JP3208944B2 - Magnet roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a facsimile,
Furthermore, the present invention relates to a magnet roll used in an electrophotographic developing device such as a laser beam printer or a cleaning device.

[0002]

2. Description of the Related Art In recent years, with the downsizing of electronic copying machines, facsimile machines, laser beam printers, and the like, there has been an increasing demand for smaller diameter magnet rolls used in developing devices and cleaning devices. Specifically, the length is A
220mm or more, 13mm in diameter that can support 4 sizes
The following dimensions are required: There is also a demand that the diameter is 10 mm or less.

In the above-mentioned magnet roll, the required value of the surface magnetic flux density (hereinafter simply referred to as magnetic force) of the main pole is 700 to 1000 gauss. A certain size or more is required. Although the specific value depends on the magnet material used, it is about 3 mm or more for a bond magnet using hexagonal ferrite that is commonly used. For this reason, in order to secure this thickness, it is necessary to use a considerably thin shaft with a small diameter magnet roll. For example, in the case of a magnet roll having a diameter of 10 mm and a length of 220 mm, a shaft having a diameter of about 3 mm and a length of about 250 mm must be used. On the other hand, as the shaft,
For example, a round bar made of soft iron, an aluminum alloy, or stainless steel is used. Further, in order to increase the strength and rigidity of the shaft, a shaft having a hollow pipe shape or a prism shape has been proposed.

[0004]

The soft iron and stainless steel shafts have a problem that the weight is large and the manufacturing cost is high as compared with the aluminum alloy shafts. In addition, although a shaft made of an aluminum alloy can be manufactured at low cost, there is a problem that it is difficult to secure sufficient strength, rigidity and abrasion resistance when the shaft has a small diameter. On the other hand, it is possible to form an aluminum alloy shaft into a hollow pipe shape or a prismatic shape to increase its strength and rigidity, but the manufacturing cost increases,
There is a problem that a support structure for rotatably supporting the shaft is complicated.

An object of the present invention is to provide a magnet roll which is small in diameter, light in weight and can be manufactured at low cost, and has a small amount of bending.

[0006]

A magnet roll according to the present invention is mounted in a cylindrical magnet body made of a material obtained by dispersing and mixing ferromagnetic powder in plastic, and is coaxially or eccentrically fitted to the magnet body. In a magnet roll having a shaft, the shaft is made of an aluminum alloy material, and the shaft is subjected to alumite treatment to form an alumite layer over the entire surface of the shaft. The thickness of the alumite layer is 5
It is desirable to set in the range of μm to 100 μm.

[0007]

In the magnet roll according to the present invention, the shaft is made of an aluminum alloy material, and the shaft is subjected to alumite treatment so that its surface has a full length.
The alumite layer is formed over
The shaft can be configured to have a small diameter without reducing rigidity.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a magnet roll of a magnetic cylinder having a sleeve. As shown in FIGS. 1 and 2, the magnetic cylinder 1 will be described. A substantially cylindrical sleeve 2 made of an aluminum alloy or stainless steel is provided.
A first flange 3 and a second flange 4 are fixedly attached to both ends of the first flange 3, and a shaft 3a is formed on the first flange 3 so as to protrude leftward. A recess 3b is formed at the center, a through hole 4a is formed at a substantially center of the second flange 4, a shaft 5 is provided at the center of the sleeve 2 coaxially with the sleeve 2, and a left end of the shaft 5 is provided. The part is the first through a bearing 7 mounted in the recess 3b.
The right end of the shaft 5 is rotatably supported by the second flange 4 via a bearing 8 mounted in the through hole 4a, and extends rightward through the through hole 4a. In the sleeve 2, a substantially cylindrical magnet body 9 is fixed to the shaft 5 so as to be fitted outside the sleeve 2 in a non-contact state with the inner peripheral surface of the sleeve 2. Flange 3
・ Supported relative to the sleeve 2 via 4 for relative rotation.

The magnet main body 9 has a general configuration made of a resin magnet or a sintered magnet having a plurality of magnetic poles formed in a circumferential direction of an outer peripheral portion. The poles are alternately arranged, or the magnets are arranged with S poles and N poles in a predetermined magnetic pattern.

Here, in order to make the magnetic cylinder 1 as small as possible and to prevent the outer peripheral surface of the magnet main body 9 from contacting the inner peripheral surface of the sleeve 2, the strength and rigidity of the shaft 5 are increased and the amount of deflection thereof is increased. Must be minimized, and the wear resistance of the shaft 5 in the bearings 7 and 8 needs to be reduced as much as possible. For this reason, the shaft 5 is made of, for example, an aluminum alloy material such as JIS No. 2000 or 4000 series, and the surface of the shaft 5 is subjected to alumite treatment to form a film as shown in FIG. An alumite layer 10 having a thickness of 5 μm to 100 μm is formed. In this alumite treatment, the shaft 5 is anodically oxidized to form a porous film on its surface, which is sealed with pressurized steam or boiling water to which a small amount of a chemical is added to form a chemically stable material. This is a general process for forming the alumite layer 10.

Next, a brief description will be given of a method of testing the amount of bending and the amount of wear performed on the shaft 5. As a test piece of the present invention, two sets of test pieces made of a shaft member having a diameter of 5 mm and a length of 250 mm and made of an aluminum alloy material of A2017 of JIS standard and an aluminum alloy material of A4032 of JIS standard were manufactured. Each of the test pieces was subjected to an alumite treatment to produce test pieces T1 and T2 having a 10 μm alumite layer 10 formed on the surface thereof.

On the other hand, as a test piece of a comparative example, a third test piece T3 of a shaft member having a diameter of 5 mm and a length of 250 mm and made of an aluminum alloy material based on JIS standard No. 2000 was manufactured as described above. The weight of the three test pieces T1, T2, and T3 of the aluminum alloy is about 35% of the weight of stainless steel, which is significantly reduced.

Next, as shown in FIG.
2. Both ends of T3 are sequentially supported by the support block 20, a uniform load of 100 g is applied to the test pieces T1, T2, and T3, and the maximum amount of deflection in this state is measured. The test results were obtained. The deflection amount of the first test piece T1 is 0.05
5 mm, the deflection of the second test piece T2 is 0.040 mm, and the third test piece T
The deflection amount of No. 3 was 0.095 mm, and the first test piece T1 of the present invention example
Is a bending amount of about の of the third test piece T3 of the comparative example,
The second test piece T2 of the present invention is the third test piece T3 of the comparative example.
It can be seen that the bending amount is smaller than の of the above, and the strength and rigidity of the test pieces T1 and T2 are increased by performing the alumite treatment, and the bending amount is significantly reduced.

Next, the amounts of wear of the three test pieces T1, T2 and T3 were measured by a Suga tester, and the following test results were obtained. The wear amount of the first test piece T1 is about 100 mg, the wear amount of the second test piece T2 is about 50 mg, and the wear amount of the third test piece T3 is
500-600 mg, and the first test piece T1 of the present invention has a wear amount of about 1/5 of the third test piece T3 of the comparative example,
In the second test piece T2 of the present invention, the wear amount is about 1/10 of that of the third test piece T3 of the comparative example, and the hardness of the test pieces T1 and T2 is increased by performing the alumite treatment. It turns out that it became much smaller. However, although the second test piece T2 provided better results in the amount of bending and abrasion than the first test piece T1, the first test piece T1 is more preferable in that the alumite treatment is easily performed.

In this embodiment, the present invention is applied to the magnetic cylinder 1 having the sleeve 2, but the present invention can be similarly applied to a sleeveless magnetic cylinder.

[0016]

According to the magnet roll of the present invention, since the shaft is made of an aluminum alloy material, the manufacturing cost and the weight can be reduced, and the alumite treatment can be performed on the entire surface of the shaft. The alumite layer is applied to improve the strength, rigidity and abrasion resistance of the shaft, and the strength and rigidity of the shaft is increased, so that the entire magnet roll can be configured with a small diameter while preventing bending. And so on.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a magnetic cylinder.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a longitudinal sectional view of the vicinity of a surface portion of a shaft.

FIG. 4 is an explanatory diagram of a test method of a deflection amount.

[Explanation of symbols]

 5 Shaft 6 Magnet roll 9 Magnet body 10 Alumite layer

Continuation of front page (56) References JP-A-1-228116 (JP, A) JP-A-63-180721 (JP, A) JP-A 4-81167 (JP, U) JP-A 60-132343 (JP , U) Hira 2-58764 (JP, U) Hira 5-25464 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/09-15/095 H01F 7/00-7/04 F16C 13/00

Claims (2)

(57) [Claims] 1. A magnet roll comprising: a substantially cylindrical magnet body made of a material obtained by dispersing and mixing ferromagnetic powder in a plastic; and a shaft coaxially or eccentrically fitted to the magnet body. was made of aluminum alloy material, all on the surface portion is subjected to alumite treatment to the shaft
A magnet roll having an alumite layer formed over a long period . 2. The film thickness of the alumite layer is from 5 μm to 1
The magnet roll according to claim 1, wherein the magnet roll is set to a range of 00 µm.