JPH06110334A - Sleeve for developing roll - Google Patents

Abstract

PURPOSE:To enhance durability and to enable the production of the sleeve at a low cost by forming an inside layer of an aluminum alloy and an outside layer of an austenitic stainless steel, respectively. CONSTITUTION:The inside layer 61 is formed of the aluminum alloy and the outside layer 62 of the austenitic stainless steel, respectively. The inside layer 61 and the outside layer 62 are integrated by plastic working. Then, the outside layer 62 of the sleeve 6 is formable of the hard austenitic stainless steel, and, therefore, the sleeve can be so formed as to have wear resistance and durability. In addition, the generation of eddy current in the surface is suppressed. Since the inside layer 61 can be formed of the inexpensive aluminum alloy of a low sp. gr., the reduction of the weight and cost is possible. Further, the heat of the sleeve 6 is easily released outside via flanges at both ends of the sleeve, etc., even if the heat is generated in the surface of the sleeve and the thermal deformation of the sleeve is therefore drastically reduced.

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 Conventionally, many developing rolls used in electrophotography, electrostatic recording and the like have a structure as shown in FIG. In FIG. 2, 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.

Further, in recent years, the demand for the developing roll has become more and more strict, and in addition to the weight reduction, the diameter reduction, and the high performance, a lower cost one has been demanded. Therefore, the structure described above cannot meet the strict demands of recent years.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems existing in the prior art and to provide a developing roll sleeve which has high durability and can be manufactured at low cost.

[0011]

In order to achieve the above object, according to the present invention, a permanent magnet member formed in a hollow cylindrical shape and provided on its outer peripheral surface with a plurality of magnetic poles extending in the axial direction is used. In the rotatably built-in sleeve for the developing roll, we adopted the technical means that the inner layer is made of aluminum alloy and the outer layer is made of austenitic stainless steel, and the inner layer and outer layer are integrated by plastic working. .

In the present invention, as a means for integrating the inner layer and the outer layer by plastic working, a tube material made of an aluminum alloy for forming the inner layer and a tube material made of austenitic stainless steel for forming the outer layer are respectively polymerized. A means for performing cold drawing by a die having a mandrel in this state is preferable.

[0013]

With the above structure, the outer layer of the sleeve can be formed of hard austenitic stainless steel.
It can have abrasion resistance and durability, and can suppress the generation of eddy currents on the surface. Moreover, since the inner layer can be formed from an aluminum alloy which has a low specific gravity and is inexpensive, the weight and cost can be reduced.

Aluminum alloy has a good thermal conductivity, for example, A5052 has a thermal conductivity (25 ° C.) of 0.33 c.
al / ° C · cm · sec. Therefore, it has a much higher value than the value of thermal conductivity (100 ° C.) of SUS304 of 0.039 cal / ° C.cm.sec. Therefore, by forming the inner layer of the sleeve with an aluminum alloy, even if the surface of the sleeve is heated, the heat is easily released to the outside through the flanges at both ends of the sleeve, so that the thermal deformation of the sleeve is greatly reduced. Can be reduced to

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical cross-sectional view of an essential part of an embodiment of the present invention. In FIG. 1, 61 and 62 are an inner layer and an outer layer, respectively, which are integrated by cold drawing.
The inner layer 61 is, for example, A6063, and the outer layer 62 is SUS.
The outer diameter after integration was 20 mm and the inner thickness was 0.7 mm.

When the sleeve is formed of the above-mentioned mating material, for example, the outer diameter of A6063 is 20.5 mm and the wall thickness is
0.5 mm tubing with an outer diameter of 22 made of SUS304, for example
mm tube with a wall thickness of 0.5 mm is inserted and the ends are crushed to prevent relative movement between the two. Next, a sleeve (No. 1) having the above dimensions was formed from the above pipe material by cold drawing using a die of tool steel having an inner diameter of 20 mm and a mandrel having a diameter of 19.4 mm.

When the fractured surfaces of the inner layer 61 and the outer layer 62 were observed with a microscope after forming the sleeve, it was confirmed that the structure was perfect and that the boundary surface between the two was completely fixed and integrated without inclusions.

For comparison, a sleeve (No. 2) formed of only SUS304 and having the same dimensions as above and A
A sleeve (No. 3) formed of only 6063 was produced. A magnet roll is assembled by incorporating the above-mentioned three types of sleeves No. 1 to No. 3 with a permanent magnet member 1 (8-pole symmetrical magnetization, surface magnetic flux density 800G on the sleeve 6) as shown in FIG. 2 and other members. It was Next, blasting is performed with glass beads (# 300) to make the surface roughness of the sleeve 6 1 μm.
(Rz).

Magnetic toner (HMT422, manufactured by Hitachi Metals, Ltd.) is formed on the surface of the magnet roll formed as described above.
The average particle size of 10 μm) is adsorbed to a thickness of 0.4 mm, the sleeve 6 is rotated at 400 rpm (fixing the permanent magnet member 1), and the durability of the surface state of the sleeve 6, that is, continuous copying with A4 size paper is possible. I decided the number of sheets.

The sleeve 6 after rotating the sleeve 6 at 2,000 rpm for 1 hour without adsorbing the magnetic toner
The surface temperature of was measured. The results of these experiments are shown in Table 1 together with the weight ratio of the sleeve 6 and the manufacturing cost ratio (the ratio of No. 1 and No. 2 when No. 3 is 1).

[0021]

[Table 1]

As is clear from Table 1, those of the present invention (N
o.1) shows good results in terms of durability and weight ratio, is lighter than the one using only stainless steel, has the same durability, and generates less heat due to eddy currents. Can be obtained.

In the present embodiment, an example in which A6063 is used as the aluminum alloy forming the inner layer 61 has been described, but the present invention is not limited to this, but other aluminum alloys can be used, but cold drawing is performed. It is preferable to use an aluminum alloy that is highly malleable.
Further, as the austenitic stainless steel forming the outer layer 62, those other than SUS304 can be used, but it is preferable to use the one having high extensibility as in the above aluminum alloy. The plastic deformation rate in the cold drawing can be appropriately selected in consideration of the mechanical properties of the material forming the inner layer 61 and the outer layer 62. The developing roll sleeve of the present invention is particularly effective as a sleeve rotation type developing means for a high-speed machine equipped with an amorphous silicon type photosensitive member.

[0024]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since the outer layer is made of high-hardness austenitic stainless steel, wear resistance and durability can be improved. (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) The inner and outer layers are in perfect contact with each other with no inclusions, so they are conductive and there is no problem in applying the bias voltage. (4) The inner layer is made of an aluminum alloy that has a low specific gravity and is inexpensive, which enables weight reduction and cost reduction.

[Brief description of drawings]

FIG. 1 is a partially omitted vertical cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a partially omitted vertical sectional view showing an example of a conventional developing roll.

[Explanation of symbols]

 6 Sleeve 61 Inner layer 62 Outer layer

Claims (1)

[Claims] 1. A sleeve for a developing roll, which is formed in a hollow cylindrical shape and has a plurality of magnetic poles extending in the axial direction on its outer peripheral surface and rotatably incorporated therein. The developing roll sleeve is characterized in that the outer layer is formed of austenitic stainless steel, and the inner layer and the outer layer are integrated by plastic working.