JPH08267122A - Production of aluminum extruded tube stock for photosensitive drum - Google Patents

Abstract

PURPOSE: To attain an aluminum extruded tube stock with high surface smoothness by eliminating the gouge-shaped defect of the aluminum extruded tube stock and the sticking of Al refuse to it, causing projecting defects after drawing and after ironing. CONSTITUTION: An extrusion is performed by using a die for extrusion, whose length L in the extrusion direction of a die bearing part 12 forming the outer surface of an aluminum extruded tube stock is <=5mm, and a relationship between center line average roughness Ra (Y) in the peripheral direction of the bearing part and center line averages roughness Ra (X) in an extrusion direction has been set to Ra (y)<R8 (x).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to a method for manufacturing an aluminum extruded raw tube for a photosensitive drum used as a photosensitive drum of an electrophotographic apparatus such as a facsimile.

In this specification, the term aluminum is used to include both aluminum and aluminum alloys.

[0003]

2. Description of the Related Art The aluminum tube used as a photosensitive drum as described above is desired to have a surface state relatively close to a mirror surface due to its property. For this reason, conventionally, aluminum pipes have been mirror-finished by cutting, but adjustment and management of cutting blades are not easy, and since skill is required for work, they are not suitable for mass production,
Therefore, it is difficult to reduce the price of the drum.

Therefore, recently, an aluminum pipe called an EI pipe obtained by ironing an aluminum extruded raw pipe,
A non-cutting aluminum tube such as an aluminum tube called an ED tube obtained by drawing an aluminum extruded raw tube is used as a photosensitive drum substrate.

[0005]

However, the uncut aluminum pipe obtained by drawing or ironing the aluminum extruded raw pipe as described above can reduce the cost because it does not require cutting. It turned out that there are drawbacks such as.

That is, on the surface of the uncut aluminum pipe,
There are defects such as scale-like or needle-like convex defects, and the convex defects cause a leak (electric leakage) when the photosensitive drum is uniformly charged. In particular, as the uniform charging method for the surface of the photosensitive drum, since the conventional corona charging method accompanies the generation of ozone, the direct charging method such as roller charging and brush charging is often adopted instead of the corona charging method. However, in such a direct charging method, since the air layer functioning as an insulating layer at the time of corona charging disappears, the load on the photosensitive drum increases,
It is more and more likely to leak.

Therefore, when the cause of the convex defect on the surface of the non-cutting aluminum tube which causes the leak of the photosensitive drum was investigated, the following was found. That is,
As shown in FIG. 3 (a), there is a muscular defect (101) on the surface of the aluminum extruded raw pipe (100) used for drawing or ironing, or as shown in FIG. 3 (b). If the Al residue (102) is adhered, the mussle-like defect (101) or the Al residue (102) is crushed by subjecting it to drawing or ironing, resulting in small scales or needles. It was found to be a convex defect.

The present invention has been made in view of the above technical background, and it has been found that the crevice-like defects and the Al residue of the aluminum extruded raw pipe, which cause the convex defects after the drawing process and the ironing process, are eliminated. The purpose of the present invention is to obtain an extruded aluminum tube having high surface smoothness by eliminating adhesion.

[0009]

In order to achieve the above object, as a result of intensive research, the inventor has found that a die for extruding an aluminum extruded raw pipe has a structure of a bearing portion forming an outer surface of the extruded raw pipe. The present invention has been completed by discovering that it has a great influence on adhesion of rustle defects and Al dust.

That is, according to the present invention, the length of the die bearing portion forming the outer surface of the aluminum extruded raw pipe in the extrusion direction is 5 mm or less, and the center line average roughness Ra (Y) in the circumferential direction of the bearing portion is equal to or less than 5 mm. And the center line average roughness Ra (X) in the extrusion direction are set such that Ra (Y) <Ra (X) is satisfied. Extrusion is performed using an extrusion die. The gist is a method of manufacturing an extruded raw pipe.

The extruding method of the extruded raw pipe is not particularly limited, and either one using a porthole die or mandrel extrusion may be used. FIG. 2 shows an example of a porthole die used for porthole extrusion. In the figure, (1)
Is a female die, and (2) is a male die. A through hole (11) is formed in the center of the female die, and the bearing surface (12) has a circular peripheral surface on the inlet side of the hole.
Has been made. In addition, (13) is a relief part. On the other hand, the male die (2) has a molding convex portion (21) having a circular cross section at the center thereof, and a circular bearing portion (22) is formed on the tip peripheral surface of the molding convex portion. Note that (2
3) is a passage hole for passing the aluminum billet.

Then, the die female die (1) and the die male die (2) described above are combined to form a molding convex portion (2) of the male die (2).
1) The front end faces the extrusion hole (11) of the female mold (1), and the bearing portions (12) (22) of both male and female dies are arranged so as to face each other through an annular molding gap (3).

In the present invention, the length L of the bearing portion forming the outer surface of the aluminum extruded raw pipe, that is, the female type bearing portion (12) in the die of FIG. 2 in the extrusion direction (indicated by the arrow X in FIG. 1) is The relationship between the center line average roughness Ra (Y) in the circumferential direction (indicated by the arrow Y in FIG. 1) of the bearing portion and the center line average roughness Ra (X) in the extrusion direction is 5 mm or less, and (Y) <Ra (X) must be set. The reason for this is as follows.

That is, when the length of the bearing portion (12) in the extruding direction is longer than 5 mm, the resistance at the time of extruding becomes large, and it cannot be formed unless the amount of pushing force is large, and the surface is rusted. It is easy to do. A particularly preferable length of the bearing portion in the pushing direction is 3 mm or less. On the other hand, if the length of the bearing portion in the pushing direction is too short, the strength of the bearing portion is lowered and the bearing portion is easily damaged, or the bearing portion is bent and the shape becomes unstable. It is good to secure the above length.

The surface roughness of the bearing portion (12) is R
The requirement a (Y) <Ra (X) is that Al dust that has adhered to and deposited on the bearing portion is more likely to be trapped in the groove on the surface of the bearing portion, causing Al dust to adhere and migrate to the surface of the extruded raw pipe. Is suppressed.

Center line average roughness Ra (Y) in the circumferential direction of the bearing portion (12) and center line average roughness Ra in the extrusion direction.
The method for making the relationship with (X) Ra (Y) <Ra (X) is not particularly limited, but for example, as shown in FIG. 1, a diamond file may be used along the circumferential direction (Y direction). And polish it.

Since the inner surface of the aluminum extruded raw tube does not affect the characteristics of the photosensitive drum, the length and surface roughness of the male bearing portion (22) forming the inner surface are not limited at all.

The material of the die is not particularly limited, and may be hot-quenched tool steel (SKD61) or cemented carbide material, or may be a nitriding die.

[0019]

The aluminum extruded raw pipe having a high surface smoothness is manufactured by preventing the crevice-like defects and the adhesion of Al dust on the surface of the extruded raw pipe.

[0020]

[Example] When extruded into an extruded raw tube using a porthole die as shown in FIG. 2, the material of the die, the length of the female bearing portion in the extrusion direction in the die, and the surface roughness Ra (X in the extrusion direction ), And the surface roughness Ra (Y) in the circumferential direction, as shown in Table 1, various port hole dies were prepared. The surface roughness was changed by changing the direction and degree of polishing with a diamond file.

Next, an aluminum billet made of A3003 alloy and having a diameter of 6 inches and a length of 510 mm was extruded by the above dies into an extruded raw pipe having an outer diameter of 40 mm and a wall thickness of 2.0 mm. Extrusion temperature is 450 ° C, extrusion speed is 30m
/ Min.

Then, the surface morphology of the obtained aluminum extruded raw pipe was observed with a microscope to check for the presence of mussles and Al dust, and the surface roughness (center line average roughness R
a) was investigated. Table 1 shows the results.

Next, after drawing each aluminum extruded raw tube described above, the surface of the obtained aluminum tube for a photosensitive drum is washed, and then a photosensitive layer having a charge generation layer and a charge transport layer in each aluminum tube. Was coated as follows. That is, the charge generation layer was formed by diluting metal-free phthalocyanine to 4% with tetrahydrofuran, coating it to a film thickness of about 0.3 μm, and drying it. Next, the CT agent (hydrazone compound) and CT resin (polycarbonate) are dissolved in methylene chloride at a ratio of 1: 2,
It was applied to a film thickness of 20 μm and dried to form a charge transport layer.

Next, these photosensitive drums were charged at a voltage of -1000 V by a direct charging method using a roller charger, and the occurrence of leak was examined. The results are shown in Table 1.
Shown in

[0025]

[Table 1] As can be seen from the results of Table 1 above, the product of the present invention has no crease or Al residue adhered to the extruded raw pipe, has high surface smoothness, and has very little leakage on the photosensitive drum. Met. Especially, when the bearing length is 1 to 3 mm, it can be seen that the surface smoothness of the extruded raw pipe can be further improved.

On the other hand, in the comparative product in which the length of the bearing portion and the surface roughness deviate from the scope of the present invention, the extruded raw tube was found to have rust and Al dust, and many leaks were generated. It was

[0027]

According to the present invention, the length of the die bearing portion forming the outer surface of the aluminum extruded raw pipe in the extrusion direction is 5 mm or less and the center line average roughness of the bearing portion in the circumferential direction is as described above. Ra (Y) and the center line average roughness Ra (X) in the extrusion direction is Ra (Y) <Ra (X)
Since it is characterized by performing extrusion using the extrusion die set to, aluminum extrusion with high surface smoothness can be prevented by preventing crevice defects and adhesion of Al dust on the surface of the extruded raw tube. A blank tube can be manufactured. As a result, the extruded raw tube can be formed into an aluminum tube having excellent smoothness which can prevent surface convex defects of the aluminum tube obtained by drawing or ironing, and the result is caused by the convex defects. It is possible to prevent the photosensitive drum from leaking.

[Brief description of drawings]

1A is a partially enlarged view of a die bearing portion forming an outer surface of an extruded raw pipe, FIG. 1B is an enlarged view taken along line Ib-Ib of FIG. 1A, and FIG. 1C is Ic- of FIG. It is an enlarged view of the Ic line cross section.

FIG. 2 is a cross-sectional view showing an example of a porthole die for extruding an extruded raw pipe.

FIG. 3A is a partial cross-sectional perspective view showing a state in which an extruded raw tube manufactured by a conventional method has a muscular defect.
FIG. 6B is a partial cross-sectional perspective view of a state where Al dust is also attached.

[Explanation of symbols]

 1 ... Die female type 2 ... Die male type 12 ... Bearing part

Claims (1)

[Claims] 1. The length L in the extrusion direction of the die bearing portion (12) forming the outer surface of the aluminum extruded raw pipe is 5 mm.
And the center line average roughness Ra (Y) in the circumferential direction of the bearing portion and the center line average roughness Ra in the extrusion direction.
A method for producing an aluminum extruded raw pipe for a photosensitive drum, which comprises extruding using an extrusion die having a relationship with (X) such that Ra (Y) <Ra (X).