JPH075767A - Sleeve for developing roll - Google Patents

Abstract

PURPOSE:To provide the sleeve for a developing roll having high wear resistance, electrical conductivity and thermal conductivity by forming the sleeve out of a Be-Cu alloy consisting of, by weight, 0.3 to 2.0% BeO, >=0.2 (Co+Ni), <=0.6% (Co+Ni+Fe) and the balance Cu. CONSTITUTION:This sleeve 6 for the developing roll is constituted by building a permanent magnet member 1 which is formed into a hollow cylindrical shape and is provided with plural pieces of magnetic poles extending in the axial direction on its outer peripheral surface relatively rotatably via flanges 3, 4 disposed at its both ends into this sleeve. The sleeve is formed out of the Be-Cu alloy consisting, by weight, 0.3 to 0.2% BeO, >=0.2% (Co+Ni), <=0.6% (Co+Ni+ Fe) and the balance Cu. The content of the Be is preferably specified to 1.8 to 2.0wt.%. The total of the Cu and the additive elements is preferably specified to >=99.5wt.%. The sleeve is formed out of the Be-Cu alloy having high hardness and high strength, thereby, the wear resistance and durability are improved and the thermal conductivity is assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve which constitutes a developing roll for carrying out development by attracting and conveying a magnetic developer from a developer tank to a developing area in electrophotography, electrostatic recording and the like.

[0002]

2. Description of the Related Art Many developing rolls conventionally used in electrophotography, electrostatic recording and the like have a structure as shown in FIG. In FIG. 1, reference numeral 1 is a permanent magnet member, which is integrally formed into a hollow cylindrical shape from a sintered powder material such as hard ferrite, and a shaft 2 is coaxially fixed to the center portion with an adhesive. Alternatively, the mixture of the ferromagnetic material and the binder is injected or filled into the molding die into which the shaft 2 is inserted, and the mixture is integrally molded.

A plurality of magnetic poles (not shown) extending in the axial direction are provided on the outer peripheral surface of the permanent magnet member 1. Next, flanges 3 and 4 are rotatably mounted on both ends of the shaft 2 via bearings 5 and 5, and a hollow cylindrical sleeve 6 is fitted to the flanges 3 and 4. The flanges 3 and 4 and the sleeve 6 are made of a non-magnetic material such as aluminum alloy or stainless steel.
A seal member 7 is fitted between the flange 3 and the shaft 2. The diameter of the permanent magnet member 1 is 15 to 60 m.
In many cases, the length is 200 to 350 mm.

With the above structure, the relative rotation between the permanent magnet member 1 and the sleeve 6 (for example, fixing the permanent magnet member 1 and rotating the flange 4) causes a magnetic developer, such as a magnetic developer, on the outer peripheral surface of the sleeve 6. A one-component magnetic toner or a two-component developer composed of a toner and a magnetic carrier is adsorbed to form a magnetic brush, and a predetermined developing operation is performed.

[0005]

When the sleeve 6 constituting the developing roll is made of an aluminum alloy, it has the advantages of being lightweight and low cost, but on the other hand, it is easily worn and has low durability. There is. Further, in order to improve the transportability of the developer, a means for roughening the surface of the sleeve 6 by blasting is adopted, but even when such processing is performed, the durability is low as described above. Therefore, there is a problem in that the predetermined rough surface cannot be maintained for a long period of time, and the developer transportability deteriorates.

In order to solve the above problems, there have been attempts to harden the surface by, for example, alumite treatment to improve wear resistance. However, the hard coating formed by such alumite treatment has an electrical insulating property. Therefore, there is a problem in that a bias voltage cannot be applied to the sleeve.

Further, when the sleeve 6 is made of an aluminum alloy, an eddy current is generated on the surface of the sleeve 6, so that the permanent magnet member 1 is rotated at a high speed (for example, 800 to 1000).
rpm), the value of this eddy current becomes large, which causes the temperature rise of the components due to Joule heat.
There is a problem that the developability is lowered.

On the other hand, when the sleeve 6 is made of stainless steel, the above problems are solved, the hardness is high, the life is long, and even when the permanent magnet member 1 is rotated at a high speed, it is not affected by the eddy current. A developing roll can be manufactured. However, stainless steel has a material cost more than double that of aluminum alloy, and has low machinability, so that there is a problem that the manufacturing cost of the entire developing roll becomes high.

The above-mentioned stainless steel is a non-magnetic austenitic stainless steel, and such austenitic stainless steel pipe is generally manufactured by plastic working from a steel plate and welded at the seam. Is. However, at the time of cooling after welding, the joint becomes ferrite and becomes magnetic. When the sleeve 6 is formed by the pipe material having the ferritic seam, the magnetic developer is more strongly attracted to the surface of the sleeve 6 due to the magnetism in the seam, which is larger than the electrostatic attraction force of the photosensitive drum. As a result of the magnetic developer not migrating from the surface of the sleeve 6, development becomes impossible. This tendency is remarkable in the case of non-contact development (jumping development) using magnetic toner.

The above phenomenon is caused by SUS304 (18Cr-
8Ni) and SUS316 (18Ni-12Ni-2.
Although it is experienced in 5 Mo) stainless steel, in order to solve such a problem, a material that is hard to become ferrite even by welding, for example, SUS305
It is conceivable to use (18Cr-13Cr-high C). However, SUS305 is the above-mentioned SUS30
4, hardness of SUS316 Hv = 180 to 190
Compared with the above, there is a problem that the hardness is low (Hv = 150 to 160) because the austenite base is soft and the durability is reduced.

That is, the sleeve 6 has its surface roughened by, for example, blasting as described above in order to improve the transportability of the developer, but when the hardness of the material forming the sleeve 6 is low, However, the fine unevenness due to the above-mentioned roughening is scraped off by friction accompanying the transport of the developer during long-term use, and the transportability of the developer is deteriorated. Therefore, there is a problem that it is not possible to maintain the predetermined number of developments guaranteed by the copying machine.

On the other hand, in recent years, a photosensitive drum using an amorphous silicon material has appeared. Amorphous silicon materials have the advantage that they are hard and have a long life. However, since they have low sensitivity, they are usually used with an internal heater installed and heated to 80 to 90 ° C. Therefore, the heat from the photosensitive drum is transferred to the developing roll arranged near the photosensitive drum, especially to the sleeve 6 constituting the outer surface. However, since the heat conductivity of stainless steel is low, it is difficult for the transferred heat to escape. As a result, the sleeve 6 is locally heated to cause thermal strain, which causes the sleeve 6 to bend.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems existing in the prior art, and to provide a sleeve for a developing roll which has high abrasion resistance and high electric conductivity and thermal conductivity.

[0014]

In order to achieve the above object, the present invention provides a permanent magnet member having a hollow cylindrical shape and provided with a plurality of magnetic poles extending in the axial direction on the outer peripheral surface thereof. In the sleeve for the developing roll, which is built in so that relative rotation is possible through the flanges provided at both ends,
Be 0.3 to 2.0% by weight, (Co + Ni) ≥ 0.2%,
(Co + Ni + Fe) ≤0.6%, Be composed of the balance Cu
The technical means of forming with a Cu alloy was adopted.

In the present invention, the Be content is 1.8 to 2.
It is preferably 0% by weight, and the total amount of Cu and the additional element is preferably 99.5% by weight or more. Note that the sleeve of the present invention has a Be content of 315 to 33 after being drawn.
Preferably subjected to aging treatment for 2-3 hours at 0 ° C., thereby high hardness and 123～ of H _RC 36-44
A high strength of 159 kg / mm ² can be obtained.

[0016]

With the above construction, the wear resistance, electrical conductivity and thermal conductivity of the sleeve can be secured. Note that the cold working rate during the pultrusion process of the blank and sleeve is 20-
Even if it changes between 80%, the magnetic susceptibility is 1 to 5
stays in the range of 10 ^-4 to 10 ^-5 in a magnetic field of kG,
For example, unlike the case of SUS316, the phenomenon that the magnetic susceptibility changes drastically depending on the cold working rate does not occur, and it is possible to sufficiently secure non-magnetism.

[0017]

Example: A sleeve 6 having an outer diameter of 20.0 mm, an inner diameter of 18.0 mm and a length of 320 mm is made of a Be-Cu alloy (Be1.8 wt%, Co + Ni).
0.2% by weight, balance Cu). This Be-Cu alloy material was obtained by cold drawing and then aging treatment at 315 ° C for 3 hours.
kg / mm ² or more and hardness H _RC 40 or more were shown. As shown in FIG. 1, the sleeve 6 was assembled with constituent members such as a permanent magnet member 1, flanges 3 and 4 to form a magnet roll.

The surface of the sleeve 6 of the magnet roll was formed by blasting so as to have a surface roughness Rz = 3 μm, incorporated into a commercially available copying machine (NP4050 manufactured by Canon Inc.) and evaluated by continuous copying. It was confirmed that the surface of the sleeve 6 was microscopically observed even after the copying, and that the sleeve 6 could be continuously used. On the other hand, regarding the image evaluation results, both the image density and the resolution were good, and defects such as white spots and background fog were not recognized.

As a comparative example, a sleeve 6 of the same size is made of SUS.
316, and the result of continuous copying as above,
After continuous copying of 20,000 sheets, deterioration of the image quality was recognized, the surface of the sleeve 6 was severely worn, and the transporting ability of the developer was significantly decreased.

A magnet roll having the sleeve 6 made of the above Be--Cu alloy as a constituent element is made of amorphous S.
As a result of continuous copying by incorporating it into a copying machine having the i material as a constituent element, it was confirmed that the sleeve 6 could withstand long-term use because local heating was not observed.

[0021]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since it is formed of a Be-Cu alloy having high hardness and high strength, abrasion resistance and durability can be improved, and life can be extended even in high-speed development. (2) The rough surface can be maintained for a long period of time even when the outer layer is roughened to improve the transportability of the developer. (3) Even if it is used in a developing device having an amorphous silicon type photoconductor, it does not cause deformation because it has good thermal conductivity.

[Brief description of drawings]

FIG. 1 is a partially omitted vertical cross-sectional view showing an example of a magnet roll that is an object of the present invention.

[Explanation of symbols]

 1 Permanent magnet member 6 Sleeve

Claims (1)

[Claims] 1. A permanent magnet member formed in a hollow cylindrical shape and having a plurality of magnetic poles extending in the axial direction on the outer peripheral surface thereof is incorporated so as to be relatively rotatable through flanges provided at both ends thereof. In the sleeve for the developing roll, Be 0.3 to 2.0% by weight, (Co + Ni) ≧ 0.2%, (Co + N)
A sleeve for a developing roll, characterized in that it is formed of a Be-Cu alloy with i + Fe) ≤ 0.6% and the balance Cu.