tailstock unit has advanced to the rubber roller 21 side. The rubber roller 21 thus held in the polishing machine is rotated via the pulley and belt 43, the main bearing 41 and the tailstock bearing 45 when the work rotation motor 44 is driven.

  Reference numeral 46 denotes a polishing grindstone, which is formed into an inverted crown shape by pressing a 47 diamond dresser while rotating the polishing grindstone 46. Reference numeral 48 denotes a grindstone bearing unit for holding the rotating polishing grindstone 46, 49 denotes a belt and pulley for transmitting the grindstone rotation, and 410 denotes a grindstone motor that drives and rotates the polishing grindstone 46 via the grindstone bearing unit 48. On this grindstone base 411, a grinding grindstone 46, a grindstone bearing 48, and a grindstone motor 410 are attached.

  The rotation center of the grinding wheel 46 of the grinding wheel base 411 is arranged in parallel to the rotation center of the rubber roller 21 held at both ends by the spindle collet chuck 42a and the tailstock collet chuck 42b. That is, the axial direction of the elastic roller 21 and the axial direction of the polishing grindstone 46 are arranged so as to be parallel to each other. The polishing grindstone 46 and the surface including the rotation center of the polishing grindstone 46 and the rotation center of the rubber roller 21 are movable in a direction perpendicular to the rotation center of the elastic roller 21.

  In the polishing machine, the main shaft side may be a collet chuck, and the core pushing shaft side may be a center or a reverse center support. Further, both ends of the elastic roller can be held by a diaphragm chuck or the like instead of the collet chuck. Furthermore, it is also possible to adopt a single drive configuration in which the main shaft side is driven to rotate and the core pressing shaft side is driven to rotate.

  Further, the main shaft unit and the tailstock unit may be mounted on a common table so that the parallelism between the axial direction of the elastic roller 21 and the axial direction of the grindstone can be adjusted precisely.

  When dressing. In a state where the polishing grindstone is rotated, the table on which the dress tool or the grindstone 46 is placed is moved relatively in the longitudinal direction and the cutting direction of the grindstone to form the grindstone in a desired shape. In many cases, it is formed into an inverted crown shape that approximates the shape of an arc, but may be freely corrected to obtain a desired shape.

  The polishing machine in FIG. 4 is provided with a unit that applies a magnetic force to the opposite side of the grindstone with respect to the held elastic roller. This unit will be described in detail in another drawing.

  Next, the grinding wheel for the plunge type polishing machine used in the present invention will be described. The surface roughness of the polishing wheel can be appropriately selected according to the polishing efficiency and the type of the constituent material of the rubber elastic layer. The roughness of the grindstone surface can be adjusted by the type of abrasive grains, the particle size, the degree of bonding, the binder, the structure (abrasive grain ratio), and the like.

  The “abrasive grain size” indicates the size of the abrasive grains, and is expressed as # 80, for example. The number in this case means how many eyes per inch (25.4 mm) of the mesh for selecting abrasive grains, and the larger the number, the finer the abrasive grains. As this particle size, it is more preferable to use a particle size of # 60 or more and # 120 or less in view of the balance between polishing properties and surface properties.

  The above-mentioned “degree of bonding of abrasive grains” indicates hardness and is represented by alphabets A to Z. This degree of bond indicates that the closer to A, the softer, the closer to Z, the harder. The more binder is included in the abrasive grains, the harder the bond.

  The “abrasive grain structure (abrasive grain ratio)” represents the volume ratio of the abrasive grains in the entire volume of the grindstone, and represents the density of the structure depending on the size of the structure. The larger the number indicating the organization, the rougher it is. A grindstone having a large structure number and having large pores is called a porous grindstone, and has advantages such as prevention of clogging and grinding of the grindstone.

  Generally, this grinding wheel can be manufactured by mixing raw materials (abrasive material, binder, pore agent, etc.), press molding, drying, firing, and finishing. As the abrasive grains, green silicon carbide (GC), black silicon carbide (C), white alumina (WA), brown alumina (A), zirconia alumina (Z) and the like can be used. These materials can be used alone or in combination of two or more.

  Moreover, as said binder, vitrified (V), resinoid (B), resinoid reinforcement (BF), rubber (R), silicate (S), magnesia (Mg), shellac (E) etc. are suitably used according to a use. Can be used.

  The shape of the grinding wheel is preferably an inverted crown shape in which the outer diameter gradually decreases from the end toward the center so that the elastic roller can be polished into a crown shape. The outer diameter shape of the grinding wheel is preferably an arc curve or a quadratic or higher-order curve shape with respect to the longitudinal direction. In addition to this, the outer diameter shape of the polishing grindstone may be a shape represented by various mathematical expressions such as a quartic curve or a sine function. The outer shape of the grinding wheel is preferably one in which the change in the outer diameter changes smoothly, but the arc curve or the like may be a shape that approximates a polygonal shape by a straight line. The width in the direction corresponding to the axial direction of the polishing grindstone is preferably equal to or greater than the axial width of the elastic roller.

  When polishing by holding the cored bar exposed portions which are both ends of the elastic roller, the elastic roller is bent in the traveling direction of the grindstone by the pressure contact force caused by the cutting of the grindstone, and the longitudinal central portion of the elastic roller is the end portion. The outer diameter is thicker than that. Accordingly, the polished elastic body roller does not have a shape in which the reverse crown shape applied to the grindstone is reliably transferred, and the crown amount increases. This is caused by the return of the core metal that was bent during polishing. If the grinding is continued for a long time with the cutting of the grindstone stopped, a shape almost equal to the reverse crown shape of the grindstone can be obtained, but this is not practical because the grinding time becomes very long. The crown amount is provided to make the pressure contact state of the roller uniform, and is adjusted to a desired value in accordance with the hardness and diameter of the elastic layer of the roller or the purpose of use. When used as a roller for electrophotography, the thickness is preferably about ± 10 μm with respect to the adjusted value. Further, when the crown amount is adjusted in a dress shape in consideration of the fluctuation range, it is preferable to adjust the crown amount as close to a predetermined value as possible (about ± 2 μm).

  In addition, in order to prevent the workpiece to be polished, a method of pressing the backup roller and preventing the deflection is also known, but particularly in a roller requiring high accuracy such as an elastic roller for OA, A phenomenon occurs in which the pressing portion is uneven or the roughness is different. In addition, when the roller is made conductive, the resistance is changed by pressing the roller, which is not preferable.

  In the present invention, not only can bending be suppressed without contact by using a repulsive force due to magnetic force, but also by using an attractive force by a magnet, a large deflection is generated by the elastic roller core during polishing, and after polishing. It is also possible to increase the amount of crown obtained. Therefore, a desired crown shape can be obtained without performing dressing work by switching between attractive force and repulsive force due to magnetic force, or controlling the magnitude of magnetic force (however, the metal core can be elastically deformed during polishing) Limited to range.)

  In order to obtain the desired crown shape, the grindstone dressing operation was conventionally performed to form the reverse crown shape on the grindstone, but in order to obtain a precise shape, dressing was performed multiple times and fine adjustment was performed. And it is necessary to finish by pressing a polishing member on the surface of the grindstone after dressing.

  5 to 7 schematically show details of a unit including a magnet or the like for applying a magnetic force schematically.

  FIG. 5 is a schematic view showing only the periphery of the chuck portion of the polishing machine, and is shown by a top view and a cross-sectional view. Reference numeral 52 denotes a bar-like electromagnet, which is an electromagnet in which an enamel wire is wound around an iron core. The electromagnet 52 is fixed on the polishing machine by a holding stand 51. The core bar of the elastic roller is held by a chuck of a polishing machine, and electromagnetic coils 53 are fitted to the core bar exposed portions at both ends of the elastic roller. An electromagnetic coil is formed by winding an enameled wire or the like around a cylindrical insulator that can be fitted to a cored bar.

  By passing a current through the electromagnetic coil, a repulsive force due to the electromagnetic force is generated between the magnetized cored bar and the rod-shaped electromagnet. By this repulsive force, the core metal of the elastic roller 21 can be bent.

  Further, by changing the polarity of the applied current, it is possible to obtain a pulling force instead of a repulsive force. Therefore, it is possible to apply a force so as to reduce the deflection of the core during polishing, or to apply a force so as to increase the deflection.

  As a method for controlling the magnetic force, the current flowing through the electromagnetic coil may be changed, or the current flowing through the electromagnet or the number of turns per unit length of the coil may be changed. Alternatively, the magnetic force may be controlled by applying a pressurizing unit that makes the applied pressure constant, such as a spring or a cylinder, to the holding unit that holds the magnet.

  FIG. 6 shows an example in which a permanent magnet is used instead of an electromagnet. Reference numeral 63 denotes a magnet, which is disposed on a magnet holding plate 62 provided on a magnet holding base. A plurality of magnets may be provided, or a long magnet may be used. In this case, only the force in the direction of pulling the elastic roller shaft center can be applied.

  FIG. 7 shows an example in which the magnet is not disposed on the opposite side of the grindstone when viewed from the elastic roller. The arrangement shown in FIG. 7 has a space in front of the polishing machine, which may be preferable from the viewpoint of workpiece attachment and removal handling.

  The electromagnet 72 is fixed to the polishing machine by the support brother 71 and is disposed above the elastic roller. Furthermore, the cored bar can be bent by bringing the electrodes 73a and 73b into contact with the exposed part of the cored bar of the elastic roller and passing an electric current. Note that the chuck portion of the polishing machine is insulated so that no current flows through the polishing machine body.

  The electrodes 73a and 73b can be made of brass or copper leaf springs or the like, and can be used as electrodes such as brush-like or wire-like so as not to damage the metal core. Anything is fine.

  Also in this configuration, depending on the direction of current flow, not only the direction of pulling the cored bar, but also the force in the direction of repulsion can be obtained.

  The shaft used for the electromagnet is not particularly limited to iron as long as it is ferromagnetic. Further, the enameled wire used for the electromagnet and the electromagnetic coil is not particularly limited to the enameled wire, and there is no problem as long as the conductor is insulated. Further, the cylindrical member used as the core of the electromagnetic coil only needs to have high slidability with the shaft core, and is not particularly limited to nylon.

  Further, if the gap H between the electromagnet and the elastic roller varies greatly in the longitudinal direction of the roller, the corresponding contact pressure varies. If the interval H is too close, the variation of the interval H with respect to the interval H increases, and the amount of deflection of the cored bar may vary from side to side. On the other hand, if the interval H is too large, it is necessary to pass a large current through the rod-shaped electromagnet or magnet in order to obtain the desired deflection of the metal core. The separation distance is preferably 0.5 mm to 10 mm.

  By controlling the current flowing through the electromagnet, electromagnetic coil, etc., controlling the distance, etc., the force for bending the cored bar can be generated from about 100 g to 3000 g, and is adjusted as appropriate.

  Besides permanent magnets, alnico magnets, ferrite magnets, neodymium magnets, samarium cobalt magnets, iron-chromium-cobalt magnets, manganese aluminum magnets and the like can be used.

  The core roller 22 of the elastic roller functions as a roller support member and an electrode, and needs to function as an electromagnet, and therefore needs to be a ferromagnetic material. For example, iron, which has been plated with iron, stainless steel, cobalt, nickel, chromium / nickel, or the like can be used. The conductive conductive support is usually in the range of 4-10 mm. Furthermore, plating treatment may be performed on these metal surfaces for the purpose of imparting rust prevention and scratch resistance as long as good conductivity is not lost. Moreover, you may apply | coat the adhesive agent of thickness 1 micrometer or more and 20 micrometers or less for the purpose of adhesion | attachment with a conductive elastic layer in the range which does not lose good electroconductivity. As for the arrangement of the magnets, any force may be used as long as an attractive force or a repulsive force is generated on the core of the elastic roller with respect to the traveling direction of the grindstone. Applying a magnetic force from the opposite side is more preferable from the viewpoint of easy control of the magnetic force. In addition, when a large number of elastic rollers are manufactured, depending on the material of the elastic rollers, the grindstone is difficult to be scraped due to dirt or wear according to the number of polished rollers, resulting in a shape larger than the desired crown shape. Also occurs. Conventionally, an elastic roller having the same shape has been manufactured by periodically re-dressing the same shape. However, since it is necessary to perform time-consuming dressing, it may not be preferable.

  In the present invention, it has been found that the variation in the crown shape correlates with the variation in the outer diameter of the elastic roller longitudinal central portion, and the outer diameter of the elastic roller longitudinal central portion after polishing is measured to make the outer diameter constant. It was clarified that a stable shape can be obtained by feeding back to the magnetic force. When performing control, it is not preferable to measure the outer diameter at a plurality of locations in the longitudinal direction of the roller every time the roller is polished, because it takes time for the measurement and requires expensive equipment. By measuring the outer diameter at one point in the center, it is possible to use one fixed outer diameter measuring sensor, so that it can be easily performed.

  The outer diameter measurement after polishing can be performed using a non-contact laser outer diameter measuring machine (for example, LS-5000 manufactured by Keyence Corporation). You may carry out in the state hold | maintained at the grinder, and you may remove and perform a measurement. FIG. 10 schematically shows an apparatus for measuring the outer shape. Based on the measured outer diameter, a deviation ΔΦ from the desired outer diameter is calculated. Further, using a formula (a and b are coefficients determined by experiments) such as (necessary current amount) = a × (deviation ΔΦ) + b, the ratio of changing the current applied to the electromagnet, the electromagnetic coil, and the like is calculated. The calculation can be performed by a personal computer or a PLC (programmable logic controller). The current applied to the electromagnet calculated above is controlled to polish the next roller. The above control may be performed every time one polishing is completed, or may be performed periodically such as every 1000 or 10,000.

  Examples of the material for the rubber elastic layer include the following. Natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR), nitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, silicone rubber, urethane rubber, fluorine rubber, chlorine Rubber, thermoplastic elastomer, etc. These materials can be used alone or in combination of two or more.

  In order to impart conductivity to the rubber elastic layer, conductive particles may be dispersed in the rubber elastic layer material. As the conductive particles, conductive carbon such as ketjen black EC, acetylene black, carbon for rubber, carbon for color (ink) subjected to oxidation treatment, and pyrolytic carbon can be used. Specific examples of carbon for rubber include the following. Super Abrasion Furnace (SAF: Super Abrasion Resistance); Intermediate Super Abrasion Furnace (ISAF: Semi Super Abrasion Resistance); High Ablation Furnace (HAF: High Abrasion Resistance); Purpose Furnace (GPF: versatility); Semi Rein Forcing Furnace (SRF: medium reinforcement); Fine Thermal (FT: medium particle pyrolysis) and Medium Thermal (MT: medium particle pyrolysis).

Also, graphite such as natural graphite and artificial graphite, gold oxide such as TiO ₂ , SnO ₂ , ZnO, solid solution such as SnO ₂ and Sb ₂ O ₃ , double oxide such as solid solution of ZnO and Al ₂ O ₃ , Cu, Various conductive particles such as metal powder such as Ag can be used. These conductive particles may be used alone or as a mixture of a plurality of types. Furthermore, conductivity may be imparted to the rubber elastic layer by using a conductive polymer or an ionic conductive agent in combination with the conductive particles.

  In the rubber elastic layer material, a vulcanizing agent, a vulcanization accelerator, a conductive agent, a charge control agent, a plasticizer, an antiaging agent, and the like can be appropriately added. Moreover, an antistatic agent, an ultraviolet absorber, a reinforcing agent, a filler, a lubricant, a release agent, a pigment, a dye, a flame retardant, and the like can be appropriately added as necessary.

  For the elastic roller after polishing as described above, a resistance adjustment layer, a stain prevention layer, etc. are further provided on the outer periphery, or the surface is treated with ultraviolet rays, electron beams, etc. Can be used as a roller. In particular, a conductive elastic roller in which conductivity is imparted to the elastic layer is used as an electrophotographic roller such as a charging roller, a transfer roller, or a developing roller. When the elastic roller obtained in the present invention is used as a charging roller, not only the shape accuracy is high and stable, but also there is no specific unevenness of roughness and resistance, so that an image can be obtained stably. I can do things.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these.

[Examples 1 to 4]
<Production of rubber roller>
The following raw materials were kneaded with a pressure kneader for 15 minutes.
・ NBR 100 parts by mass (trade name “Nipol DN219”: manufactured by Nippon Zeon Co., Ltd.)
・ 14 parts by mass of carbon black 1 (trade name “Asahi HS-500” manufactured by Asahi Carbon Co., Ltd.)
・ Carbon black 2 4 parts by mass (trade name “Ketjen Black EC600JD” manufactured by Lion)
・ Zinc stearate 1 part by mass ・ Zinc oxide 5 parts by mass ・ Calcium carbonate 40 parts by mass (trade name “Nanox # 30” manufactured by Maruo Calcium Co., Ltd.)
Furthermore, 1 part by mass of a vulcanization accelerator (DM: di-2-benzothiazolyl disulfide), 3 parts by mass of a vulcanization accelerator (TBzTD: tetrabenzylthiuram disulfide) and 1.2 parts by mass of sulfur as a vulcanizing agent In addition, an unvulcanized rubber composition was prepared by kneading with an open roll for 15 minutes. Subsequently, a stainless bar core bar having an outer diameter of 6 mm and a length of 252 mm was prepared. Here, the core metal and the unvulcanized rubber composition were integrally extruded using a crosshead extruder to form a rubber roller. Thereafter, heat vulcanization was performed at 160 ° C. for 1 hour, and the elastic layer was cut and removed in order to expose the core metal portions 10 mm at both ends of the roller.

  The resulting unpolished elastic roller was polished using a plunge type polishing machine schematically shown in FIG.

  The polishing was performed while rotating the polishing grindstone so that the outer peripheral surface of the polishing grindstone was in contact with the outer peripheral surface of the rubber roller. The polishing conditions at this time were set to 8 seconds from the contact of the rubber roller with the polishing grindstone to the end thereof, the rotation speed of the grinding wheel 2050 rpm, and the rotation speed of the rubber roller 350 rpm. Further, an upper cut method was adopted in which the rotational directions of the grinding wheel and the rubber roller were the same. Then, polishing was performed so that the outer diameter of the central portion of the rubber roller after polishing was 8.5 mm, whereby the elastic roller 1 was obtained. As the grindstone, a porous grindstone made of abrasive grains of GC120 (manufactured by Noritake) having a width of 235 mm and a diameter of Φ305 mm is used.

  The reverse crown shape is formed by moving the diamond dresser along a path approximating the arc shape so that the reverse crown amount of the grindstone is 60 μm (maximum outer diameter−minimum outer diameter).

  The electromagnet used is a φ6 iron core wound with a φ0.26 enamel wire at 200 turns / cm, and the electromagnetic coil has a φ0. 26 enamel wires wound at 20 turns / cm were used.

  Using the above-described electromagnetic coil and electromagnet, the charging roller having a φ9 elastic layer was maintained at a distance H to the electromagnet of about 1 mm, and the magnetic force was changed by changing the current flowing through the electromagnetic coil. The length of the electromagnet was 230 mm.

  The magnetic force is adjusted by applying a magnetic force while holding only the cored bar in the polishing machine, and measuring the amount of deflection at the center in the longitudinal direction of the cored bar so that the desired amount of deflection can be obtained. The polarity was changed. For the measurement, a contact-type pick gauge or a non-contact laser displacement meter can be used.

  Table 1 shows the amount of deflection in Examples 1 to 4. When the amount of deflection is positive, the metal core is displaced in the direction of the grindstone, and when negative, it is displaced in the direction away from the grindstone.

  Note that the outer diameter of two points that are equidistant (for example, 90 mm) from the longitudinal center of the roller to both ends is measured, and the parallel between the grindstone and the workpiece is adjusted in advance so that the difference between the two points is 15 μm or less. Oita.

  In each example, 10 elastic rollers were polished with the adjusted amount of deflection, and the results of the amount of crown and unevenness after polishing are shown in Table 1. The result represents the average of n = 10.

  The measurement of the crown shape and the like of the elastic roller was performed as follows.

  FIG. 10 schematically shows an outer diameter measuring jig. The measurement is performed by arranging the cored bar exposed portions of the elastic roller on a jig provided with the V block 101. On the jig, there is further provided a slider 103 capable of moving the outer diameter measuring machine 102 in the longitudinal direction of the roller.

  The sensor used for the measurement is performed by a non-contact laser outer diameter measuring machine or the like (for example, manufactured by LS-5000 Keyence Corporation), and is arranged in a direction perpendicular to the roller. The outer diameter was measured at a pitch of 5 mm in the longitudinal direction of the roller (excluding 6 mm at both ends), and the maximum outer diameter−the minimum outer diameter = the crown amount.

  Further, the obtained data was approximated by a second-order polynomial (for example, manufactured by Excel Microsoft), and the maximum value of the deviation amount between the obtained approximate expression and the data before approximation was defined as the unevenness amount. (Approximate original data, calculation of deviation amount is excluding 20 mm at both ends of elastic body) When the unevenness amount is large, it is not preferable because the contact state is not uniform. appear. The thickness is preferably 8 μm or less, particularly preferably 5 μm or less.

  Since the obtained crown amount is changed by adjusting the deflection amount by the magnetic force, it can be seen that the desired crown amount can be obtained by adjusting the magnetic force. Further, if the technique of the present invention is used, the crown amount can be changed by adjusting the magnetic force without performing a dressing operation, so that the productivity is greatly improved as compared with the comparative example. Furthermore, since the amount of unevenness was small compared to Comparative Example 2, a roller having a highly accurate shape was stably obtained.

  Further, when positive deflection is applied to the core metal, an elastic roller having a small crown amount can be obtained when compared with the same dress shape as compared with the case where no deflection is applied. When the grindstone is stopped at a predetermined position during polishing, the crown amount increases due to the deflection of the core metal immediately after it is stopped, and the elastic deformation force that reduces the deflection of the core metal when held in this state. The center part is shaved using, and the amount of crown decreases. In other words, the fact that a small amount of crown can be obtained with the same dress shape and polishing conditions means that if the same amount of crown is to be obtained, the required polishing time can be shortened, greatly increasing productivity. You can also do things.

  Next, the obtained elastic roller was irradiated with ultraviolet rays under the following conditions.

Ultraviolet irradiation was performed for 5 minutes by using a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) and rotating the vulcanized rubber roller in parallel with the lamp. The distance from the ultraviolet lamp was about 30 mm, and the rotation speed was 30 rpm. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Image evaluation was performed using the elastic roller after the ultraviolet irradiation as a charging roller. Image evaluation is incorporated into a black cartridge of an electrophotographic apparatus (LBP-5050 manufactured by Canon Inc.), and 10 sheets of halftone images are output in an environment of 23.5 ° C./60%, unevenness caused by a charging roller on the image, It was confirmed whether streaks, etc. occurred. Unevenness or the like on the image did not occur as in Comparative Example 2.

Example 5
An elastic roller was manufactured in the same procedure as in Example 1 except that the magnetic back-up mechanism shown in FIG. 6 was used. In this embodiment, the magnet is a 10 × 8 × 5 mm neodymium magnet, and the amount of deflection is adjusted by arranging the necessary number of magnets in the longitudinal direction in a state where the separation distance H between the magnet and the elastic roller is 1 mm. Went. As shown in Table 1, the crown shape could be changed by changing the deflection of the metal core. Therefore, the crown amount can be adjusted by changing the configuration of this embodiment (the number of magnets, the separation distance H, etc.). Further, the ultraviolet ray treatment was performed in the same manner as in Example 1 and the image evaluation was performed, but no image defect occurred.

[Examples 6 to 8]
An elastic roller was manufactured in the same procedure as in Example 1 except that the magnetic back-up mechanism shown in FIG. 7 was used. In this embodiment, the same magnet as that used in Embodiment 1 is placed above the elastic roller held by the polishing machine, and brass contact terminals 73a and 73b are brought into contact with the core metal. This was done with current flowing. The chuck part of the polishing machine was insulated from the main body. In addition, the distance H between the magnet and the elastic roller was 1 mm, and the amount of deflection was adjusted by changing the amount of current flowing through the electromagnet and the cored bar. As shown in Table 1, the crown shape could be changed by changing the deflection of the metal core. Therefore, the crown amount can be adjusted also in the configuration of the present embodiment. Further, the ultraviolet ray treatment was performed in the same manner as in Example 1 and the image evaluation was performed, but no image defect occurred.

Example 9
In the same procedure as in Example 1, 10,000 elastic rollers were manufactured. However, each time one polishing was performed, the outer diameter of the central portion in the longitudinal direction was measured, and the magnetic force was adjusted so that the outer diameter was constant, and the next elastic roller was polished. This was repeated to obtain 10,000 elastic rollers. The adjustment of the magnetic force was controlled by collecting basic data for obtaining the required amount of magnetic force with respect to the change amount ΔΦ of the outer diameter in advance, determining the coefficient of the approximate expression, and inputting the calculation formula into the PLC. The magnetic force was controlled by adjusting the current value flowing through the electromagnetic coil. In addition, for comparison with the comparative example, the initial deflection amount is 0, that is, a state where no magnetic force is applied, the fluctuation of the outer diameter of the central portion is measured, and the magnetic force is applied by the calculated amount. Control was performed. Next, the crown amount of the obtained 10,000 elastic rollers was measured, and the maximum value-minimum value of the crown amount was 4 μm and was stable. Since it is significantly smaller than that of Comparative Example 1, it can be seen that by controlling the magnetic force, an elastic roller having a stable shape can be manufactured without trouble such as a dress.

[Comparative Example 1]
An elastic roller was manufactured in the same procedure as in Example 1 except that the magnetic back-up mechanism was not used.

  When the desired crown amount was set to 90 ± 2 μm, in order to obtain an elastic roller in the above range, it was necessary to perform dressing three times and finely adjust the grindstone shape. Similarly, as a result of polishing 10,000 pieces, the crown amount increased by 14 μm. (Maximum crown amount per 1000-minimum crown amount) In order to continue production, it is necessary to dress again and adjust the shape.

[Comparative Example 2]
An elastic roller was manufactured in the same procedure as in Example 1 except that the elastic roller being polished was pressed by the backup roller.

  The mechanism for pressing the elastic roller with the backup roller is shown in FIG. The backup roller 82 is rotatably supported and is held on a polishing machine via a holding table 81. The backup roller is pressed against the elastic roller being polished by a spring 83. The pressure can be adjusted by changing the strength of this spring. Further, the backup roller used in this example is provided with an elastic layer having a thickness of 2 mm made of rubber having a hardness of 80 (JIS K6253 type A) around a metal core Φ8. If the width of the backup roller is too long, the central portion in the longitudinal direction does not come into contact with the backup roller. The adjustment of the applied pressure was performed by measuring the amount of deflection of the metal core, and adjusted so as to be the values shown in Table 1. As shown in Table 1, the measurement results of the crown amount and the like showed that although the crown amount could be changed as compared with Comparative Example 1, the unevenness amount became large. In addition, uneven gloss was also observed on the appearance. This is probably because the portion that was pressed during polishing recovered after polishing and became uneven. After that, surface treatment with ultraviolet rays was performed in the same manner as in Example 1 and image evaluation was performed as a charging roller. .

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging member 3 Exposure light 4 Developing member 5 Transfer member 6 Transfer material 7 Fixing member 8 Cleaning member 9 Toner 10 Rotating shaft 21 Rubber elastic layer 22 Core metal

Claims (4)

Manufacturing method for polishing the outer peripheral surface of an elastic roller by rotatably supporting both ends of an elastic roller formed with a cylindrical elastic layer around a ferroelectric core and pressing a wider cylindrical grindstone than the elastic layer The method of manufacturing an elastic roller, comprising: polishing the cored bar while applying a magnetic force in the approaching direction of the grindstone or in the opposite direction thereof. The method for producing an elastic roller according to claim 1, wherein the means for applying the magnetic force is a magnet and is disposed on the opposite side of the grindstone with respect to the elastic roller that rotatably supports the both ends. The elastic body roller according to claim 1 or 2, wherein an electromagnetic coil is disposed at an end portion of the core bar of the elastic roller rotatably supported at both ends so that a magnetic field is generated in a direction along a central axis of the core bar. Manufacturing method. In the manufacturing method of sequentially polishing a plurality of rollers, a step of calculating a magnetic force for setting the outer diameter of the roller after polishing to the target outer diameter from the deviation between the outer diameter of the roller at the longitudinal center after polishing and the target outer diameter; 4. The method of manufacturing an elastic roller according to claim 1, further comprising a step of polishing a next roller by controlling a current flowing through the electromagnet based on the calculated magnetic force. 5.