GB2077154A - A method of polishing a peripheral surface of a cylindrical drum for electrophotography - Google Patents

Abstract

A method of polishing the peripheral surface (1) for manufacturing a photosensitive drum by frictionally abrading the surface (1) uses a rotary grinder (2), the axis (Y) of which is disposed so as not to form a right angle with a plane orthogonal to the rotary axis (X) of the drum. The peripheral surface of the drum is abraded by a rotating grinder surface which is not parallel to the rotary axis (Y) of the grinder. The grinder axis (Y) may intersect or be displaced from the drum axis (X). The grinder axis may be at 0 DEG to 45 DEG to the orthogonal plane. The grinder is applied by an adjustable weight (7) contracted by a weight (6). <IMAGE>

Description

SPECIFICATION A method of polishing a peripheral surface of a cylindrical drum for electrophotography The present invention relates to a new method of manufacturing a photosensitive drum for electrophotography. More specifically the present invention relates to a method of treating a cylindrical drum substrate for manufacturing a photosensitive drum for use in electrophotography.

In electrophotography a photo-sensitive member is generally constituted by providing a photoconductive layer directly or indirectly through an optional barrier layer on an electrically conductive substrate. As the substrate for the photo-sensitive member, there are known substrates of various configurations. Among them that having a cylindrical configuration has been popularly utilised, and as for the material thereof alminium, copper, stainless steel, brass or the like material is widely used.

The substrate for the photo-sensitive member for electrophotography is usually manufactured by treating the peripheral surface of a cylindrical or tubular body by means of a turning process by the use of, for example, a diamond or the like material, or by means of a buffing process, a superfinishing process, a liquid honing process or the like process. In any case, in order for the finished product to be advantageously used as the substrate for photo-sensitive member, it is required that the surface of such substrate can satisfy certain conditions, inter alia, the surface of the substrate has to possess an appropriate physical roughness within a predetermined range.

Although the surface roughness can differ more or less depending on the nature of the material to be used, types of of the photoconductive layer or if any, barrier layer to be formed thereon, it is generally preferable for the surface to have a surface roughness between about 0.3 limS and about 3.0 #mS. In the case where such substrate having the surface roughness of less than 0.3 ,umS is used, one may encounter with the difficulty that the photoconductive layer becomes easy to come off after repeated use thereof.On the other hand, when the photo-sensitive member is prepared by using a substrate having the surface roughness greater than 3.0 ymS, there will be such disadvantages that the photoconductive layer formed on such a rough surface often shows a rather large dark decay property after the layer is electrically charged or that images formed by the use of such photo-sensitive member tend to be coarse in its image quality.

Further in another technical respect, it would become possible for the manufacturing cost of such photo-sensitive member to be greatly reduced if the same substrate can be reused, when a photoconductive layer becomes fatigued and its properties are deteriorated, by removing such degraded photoconductive layer and constructing a new photoconductive layer thereon. In order to make the aforesaid process possible, it is required to treat the substrate for regeneration, removing used photoconductive layer from the surface of the substrate.

As for the treating method of such used photo-sensitive member for the purpose of regeneration, there have been known various methods. For example, there has been known to remove only a photoconductive layer by means of a known method and therafter to wash the substrate. This method is advantageous in that the surface of the substrate is not subjected to unnecessary changes in the regeneration process, and, therefore, the physical conditions of the surface may be maintained almost unchanged. However, the photo-sensitive member prepared by the use of a substrate treated by the above-mentioned process tends to undergo rapid deterioration and the life of such photo-sensitive member often becomes considerably shortened.

This may be attributed to the fact that the exhaust photoconductive layer may not have been completely removed, or to the fact that even if the photoconductive layer is revomed fairly completely, the surface of the substrate may not still be cleaned to its satisfaction.

In the light of the above-mentioned disadvantages, it may be said to be more advantageous to regenerate a substrate by polishing the surface by grinding it by an appropriate depth, after used photoconductive layer is removed from the substrate. For example, by grinding such substrate by the depth of less than 50 microns and, more preferably, less than 10 microns, a regenerated substrate having a new surface may be obtained. By this method, however, it should be noted that when the grinding thickness exceeds 50 microns, the outer diameter of the drum substrate will be decreased, so that this will make it necessary for the various parts of a photo copying machine to be positionally readjusted and such adjustment may eventually hinder production of copied image having desirable image qualities.

Further, the grinding treatement of the substrate should desirably be carried out in such a manner that the reflectance of the regenerated surface may have the same value as that of the surface before the regeneration treatment. For if the new surface has the same reflectance it is considered to indicate that the conditions of the surface, on which a new photoconductive layer is to be formed, are also the same, and thus a new photo-sensitive member having invariable photographic properties may be easily obtainable.Further the light reflectance of the surface of the substrate can be preferably used for the purpose of detecting such a trouble in the photocopying machine of winding of transfer sheet around the peripheral surface of the photo sensitive drum or for the purpose of providing toner image to be formed with constant density, by comparing the light intensity of the reflected light from the substrate itself with that from the transfer sheet wound around the photo-sensitive drum, or that from a toner image developed on the photo-sensitive drum by the use of an original having a standard density.

Further it is as a matter of course preferable for a photo-sensitive drum to have the crosssectional profile which approximates to a true circle as much as possible and, also, not to be injured or damaged by such as abrasion or have agy waviness on the surface.

As mentioned above, despite that there are various requirements for the satisfactory treatment of the surface of the photo-sensitive drum, none of the methods hereinbefore mentioned can fulfill all the requirements satisfactorily. For example, by means of the turning process by the use of a diamond cutter or the like cutter, the grinding thickness or depth easily amount to about 100 microns. By means of the buffing process, on the other hand, although it is possible to obtain a substrate having a very smooth and mirror-like surface, periodical waviness tend to be caused on the surface. This waviness can have adverse effects on the performance of the photo-sensitive drum in its imageforming abilities.

Further according to the superfinishing process, it may not be very difficult to obtain a surface having a surface roughness between 0.3 sumS and 3.0 pmS, however, this process often causes scratch-like abrasions over the surface of the regenerated substrate, and this often results in the occurrence of defects in the images produced by the use of such regenerated photo-sensitive drum. Further it has often been observed in the regenerated substrate by the superfinishing method that the reflectance of the surface is changed largely even if the treatment of the surface is conducted under constant conditions. Occurrence of such scratch-like abrasions on the surface may be attributed to the fact that broken pieces of delaminated photoconductive layer fall between the grind stone and the surface of the cylindrical drum substrate.

Further, according to the liquid honing process, it is difficult to obtain a regenerated surface having the surface roughness within the range of 0.3 umS to 3.0 umS.

As mentioned above, the hitherto known methods of manufacturing a cylindrical drum substrate for electrophotography have involved various unavoidable disadvantages.

According to the invention there is provided a method of polishing a peripheral surface of a cylindrical drum substrate for manufacturing a photosensitive drum for electrophotography, said method comprising frictionally rubbing the peripheral surface by the use of a rotary grinder, wherein the rotary grinder is disposed so that the rotation axis thereof does not form a right angle with a plane which is orthogonal to the rotation axis of the cylindrical drum substrate and the peripheral surface thereof is subject to frictional rubbing by a rotating grinder surface of the rotary grinder which grinding surface is not in parallel with the rotation axis thereof.

An advantage of the invention is that it makes is possible to provide a method of manufacturing a cylindrical drum substrate for electrophotography having appropriate and uniform surface roughness all over the surface as well as an invariably constant surface reflectance and a desired shape, and thus allows to provide a photo-sensitive drum member having improved capability of producing excellent images and improved durability.

Another advantage of the present invention is that it makes it possible to provide an effective method of processing a used photo-sensitive drum and regenerating the surface of the cylindrical drum substrate.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figures 1 and 2 are schematic diagrams of respective apparatus for performing a method according to the invention; Figures 3 and 4 are cross-sectional details of apparatus for performing a polishing method of the invention.

Fig. 1 shows a schematic diagram of a spacial arrangement of a rotary grinder and the cylindrical drum member for performing the present invention. A cylindrical drum member for the drum substrate for electrophotography is rotated about the rotation axis X which may extend horizontally. A grinder surface of a rotary grinder 2 is rotated abut a rotation axis Y. Thus the peripheral surface of the cylindrical drum member 1 is made to be in pressure contact with a grinder surface of the rotary grinder 2 and the peripheral surface of the cylindrical drum member is subjected to frictional rubbing. In the present invention the rotary grinder is disposed against the cylindrical drum member so that the grinder surface which is to pressurizingly contact with the peripheral surface of the cylindrical drum member is not in parallel relation with the rotation axis Y of the rotary grinder. Further in the present invention the rotation axis Y of the rotary grinder may form an angle with an imaginary plane which lies orthogonal with respect to the rotation axis X of the cylindrical drum member except right angles.

According to one of the preferable embodiments of the present invention, the rotary grinder is disposed against the cylindrical drum member so that the rotation axis thereof lies in the imaginary plane itself which is orthogonal to the rotation axis of the cylindrical drum member, which embodiment is illustrated in Fig's. 1 thru 3.

According to more preferable embodiment of the present invention, the rotary grinder is disposed against the cylindrical drum member so that the rotation axis thereof and the imaginary plane which is orthogonal to the rotation axis of the cylindrical dru member forms an angle 0, which satisfies the follwing relation: 0 < O#45'.

Example of such embodiment is illustrated in Fig. 4. In order for the whole peripheral surface of the cylindrical drum member to be polished by frictional rubbing by the rotary grinder, either the rotary grinder or the cylindrical drum memmer may move, preferably, along the direction of the rotation axis X of the cylindrical drum member, however, according to the preferable embodiment of the present invention it is more advantageous for the rotary grinder to move along the direction of the rotation axis of the cylindrical drum member.

Further in the present invention, the rotation axis Y of the rotary grinder does not necessarily intersect the rotation axis of the rotary cylindrical drum member X, but as shown in Fig. 2, it may be off the rotation axis X.

In Fig. 1, an apparatus including a rotary grinder to used in the present invention is shown, wherein the rotary grinder 2 is mounted at one end of a swingable lever 5 which is pivotally supported by a supporting stand 4 at an intermdiate point or a fulcrum 3. The lever 5 has the other end provided with a stationary weight 6. Further, a weight 7 for adjusting the pressure, under which the grinder 2 is brought into contact with the surface of the cylindrical drum member 1, may be mounted on the lever 5 movably in the longitudinal direction. Thus by adjusting the weight of the counter weight 6 and/or position of the adjusting weight 7, the pressure under which the grinder is brought into contact with the cylindrical drum member 1 can be regulated in a desirable manner.Further, movement or displacement of the rotary grinder in the direction of the rotation axis X of the cylindrical drum member can be attained by constructing the supporting member 4 slidable by, for example, disposing the supporting member 4 on a suitble guiding path such as a rail. The rotary grinder 2 may be driven by a motor or the like which may also serve as a counter weight.

Figs. 3 and 4 show partially enlarged projection views of Figs. 1 and 2 projected on a plane vertical to the plane of the drawing sheet and in parallel to the rotation axis of the rotary grinder.

In the case of the illustration of Fig. 3, an angle formed between a plane orthogonal to the rotary axis X of the cylindrical drum substrate member 1 and the rotation axis Y of the rotary grinder 2 is so set as to be equal to 0'. In this case, since the polishing is effected by various portions of the rotary grinder which exhibit different polishing forces in different polishing directions, the surface of the cylindrical drum to be polished is subjected to different or various polishing actions, resulting in a uniformely polished surface having an appropriate surface roughness without waviness. When the rotary grinder is disposed so that the axis X is off the axis Y as is illustrated in Fig. 2, then, different polishing actions are exerted on the surface of the cylindrical drum member and the effects attained becomes more significant.

Fig. 4 illustrates a case where the rotary grinder 2 is so disposed that the angle 8 becomes equal to 45". With such polishing arrangement, no unbalance in the force applied to the rotary grinder is produced across the axis Y, as the result of which the rotary grinder can be operated in a more stable state without being subjected to any appreciable vibrations ascribable to the unbalanced state.

The disposition of the rotary grinder in the manner shown in Fig. 4, i.e. disposition of the rotary grinder in such arrangement that the rotation axis of the rotary grinder is made inclined as viewed in the projection thereof, is convenient in attaining the stability of the grinding actions of the rotary grinder. The angle 8 defined above may take various values, however, according to preferable embodiments of the present invention it takes a value between 0 and 45".

A polishing apparatus to be made use of for the purpose of carrying out the present invention is disclosed in Japanese Patent Publication No. 4631 5/1976, and such machine is commercially available from Sanko Kikai Inc. of Japan under the trade name ''Cylinder Polishing Mirror Finishing Machine" In carrying out the method according to the invention, any grind stone which are commonly used can be employed. For example, "PVA Grinding Wheel" and "FBB Grinding Wheel" available from Nippon Tokushu Kento Inc. and the like can be made use of.

As will be appreciated from the foregoing description, the method according to the invention allows the surface of a cylindrical drum member to be polished with a high dimensional accuracy, while the surface roughness of the finished substrate can be controlled to 0.05 ELmS at minimum in dependence on the types of the grind stone 2 as well as the pressure thereof exerted to the cylindrical drum, making it easy or sure to manufacture the cylindrical drum substrate having the surface roughness in the range of 0.3 ymS to 3.0 ymS, which is very suitable for the drum substrate for electrophotography.Further, according to the present invention substantially no unevenness can be recognized in the reflectance of the finished substrate, and with the same polishing conditions, constant reflectance value can be obtained.

Further, cylindrical substrate with a surface close to a true circle without waviness on the surface can be obtained.

Additionally, even the cylindrical drum substrate which was once used as the photo-sensitive drum can be advantageously regenerated so as to have a surface having substantially same surface roughness and reflectance as those of the fresh substrate and so as to be evaded from such inconveniences of the formation of waviness, scratches of the like.

Further, according to the invention, it is easily possible to control the grinding depth (i.e. the thickness of the cylindrical drum substrate to be removed by frictional rubbing the surface thereof) to less than 10 microns. Consequently, the outer diameter of the regenerated cylindrical drum substrate and the outer diameter of the photo-sensitive drum manufactured by the use of such regenerated cylindrical drum substrate are scarcely changed, obviating positional adjustments of various parts of the electrophotographic copying machine in which such regenerated photo-sensitive drum is employed. Further, since the cylindrical drum substrate can thus be regenerated may times, costs for manufacturing the photo-sensitive drum can be reduced significantly.By the use of a photo-sensitive drum with a cylindrical drum substrate manufactured according to the invention, an excellent image without having unnecessary unevencess or roughness can be obtained and even after repeated use of such cylindrical drum substrate no substantial accident such as delamination of the photoconductive layer and thus the enhanced durability can be demonstrated.

Various types of the photoconductive layers can be used in combination with the cylindrical drum substrate fabricated according to the invention. for example, photoconductive layers or amorphous selenium or alloys of amorphous selenium series, photoconductive layers containing lead oxides, photoconductive layers containing organic photoconductive materials and the like may be used. If necessary, there may be provided between the photoconductive layer and the substrate a barrier layer of any conventional type which include that formed of a metal oxide, various types of inorganic compounds, or of various types of organic compounds.

The invention will be further illustrated with reference to examples.

Example 1 Using as the cylindrical drum substrate a tubular member or aluminium which was fabricated through a turning process using a cutting tool and which has an outer diameter of 120.007 mm, a length of 340.00 mm and a surface roughness of 30 ymS, surface processing was carried out according to the method of the invention under the conditions mentioned below: Processing apparatus: "Cylinder Grinding/Mirror Finishing Machine-SM-1 A-i 500 (manufactured by Sanko Kikai Inc.) Grinding Wheel: "FBB-GC 2000" (outer diameter is 20 mm, thickness is 50 mm, and diameter of mounting center bore is 50 mm, manufactured by Nippon Tokushu Kento Inc.) Revolution number of grinding wheel: 600 r.p.m.

Feed rate of grinding wheel: 0.7 m/min.

Pressing force of grinding wheel: 35 kg Angle formed between a plane orthogonal to the center axis of the substrate and the rotation axis of the grinding stone (this angle will hereinafter be represented by 8): 0 Peripheral rotation speed of substrate material: 160 m/min.

Polishing stroke: a single reciprocation (a round) Polishing liquid: running water The tube as obtained had a uniform surface roughness of 0.3 limS, an outer diameter or 120.004 mm and a reflection factor of 37% at wavelength of 930 nm.

The ground tube was washed in a weakly alkaline solution, and then rinsed with water and dried. Subsequently, photoconductive layer of selenium series of 70 microns in thickness was formed on the surface of the tubular substrate through a conventional vacuum evaporation of a selenium-tellurium alloy (containing 10.0% by weight of tellurium), to thereby accomplish a photo-sensitive drum. The photo-sensitive drum exhibited satisfactory performances and the image obtained by the use of thus manufactured photo-sensitive drum were found to have high image qualities.

Durability test was conducted by installing thus manufactured photo-sensitive drum in a electrophotographic copying machine "U-Bix V" (commercially available from Konishiroku Photo Industry Co., Ltd. of Japan). After 60,000 times of operations, fault such as delamination of the photoconductive layer was not observed at all.

Next, according to a method described in Example 7 of Japanese Laid-Open Patent Application No. 87651/1975, attempt was made to delaminate the photocinductive layer after the durability test. The photoconductive layer at end portions of the substrate could not be delaminated even after the delaminating process had been repeated several times. Under the circumstance, the polishing process described above was adapted in order to eliminate completely the remaining photoconductive layer.

The substrate thus regenerated was substantially identical with the tubular substrate fabricated from the fresh substrate material and had a surface roughness of 0.3 #mS, an outer diameter of 120.002 mm and a reflection factor of 37 %.

The regenerated substrate was employed for fabricating a photo-sensitive drum by forming thereon a photoconductive layer of selenium series in the same manner. as described above. The photo-sensitive drum thus obtained exhibited the performances compatible to those of the photo-sensitive drum of the fresh substrate. Further, satisfactory results were obtained in the durability test.

In this example the measurement of the outer dimeter of the tubular member was made with the aid of "Three-Dimensional Coordinate Measuring Apparatus, TYPE E-DC-M760-3B" (available from Tokyo Seimitsu Inc.).

The surface roughness was measured by "Surface Roughness Meter, TYPE E-ST-SO3" (available from Tokyo Seimitsu Inc.).

The reflection factor was measured by "Ultraviolet/Visible Ray Spectrophotometer, TYPE EPS3T" (manufactured by Hitachi Seisakujo Inc.).

Example 2 Using the same tubular member of aluminium as the one employed in the Example 1 as the cylindrical drum substrate, the surface processing was conducted according to the teaching of the invention on the following condtions: Processing apparatus: Same as the one Used in the Example 1 Grinding wheel: "PVA-1 500" (outer diameter is 200 mm, thickness is 50 mm, and diameter of a mounting center bore is 50 mm, manufactured by Suibosha Inc.) Revolution number of grinding wheel: 800 r.p.m.

Feed rate of grinding wheel: 0.7 m/min.

Pressing force of grinding wheel: 40 kg Angle 0 formed between the rotation axis of the grinding wheel and a plane extending orthogonally to the center axis of the substrate: 0 Peripheral rotation speed of substrate: 75 m/min.

Polishing stroke: a round Polishing liquid: "PVA Polish Liquid No. 3" (available from Nippon Grease Inc.) The tubular member as obtained had a uniform surface roughness of 0.7 ijmS, an outer diameter of 1 20.003 mm and a reflection factor of 24 % at the wavelength of 930 nm.

The fabricated tubular member was washed in a weakly alkaline solution, and then rinsed and dried. This tubular member was used as the cylindrical drum substrate and left in a steam environment at a temperature of 95 C for 120 seconds, whereby a barrier layer of crystal of aluminium hydroxide (boehmite) was formed over the surface of the substrate (refer to Japanese Laid-Open Patent Application No. 11692/1979). A liquid mixture containing 10 g of dibromoanthanthrone, 20 g of polycarbonate resin, and 500 ml of 1,2-dichloroethane was applied to the surface of the substrate while the latter was being rotated, and dried to form a layer of 2 microns in thickness.Further, a liquid phase mixture containing 50 g of 1,1-bis-(4-N, Ndiethylamino-2-methyl phenyl)-1 -phenylmethane and 100 g of polycarbonate resin solved in 1000 ml of 1,2-dichloroethane was applied onto the layer while the substrate was rotated, and dried to form a layer of 15 microns thick. Thus, a photo-sensitive drum having an organic photoconductive layer was fabricated. This photo-sensitive drum exhibited satisfactory performances and the image produced had a good quality without any blurs and roughness. The photo-sensitive medium was installed in a electrophotographic copying apparatus commercially available from Konishiroku Photo Industry Co., Ltd. under the trade name "U-Bix V", however, in this example polarities of various electrically active units of the copying apparatus had been inverted, and a durablility test was carried out.Even after 20,000 times of operation, faults such as delamination of the photoconductive layer and the like did not occur at all.

After the durability test, the photo-sensitive drum was immersed in 1,2-dichloroethane to remove a major portion of the photoconductive layer. Subsequently, the polishing process was carried out in the same manner as described above all the remaining photoconductive layer. A regenerated substrate was thus obtained. The regenerated substrate was substantially identical with the processed tubular member described above and had a surface roughness of 0.7 ymS, an outer diameter of 119,996 mm and a reflection factor of 24 %. A photo-sensitive drum formed on thus regenerated substrate by applying thereon the barrier layer and the photoconductive layer in this order in the same manner as described above exhibited performances compatible to those of the photo-sensitive drum of the fresh material and allowed image of high quality.

Further no problem arised in respect to the durability.

Example 3 A cylindrical drum substrate of an aluminium tube was processed according to the method of the invention on the same conditions as in the case of Example 1 except that the angle O was set equal to 30".

The processed tubular member had a uniform suface roughness of 0.3 ymS, an outer diameter of 120.003 mm and a reflection factor of 35 % at wavelength of 930 nm.

Using thus prepared cylindrical drum substrate a photosensitive drum was manufactured through the same procedures as in the case of Example 1. The photo-sensitive drum thus obtained exhibited satisfactory performances and produced images of a good quality.

This photo-sensitive drum was subjected to the durability test in the same manner as in the case of Example 1. Even after 60,000 times of operations, faults or failures such as delamination of the photoconductive layer was not observed at all.

After the durability test, the photoconductive layer was removed in the same manner as in Example 1.

The regenerated substrate thus obtained was substantially identical with the processed tubular member of the fresh material and had a surface roughness of 0.3,umS, an outer-diameter of 120.001 mm and a reflection factor of 34 %.

The regenerated substrate was formed thereon with a photoconductive layer of selenium series in the same manner as described above. The photo-sensitive drum thus fabricated exhibited performances equivalent to those of the of a fresh drum, and the durability was also sufficiently satisfactory.

Example 4 A cylindrical drum substrate of aluminium was processed according to the teaching of the invention under the same conditions as in the case of Example 2 except that the angle 8 of 15 was used.

The processed substrate had a uniform surface roughness of 0.7 ymS, an outer diameter of 120.002 mm and a reflection factor of 26 % at the wavelength of 930 nm.

A photo-sensitive drum was prepared in the same manner as in the case of Example 2. The photo-sensitive medium exhibited satisfactory performance and image of good qualities was produced.

The durability test carried out in the same manner as in the case of Example 2 resulted in no occurence of failures such as delamination of the photoconductive layer and the like even after 20,000 times of operations.

After the durability test, the photoconductive layer was removed and subjected to the polishing process in the same manner as in the case of Example 2.

The regenerated substrate was substantially same as the tubular member of the fresh material and had a surface roughness of 0.7 ymS, an outer diameter of 119.996 mm and a reflection factor 26 % at the wavelength of 930 nm.

Using the regenerated substrate, a photo-sensitive drum was prepared in the same manner as in Example 2. The photo-sensitive drum thus fabricated exhibited satisfactory performances, and images of a satisfactory quality were produced. Further, durability was also attained.

Example for Comparison Four cylindrical drum substrates of a aluminium as the one employed in Exampe 1 were used and processed by means of (1) a turning process by means of a diamond tool, (2) a buffing process, (3) a superfinshing process, and (4) a liquid honing process, respectively, on the following conditions.

(1) Turning with a diamond cutting tool.

Processing apparatus: "Superprecision Lathe, TYPE L-3001" (manufactured by Toyota Koki Inc.) Cutting tool: "Miracle Diamond Tool" (manufactured by Tokyo Diamond Tool Seisakujo Inc.) Peripheral rotation speed of substrate material: 942 m/min.

Feed rate of substrate material: 471 m/min.

Turning stroke: 1 Turning liquid: Kerosene (2) Buffing Processing apparatus: "TYPE LPT-35C" (manufactured by Washino Kikai Inc.), "Buffing Machine, TYPE 1 VM" (manufactured by Todoroki Seisakujo Inc.) Buff: "Tobacopackard 1 H 36" (manufactured by Tokyo Buff Inc.) Buffing agent: "Torpori K-2000" (manufactured by Koyo Inc.) Peripheral speed of buff: 2000 m/min.

Peripheral rotation speed of substrate material: 75 m/min.

Feed rate of substrate material: 68 m/min.

Buffing stroke: 1 (3) Superfinishing Processing apparatus: Lath "TYPE -35C" (manufactured by Washino Kikai Inc.), Superfinishing machine "TYPE T-Se 1 40" (manufactured by Toyo l < ogyo Inc.) Grinding stone: "FBB GC 1000" (manufactured by Nippon Tokushu < ento Inc.) Vibration cycle of grinding stone: 150 c/min Pressing force of grinding stone: 0.6 kg/cm2.

Peripheral rotation speed of substrate material: 150 m/min.

Feed rate of grinding stone: 500 mm/min.

Polishing stroke: 1 Polishing liquid: running water (4) Liquid Honing Processing apparatus: "TYPE F-5" (manufactured by Fuji Seiko Seizojo Inc.) Honing agent: Pulverised silica "#2000" Honing liquid: running water (ratio of honing agent to water is 4 : 1 in weight) Air pressure: 3.0 kg/cm2 Distance between nozzle and substrate material: 80 mm Injection angle: 60 Nozzle orifice diameter: 8.3 mm For four types of tubular members obtained from the processings enumerated above, measurements were made in respect to the surface roughness, outer diameter and the light reflection factor at the wavelength of 930 nm.The processed tubular members were washed in a weakly alkaline solution, rinsed and dried, and subsequently used for manufacturing four kinds of photo-sensitive drums of selenium series, respectively, in the same manner as described hereinbefore in Example 1. Those photo-sensitive drums were subjected to the tests for image producing performances and durability.

After the durability test, the photoconductive layer of each of the light sensitive media was at first preparatorily removed in the same manner as in the case of Example 1, which was followed by removal of the remaining photoconductive material by the same process adopted in preparing respective cylindrical drum substrates. Thus, four regenerated substrates were obtained.

Measurements were performed for these regenerated substrates in respect of the surface roughness, outer diameter and the reflection factor at the wavelength of 930 nm. Subsequently, these regenerated substrates were used for manufacturing photo-sensitive drum of selenium series, respectively. Tests for the image producing performance and durability were performed by the use of these photo-sensitive drum.

The results of various measurements and the tests are listed in following tables togerther with the corresponding results obtained in the Example 1 and Example 3. As can be seen from the tables, the turning process using the diamond tool, the buffing process, the super finishing process and the liquid honing process suffer serious drawbacks. In contrast, according to the method of the present invention. a substrate for an excellent light-sensitive medium can be fabricated.

Table 1 Initially Processed Cylindrical Photo-Sensitive Processings Drum Substrate Media Surface Outer Reflection Roughness Diameter Factor Surface (yams) (mm) (%) State Image Durability Turning with a diamond 0.2 119.912 68 X ( G Buffing 0.3 120.002 57 A D O Superfinishing 0.8 120.001 26 (^) O Liquid Honing 4.2 119.962 9 B E Example 1 0.3 120.004 37 r, O O Example 3 0.3 120.003 35 f > ) O O Table II Regenerated Cylindrical Drum Photo-Sensitive Processings Substrate Drum Surface Outer Reflection Roughness Diameter Factor Surface (iLmS) (mm) (%) State Image Durability Turning with diamond 0.2 119.791 68 f i D G Buffing 0.3 120.000 55 A D O Superfinishing 0.8 119.979 12 C F (3 Liwuid Honing 4.3 119.717 10 B E C Example 1 0.3 120.002 37 0 O O Example 3 0.3 120.001 34 G O G In the Tables I and 11, symbol "" represents satisfactoriness. In respect to the surface state, symbol "A" represents the presence of waviness, symbol "B" represents the presence of undesirable roughness and symbol "C" represents the presence of scratches or the like injuries.

Concerning the image as produced, symbol "0' represents non-uniformity in the density, and symbols "E" and "F" represent defects ascribable to the roughness and the scratch, respectively. Symbol "G" represents a poor durability typified by delamination of the photoconductive layer.

As described hereinbefore, according to the present invention cylindrical drum substrate having an appropriate surface roughness can be obtained. The polishing pattern surrounding the processed surface of the substrate may be an inclined parallel strip pattern, mesh-like pattern and so forth in dependence on the following factors: 1. Rotation speed and direction of the rotary grinder; 2. Rotation speed and direction of the cylindrical drum substrate; 3. Direction and magnitude of the offset between the rotation axis of the rotary grinder and the rotation axis of the cylindrical drum substrate; 4. Angle 0 formed between the rotation axis of the rotary grinder and the rotation axis of the cylindrical drum substrate; 5. Direction, speed, the number of strokes of the rotary grinder and other factors.

Claims (9)

1. A method of polishing a peripheral surface of a cylindrical drum substrate for manufacturing a photosensitive drum for electrophotography, said method comprising frictionally rubbing the peripheral surface by the use of a rotary grinder, wherein the rotary grinder is disposed so that the rotation axis thereof does not form a right angle with a plane which is orthogonal to the rotation axis of the cylindrical drum substrate and the peripheral surface thereof is subject to frictional rubbing by rotation grinder surface of the rotary grinder which grinding surface is not in parallel with the rotation axis thereof.

2. A method according to claim 1, wherein said rotary grinder is attached to a swingable supporting member.

3. A method according to claim 2, wherein the rotary grinder is movable along the axial direction of the cylindrical drum substrate.

4. A method according to any preceding claim, wherein the rotation axis of the rotary grinder is in said plane orthogonal to the rotation axis of the cylindrical drum substrate.

5. A method according to any of claims 1 to 3 wherein the rotary grinder is disposed so that the angle formed by the rotation axis of the rotary grinder and said plane orthogonal to the rotation axis of the cylindrical drum substrate satisfies the following relation; O', < 0#45'

6. A method according to claim 5, wherein the rotation axis of the rotary grinder is in a plane orthogonal to said plane which is orthogonal to the rotation axis of the cylindrical drum substrate.

7. A method of polishing a peripheral surface of a cylindrical drum substrate, substantially as hereinbefore described with reference to the accompanying drawings.

8. A method or polishing a peripheral surface of a cylindrical drum substrate, substantially as described in any one of Examples 1 to 4.

9. A drum having a peripheral surface of a cylindrical drum substrate which has been polished by a method as claimed in any preceding claim.