JP4038632B2 - Method for manufacturing substrate for photosensitive drum - Google Patents

Description

【００３４】
以上の結果より、本発明に係る成形法は、真円度、真直度に優れた感光ドラム用の円筒状基体を成形し得ることが認められる。なお、サイドゲート方式の場合、樹脂が最初に流れ込むスプルーは、本発明例のようなパイプ中心部の位置でなく、パイプの側面の位置からの１点で、そこから樹脂が流れ込む構造となる。そのため、本発明例１，２がパイプの周方向に均一に樹脂が充填されるのに対して、サイドゲート方式はパイプ全体に樹脂が充填される過程において充填速度に偏りが見られ、周方向に均一な充填は行われない。また、パイプのゲートと反対側の位置（図でいうパイプの下側全体）に、ウェルドラインが発生してしまう場合がある。ウェルドラインは成形品の強度低下の恐れがあり、またその部分の表面性は位置著しく低下する。
【００３５】
【発明の効果】
本発明によれば、真円度、真直度等の寸法精度に優れ、しかもフランジの組み付け作業が簡略化され、アース用の金属板などの取り付け作業を省略し得る感光ドラム用の円筒状基体を生産性よく製造することができる。
【図面の簡単な説明】
【図１】本発明によって製造される基体を用いた感光ドラムの一例を示す概略断面図である。
【図２】本発明で用いるピンゲート方式による金型の一例を示す概略断面図である。
【図３】本発明で用いるディスクゲート方式による金型の一例を示す概略断面図である。
【図４】従来の感光ドラムを示す概略断面図である。
【符号の説明】
１１ 円筒状本体
１２ フランジ
１０ 円筒状基体（感光ドラム用基体）
２６ ピンゲート
２６’ ディスクゲート
２０ 金型
２４ 円筒状本体形成用キャビティ
２５ フランジ形成用キャビティ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a substrate for a photosensitive drum for forming an electrostatic latent image on a surface for image formation in an electrophotographic apparatus such as a copying machine, a facsimile machine, a printer, or an electrostatic recording apparatus.
[0002]
[Prior art and problems to be solved by the invention]
In an electrostatic recording process in a copying machine, facsimile, printer, etc., first, the surface of the photosensitive drum is uniformly charged, and an image is projected from the optical system onto the surface of the photosensitive drum to erase the charged portion. Then, an electrostatic latent image is formed, and then toner is supplied to the electrostatic latent image to form a toner image by electrostatic adhesion of the toner, and this is applied to a recording medium such as paper, OHP, photographic paper, etc. A method of printing by transferring is employed.
[0003]
As a photosensitive drum used in such an electrostatic recording process, a photosensitive drum having the structure shown in FIG. 4 is generally used.
[0004]
That is, flanges 2a and 2b made of metal or resin are fitted and fixed to both ends of a cylindrical base 1 made of a metal such as aluminum or conductive resin, and the photoconductive layer 3 is formed on the outer peripheral surface of the cylindrical base 1. As shown in FIG. 3, this photosensitive drum generally has support shafts 4 and 4 provided on the main body a of the electrostatic recording apparatus, and both flanges 2a and 2b. Is inserted into the shaft holes 5 and 5 provided in the shaft 2 and is rotatably supported. On the other hand, a gear 7 connected to a driving source such as a motor is engaged with a driving gear 6 formed on the flange 2b to rotate. Is done.
[0005]
In this case, in order to charge the photoconductive layer 3 of the photosensitive drum and to form an electrostatic latent image on the photoconductive layer 3 by exposure, it is necessary to ground the photosensitive drum. When 2b is formed of an insulating resin, a metal plate is attached to the inner surface of the flange for grounding to connect the cylindrical substrate 1 and the support shaft 5 and grounded to the apparatus body a. .
[0006]
However, since the conventional photosensitive drum is assembled by fitting and fixing the flanges 2a and 2b to both ends of the cylindrical substrate 1, two assembly operations for assembling the flanges at both ends of the cylindrical substrate are necessary. In addition, since the cylindrical base 1 and the flanges 2a and 2b are formed separately, a high degree of processing accuracy is required when forming each of these parts, which increases the manufacturing cost. .
[0007]
Further, when the above-mentioned ground metal plate is required, it is necessary to assemble the ground metal plate, which further increases the manufacturing cost and wears the metal plate during operation of the drum. There is a possibility that good conduction with the support shaft 5 may not be obtained, and the reliability is not necessarily sufficient.
[0008]
In response to such a problem, the present applicant is provided with flanges on both end surfaces of the cylindrical base body on which the photoconductive layer is formed on the outer peripheral surface, and is supported rotatably by supporting both flanges. The photosensitive drum is characterized in that the cylindrical base is formed of a conductive resin and one flange is formed integrally with the cylindrical base using the same conductive resin. Japanese Patent Application No. 9-323805). In this photosensitive drum, one of the flanges provided at both ends of the cylindrical base is integrally formed of a conductive resin that forms the cylindrical base. Therefore, at least one end of the cylindrical base is attached to the flange. This flange is made of a conductive resin formed integrally with the cylindrical base body, and good conduction between the support shaft supporting the drum and the cylindrical base body can be reliably obtained by this flange. In addition, it is not necessary to use a metal plate for grounding, and high reliability can be obtained. Furthermore, since one flange is integrally formed with the cylindrical base body, its processing accuracy is also excellent.
[0009]
By the way, the conventional cylindrical substrate 1 shown in FIG. 4 is usually manufactured by injection molding using a side gate type mold in which a gate is provided outside the cylindrical cavity for molding the cylindrical substrate 1. However, in this method, there is a problem that a gate mark remains on the outer peripheral surface of the molded cylindrical substrate 1, and the resin is not uniformly filled in the cylindrical cavity, and the obtained cylindrical substrate is straight. There is a problem that the dimensional accuracy such as degree and roundness is inferior, and as a result, the printing and image characteristics of the photosensitive member are affected. In this respect, the same problem occurs when a cylindrical base body in which the one flange is integrally formed is used when a die using the side gate method is used.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a photosensitive drum substrate that solves the above-described problems, has excellent dimensional accuracy, and provides good print image characteristics.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a mold for forming a photosensitive drum substrate, which is integrally formed with a flange projecting inwardly on the inner peripheral edge of one end surface of a cylindrical body made of a conductive resin. In this case, three to six pin gates or disk gates are provided in communication with the flange forming cavity of the mold, and the flange forming cavity is electrically conductive from the flange forming cavity through the pin gate or disk gate. A method for producing a substrate for a photosensitive drum, characterized by injecting a resin material.
[0012]
According to the present invention, the conductive resin material is not injected from the cylindrical body forming cavity, but is injected from the flange forming cavity, and the resin material flows from the flange forming cavity to the cylindrical body forming cavity. Therefore, the molded substrate has no trace of the gate on the outer peripheral portion of the cylindrical body, and has good roundness and straightness and excellent dimensional accuracy as shown in the experimental examples described later.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for manufacturing a photosensitive drum substrate according to the present invention includes a cylindrical substrate 10 in which a flange 12 projecting inwardly on the inner peripheral edge of one end surface of a cylindrical body 11 as shown in FIG. How to get. The base body 10 has a flange 13 formed separately at the other end opening of the cylindrical main body 11 and is fixed thereto, and a photoconductive layer 14 is formed on the outer peripheral surface of the cylindrical main body 11. Used in the same manner as in FIG. The both flanges 12 and 13 are formed with shaft holes 15 and 15, respectively.
[0014]
As the conductive resin forming the cylindrical main body 11 and the one flange 12 formed integrally with the cylindrical main body 11, a conductive resin imparted with conductivity by blending a conductive agent is usually used. The resin used in this case is not particularly limited as long as it has an appropriate strength and can be molded by an injection molding method. Polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyamide resin (nylon) 6, Nylon 66, etc.), polyphenylene sulfide (PPS), polyacetal and the like are preferably used from the viewpoints of thermoplasticity, excellent moldability, and excellent mechanical strength and sliding properties.
[0015]
Further, the conductive agent may be any as long as it can be uniformly dispersed in the resin, and is not particularly limited, but carbon black, graphite, aluminum, copper, nickel, etc. Powders such as metal powder and conductive glass powder are preferably used. The blending amount of the conductive agent is preferably about 5 to 40% by weight, particularly about 5 to 20% by weight, so that the surface resistance value of the cylindrical substrate and the flange is 10 ⁴ Ω / □ or less, particularly 10 ² Ω. / □ It is preferable to adjust to below.
[0016]
In this conductive resin, each fiber or the like can be used as a filler for the purpose of reinforcing or increasing the amount. As the fibers, conductive fibers such as carbon fibers, conductive whiskers and conductive glass fibers, and nonconductive fibers such as whiskers and glass fibers are used. In this case, the conductive fiber can also act as a conductive agent, and the amount of the conductive agent used can be reduced by using the conductive fiber. It is preferable to use fibers and increase the amount of the conductive agent used.
[0017]
The amount of these fillers is appropriately selected according to the type of resin and the length and diameter of the fibers used, and is not particularly limited, but is usually 2 to 25% by weight, particularly 5 to 15% by weight. It is preferable to set the degree.
[0018]
In addition to the above conductive agent and filler, an appropriate amount of a known additive such as PTFE (polytetrafluoroethylene), silicone, molybdenum disulfide (MoO ₂ ) is added to the conductive resin as necessary. Can do.
[0019]
The photoconductive layer can be formed of a known material and composition.
[0020]
In the present invention, the base body on which the main body 11 and the one flange 12 are integrally molded is molded by injection molding with a mold using a pin gate system or a disk gate system of 3 to 6 points.
[0021]
FIG. 2 illustrates a molding method using this pin gate method. In FIG. 2, reference numeral 20 denotes a mold body 21 having a cylindrical hollow portion therein, and one end surface of the mold body 21, and the hollow portion. A mold auxiliary member 22 that is closed at one end opening of the mold and a core 23 having a tip 23 that is inserted into the hollow part so as to be axially movable from the other end opening. A cylindrical cavity 24 for forming the cylindrical main body 11 of the base body 10 is formed between the inner peripheral surface of the mold body 21 and the outer peripheral surface of the core 23, and the other end surface of the auxiliary member 22 and the core are formed. A cavity 25 for forming the flange 12 is formed between one end face (tip face) of the flange 23 and the one end part in the axial direction of the cylindrical cavity 24. A small-diameter cylindrical portion 23a projects from the center of the distal end surface of the core 23. When the distal end surface of the small-diameter cylindrical portion 23a comes into contact with the auxiliary member 22, the flange-forming cavity 25 has a substantially circular ring shape. Is formed.
[0022]
In the mold 20, the auxiliary member 22 is provided with 3 to 6 pin gates 26 which are spaced apart from each other at equal intervals. The tip ends of the pin gates 26 communicate with the flange forming cavity 25. In addition, the base end portion of the pin gate 26 is connected to the sprue 27. Reference numeral 28 denotes a projecting pin provided on the auxiliary member 22 so as to be movable in the axial direction. The projecting pin 28 is operated so as to project after the base 10 is molded and the core 23 is extracted from the mold body 21. Thus, the molded base 10 is removed from the mold 20. Reference numeral 29 denotes a cooling water circulation hole.
[0023]
When molding the photosensitive drum substrate 10 using the mold 20, the mold 20 is set in the state shown in FIG. 2, and the molding material (the conductive resin material) is passed through the sprue 27 and the above 3-6. It is injected from the pin pin 26 into the flange forming cavity 25. As a result, the resin material flows from the flange forming cavity 25 to the cylindrical cavity (cylindrical main body forming cavity) 24, and the cylindrical base body 10 in which the flange 12 is integrally connected to the cylindrical main body 11 is injection-molded. Is.
[0024]
Therefore, in the molded substrate, even if a gate mark due to the pin gate 26 remains on the end face of the flange, there is no gate mark on the outer peripheral surface of the cylindrical main body, and thus a photoconductive layer is formed thereon. There is no risk of problems due to gate traces. Moreover, when this method is used, gate cutting is automatically performed in the molding cycle by the above-described mold structure, so that a post-processing step can be omitted. As a result, the productivity is high and the manufacturing cost can be reduced as compared with the case where the side gate method requires individual gate processing.
[0025]
FIG. 3 illustrates a molding method using a disk gate method (in FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals and the description thereof is omitted). Has a cylindrical projection 22a integrally projecting from the center of the other end surface of the auxiliary member 22, and projecting the projection 22a into the hollow portion of the mold body 21 (the hollow of the ring-shaped flange forming cavity 25). The sprue 27 provided on the auxiliary member 22 extends to the columnar protrusion 22a, and a disc gate 26 'is attached to the tip of the sprue 27 and the outer periphery of the gate 26'. This portion is formed so as to communicate with the inner peripheral portion of the flange forming cavity 25.
[0026]
Also in the case of using the mold shown in FIG. 3, the conductive resin material flows through the sprue 27 and is injected from the disk gate 26 ′ to the inner peripheral portion of the flange forming cavity 25, and is cylindrical from the flange forming cavity 25. The cylindrical base 10 is formed by flowing into the cavity 24. Therefore, even if the gate mark remains on the inner peripheral surface of the flange, there is no possibility that the gate mark is generated on the outer peripheral surface of the cylindrical main body. In addition, when such a disc gate is used, sprue cutting is possible only by punching after taking out the substrate, and the productivity is high.
[0027]
According to the above-described injection molding method, the molding material (conductive resin material) uniformly flows in the circumferential direction from the flange forming cavity 25 and uniformly flows into the cylindrical body forming cavity 24. Since it fills up to the end quickly, dimensional accuracy such as roundness and straightness of the cylindrical body is improved.
[0028]
Further, as described above, post-processing such as gate cutting and sprue cutting is omitted or simplified, and the production efficiency is high.
[0029]
Moreover, according to the above method, a cylindrical base body in which the cylindrical main body and a flange having a metal shaft through hole at one end thereof are integrally formed can be obtained, so that the mounting operation of the flange can be performed only on one side of the cylindrical main body. This simplifies the work. In this case, by integrally molding using a conductive resin material as a molding material, it is possible to omit the incorporation of metal parts for conduction with the flange and the shaft.
[0030]
When molding is performed by the above-described injection molding method, molding conditions such as molding temperature and injection pressure can be normal conditions according to the type of resin used.
[0031]
Next, an effect of the above molding method will be specifically described by an experimental example.
[Experimental example]
The following composition nylon 66 80 parts by weight carbon fiber 10 parts by weight carbon black 10 parts by weight of conductive resin material The following conditions molding temperature 260-290 ° C
Injection pressure 500-900Kg / cm ²
1 to produce a cylindrical substrate in which a ring-shaped flange is integrally formed at one end of a cylindrical body having a length of 230 mm, an outer diameter of 30 mm, and an inner diameter of 26 mm as shown in FIG.
[0032]
In this case, as a mold, a pin gate type (three pins) mold (present invention example 1) shown in FIG. 2, a disk gate type mold (present invention example 2) shown in FIG. 3, and a side gate are used. A method mold (comparative example) was used. In the case of the side gate type mold, the side gate is communicated with one end of the outer peripheral portion of the cylindrical body forming cavity, thereby injecting the resin material.
For the cylindrical substrate molded by the above method, the roundness was measured using a roundness measuring machine, and the straightness was measured using a laser scan micrometer. The results are shown in Table 1.
[0033]
[Table 1]

[0034]
From the above results, it can be seen that the molding method according to the present invention can form a cylindrical substrate for a photosensitive drum having excellent roundness and straightness. In the case of the side gate method, the sprue into which the resin flows first is not at the center of the pipe as in the present invention example, but at a single point from the position on the side surface of the pipe. Therefore, while Examples 1 and 2 of the present invention are uniformly filled with resin in the circumferential direction of the pipe, the side gate method shows a bias in the filling speed in the process of filling the entire pipe with resin, and the circumferential direction Uniform filling is not performed. In addition, a weld line may occur at a position on the opposite side of the pipe gate (the entire lower side of the pipe in the figure). The weld line may cause a reduction in strength of the molded product, and the surface property of the portion is significantly lowered.
[0035]
【The invention's effect】
According to the present invention, there is provided a cylindrical substrate for a photosensitive drum which is excellent in dimensional accuracy such as roundness and straightness, which simplifies the assembly work of the flange and can omit the work of attaching a metal plate for grounding. It can be manufactured with high productivity.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a photosensitive drum using a substrate manufactured according to the present invention.
FIG. 2 is a schematic cross-sectional view showing an example of a pin gate type mold used in the present invention.
FIG. 3 is a schematic cross-sectional view showing an example of a disk gate type mold used in the present invention.
FIG. 4 is a schematic sectional view showing a conventional photosensitive drum.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Cylindrical main body 12 Flange 10 Cylindrical base | substrate (base | substrate for photosensitive drums)
26 Pin gate 26 'Disc gate 20 Mold 24 Cylindrical body forming cavity 25 Flange forming cavity

Claims (1)

A cavity for forming a flange of the above-mentioned mold is formed when a base for a photosensitive drum, in which a flange projecting inward is integrally formed on the inner peripheral edge of one end surface of a cylindrical main body formed of a conductive resin, is injection-molded by a mold. 3 to 6 pin gates or disk gates are provided in communication with each other, and a conductive resin material is injected from the flange forming cavities through the pin gates or disk gates into the cylindrical body forming cavities. A method for producing a drum substrate.

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