JPS6354078B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of surface processing a rotationally symmetrical object surface having a magnet inside by using electrolytic action. This is a method of processing. In the present invention, rotationally symmetrical objects containing magnets include various magnetic couplings, generators, etc. in addition to the magnetic sleeve of an electrophotographic developing device. Specifically, for example, when plating the outer surface of a low-cost product such as a bicycle generator for anti-corrosion decoration, the present invention allows the plating to be applied after the generator is assembled, thereby preventing scratches after plating. Also, since it is plated uniformly, the appearance will not be damaged. Next, the present invention will be explained in detail regarding a developing sleeve for electrophotography. Generally, in order to improve the durability of electrophotographic developing sleeves, the surface of the developing sleeve is subjected to electrolytic plating or anodic oxidation treatment as a method of hardening the surface. The permanent magnet rolls used in the one-component development system include a magnet rotation type, a sleeve rotation type, or a composite type in which a magnet and a sleeve rotate relative to each other. For the inner circumferential surface of the cylindrical sleeve,
A magnet structure in which magnetic poles are arranged so as to alternately constitute different magnetic poles, and magnets are provided over the entire width in the axial direction of the sleeve, or a groove is provided in a part of the magnetic poles of this magnet structure, and the magnetic force distribution waveform is A magnet structure configured to produce unevenness is supported by a shaft and is provided so as to be freely rotatable relative to the sleeve. The developer magnetically attracted to the surface of the sleeve is adjusted to a predetermined thickness by a doctor plate that protrudes from the sleeve, and is applied to the magnetic brush pole by rotation of the sleeve or magnet structure. A brush is formed on the developing roller by the developer in a uniform fluffy state over the entire effective width of development in the axial direction of the sleeve. In the conventional permanent magnet roll constructed and operated as described above, the gap between the sleeve and the doctor plate is approximately 0.1 to 0.7 mm, and high circumferential precision is required. In other words, the accuracy is generally 0.02 to 0.03 mm for roundness, 0.03 to 0.05 mm for cylindricity, and 0.05 mm for the outer circumference of the sleeve relative to the magnet structure.
The accuracy is as follows. Therefore, a conductive non-magnetic material sleeve made of aluminum or the like manufactured by a normal drawing method cannot be used in the one-component development method that requires high accuracy as described above if it is drawn as is. Therefore, in general, the outer circumference of this sleeve is processed by lathe processing or coreless polishing machine processing, etc.
Processed to a surface roughness of ~30μm order.
When electrolytically processing the surface of such a developing sleeve, the following two methods can be considered. 1) Process only the sleeve surface first and then attach the magnetic shaft flange. 2) After attaching the magnetic shaft flange etc. to the sleeve, perform surface processing on the sleeve. In the case of 1), the problems with electrolytic machining include the method of applying voltage to the sleeve, the method of holding the sleeve, unnecessary machining not only on the outer surface of the sleeve but also on the inner surface, and processing other than electrolytic machining. It has drawbacks such as difficulty in polishing and roughening the surface. On the other hand, in case 2), if plating is performed with a magnet inside, the thickness of the plating layer will change in response to the magnetic field, which is undesirable. The mechanism by which the plating layer thickness changes depending on the magnetic field is as follows (see Figure 1). Generally, plating is carried out by immersing the surface to be plated in a plating solution containing metal ions (cations) and arranging the object to be plated so that the potential is negative and a uniform electric field is applied to the surface to be plated. If there is no magnetic field, the metal ions (cations) in the plating solution are attracted by the electric force in the direction and speed shown by ⓓ in FIG. 1, and uniform plating can be performed. However, when a magnetic field exists, the Lorentz force, ie, the force =q(〓+〓×〓) is applied to the metal ions (cations) in the plating liquid. In the vicinity of the magnetic pole, as shown in b in FIG. 1, the direction of the magnetic field and the direction of ion movement are parallel or antiparallel, resulting in the state shown in the figure. However, at points a and c, in addition to the electric force, the ion is subjected to a force perpendicular to the plane of the paper due to the magnetic force. The direction is the direction from the back to the front with respect to the paper surface in a, and the direction from the front to the back with respect to the paper surface in c. The above forces act on the ions and the ions move in the axial direction of the cylinder at points a and c, resulting in uneven plating in correspondence with the magnetic poles. On the other hand, as shown in FIG. 2, the magnetic flux at the ends of the sleeve is different from that at the center, which also causes uneven plating. In addition to this, there is also the uneven plating caused by the uneven electric field at the edges, which has a very negative effect on the uniform finish of the plating. In order to eliminate the above-mentioned drawbacks, the present invention is designed to remove uneven plating caused by the magnetic field by rotating the internal magnet relative to the surface to be machined during electrolytic machining of items that have a magnet inside, such as a magnetic sleeve. This is the purpose. Further, at this time, a method of arranging a magnetic material around the sleeve may also be used, which improves processing unevenness at the end. In the present invention, when rotating the internal magnet with respect to the surface to be machined, it is preferable that the circumferential speed of the internal magnet be set to v=μE or more. μ
is the mobility of ions in the electrolyte and E is the electric field strength. Since ions in the electrolyte move at this speed, it is sufficient if the peripheral speed of the internal magnet is higher than this. The value of μ is approximately H ⁺ 349.8cm ² /secV Ag ⁺ 61.9 Cu ²⁺ 53.6 (25℃ aqueous solution). Taking H ⁺ as an example, under an electric field of approximately 10V/cm, a circumferential speed of 35cm/sec or more is obtained. This would be a good thing, and for a sleeve with a diameter of 30mm, it would be 180rpm. The reason for rotating the electrolytically processed object is as follows. In general, ions such as Cr ²⁺ Ni ²⁺ Cu ⁺ exhibit magnetism, so in addition to the Lorentz force described above, a force due to the magnetic field acts on the magnetic dipole of each ion, making the plating unevenness corresponding to the magnetic pole even worse. Rotating the sleeve is also effective against such magnetic ions. Example 1 A stainless steel (SUS304) sleeve with a built-in four-pole magnet roll shown in FIG. 1 was used as a developing sleeve for electrophotography. The magnetic flux density on each sleeve surface is 700G. After sandblasting the sleeve surface with irregularly shaped particles of particle size #600, a chromic acid plating solution containing a small amount of sulfuric acid (liquid composition CrO ₃ 300g/, SO ^2- ₄ /CrO ₃ =
1/100), plating liquid temperature 40℃, current density 18A/
When hard chrome plating with a thickness of 5 μm was applied at dm ² , uneven plating occurred corresponding to the magnetic poles inside the sleeve.
This was clearly visible from the outside, and the unevenness in thickness was several tens of percent. On the other hand, according to the present invention, as shown in Fig. 3, the sleeve 2 was fixed and the magnet 1 inside the sleeve was rotated from the outside at 100 to 500 rpm by the rotating means 5, and a uniform hard chrome plating with no uneven thickness was obtained. . In the figure, 3 is an electrolytic solution, 4 is a sleeve support, 6 is an electrolytic cell, and 7 is a power source. In this example, since it was necessary to mask both ends of the sleeve without plating, one end was masked with the fixing member 4 of the sleeve and the other with a seal. In such cases, uneven plating at both ends of the plating layer did not pose a problem. Example 2 In the embodiment shown in FIG. 4, a mesh 8 made of magnetic material (nickel) is arranged around the sleeve 2 in order to uniformly plate both ends. Nickel mesh 8
was used as an anode and nickel-metallic was applied. As the sleeve 2, the same one as in Example 1 was used. By doing this, the magnetic flux at the end of the sleeve became as shown in FIG. 5, and a more uniform magnetic field could be obtained than in the case of FIG. 2. Furthermore, because the electric field was made uniform due to the electrode effect of the nickel mesh, it was possible to obtain a uniform plating thickness even at the edges. This nickel mesh used was one with 50 to 200 mesh. As the nickel, those having high purity such as electrolytic nickel, rolled nickel, depolarized nickel, and carbonized nickel are preferable. Also, the electrolyte
_NiSO4 - _{NH4Cl - H3BO3} , 20℃~35℃, 0.5~
Plating is performed under the condition of 1A/ ^dm2 . This nickel mesh is machined into a cylindrical shape with a diameter 1.5 to 3.0 times the diameter of the sleeve, and the sleeve and the mesh are placed coaxially. Example 3 In a 2% oxalic acid electrolyte at 20°C, using an aluminum sleeve as an anode, voltage 100V, current density 2.0
When anodic oxidation is performed at A/ ^dm2 to form alumite on the surface, the magnet is
When the test was carried out by rotating at 500 rpm, a uniform alumite layer was obtained. Example 4 The plating tank 6 was placed in a rotating magnetic field as shown in FIG. 6, and the magnet inside the sleeve 2 was rotated, but the other aspects were the same as in Example 1. When an 8-pole rotating magnetic field was used and a 50Hz alternating current was passed through the coil 9, the magnet 1 inside the sleeve was approximately
The same effect as in Example 1 was obtained by rotating at 600 rpm. In the figure, 10 indicates a yoke. Next, Table 1 shows the surface roughness in each example.

[Table] As shown in the above examples, the present invention exhibits the following remarkable effects. Effects of rotating the magnet: 1. As mentioned above, it prevents unevenness due to the influence of the magnetic field. 2. It is best to rotate the sleeve to ensure uniform plating, but this has the disadvantage that bubbles are generated around the sleeve and interfere with plating. In the present invention, the ion flow is stirred by fixing the sleeve and rotating the magnet, so uniform plating can be achieved. 3. The surface finish can be easily controlled by selecting the speed of plating, anodizing, electrolytic polishing, etc. and the rotation speed of the magnet.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the manner in which the plating layer changes due to the magnetic field, Fig. 2 is an explanatory diagram of the manner in which the magnetic field changes at the end of the sleeve, and Figs. 3 and 4 are explanatory diagrams of the embodiment of the embodiment of the present invention. FIG. 5 is an explanatory diagram showing changes in the magnetic field in the same embodiment, and FIG. 6 is an explanatory diagram of an embodiment of another embodiment. 1: Magnetic shaft, 2: Sleeve, 3: Electrolyte, 4: Sleeve support, 5: Magnetic rotating member, 6: Electrolytic cell, 7: Power source, 8: Nickel mesh, 9: Coil, 10: Yoke.

Claims (1)

[Scope of Claims] 1. A surface treatment characterized by fixing the developing sleeve and rotating the magnet when performing electrolytic processing such as electrolytic plating or anodizing electrolytic polishing on the surface of a developing sleeve having a magnet inside. Law. 2. The surface processing method according to claim 1, characterized in that a magnetic material is arranged around the developing sleeve. 3. The surface processing method according to claim 1, characterized in that the developing sleeve is placed in a rotating magnet.