JP2008133888A - Hollow shaft for roller, roller, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight hollow shaft for a roller contributing to form a high-quality image, and a lightweight roller and an image forming device forming the high-quality image over a long period of time. <P>SOLUTION: The hollow shaft for the roller includes a cylindrical shaft body 5A, and shaft end parts 10A inserted into both end parts of the shaft body 5A. In the hollow shaft 1A for the roller, a relation between the whole length Lg of the shaft body 5A and the total length Lc of the axial insertion length of the shaft end parts 10A into both end parts of the shaft body 5A satisfies the formula; 0.025<Lc/Lg<0.20, and a relation between the whole length Lg of the shaft body 5A and the whole length Ls of the hollow shaft 1 for the roller satisfies the formula; 0.75<Lg/Ls≤1. The roller is provided with an elastic layer on the peripheral surface of the hollow shaft 1A for the roller. The image forming device is provided with the above roller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hollow shaft for a roller, a roller, and an image forming apparatus, and more particularly, a lightweight hollow shaft for a roller that contributes to forming a high-quality image, a roller including the hollow shaft for a roller, and The present invention relates to an image forming apparatus provided with this roller.

  2. Description of the Related Art Conventionally, for example, printers such as laser printers and video printers, copiers, facsimiles, and composite machines of these types are equipped with various rollers having an elastic layer formed on the outer peripheral surface of a shaft. Examples of the various rollers include a cleaning roller, a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feeding / conveying roller, and a fixing roller.

  In recent years, image forming apparatuses have been made into color images, and performances such as downsizing, higher image definition, and higher printing speed have been rapidly improved. In order to improve these performances in the image forming apparatus, it is effective to reduce the weight of various rollers for the purpose of downsizing the driving mechanism for driving the rollers, reducing the rotational torque of the rollers, and the rotational stability of the rollers. . In order to reduce the weight of the roller, the elastic layer of the roller is designed to achieve a predetermined function. Therefore, rather than reducing the weight of the elastic layer without degrading these functions, a relatively small amount of metal or the like is used. It is advantageous to reduce the weight of the shaft, which is often formed in a solid body with a heavy material.

  As an example of a roller whose shaft is lightened, for example, a roller using a shaft formed in a hollow body is known, and more specifically, “a steel shaft end at both ends of a steel pipe portion”. There is a developing roll characterized in that it comprises a core metal that is airtightly friction-welded at the portion and a rubber elastic layer provided on the outer periphery of the core metal (see Patent Document 1). Further, as another example of a roller whose shaft is lightened, for example, a roller using a shaft formed of a resin in a solid body or a hollow body is also known (see, for example, Patent Document 2).

  By the way, in order to form a high-quality image in the image forming apparatus, it is necessary that the roller mounted on the image forming apparatus abuts or presses the contacted body evenly in the longitudinal direction with a predetermined contact pressure. is there. However, if a roller with a lighter shaft is attached to the image forming apparatus, the contact state or pressure contact state between the roller and the contacted body cannot be adjusted uniformly in the circumferential direction and / or longitudinal direction of the roller. In some cases, the quality of the formed image deteriorates. In particular, when a roller having a lighter shaft is attached to an image forming apparatus with improved characteristics, the quality of the formed image may be greatly reduced.

JP 2000-275955 A JP 2003-195601 A

  An object of the present invention is to provide a lightweight roller hollow shaft that contributes to forming a high-quality image, and to provide a lightweight roller and an image forming apparatus capable of forming a high-quality image. To do.

As means for solving the problems,
Claim 1 is a hollow shaft for a roller having a cylindrical shaft main body and shaft end portions fitted into both end portions of the shaft main body, and an axis line between the both end portions of the shaft main body and the shaft end portion. The relationship between the total insertion length Lc along the direction and the total length Lg of the shaft body satisfies the following formula (1), and the relationship between the total length Lg of the shaft body and the total length Ls of the hollow shaft for rollers is as follows. It is a hollow shaft for rollers characterized by satisfying formula (2),
(1) 0.025 <Lc / Lg <0.20
(2) 0.75 <Lg / Ls ≦ 1
Claim 2 is the hollow shaft for rollers according to claim 1, wherein the shaft end portion has a support shaft sharing an axis with the shaft end portion.
The roller shaft according to claim 1 or 2, wherein the shaft main body and the shaft end are formed of the same material.
Claim 4 is a roller comprising an elastic layer on the outer peripheral surface of the hollow shaft for rollers according to any one of claims 1 to 3,
A fifth aspect of the present invention is an image forming apparatus comprising the roller according to the fourth aspect.

  In the roller hollow shaft according to the present invention, the insertion length of the shaft end inserted into both ends of the cylindrical shaft body, and the total length of the shaft body with respect to the total length of the roller hollow shaft are adjusted to an appropriate length. As a result, the weight of the shaft main body and the axis of the shaft end coincide with each other without sacrificing the weight reduction, and at the same time, the shaft does not become eccentric even if rotated. That is, in the hollow shaft for a roller according to the present invention, the insertion length Lc of the shaft end and the total length Lg of the shaft main body are in the following relationship, Lc / Lg is more than 0.025 and less than 0.20. The total length Ls of the hollow shaft for the roller and the total length Lg of the shaft main body are in the following relationship: Lg / Ls is in the range of more than 0.75 and 1 or less. The distance from the center line of the shaft to the outer peripheral surface is uniform in the circumferential direction, and is not greatly decentered even when rotated. As a result, a roller having an elastic layer formed on the hollow shaft for the roller is used in the image forming apparatus. In addition to the case where the roller is mounted, when the roller is mounted on the image forming apparatus and rotated, the roller is in contact with or pressed against the contacted body evenly in the longitudinal direction with a predetermined contact pressure. Can hold That. Therefore, according to the present invention, a lightweight roller hollow shaft that contributes to forming a high-quality image, a lightweight roller capable of forming a high-quality image, and a high-quality image are formed. An image forming apparatus capable of performing the above can be provided.

1 and 2 are views showing a roller hollow shaft 1A (sometimes referred to as a shaft 1A) which is an embodiment of a roller hollow shaft according to the present invention. The shaft 1A is a cylindrical shape. A shaft main body 5A and two shaft end portions 10A fitted into both end portions of the shaft main body 5A are provided. The roller hollow shaft 1A has a total length Lc of insertion lengths (Lc ₁ and Lc ₂ , see FIG. 2) along the axial direction between both ends of the shaft main body 5A and the shaft end 10A, and the shaft main body 5A. The relationship between the total length Lg and the total length Lg of the shaft body 5A and the total length Ls of the roller hollow shaft 1A satisfy the following expressions (1) and (2 ′), respectively.

(1) 0.025 <Lc / Lg <0.20
(2 ′) 0.75 <Lg / Ls <1

  As shown in FIGS. 1 and 2, the shaft body 5A has openings at both ends thereof (hereinafter referred to as both-end openings), and a fitting portion 6 together with a shaft end 10A to be described later. A cylindrical body having an enlarged inner diameter in a region from a predetermined position to both end openings is formed, and a later-described elastic layer is formed on a part or all of the outer surface. A region in which the inner diameter from a predetermined position to the opening of both ends is expanded so that the shaft body 5A forms a fitting portion 6 together with a shaft end portion 10A described later at both ends (hereinafter referred to as an inner diameter expanded region). 10A), a shaft end portion 10A, which will be described later, is fitted into the inner diameter enlarged region, thereby forming a fitting portion 6 that is firmly fitted, and the shaft end portion 10A. Is prevented from entering the shaft main body 5A, and the dimensional stability of the entire length Ls of the hollow roller shaft 1A can be maintained. The shaft body 5A may or may not have conductive properties, and the presence or absence of the conductive properties is determined according to the use of the roller.

  The shaft main body 5A only needs to have a uniform outer diameter over the axial direction, and is adjusted to a desired thickness according to the use of the roller. The outer diameter of the shaft body 5A is usually adjusted to, for example, about 5 to 60 mm, and preferably adjusted to about 10 to 30 mm. When the shaft main body 5A has an outer diameter within the above range, and the thickness of the shaft main body 5A is adjusted to, for example, about 0.5 to 8 mm, preferably about 1 to 5 mm. As a result, it is possible to maintain a state in which the roller manufactured using the shaft 1A is in contact with or pressed against the contacted body evenly in the longitudinal direction with a predetermined contact pressure. it can. Further, by satisfying the expressions (1) and (2) and optimizing the thickness of the shaft body 5A as described above, the weight reduction of the roller hollow shaft 1A can be greatly sacrificed. In addition, the axis of the shaft main body 5A and the axis of the shaft end portion 10A can be made to coincide with each other, and at the same time, the roller hollow shaft 1A can be prevented from being eccentric.

The shaft main body 5A has a uniform thickness over its axial direction. As shown in FIG. 2, the inner diameter enlarged region is formed such that the inner diameter is increased and the thickness is reduced. Yes. The thickness of the inner diameter expanded region may be a thickness that can maintain the state where the shaft end portion 10A is fitted in the inner diameter expanded region of the shaft body 5A. The inner diameter of the inner diameter enlarged region may be adjusted so as to have the thickness. However, if the inner diameter is too smaller than the outer diameter of the fitting portion 12A described later, the fitting portion 12A is inserted into the inner diameter enlarged region. In addition, even if the insertion portion 12A can be inserted into the inner diameter enlarged region, the vicinity of the end portion of the shaft body 5A may be enlarged due to the insertion of the insertion portion 12A. In consideration of this point, the inner diameter of the inner diameter enlarged region is preferably adjusted to an inner diameter that is within the thickness range and has a predetermined tolerance with respect to an outer diameter of the insertion portion 12A described later. Here, the predetermined tolerance is “squeeze fit” defined in “2.2 Correlation of Tolerance Areas in Commonly Used Axis Reference Fits” of JIS B0401 (1986) with respect to the outer diameter of the insertion portion 12A. The tolerance corresponding to the tolerance zone class “P6 to X7” of the axis of the shaft, that is, the dimensional difference is about −10 to about −70 μm. When the inner diameter of the inner diameter enlarged region is adjusted to an inner diameter having a predetermined tolerance, a shaft end portion 10A described later is fitted into the shaft body 5A to form a strong fitting portion 6, and the drive generated by the roller driving mechanism The force can be reliably transmitted to the shaft body 5A. As shown in FIG. 2, the length in the axial direction in the inner diameter enlarged region is preferably the same as the length into which the shaft end portion 10A is fitted. Therefore, in the shaft body 5A, the insertion lengths Lc ₁ and Lc It is adjusted to the same length as ₂ .

  The shaft body 5A only needs to have a length capable of forming an elastic layer having a predetermined length in accordance with formulas (1) and (2 ′) described later and the use of a roller. The length is adjusted so that an elastic layer having a length to which A3 paper can be applied can be formed. Specifically, for example, the shaft body 5A is adjusted to a length Lg of about 200 to 400 mm.

  The shaft body 5A may be formed of a material having a desired strength. Examples of such a material are usually metals such as iron, aluminum, stainless steel, brass, and alloys thereof, or thermoplastic resins. Or resin, such as a thermosetting resin, etc. are mentioned. Among these, a metal is preferable, and aluminum or stainless steel is particularly preferable in that it can be reduced in weight and has desired strength and conductivity.

  When the shaft body 5A requires electrical conductivity, the metal may be used, or, for example, an insulating core formed of the resin may be plated, and the resin is electrically conductive. You may use the material which mix | blended carbon black or metal powder etc. as a property provision agent.

  As shown in FIGS. 1 and 2, the shaft end portion 10A is inserted into both end portions (both end opening portions) of the shaft main body 5A, more specifically, an inner diameter enlarged region, thereby the shaft main body 5A. Close both ends of the. The shaft end portion 10A integrally supports the shaft body 5A, transmits a driving force generated by a roller driving mechanism (not shown) to the shaft body 5A, and rotates the shaft body 5A. The shaft end portion 10A may or may not have conductive characteristics, and the presence or absence of the conductive characteristics is determined according to the use of the roller.

  As shown in FIGS. 1 and 2, the shaft end portion 10A is fitted into the shaft main body 5A and a fitting portion 12A that forms a solid cylindrical body having an outer diameter that can be fitted into the inner diameter enlarged region of the shaft main body 5A. And a support shaft 13 that forms a cylindrical body having an outer diameter smaller than that of the fitting portion 12 </ b> A, which is formed so as to protrude concentrically from one surface that is not formed.

  The fitting portion 12A only needs to have an outer diameter that can be fitted into the inner diameter enlarged area. For example, within a predetermined tolerance in the inner diameter of the inner diameter enlarged area, The outer diameter should be slightly larger. In addition, from the viewpoint of manufacturing, the outer diameter of the insertion portion 12A may have an appropriate tolerance.

  The fitting portion 12A is fitted into the inner diameter enlarged region of the shaft body 5A to form the fitting portion 6 together with the inner diameter enlarged region, that is, the shaft body 5A. Therefore, the insertion portion 12A has a length of the axial line so that the total length Lg of the shaft main body 5A and the total length Lc of the axial length of the fitting portion 6 satisfy Expression (1) described later. Adjusted.

  The insertion portion 12A is formed solid. When the fitting portion 12A is formed solid, fitting portions 6 described later formed at both ends of the shaft main body 5A also become solid, and the strength of the shaft 1A can be maintained. As a result, when a roller manufactured using the shaft 1A is attached to the image forming apparatus, the roller can be brought into contact with or pressed against the contacted body evenly in the longitudinal direction with a predetermined contact pressure, and the shaft end The fitting state between the portion 10A and the shaft main body 5A becomes strong, and the shake of the shaft 1A can be reduced.

  As shown in FIGS. 1 and 2, the support shaft 13 is concentric with the insertion portion 12A, that is, is formed in a cylindrical body that shares the shaft with the insertion portion 12A and protrudes from the insertion portion 12A. . The support shaft 13 is rotatably supported by a bearing provided in an image forming apparatus (not shown) or the like, and transmits a driving force generated by a driving mechanism (not shown) to the shaft body 5A via the fitting portion 12A. The length of the support shaft 13 is adjusted according to the supported bearing and the like, but the relationship between the total length Lg of the shaft body 5A and the total length Ls of the shaft 1A satisfies a formula (2 ′) described later. Adjusted. The diameter of the support shaft 13 is arbitrarily adjusted according to a bearing or the like.

As shown in FIGS. 1 and 2, the two shaft end portions 10A are formed in the same shape. That is, the lengths of the fitting portions 12A in the two shaft end portions 10A are adjusted to the same length. In other words, as shown in FIG. 2, the two fitting portions 6 in the shaft 1A are fitted in the axial direction. The lengths Lc ₁ and Lc ₂ are adjusted to the same length. The shaft end portion 10A may be formed integrally with the fitting portion 12A and the support shaft 13, or may be integrated by bonding or the like after being formed separately.

  The shaft end portion 10A, particularly the insertion portion 12A, may be formed of a material having a strength capable of supporting a roller that is inserted into the shaft body 5A and has an elastic layer formed on the outer peripheral surface of the shaft body 5A. Examples of such materials usually include metals such as iron, aluminum, stainless steel, brass, and alloys thereof, or resins such as thermoplastic resins and thermosetting resins. Among these, a metal is preferable and aluminum or stainless steel is particularly preferable in that sufficient strength and conductivity can be ensured. The support shaft 13 may be formed of the same material as the insertion portion 12A or may be formed of a different material.

  The shaft end portion 10A may be formed of the same material as the shaft main body 5A or may be formed of a different material. When the shaft main body 5A and the shaft end portion 10A are formed of different materials, for example, the shaft main body 5A formed of aluminum with light weight and high strength and the shaft end portion 10A formed of stainless steel with higher strength are used. Is mentioned.

As shown in FIGS. 1 and 2, the shaft 1A is formed of a shaft main body 5A and two shaft end portions 10A, and the shaft end portions 10A are fitted into both end portions of the shaft main body 5A. 6. In other words, the shaft has a fitting portion 6 formed by fitting the fitting portion 12A of the shaft end portion 10A into the inner diameter enlarged region of the shaft body 5A. In the shaft 1A thus formed, the relationship between the total length Lc of the insertion length along the axial direction between the both ends of the shaft main body 5A and the shaft end 10A and the total length Lg of the shaft main body 5A is expressed by the following formula (1 ) Is satisfied.
(1) 0.025 <Lc / Lg <0.20

That is, as shown in FIG. 2, when the shaft end portion 10A is inserted into the end portion of the shaft body 5A, the fitting portion 6 formed by inserting the shaft end portion 10A into the end portion of the shaft body 5A is It has an appropriate length so as not to cause eccentricity of the portion 10A, and is along the axial direction between the both ends of the shaft main body 5A and the shaft end 10A with respect to the total length Lg of the shaft main body 5A. The total length Lc (Lc / Lg) of the insertion lengths Lc ₁ and Lc ₂ is in the range of more than 0.025 and less than 0.20. When the Lc / Lg is 0.025 or less, the distance from the center line to the outer peripheral surface of the shaft 1A becomes non-uniform in the circumferential direction, and the non-uniformity of the distance is particularly large when the shaft 1A is rotated. That is, the shake of the shaft 1A increases, and as a result, when the shaft 1A is rotated, the shaft 1A may be greatly decentered. On the other hand, when Lc / Lg is 0.20 or more, the weight of the shaft 1A cannot be sufficiently reduced. That is, when the Lc / Lg of the shaft 1A is in the above range, the driving torque of the roller is reduced not only when the roller having the elastic layer formed on the shaft 1A is attached to the image forming apparatus but also when the roller is rotated. In addition, the roller can maintain a state in which the roller abuts against or presses against the contacted body evenly in a circumferential direction and / or a longitudinal direction with a predetermined contact pressure. Despite being lightweight, it can contribute to forming a high-quality image. The Lc / Lg is preferably 0.04 or more and 0.18 or less, more preferably 0.08 or more and 0.16 or less, in that the weight reduction and the small runout of the shaft 1A can be achieved at a higher level. Is particularly preferred.

  Here, the deflection of the shaft 1A represents the uniformity of the distance from the center point of the shaft 1A to the outer peripheral surface of the shaft body 5A located on the plane when the shaft 1A is cut along an arbitrary plane perpendicular to the axis. . The shaft 1A is adjusted to a deflection of 0.05% or less. When the deflection of the shaft 1A is adjusted to 0.05% or less, not only when the roller having the elastic layer formed on the shaft 1A is mounted on the image forming apparatus, but also when the roller is rotated at a predetermined contact pressure. A high-quality image can be formed by contacting or pressing the contacted body evenly in the circumferential length and / or longitudinal direction.

Deflection of the shaft 1A, for example, the longest distance (maximum radius) L ₂ and the shortest distance to the outer circumferential surface of the shaft body 5A located on perpendicular the plane shaft 1A including the center point from the center point of the shaft 1A ( minimum radius) the difference between _{L 1} and _{(L 2 -L 1) (L} 2 and _{L 1} are not shown), as the value indicated by percentage with respect to the outer diameter of the shaft main body 5A, it is calculated. Specifically, the deflection of the shaft 1A is the longest distance from the center point of the shaft 1A to the outer peripheral surface of the shaft body 5A at a measurement point on a plane perpendicular to the shaft body 5A with respect to the outer diameter (r) of the shaft body 5A. It is a value indicating the difference (L ₂ −L ₁ ) between L ₂ and the shortest distance L ₁ as a percentage. More specifically, at each measurement point, the formula [(L ₂ −L ₁ ) / r] × Calculated as 100 (%). Here, the deflection of the shaft 1A is the longest measured by measuring the distance from the center point of the shaft 1A to the outer peripheral surface of the shaft body 5A at each measurement point with a laser length measuring machine while rotating the shaft 1A. From the distance and the shortest distance, it can be calculated by the above formula.

In the shaft 1A, the relationship between the total length Lg of the shaft main body 5A and the total length Ls of the shaft 1A satisfies the following formula (2 ′).
(2 ′) 0.75 <Lg / Ls <1

  That is, in the shaft main body 5A, the total length Lg with respect to the total length Ls of the shaft 1A is in the range of more than 0.75 and less than 1. When the Lg / Ls is 0.75 or less, the length of the support shaft 13 becomes too long, and the distance from the center line in the shaft 1A becomes non-uniform in the circumferential direction, especially when the shaft 1A is rotated. In addition, the non-uniformity of the distance becomes large, that is, the deflection of the shaft 1A becomes large. As is clear from FIGS. 1 and 2, the Lg / Ls does not become 1 or more in the shaft 1A. That is, if the Lg / Ls of the shaft 1A is in the above range, the roller having the elastic layer formed on the shaft 1A is not only applied to the image forming apparatus, but also when the roller is rotated. The state of being in contact with or pressed against the contacted body evenly in the longitudinal direction by the contact pressure can be maintained, and as a result, the shaft 1A can contribute to forming a high-quality image. The Lg / Ls is preferably 0.78 or more and 0.9 or less, and particularly preferably 0.8 or more and 0.9 or less in that the deflection of the shaft 1A can be adjusted to be smaller.

  The overall length Ls of the shaft 1A is adjusted according to the formulas (1) and (2 ′) and the usage of the roller. Specifically, for example, the overall length Ls of the shaft 1A is adjusted to about 200 to 500 mm. Is done.

  For example, when the shaft 1A is disposed in the image forming apparatus shown in FIG. 9 or the like, one end of the shaft 1A is grounded or a bias voltage is applied, for example, to the voltage of the image carrier or the developer. Functions such as the injection of the electric charge and the development of the latent image by conveying the developer from the image carrier.

  As shown in FIGS. 1 and 2, the shaft 1 </ b> A has a shaft end portion 10 </ b> A on the shaft main body 5 </ b> A so that the end portion of the inner diameter enlarged region of the shaft main body 5 </ b> A and the end face of the insertion portion 12 </ b> A come into contact with each other. It is inserted. At this time, the fitting portion 12A is adjusted to an outer diameter that can be fitted into the inner diameter enlarged region, and preferably, the inner diameter enlarged region is adjusted to an inner diameter having a predetermined tolerance with respect to the outer diameter of the fitting portion 12A. Therefore, the entire opening of the shaft main body 5A is fitted into the inner diameter enlarged region without greatly expanding the diameter. Therefore, the shaft main body 5A and the shaft end portion 10A are firmly fitted, and the driving force generated by the driving mechanism (not shown) is applied to the shaft main body 5A via the support shaft 13 and the fitting portion 12A supported by the bearing (not shown). As a result, the shaft body 5A can be rotationally driven as desired. Further, as shown in FIG. 2, the shaft 1 </ b> A includes the hollow portion of the shaft body 5 </ b> A and the solid fitting portions 6 at both ends thereof, so that the shaft 1 </ b> A can be reduced in weight. Since the shaft 1A has the total length Ls of the shaft 1A, the total length Lg of the shaft main body 5A, and the total length Lc of the fitting length, the shaft 1A is reduced in weight. However, the vibration of the shaft 1A can be reduced. As a result, not only when the roller having the elastic layer formed on the shaft 1A is mounted on the image forming apparatus, but also when the roller is rotated, the predetermined contact pressure is maintained. It is possible to maintain the contact state of the roller that is in contact with or pressed against the contacted body evenly in the longitudinal direction. Therefore, the shaft 1A can maintain high quality image quality even when the weight is reduced. In other words, the shaft 1A can contribute to forming a high quality image even when the weight is low.

  FIG. 3 is a view showing a roller hollow shaft 1B (sometimes referred to as a shaft 1B) which is another embodiment of the roller hollow shaft according to the present invention. The shaft 1B is a cylindrical shaft. A main body 5B and two shaft end portions 10A fitted into both end portions of the shaft main body 5B are provided, and the inner diameter in the vicinity of both end portions of the shaft main body 5B is not increased, and the thickness is uniform from one end to the other end. Is basically the same as the shaft 1A, except that In the shaft 1B, the inner peripheral surface region of the shaft main body 5B in contact with the fitting portion 12A that forms the fitting portion 6 shown in FIG. 3 corresponds to the inner diameter enlarged region of the shaft 1A.

  Therefore, the shaft 1B is similar to the shaft 1A because the total length Ls of the shaft 1B, the total length Lg of the shaft main body 5B, and the total length Lc of the insertion length satisfy the expressions (1) and (2 ′). Even if the weight of 1B is reduced, the shake of the shaft 1B can be reduced. As a result, in addition to the case where the roller having the elastic layer formed on the shaft 1B is attached to the image forming apparatus, It is possible to maintain the contact state of the roller that contacts or presses against the contacted body evenly in the circumferential direction and / or the longitudinal direction with a predetermined contact pressure. Therefore, the shaft 1B can maintain high quality image quality even when the weight is reduced, in other words, can contribute to forming a high quality image even when the weight is light.

  4 and 5 are diagrams showing a roller hollow shaft 1C (sometimes referred to as a shaft 1C) which is another embodiment of the roller hollow shaft according to the present invention. A cylindrical shaft main body 5B and two shaft end portions 10B fitted into both end portions of the shaft main body 5B are provided, and the inner diameter in the vicinity of both end portions of the shaft main body 5B does not increase, and extends from one end to the other end. It is basically the same as the shaft 1A except that it has a uniform thickness and the shaft end portion 10B has the flange portion 11 between the fitting portion 12A and the support shaft 13.

  The shaft body 5B is the same as the shaft body 5B of the shaft 1B. As shown in FIGS. 4 and 5, the shaft end portion 10 </ b> B is concentrically formed from a flange portion 11 that forms a disc body having a diameter substantially the same as the outer diameter of the shaft body 5 </ b> B, and one surface of the flange portion 11. 12A of insertion parts which form the solid cylindrical body which has a diameter smaller than the flange part 11 which protrudes, and the outer side smaller than the flange part 11 formed concentrically from the other surface of the flange part 11 It is basically the same as the shaft end portion 10A of the shaft 1A except that it includes a support shaft 13 that forms a cylindrical body having a diameter.

  As shown in FIGS. 4 and 5, the flange portion 11 is in contact with the end portion of the shaft body 5B, and the insertion length along the axial direction between the both ends of the shaft body 5B and the shaft end portion 10B, that is, The insertion amount of the insertion portion 12A is regulated. As shown in FIGS. 4 and 5, the insertion portion 12 </ b> A has a concentricity with the flange portion 11 on one surface of the flange portion 11, that is, shares a shaft with the flange portion 11, and has one end of the flange portion 11. It is formed in the cylindrical body which protrudes from the surface. 12 A of insertion parts are smaller than the diameter of the flange part 11, and the internal diameter expansion area | region (The inner peripheral surface area | region of the shaft main body 5B which contact | connects the insertion part 12A which forms the fitting part 6 shown by FIG. 5 in the shaft 1B) ) Is adjusted to an outer diameter that can be inserted into the outer diameter. Further, the fitting portion 12A forms the fitting portion 6, and the length of the axis is adjusted to a length satisfying the expression (1), similarly to the fitting portion 12A of the shaft 1A. . As shown in FIGS. 4 and 5, the support shaft 13 is on the opposite side of the portion to be inserted into the shaft body 5 </ b> B, in other words, on the surface opposite to the surface on which the insertion portion 12 </ b> A is formed in the flange portion 11. The flange portion 11 is concentric, that is, is formed so as to share the shaft with the flange portion 11.

  Since this shaft 1C is similar to the shaft 1A, the total length Ls of the shaft 1C, the total length Lg of the shaft body 5B, and the total length Lc of the insertion length satisfy the expressions (1) and (2 ′). Even if the weight of the shaft 1C is reduced, the shake of the shaft 1C can be reduced. As a result, in addition to the case where the roller having the elastic layer formed on the shaft 1C is attached to the image forming apparatus, the predetermined amount is also obtained when the roller is rotated. It is possible to maintain the contact state of the roller that is in contact with or pressed against the contacted body evenly in the circumferential direction and / or the longitudinal direction with this contact pressure. Therefore, according to the shaft 1C, high quality image quality can be maintained even if the weight is reduced. In other words, it is possible to contribute to forming a high quality image even if the weight is light.

  FIG. 6 is a view showing a roller hollow shaft 1D (sometimes referred to as a shaft 1D) which is another embodiment of the roller hollow shaft according to the present invention, and this shaft 1D is the shaft 1A. This is basically the same as the shaft 1A except that the fitting means 6 is provided with a fixing means 15.

  Therefore, the shaft 1D is similar to the shaft 1A because the total length Ls of the shaft 1D, the total length Lg of the shaft main body 5A, and the total length Lc of the insertion length satisfy the expressions (1) and (2 ′). Even if 1D is reduced in weight, the shake of the shaft 1D can be reduced. As a result, in addition to the case where a roller having an elastic layer formed on the shaft 1D is attached to the image forming apparatus, It is possible to maintain the contact state of the roller that contacts or presses against the contacted body evenly in the circumferential direction and / or the longitudinal direction with a predetermined contact pressure. Therefore, the shaft 1D can maintain high quality image quality even when the weight is reduced. In other words, the shaft 1D can contribute to forming a high quality image even when the weight is light.

  Further, since the fitting portion 6 is firmly joined to the shaft 1D by the fixing means, the shaft 1D receives the driving force generated by the driving mechanism when the roller having the elastic layer formed on the shaft 1D is attached to the image forming apparatus. Can be transmitted to the shaft body 5A as desired through the fitting portion 12A. As the fixing means, the shaft 1D employs a pin that penetrates the fitting portion 6 from the outer peripheral surface of the shaft main body 6A to the outer peripheral surface on the opposite side via the center of the shaft main body 5A. Without limitation, for example, a ring-shaped fixture that is provided on the outer peripheral surface of the shaft main body 6A and presses toward the center of the shaft main body 5A, a female screw formed on the inner peripheral surface in the vicinity of both ends of the shaft main body 5A, A combination with a male screw formed on the outer peripheral surface of the fitting portion 12 </ b> A and screwed into the female screw, adhesion, adhesion, or the like can be given. The fixing means 15 is preferably flush with the outer peripheral surface of the shaft body 5A.

  FIG. 7 is a view showing a roller hollow shaft 1E (sometimes referred to as a shaft 1E), which is still another embodiment of the roller hollow shaft according to the present invention, and this shaft 1E has a cylindrical shape. The shaft main body 5A is the same as the shaft 1A except that it includes a shaft main body 5A and two shaft end portions 10C fitted into both end portions of the shaft main body 5A, and the shaft end portion 10C does not have the support shaft 13.

  That is, as shown in FIG. 7, the shaft end portion 10 </ b> C is a solid disc body that forms an insertion portion 12 </ b> A having an outer diameter that can be inserted into an inner diameter enlarged region of the shaft body 5 </ b> A. In this case, on the outer peripheral surface of the end portion of the shaft main body 5A, there is a transmission means for transmitting a driving force generated by a driving mechanism equipped in the image forming apparatus, for example, teeth (not shown).

In the shaft 1E, as in the shaft 1A, the total length Lg of the shaft main body 5A and the total length Lc of the fitting length satisfy the formula (1), and the total length Ls of the shaft 1E and the total length Lg of the shaft main body 5A are The following formula (2 ″) is satisfied.
(2 ″) Lg / Ls = 1

  Therefore, since the shaft 1E satisfies the formula (1), as described above, the weight reduction and the small run-out of the shaft 1E can be achieved at a high level, and the shaft 1E satisfies the formula (2 ″). Therefore, the deflection of the shaft 1E can be adjusted to be smaller, and therefore, when the roller having the elastic layer formed on the shaft 1E is mounted on the image forming apparatus, the predetermined contact also occurs when the roller is rotated. It is possible to maintain the contact state of the roller that is in contact with or pressed against the member to be contacted evenly in the circumferential direction and / or the longitudinal direction with pressure. In other words, it is possible to contribute to forming a high-quality image even if it is lightweight.

  The roller hollow shafts 1 </ b> A to 1 </ b> E (hereinafter also referred to as the shaft 1) according to the present invention are formed of the shaft main bodies 5 </ b> A and 5 </ b> B (hereinafter may be referred to as the shaft main body 5), using the material. And shaft end part 10A-10C (henceforth the shaft end part 10) can be produced by a conventional method. For example, the shaft body 5 and the shaft end portion 10 can be formed into desired shapes by cutting, grinding, cutting out, various molding methods, and the like.

  The roller hollow shaft according to the present invention is not limited to the above-described embodiments, and various modifications can be made within a range in which the object of the present invention can be achieved.

  For example, in any of the shafts 1, the two shaft end portions 10 are formed in the same shape. However, in the present invention, the two shaft end portions do not need to be formed in the same shape, and are formed in different shapes. May be.

  Further, in the shaft 1, the lengths of the two fitting portions formed by fitting the shaft end portions 10 into the respective end portions of the shaft main body 5 are adjusted to the same length. The lengths of the joint portions do not need to be adjusted to the same length, and may be formed to different lengths.

  Furthermore, the shaft 1 has the entire insertion portion 12A or 12B in the shaft end portion 10 inserted into both end portions of the shaft body 5, but in this invention, the insertion portions to be inserted into both end portions of the shaft body 5 are It may be a part of it.

  Further, the shaft 1 has a hollow portion in an airtight state by the shaft body 5 and the shaft end portion 10, but in the present invention, the hollow portion of the shaft does not have to be in an almost airtight state. For example, the outer peripheral surface of the fitting portion may be formed in a concavo-convex shape so that the hollow portion of the shaft is opened, or a through hole is formed in the fitting portion so that the hollow portion of the shaft is opened. It may be made up.

  The shaft 1 is formed by inserting a cylindrical shaft end portion 10 into a cylindrical shaft main body 5. However, in the present invention, the shaft main body and the shaft end portion do not need to be cylindrical. For example, The shaft body and / or the shaft end may be an elliptical column or a polygonal column.

  As shown in FIG. 8, a roller 20 as an embodiment of the roller according to the present invention includes the roller hollow shaft 1 and an elastic layer 21. For example, in the image forming apparatus shown in FIG. Arranged.

The elastic layer 21 is formed by curing a rubber composition to be described later on the outer peripheral surface of the roller hollow shaft 1. The properties of the elastic layer 21 are determined according to the use of the roller, for example, an elastic layer that does not contain bubbles, a foamed elastic layer that contains bubbles or hollow portions, a conductive elastic layer, an insulating elastic layer, and the like. Formed. When the elastic layer 21 is formed on a conductive elastic layer, the elastic layer 21 preferably has an electric resistance value of 10 ¹ to 10 ⁷ Ω. The electric resistance value of the elastic layer 21 is determined by using an electric resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A, manufactured by Advantest Co., Ltd.), placing the roller 20 horizontally, a thickness of 5 mm, a width of 30 mm, and the roller 20 Applying 100V DC between the roller hollow shaft 1 and the electrode with a load of 500 g supported on both ends of the roller hollow shaft 1 by using a gold-plated plate having a length capable of mounting Then, it can be measured by reading the value of the electric resistance meter after one second and using this value as the electric resistance value.

  The elastic layer 21 preferably has a JIS A hardness of 20 to 70. When the elastic layer 21 has a JIS A hardness of 20 to 70, the contact area between the roller 20 and the contacted body can be increased, and a high-quality image can be formed.

  The elastic layer 21 has a thickness of 1 mm or more in that a uniform nip width between the contacted body and the elastic layer 21 can be secured in a contact state with the contacted body. Preferably, it is 4 mm or more. On the other hand, the upper limit of the thickness of the elastic layer 21 is arbitrarily adjusted according to the application, and is preferably, for example, 30 mm or less, and more preferably 20 mm or less.

  The rubber composition forming the elastic layer 21 contains rubber, and optionally further contains various additives, a conductivity imparting agent, and a foaming agent.

  The rubber is not particularly limited. For example, silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene. Examples thereof include liquid rubbers such as rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluororubber. Silicone or silicone-modified rubber is preferable in terms of excellent heat resistance and charging characteristics. These rubbers may be a liquid type or a millable type, and can be appropriately selected according to a molding method of the elastic layer 21, characteristics required for the elastic layer 21, and the like.

  Examples of the various additives include auxiliary agents such as chain extenders and crosslinking agents, catalysts, dispersants, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, and plasticizers. , Emulsifiers, heat resistance improvers, flame retardant improvers, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The conductivity-imparting agent is not particularly limited as long as it has conductivity, and examples thereof include conductive powder and ion conductive material. More specifically, examples of the conductive powder include carbons for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT in addition to conductive carbon such as ketjen black and acetylene black. In addition, metals such as titanium oxide, zinc oxide, nickel, copper, silver, germanium, and conductive polymers such as metal oxides, polyaniline, polypyrrole, polyacetylene, etc. can be mentioned. Specific examples include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride. The conductivity-imparting agent is added in an appropriate content so as to exhibit a desired electric resistance value when the elastic layer 21 is used alone or in combination of two or more. For example, the content of the conductivity-imparting agent in the rubber composition can be 2 to 80 parts by mass with respect to 100 parts by mass of the rubber.

  The foaming agent may be any foaming agent conventionally used for foamed rubber. Examples of the inorganic foaming agent include sodium bicarbonate and ammonium carbonate. Examples of the organic foaming agent include diazoamino derivatives, azonitrile derivatives, and azodicarboxylic acids. And organic azo compounds such as acid derivatives. Usually, an inorganic foaming agent is used when forming an open cell in which a plurality of bubbles are continuous, and when forming a closed cell in which a plurality of bubbles are dispersed or scattered without contacting each other. An organic foaming agent is used. The content of the foaming agent is appropriately adjusted according to the type of foaming agent.

  The rubber composition is prepared by using a rubber kneader such as a two-roller, a three-roller, a roll mill, a Banbury mixer, a dough mixer (kneader), etc., and the rubber, if necessary, various additives, a conductivity-imparting agent and a foaming agent. It is obtained by kneading, for example, for several minutes to several hours, preferably 5 minutes to 1 hour, at room temperature or under heating until uniformly mixed.

  The rubber composition should have a viscosity of, for example, 5 to 500 Pa · s at 25 ° C. in terms of excellent handling properties such as being able to be easily and uniformly injected into a mold. It is particularly good to have a viscosity of 5 to 200 Pa · s. The viscosity of the rubber composition can usually be adjusted by the type and / or blending amount of each component contained therein. If necessary, the viscosity can be adjusted with a solvent or the like.

  Examples of the rubber composition preferably used include a millable conductive silicone rubber composition and an addition-curable liquid conductive silicone rubber composition.

  The millable conductive silicone rubber composition comprises (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) a conductive material other than those belonging to the component (B). Contains functional materials.

R _n SiO _{(4-n) / 2} (1)
Here, R may be the same or different and is a substituted or unsubstituted monovalent hydrocarbon group, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. It is a hydrogen group, and n is a positive number of 1.95 to 2.05.

The addition-curable liquid conductive silicone rubber composition comprises (D) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (E) bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms; (F) an inorganic filler having an average particle size of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; and (G). An addition-curable liquid conductive silicone rubber composition containing a conductivity imparting agent and (H) an addition reaction catalyst can be mentioned.

  The roller 20 may include a coating layer (not shown) on the outer peripheral surface of the elastic layer 21. The material for forming the coating layer is not particularly limited, but when the roller 20 is used in the image forming apparatus 30 shown in FIG. 9 or the like, the roller 20 contacts or presses against the contacted body. Therefore, it is preferable that the material is hard to be permanently deformed, for example, alkyd resin, phenol-modified silicone modified alkyd resin, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluororesin, phenol Examples thereof include resins, polyamide resins, urethane resins, polyamideimide resins, and mixtures thereof. The coating layer is formed with a thickness of 1 to 100 μm, for example.

  The roller 20 can be manufactured by a conventional method. For example, after the shaft 1 is manufactured, a rubber composition is heat-molded on the outer peripheral surface of the shaft 1 using a mold whose inner surface has a mirror surface structure. Alternatively, the rubber composition can be produced by extrusion molding together with the shaft 1. The roller 20 is formed by heat-molding a rubber composition using a mold on the outer peripheral surface of the shaft body 5 or extruding the rubber composition together with the shaft body 5 to form the elastic layer 21, The shaft end portion 10 can be fitted into both end portions of the shaft body 5 for manufacturing. The molding conditions and molding method of the elastic layer 21 are not particularly limited as long as the rubber composition is cured, and the mold to be used is not particularly limited.

  Since the roller 20 is formed with the elastic layer 21 on the outer peripheral surface of the shaft 1, it is lightweight and can form a high-quality image over a long period of time.

  Next, an example of an image forming apparatus including the roller according to the present invention (hereinafter sometimes referred to as an image forming apparatus according to the present invention) will be described with reference to FIG.

  As shown in FIG. 9, the image forming apparatus 30 according to the present invention includes a rotatable image carrier 31 on which an electrostatic latent image is formed, for example, a photosensitive member, and abuts or presses against the image carrier 31 or A charging unit 32 that charges the image carrier 31, for example, a charging roller, and an exposure unit 33 that is provided above the image carrier 31 and forms an electrostatic latent image on the image carrier 31. A developing means 40 which is provided in contact with or pressure contact with the image carrier 31 or at a predetermined interval, supplies the developer 42 with a constant layer thickness to the image carrier 31 and develops the electrostatic latent image; The transfer unit 34 is provided so as to be pressed against the lower side of the image carrier 31 and transfers the developed electrostatic latent image from the image carrier 31 onto the recording paper 36, for example, a transfer roller, and the conveying direction of the recording paper 36. Developer 42 (provided downstream and transferred to recording paper 36) Fixing means 35 for fixing the electrostatic latent image), for example, a fixing device, and cleaning means 37 for removing the developer 42 not transferred to the recording paper 36 and remaining on the image carrier 31 and / or dust adhering to the image carrier 31. And. That is, the image carrier 31 is subjected to each action by the cleaning unit 37, the charging unit 32, the exposure unit 33, the developing unit 40, and the transfer unit 34 in order from the upstream side in the rotation direction. The image forming apparatus 30 includes a neutralizing unit (not shown) for removing an electrostatic latent image remaining on the surface of the image carrier 31 between the cleaning unit 37 and the charging unit 32 or the transfer unit 34 and the cleaning unit. 37 may be provided.

  The developing means 40 is basically formed in the same manner as the developing means provided in the conventional image forming apparatus, and is arranged in the same manner. For example, as illustrated in FIG. 9, the developing unit 40 has an opening at a position facing the image carrier 31, and includes a developer storage unit 41 that stores the developer 42, and a developer storage unit 41. A stirrer 43 that uniformly stirs the developer 42 and an opening of the developer storage portion 41 are provided in contact with the image carrier 31 or at a predetermined interval. 42 is provided above the developer carrier 44, and is provided in contact with the developer carrier 44 so as to reduce the layer thickness of the developer 42. A developer regulating member 45 that regulates and charges the developer 42 by frictional charging is provided.

  The developer 42 accommodated in the developer accommodating portion 41, that is, the developer 42 used in the image forming apparatus 30 according to the present invention, is a one-component system that can be charged by friction and can be fixed to the recording paper 36. The developer may be a dry developer or a wet developer, and may be a non-magnetic developer or a magnetic developer.

  The developer carrier 44 in the developing unit 40 contacts the blade 46 of the developer regulating member 45 to charge the developer 42. Therefore, the developer carrier 44 only needs to be configured so as to be able to charge the developer 42 by contacting the blade 46 of the developer regulating member 45, and includes, for example, an elastic layer having conductivity. Developing roller and the like. For example, for example, the roller 20 according to the present invention can be used as such a developer carrying member 44, particularly a developing roller.

  The image forming apparatus 30 includes a charging roller of a charging unit 32, a developing roller of a developer carrier 44, a transfer roller of a transfer unit 34, a fixing roller of a fixing unit 35, a cleaning roller (not shown) of a cleaning unit, and a pressure roller. Various rollers such as a paper feed / conveying roller (not shown) are provided, and the roller 20 according to the present invention is used as at least one of these various rollers. Preferably, the roller 20 according to the present invention is used as at least one of a charging roller, a developing roller, a transfer roller, and a fixing roller.

  The image forming apparatus 30 operates as follows. The developer regulating member 45 is disposed at the opening of the developing unit 40 such that the blade 46 is curved so that the blade 46 contacts the surface of the developer carrier 44 with a predetermined pressure. First, in the image forming apparatus 30, the developer 42 and / or dust on the surface thereof are removed by the cleaning unit 37 while the image carrier 31 rotates clockwise as indicated by the arrow in FIG. 9. Thereafter, it is uniformly charged by the charging means 32. Next, the image is exposed by the exposure means 33, and an electrostatic latent image is formed on the surface of the image carrier 31.

  On the other hand, in the developing means 40, the developer 42 uniformly mixed by the stirrer 43 is supplied to the developer carrier 44, and the developer carrier 44 rotates in the direction of the arrow shown in FIG. The developer 42 attached to the surface of the carrier 44 passes between the developer carrier 44 and the blade 46 of the developer regulating member 45 in contact with the developer carrier 44. At this time, the developer 42 is regulated to a desired layer thickness, and the developer 42 can be charged as desired. That is, as the developer 42 passes between the developer carrier 44 and the blade 46, the layer thickness of the developer 42 on the surface of the developer carrier 44 is regulated, and the developer regulating member 45 The developer 42 on the developer carrier 44 is charged as desired by frictional charging between the blade 46 and the developer carrier 44 and / or the developer 42.

  Next, the developer 42 having a desired layer thickness and charge amount is supplied from the developing means 40 to the image carrier 31 in this way, and the electrostatic latent image formed on the image carrier 31 is developed. The electrostatic latent image is visualized as a developer image. In this way, the developing unit 40 can supply the developer 42 having a desired layer thickness and charge amount to the image carrier 31 to develop the electrostatic latent image. Next, the developer image developed on the image carrier 31 is transferred onto the recording paper 36 conveyed between the image carrier 31 and the transfer unit 34 by a conveyance unit (not shown). Transfer is performed by the transfer means 34. Next, the recording paper 36 onto which the developer image has been transferred is transported to the fixing unit 35 by a transport unit (not shown), and heated and / or pressurized by the fixing unit 35, and the transferred developer image is recorded as a permanent image. It is fixed on the paper 36. In this way, an image can be formed on the recording paper 36.

  The image forming apparatus 30 according to the present invention includes a charging roller, a developing roller, a transfer roller, a fixing roller, a cleaning roller (not shown), a pressure roller (not shown), a paper feed / conveying roller (not shown), and the like. The roller 20 according to the present invention is used as at least one of the various rollers. Therefore, the roller 20 manufactured using the shaft 1A according to the present invention is lightweight and can act uniformly on the abutted body in the longitudinal direction thereof, thereby producing a high-quality image. Can be formed.

  The image forming apparatus 30 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus 30 is a monochrome image forming apparatus in which the developing unit 40 contains only a single color developer 42. However, in this invention, the image forming apparatus is not limited to a monochrome image forming apparatus. It may be an image forming apparatus. Examples of the color image forming apparatus include a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier to an intermediate transfer body, and a plurality of image carriers provided with developing means for each color. Examples thereof include a tandem type color image forming apparatus in which a body is arranged in series on an intermediate transfer body or a transfer conveyance belt. The image forming apparatus 30 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

(Example 1)
A shaft end portion 10A having a fitting portion 12A having an outer diameter of 9.7 ± 0.005 mm and an axial length of 12 mm and a support shaft 13 having an outer diameter of 7.5 mm and an axial length of 23 mm is made of stainless steel (SUS 304). Further, it has a cylindrical shape with an outer diameter of 12 mm, a thickness of 1.3 mm, and an axial length (Lg) of 235 mm, and has an inner diameter of 9.7 mm (tolerance: JIS B0401 (1986) with respect to the outer diameter of the fitting portion 12A). The shaft main body 5A in which the inner diameter enlarged region (12 mm in length in the axial direction) of the “tolerance fit” shaft tolerance region class “P6” in FIG. Next, the shaft I was manufactured by fitting the fitting portions 12A of the shaft end portion 10A into the both ends of the shaft body 5A.

The shaft I produced in this way has an overall length Ls of 281 mm, the length of each fitting portion, that is, the insertion lengths Lc ₁ and Lc along the axial direction of both end portions of the shaft body 5A and the shaft end portion 10A. ₂ was 12 mm, and the total length Lc was 24 mm. That is, Lc / Lg in the shaft I was 0.102, and Lg / Ls was 0.83, which satisfied the expressions (1) and (2 ′). Moreover, the run-out of the shaft I measured by the above-mentioned method (measurement points are a total of three points including a substantially central portion of the shaft I and the vicinity of both end portions of 5 mm from both end portions of the shaft I) is 0.03%, The mass was 45 g.

(Example 2)
A shaft II was produced in the same manner as in Example 1 except that both the length in the axial direction of the insertion portion 12A and the length in the axial direction of the inner diameter enlarged region were changed to 3 mm. The Lc / Lg of this shaft II is 0.026, Lg / Ls is 0.83, the runout of the shaft II measured in the same manner as in Example 1 is 0.05%, and the total mass is 34 g. there were.
(Example 3)
A shaft III was produced in the same manner as in Example 1 except that both the length in the axial direction of the insertion portion 12A and the length in the axial direction of the inner diameter enlarged region were changed to 22 mm. The Lc / Lg of this shaft III is 0.187, Lg / Ls is 0.83, the deflection of the shaft III measured in the same manner as in Example 1 is 0.03%, and the total mass is 59 g. there were.

Example 4
A shaft IV was produced in the same manner as in Example 1 except that the length of the support shaft 13 in the axial direction was changed to 36 mm. The Lc / Lg of this shaft IV is 0.102, Lg / Ls is 0.76, the runout of the shaft IV measured in the same manner as in Example 1 is 0.04%, and the total mass is 62 g. there were.
(Example 5)
A shaft V was produced in the same manner as in Example 1 except that the length of the support shaft 13 in the axial direction was changed to 8 mm. Lc / Lg of this shaft V is 0.102, Lg / Ls is 0.93, the runout of the shaft V measured in the same manner as in Example 1 is 0.03%, and the total mass is 36 g. there were.

(Example 6)
A shaft VI was produced in the same manner as in Example 1 except that the shaft body was made of stainless steel (SUS 304). The deflection of the shaft VI measured in the same manner as in Example 1 was 0.03%, and the total mass was 58 g.

(Comparative Example 1)
A shaft VII was produced in the same manner as in Example 1 except that the shaft body 5A was formed in a solid cylindrical shape. In the case of this shaft VII, the total length of the solid shaft main body 5A was regarded as Lc, that is, the total length of the fitting lengths along the axial direction of the both ends of the shaft main body 5A and the shaft end 10A. Therefore, Lc / Lg of this shaft VII was 1. The runout of the shaft VII measured in the same manner as in Example 1 was 0.02%, and the total mass was 154 g.

(Comparative Example 2)
A shaft VIII was manufactured in the same manner as in Example 1 except that both the length in the axial direction of the insertion portion 12A and the length in the axial direction of the inner diameter enlarged region were changed to 2 mm. The Lc / Lg of this shaft VIII is 0.017, Lg / Ls is 0.83, the runout of the shaft VIII measured in the same manner as in Example 1 is 0.10%, and the total mass is 30 g. there were.
(Comparative Example 3)
A shaft IX was manufactured in the same manner as in Example 1 except that both the length in the axial direction of the insertion portion 12A and the length in the axial direction of the inner diameter enlarged region were changed to 25 mm. The Lx / Lg of this shaft IX is 0.213, Lg / Ls is 0.83, the runout of the shaft IX measured in the same manner as in Example 1 is 0.03%, and the total mass is 66 g. there were.

(Comparative Example 4)
A shaft X was produced in the same manner as in Example 1 except that the length of the support shaft 13 in the axial direction was changed to 40 mm. The Lc / Lg of this shaft X is 0.102, Lg / Ls is 0.746, the runout of the shaft X measured in the same manner as in Example 1 is 0.07%, and the total mass is 71 g. there were.

  These shafts I to X were washed with toluene, and a silicone primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface. The primer-treated shafts I to X were fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surfaces of the shafts I to X.

  On the other hand, 100 parts by weight of methyl vinyl silicone raw rubber (trade name “KE-78VBS”, manufactured by Shin-Etsu Chemical Co., Ltd.) and 20 parts by weight of dimethyl silicone raw rubber (trade name “KE-76VBS”, manufactured by Shin-Etsu Chemical Co., Ltd.) , 10 parts by mass of carbon black (trade name “Asahi Thermal”, manufactured by Asahi Carbon Co., Ltd.) and fumed silica-based filler (trade name “AEROSIL200”, average primary particle size 12 μm, bulk density 50 g / L, Nippon Aerosil Co., Ltd. 15 parts by mass of company), 0.5 parts by mass of platinum catalyst (trade name “C-19A”, manufactured by Shin-Etsu Chemical Co., Ltd.), hydrogen polysiloxane (trade name “C-19B”, Shin-Etsu Chemical Co., Ltd.) 2 parts by mass) were mixed and kneaded with a pressure kneader to prepare a conductive rubber composition.

  Next, the shafts I to X on which the primer layer was formed and the conductive rubber composition were integrally extracted with a crosshead type extruder and heated at 250 ° C. for 30 minutes using a gear oven. Thereafter, using a gear oven, secondary heating was performed at 200 ° C. for 4 hours, and the mixture was allowed to stand at room temperature for 24 hours. Next, the surface of the elastic layer was polished by a cylindrical grinder so that the formed elastic layer had a diameter of 20 mm.

The electric resistance value and JIS A hardness of the elastic layer thus formed were measured by the above method. The electric resistance value was 2 × 10 ⁴ Ω · cm, and the JIS A hardness was 40.

  Next, a silicone primer (trade name “Primer No. 19”, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the elastic layer. On the surface of the elastic layer coated with the primer, 100 parts by mass of urethane-based paint (trade name “Nipporan 5196”, manufactured by Nippon Polyurethane Co., Ltd.) and fumed silica-based filler (trade name “AEROSIL 200”, Nippon Aerosil Co., Ltd.) Spray coating a coating solution of a resin composition containing 25 parts by mass of a company), 15 parts by mass of carbon black (trade name “Asahi Thermal” manufactured by Asahi Carbon Co., Ltd.) and 14 parts by mass of an isocyanate-based crosslinking agent. According to the method, it was applied once and heated at 150 ° C. for 30 minutes to crosslink and / or cure the primer and the urethane-based paint to form a coat layer having a layer thickness of 10 μm. In this way, rollers I to X were produced.

  Each of the rollers I to X thus prepared was prepared and mounted as a developer carrier (developing roller) in the electrophotographic printer (trade name “HL-1850” manufactured by Brother Industries, Ltd.) shown in FIG. did. The developer and the developer regulating member used were a developer and a blade attached to the electrophotographic printer. This electrophotographic printer performs printing on 10,000 sheets in an environment of temperature 20 ° C. and relative humidity 50%, pulls out a recording sheet for every 1,000 sheets, and improves the quality of the printed image. confirmed. As a result, the rollers I to VII and IX using the shafts I to VII and IX formed a high-quality image without any “blurring” or “white spot” on any recording paper. On the other hand, in the rollers VIII and X using the shafts VIII and X, “blurred” or “white spots” or the like may occur on the recording paper. The reason is that the rollers I to VII and IX have small fluctuations, and the distance between the rollers I to VII and IX and the image carrier (photoconductor) is constant in the axial direction of the rollers I to VII and IX. As a result, the developer carried on the rollers I to VII and IX was uniformly transferred to the image carrier in the axial direction, whereas the rollers VIII and X had a large shake, and the rollers VIII and X Since the distance from the image carrier (photoreceptor) is not constant in the axial direction of the rollers VIII and X, the developer carried on the rollers VIII and X is not easily transferred to the image carrier in the axial direction. As a result, it is presumed that “blurred” or “white spot” or the like has occurred in the formed image.

  Further, the shafts VII and IX have a large mass, and it is expected that the shafts VII and IX cannot sufficiently contribute to performance such as downsizing of the image forming apparatus, high definition of the image, and high speed of the printing speed.

FIG. 1 is a schematic perspective view showing an embodiment of a roller hollow shaft according to the present invention. FIG. 2 is a schematic cross-sectional view showing a cross section in one embodiment of the roller hollow shaft according to the present invention. FIG. 3 is a schematic cross-sectional view showing a part of a cross section in another embodiment of the roller hollow shaft according to the present invention. FIG. 4 is a schematic perspective view showing another embodiment of the roller hollow shaft according to the present invention. FIG. 5 is a schematic cross-sectional view showing a part of a cross section in still another embodiment of the roller hollow shaft according to the present invention. FIG. 6 is a schematic cross-sectional view showing a cross section of still another embodiment of the roller hollow shaft according to the present invention. FIG. 7 is a schematic cross-sectional view showing a part of a cross section in still another embodiment of the roller hollow shaft according to the present invention. FIG. 8 is a perspective view showing an embodiment of the roller according to the present invention. FIG. 9 is a schematic view showing an example of an image forming apparatus according to the present invention.

Explanation of symbols

1, 1A, 1B, 1C, 1D, 1E Roller hollow shaft 5, 5A, 5B Shaft body 6 Fitting portion 10A, 10B, 10C Shaft end 11 Flange portion 12A, 12B Fitting portion 13 Support shaft 15 Fixing means 20 Roller 21 Elastic layer 30 Image forming apparatus 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Recording paper 37 Cleaning means 40 Developing means 41 Developer container 42 Developer 43 Stirrer 44 Developer carrier 45 Developer Regulating member 46 Blade

Claims (5)

A hollow shaft for a roller having a cylindrical shaft body and shaft ends fitted into both ends of the shaft body,
The relationship between the total length Lc of the fitting length along the axial direction between the both ends of the shaft main body and the shaft end and the total length Lg of the shaft main body satisfies the following formula (1), and the total length of the shaft main body: A roller hollow shaft, wherein the relationship between Lg and the total length Ls of the roller hollow shaft satisfies the following formula (2).
(1) 0.025 <Lc / Lg <0.20
(2) 0.75 <Lg / Ls ≦ 1   The hollow shaft for a roller according to claim 1, wherein the shaft end portion has a support shaft sharing an axis with the shaft end portion.   The hollow shaft for a roller according to claim 1 or 2, wherein the shaft body and the shaft end are formed of the same material.   A roller comprising an elastic layer on the outer peripheral surface of the hollow shaft for a roller according to claim 1.   An image forming apparatus comprising the roller according to claim 4.

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