JP2011021675A - Conductive rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rolling bearing with conductivity low time-serially without using a conductive grease in the rolling bearing, and to not disturb an image by preventing an electrostatic image forming device using the same from being charged, and to exhibit an image fixing function under a satisfactory state stable along the lapse of time, in a fixing device provided with the electrostatic image forming device. <P>SOLUTION: A double plated layer 1a layered with a silver plated layer 1a<SB>2</SB>on a copper plated layer 1a<SB>1</SB>is provided on a surface of an inner ring 1 in the rolling bearing having a retainer 4 for holding rotatably a plurality of steel rolling elements 3 between the inner ring 1 and an outer ring 2, and a double plated layer 2a layered with a silver plated layer 2a<SB>2</SB>on a copper plated layer 2a<SB>1</SB>is provided on a surface of the outer ring 2. Surfaces of one or more of the rolling elements are formed of a coating film containing graphite or graphite steel, out of the plurality of steel rolling elements. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a conductive rolling bearing, an electrostatic image forming apparatus equipped with the conductive rolling bearing, and a fixing device of the electrostatic image forming apparatus.

  In general, in an electrophotographic apparatus such as a copying machine or a printing machine (printer) using an electrostatic image forming apparatus that develops and fixes an electrostatic latent image into a toner image, the electrostatic latent image is developed or fixed. In addition, it is necessary to rotatably support a photosensitive drum, a roll, and the like, and a rolling bearing is used for a rotating portion of such an apparatus.

  More specifically, the electrostatic image forming apparatus forms an electrostatic latent image on the surface of the photosensitive drum, attaches toner to the surface in a charged state, transfers it to a sheet such as paper, develops it, and heats it The roller bearing provided is pressed and fixed, and if it is charged, the electrostatic latent image and the unfixed image on the photosensitive drum are disturbed, so that a grounding mechanism for discharging static electricity from the end surface of the roll is required. .

  During a series of steps in such an electrostatic image forming apparatus, a fixing device that performs a fixing step is between a heating roller and a pressure roller that are in pressure contact with each other in order to heat and press a sheet on which an unfixed image is placed. However, the heat-resistant rolling bearing that supports the rotating roller also needs to be grounded and needs to be conductive.

  However, it is not preferable to separately provide a grounding mechanism for such a rolling bearing because the number of parts increases, and it is not preferable to discharge the charge using a conductive rolling bearing that can energize the inner ring and the outer ring without increasing the number of parts. It is preferable to be in a ground state.

As a conventional conductive rolling bearing, a conductive rolling bearing equipped with conductive grease, a conductive seal, and other conductive parts is well known.
For example, as a conductive grease to be filled in a rolling bearing, there is known a conductive grease in which carbon black having a particle diameter of 50 μm or less is added to a lubricating grease and this is used as a conductivity imparting agent or as a thickener. (Patent Document 1).

  Also known are rolling bearings for office machines such as copying machines, in which a coating with nickel plating or tin that has corrosion resistance and conductivity is formed on the inner diameter part of the inner ring and the outer diameter part of the outer ring (patent) Reference 2).

  Furthermore, a conductive lubricating film made of graphite, nickel containing polytetrafluoroethylene, or the like is provided on at least one of the inner ring and outer ring surfaces, or the surface of the rolling element. It is known to perform by electrolytic plating (Patent Document 3).

JP 2002-53890 A JP 2007-32607 A JP 2008-133877 A

  However, conventional rolling bearings for office machines such as copying machines formed with conductive nickel plating as described above have corrosion resistance in the coating, but the frictional force is not reduced sufficiently, and the lubricating material is insufficient. Must be supplemented with conductive lubricating grease.

  However, when conductive grease is used, the resistance value indicating the conductivity of the bearing becomes unstable over time. For example, a rolling bearing filled with conductive grease containing conductive carbon is used at a normal load of 12.3 N When used at 130 rpm, the resistance value becomes unstable after about 1 hour of use (see FIG. 5).

  Accordingly, an object of the present invention is to solve the above-described problems, and to use a conductive rolling bearing that has a low and stable conductivity over time without using conductive grease for the rolling bearing. In the electrostatic image forming apparatus, the electrostatic image is not disturbed, and in particular, the fixing device in such an electrostatic image forming apparatus has a good electrostatic image fixing function stably over time. .

  In order to solve the above-described problems, in the present invention, in a rolling bearing that rotatably holds a plurality of rolling elements between an inner ring and an outer ring, a copper plating layer is formed on the surface of the inner ring or the outer ring or both of these parts. This is a conductive rolling bearing characterized by providing a multi-layer plating in which silver plating layers are stacked.

  The conductive rolling bearing of the present invention configured as described above has a solid lubricating property and a conductive property on the inner ring or outer ring or the surfaces of both of these parts by a predetermined multi-layer plating. The nature is also sufficiently enhanced.

  Therefore, the conductivity of the rolling bearing is stably exhibited regardless of the dispersibility of the conductivity-imparting agent in the lubricating grease, that is, the conductivity (resistance value) is stable over time, and the rotational torque is solid lubricated. Is sufficiently low. In addition, the silver plating layer exhibits excellent effects on lubricity, thermal stability, corrosion resistance, and extreme pressure.

  Further, the conductive rolling bearing of the present invention does not necessarily contain, for example, conventional conductive grease, and since no conductive grease is used, a contact seal for preventing grease leakage is unnecessary, and the number of parts is reduced. It is possible to achieve both a reduction in torque and a reduction in torque.

When the silver plating layer is formed so as to be a silver plating layer having a layer thickness of 3 to 15 μm, the low friction characteristic is more stable with time and the conductivity is further stabilized with a sufficient thickness.
The reason for limiting the numerical value of the silver plating layer thickness as described above is that a thin film having a layer thickness of less than 3 μm is not preferable because the lubricity is not sufficient, and even if it is formed in a thick film having a thickness exceeding 15 μm, it is more remarkable. This is because there is no improvement in lubricity and conductivity, and the practicality is lowered, which is not preferable.

In addition, if the inner ring or outer ring provided with a multilayer plating on the surface or both of these parts are an inner ring or outer ring based on a conductive resin or both of these parts, it is also preferable in terms of weight reduction.
The inner ring or outer ring or both of these parts may be an inner ring or outer ring or both of these parts having a conductive resin film on the surface of the base material. As a result, the base material is made of various materials such as metal, resin, and ceramics. Can be adopted.

  In addition, the rolling elements are usually made of metal that is electrically conductive to some extent, such as steel balls, but in order to reduce the coefficient of friction and increase the conductivity without using lubricating grease, a plurality of rolling elements are used. Among the rolling elements, it is preferable that the surface of at least one or more rolling elements is formed of a film containing graphite. Further, not only the surface of the rolling element but also the entire rolling element is formed of a conductive material is more preferable in order to obtain durable conductivity, and in particular, among the plurality of rolling elements, A mode in which one or more rolling elements are formed of graphite steel can be applied.

  The conductive rolling bearing configured as described above does not require charging for electrostatic image formation if an electrostatic image forming apparatus such as a copier or printer is equipped to support a rotating shaft such as a photosensitive drum or roller. This is preferable in order to effectively eliminate static electricity in such a portion and form an electrostatic image on the photosensitive drum in the electrostatic image forming apparatus precisely and without disturbance. Further, if the rotating roller is a fixing device of the electrostatic image forming apparatus supported by the conductive rolling bearing described above, the image fixing function is good and can be stably exhibited over time.

  Since the present invention is a conductive rolling bearing provided with a multilayer plating in which a silver plating layer is superimposed on a copper plating layer on the surface of the inner ring or outer ring or both of these parts, there is no need to use conductive grease. There is an advantage that the conductive rolling bearing is stable with low conductivity over time.

  If the inner ring or outer ring, or both of these parts are based on a conductive resin, or have a conductive resin film on the surface of the base, the above effects can be reduced and the substrate can be diversified. To become.

  In addition, the electrostatic image forming apparatus using such a conductive rolling bearing has no disturbance of the electrostatic image on the photosensitive drum, and the image fixing function also in the fixing apparatus having such an electrostatic image forming apparatus. Is stable over time, and has an advantage that the function can be satisfactorily exhibited.

Cross-sectional view of main parts of conductive rolling bearing and fixing roller of embodiment 1 is an enlarged cross-sectional view of the inner plating of the inner ring of FIG. 1 is an enlarged cross-sectional view of the outer ring of FIG. Sectional view of the fixing roller of the embodiment Chart showing the relationship between resistance value and time of conventional conductive rolling bearings

Embodiments of a conductive rolling bearing and a fixing device of an electrostatic image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.
First, as shown in FIGS. 1 to 3, the embodiment of the conductive rolling bearing according to the present invention includes a cage 4 that rotatably holds a plurality of rolling elements 3 made of steel balls between an inner ring 1 and an outer ring 2. A rolling bearing having a multilayer plating 1a in which a silver plating layer 1a ₂ is superimposed on a copper plating layer 1a ₁ on the surface of the inner ring 1 and a silver plating layer on the copper plating layer 2a ₁ on the surface of the outer ring 2; This is a conductive rolling bearing provided with a multilayer plating 2a in which 2a ₂ is stacked.

The high conductivity of silver and copper constituting the multilayer plating 1a and 2a shown in FIG. 1 is well known, and the excellent solid lubricity of the soft metal by the silver plating layers 1a ₂ and 2a ₂ is exhibited. The copper plating layers 1a ₁ and 2a ₁ provided on the surface exhibit excellent conductivity.

  In order to provide such a copper plating layer or silver plating layer, a known electrolytic plating or electroless plating technique may be used. As a known copper plating bath, for example, as a copper bath for electrolysis, a copper sulfate bath or a borofluoride bath is used. Examples thereof include a copper halide bath, a copper cyanide bath, a copper pyrophosphate bath, or an electroless copper bath.

  The base material, which is the main constituent material other than the inner ring or outer ring or the surfaces of both parts provided with the multi-layer plating, may be made of a conductive resin as well as a metal such as a bearing steel. The conductive resin is a resin in which a conductivity-imparting agent is mixed, and the resin used at that time may be either a thermoplastic resin or a thermosetting resin, and has moldability, mechanical strength, and heat resistance. In view of the above, a resin such as a well-known engineering plastic may be employed, and a typical example thereof is a polyphenylene sulfide resin.

  Examples of the conductivity-imparting material added to the resin, that is, a conductive material in powder, fiber, flake or other form that is miscible with the resin include, for example, metals such as silver, copper, and nickel, graphite, carbon black, and zinc oxide. Etc.

  Further, even when the entire base material of the inner ring or the outer ring is not the conductive resin as described above, it is sufficient that at least the entire surface of the base material or a part thereof is formed of the conductive resin. In order to cover a part or the whole of the base material of the inner ring or the outer ring with the conductive resin film, a coating solution obtained by dissolving the resin constituting the conductive resin with a solvent is applied to a part or the whole of the base material, If necessary, a film made of a conductive resin cured by heat-treating the coating film can be obtained.

Also, among the plurality of rolling elements, one or more rolling elements are formed of graphite steel, or the surface of one or more rolling elements contains a conductive material, preferably a conductive film containing graphite. It is also possible to adopt an embodiment formed by
In order to form a conductive film on the surface of a rolling element, for example, as described above, a mixed liquid of graphite, a resin material, and a solvent is applied, and a conductive film is formed by heat-treating the coating film as necessary. Can do.

  The binder resin used when preparing a conductive coating solution by dispersing a conductive material such as graphite in the resin includes polyamide-imide resin, polyimide resin, epoxy resin, phenol resin, and polyether sulfone. And polyarylene sulfide resins such as polyphenylene sulfide resins and the like. Among these, a material having a crosslinking property is preferable because of high adhesion strength.

  For example, the content of graphite or the like is 10 to 70% by weight, preferably 20 to 60% by weight, and more preferably 30 to 50% by weight with respect to the binder resin. When the content of the fluorinated graphite is less than the predetermined range, the lubricity is insufficient, and when the content exceeds the predetermined amount, the binder resin that plays a role as a binder of the coating is relatively less, so the base material This is because the adhesion strength to the lowering is not preferable.

  Such a binder is diluted with, for example, ethylbenzene, xylene, N-methylpyrrolidone, methyl ethyl ketone, toluene, or another organic solvent called so-called thinner, and the graphite described above is mixed therewith. In this way, coating for forming a resin film containing graphite on the inner ring or outer ring or the surface of both these parts can be performed easily. That is, as a method of forming the film, so-called spraying, dipping, etc. The painting method can be adopted.

  As shown in FIGS. 1 to 4, the conductive rolling bearing manufactured as described above is applied to a fixing device of an electrostatic image forming apparatus. The fixing roller 5 is made of a soft metal in which a linear or rod-like heater 6 is built in a shaft center portion, and is formed in a cylindrical shape with a small-diameter shaft portion 5a protruding at both ends.

  The fixing roller 5 is made of a metal material having excellent thermal conductivity such as aluminum or aluminum alloy (A5056, A6063, etc.), and the surface is finished by turning or polishing, and the surface is non-adhesive such as fluororesin. High resin is coated. The fixing roller 5 is rotatably supported by a housing 8 via a conductive rolling bearing 7 formed of a deep groove ball bearing with small-diameter shaft portions 5a at both ends, and a gear (not shown) that receives rotational power at a separate end. Is provided.

A pressure roller (not shown) is provided in contact with the fixing roller 5 in parallel, and it is preferable that both ends of the pressure roller are rotatably supported by the housing 8 via conductive rolling bearings.
The pressure roller is typically a core metal such as iron or aluminum with a coating made of silicon rubber or the like, but like the fixing roller, a linear or rod-like heater is attached to the axial center of the pressure roller. Some are built-in and are supported by bearings at both ends with conductive rolling bearings.

The copy paper is sent between the rotationally driven fixing roller 5 and the driven pressure roller, and the toner image is fixed by heat fusion by the fixing roller 5.
Therefore, the electrostatic image forming apparatus in which the conductive rolling bearing is mounted for supporting the roller is not charged and does not disturb the image of the electrostatic image, and the fixing device including such an electrostatic image forming apparatus is The image fixing function can be exhibited stably and in good condition over time.

  The above fixing device is used in an electrostatic image forming apparatus such as a copying machine. However, instead of the roller, the rotating shaft of the photosensitive drum may be supported by the same conductive rolling bearing as described above. The electrostatic image forming apparatus can discharge a charge other than a necessary portion to secure a stable ground state.

[Example 1]
The inner ring and the outer ring of a deep groove ball bearing (ball: made of bearing steel) having an inner diameter of 30 mm, an outer diameter of 42 mm and a width of 7 mm are covered with a copper plating layer (layer thickness: 5 μm) by electrolytic plating, and silver is superimposed on the outer ring. A plating layer (layer thickness: 10 μm) was coated to provide multilayer plating.
For the obtained conductive rolling bearing, the electrical resistance value between the inner diameter surface of the inner ring and the outer diameter surface of the outer ring was measured continuously for 3 hours, and the maximum resistance value (kΩ) as a result was shown in Table 1. .

[Example 2]
In Example 1, the conductive property was exactly the same except that it was coated with a copper plating layer (layer thickness: 10 μm) and overlaid with a silver plating layer (layer thickness: 5 μm) to provide a multilayer plating. A rolling bearing was produced, and the electrical resistance value was measured in the same manner as in Example 1. The results are also shown in Table 1.

[Examples 3 and 4]
In Example 1, among a plurality of rolling elements, the rolling element is formed of graphite steel (graphite 90% or more) (Example 3) or coated with an epoxy resin containing 25% of graphite (Example 4). These were incorporated as balls in a deep groove ball bearing having an inner diameter of 30 mm, an outer diameter of 42 mm, and a width of 7 mm made of bearing steel.
With respect to the obtained conductive rolling bearing, the electrical resistance value between the inner diameter surface of the inner ring and the outer diameter surface of the outer ring was measured, and the result is shown in Table 1.

[Comparative Example 1]
In Example 1, a conductive rolling bearing was manufactured in exactly the same manner except that it was coated with a copper plating layer (layer thickness: 20 μm) instead of the multilayer plating, and the electric resistance value was measured in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative Example 2]
An inner ring and an outer ring of a deep groove ball bearing (ball: made of bearing steel) having an inner diameter of 30 mm, an outer diameter of 42 mm, and a width of 7 mm were made by cutting with polyphenylene sulfide resin (mixed with 35% by weight of carbon).
With respect to the obtained conductive rolling bearing, the electrical resistance value between the inner diameter surface of the inner ring and the outer diameter surface of the outer ring was measured, and the result is shown in Table 1.

[Comparative Example 3]
About the conductive rolling bearing obtained by dropping 0.05 ml of conductive ionic liquid (commercially available) inside a deep groove ball bearing (ball: made of bearing steel) with an inner diameter of 30 mm, an outer diameter of 42 mm and a width of 7 mm. The electrical resistance value between the inner diameter surface of the outer ring and the outer diameter surface of the outer ring was measured, and the results are shown in Table 1.

[Comparative Example 4]
Except that a ternary alloy film of nickel (Ni), phosphorus (P), and boron (B) was formed as a plating layer in Example 1 (referred to as caniboron plating in the table), it was exactly the same as Example 1. In this way, a conductive rolling bearing was manufactured, and the electrical resistance value was measured in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative Example 5]
Deep grease ball bearing with inner diameter 25mm x outer diameter 37mm x width 7mm made of bearing steel made by blending 70wt% of lubricating grease with base oil of poly α olefin oil and 30wt% of conductive carbon The electrical resistance value between the inner ring surface of the inner ring and the outer ring surface of the outer ring was measured, and the results are also shown in Table 1.

  As is clear from the results in Table 1, the rolling bearings of the examples in which the surfaces of the inner ring, the outer ring, or both of these parts are formed by predetermined multilayer plating have solid lubricity and conductivity. Its durability was also sufficiently high.

  On the other hand, with a single layer copper plating, conductive PPS film, ionic liquid, and craniboron plating that is not a predetermined multi-layer plating, the inner ring or the outer ring, or a rolling bearing formed with the surface of these parts, or lubricated with conductive grease The rolling bearing has a maximum resistance value as high as 10 KΩ or more, and its lubricity, conductivity and durability cannot be sufficiently obtained.

DESCRIPTION OF SYMBOLS 1 Inner ring 1a, 2a Multi-layer plating 2 Outer ring 1a ₁ , 2a ₁ Copper plating layer 1a ₂ , 2a ₂ Silver plating layer 3 Rolling element 4 Cage 5 Fixing roller 5a Small diameter shaft part 6 Heater 7 Conductive rolling bearing 7
8 Housing

Claims (8)

  In a rolling bearing that rotatably holds a plurality of rolling elements between an inner ring and an outer ring, a multilayer plating in which a silver plating layer is superimposed on a copper plating layer is provided on the surface of the inner ring or the outer ring or both of these parts. Characteristic conductive rolling bearing.   The conductive rolling bearing according to claim 1, wherein the silver plating layer is a silver plating layer having a layer thickness of 3 to 15 μm.   3. The conductive rolling bearing according to claim 1, wherein the inner ring or the outer ring or both of these parts are an inner ring or an outer ring based on a conductive resin, or both of these parts.   The conductive rolling bearing according to claim 1 or 2, wherein the inner ring or the outer ring or both of these parts are an inner ring or an outer ring having a conductive resin film on the surface of the base material, or both of these parts.   The electroconductive rolling bearing in any one of Claims 1-4 in which the surface of one or more rolling elements is formed with the membrane | film | coat containing graphite among several rolling elements.   The conductive rolling bearing according to any one of claims 1 to 4, wherein at least one of the plurality of rolling elements is formed of graphite steel.   An electrostatic image forming apparatus in which a rotating drum or roller is supported by the conductive rolling bearing according to claim 1.   A fixing device for an electrostatic image forming apparatus, wherein the rotating roller is supported by the conductive rolling bearing according to claim 1.

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