JP3514028B2 - Roll for electrophotographic copier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll for an electrophotographic copying machine.

[0002]

2. Description of the Related Art Electrophotographic copying machines (electrophotographic copying machines and laser beam printers and Facsimile printers, which basically have the same principle as the printing section thereof), have various types as shown in FIG. A roll 10 (fixing roll, charging roll, paper feeding roll, developing roll, etc.) is used. Usually, such a roll 10 is, as shown in FIGS. 8 and 9, a base roll including a core metal 11 and a rubber layer 13 provided on an outer peripheral portion of the core metal 11 with an adhesive layer 12 interposed therebetween. The outer peripheral portion of 14 is formed with one or a plurality of coating layers 15 formed according to the required function.

[0003]

SUMMARY OF THE INVENTION Roll 1 as described above
In producing the base roll 14 (see FIG. 10) constituting 0, the rubber layer 13 of the base roll 14 is
The rubber material is extruded or injection-molded onto the adhesive layer 12 of the cored bar 11 having the adhesive layer 12 formed on the outer peripheral portion. Therefore, the outer diameter of both ends of the molded rubber layer 13 of the base roll 14 becomes larger than the outer diameter of the central part due to thermal contraction after extrusion and the like. That is, the rising portion (large diameter portion) is formed at both ends of the base roll 14.
13a is formed. Usually, the large diameter portions 13a at both ends of the rubber layer 13 are polished and removed to make the outer peripheral portion of the base roll 14 have a uniform outer diameter. Also,
In forming the coating layer 15 on the outer peripheral portion of the base roll 14, the vertical base roll 14 is immersed in the coating liquid, and then vertically pulled up to be dried. In this case, as shown in FIG. 11, the coating liquid 16 drips during drying from the upper side to the lower side of the outer peripheral surface of the base roll 14, and the coating liquid 16 in which the solvent is not completely evaporated dries downward to form the coating layer 15. The film thickness tends to be thicker in the lower part than in the upper part. Therefore, even when the above-mentioned polishing is performed, the resulting roll often has a non-uniform outer diameter.

As described above, when the roll 10 is manufactured, the large diameter portions 13 at both ends of the rubber layer 13 of the base roll 14 are manufactured.
When a is subjected to a polishing process or the like to be corrected, a roll having a uniform outer diameter can be obtained, but there is a problem that the polishing process or the like is required, resulting in an increase in cost. Further, even with the base roll 14 that has been subjected to a polishing process or the like, there is a problem that the outer diameter becomes nonuniform when the coating layer 15 is formed on the outer peripheral portion of the base roll 14. Also, the large diameter portions 1 at both ends of the rubber layer 13
Base roll 14 without polishing 3a is roll 1
When used as 0, the outer diameter of the roll 10 naturally becomes non-uniform. As described above, when the outer diameter of the outer peripheral portion of the roll 10 is not uniform in the length direction (in particular, the outer diameters of both end portions are larger than the outer diameter of the central portion), for example, the roll 10 becomes When it is used as the photosensitive drum 17 and is brought into contact with the photosensitive drum 17 (see FIG. 12), the following problems occur. That is, since the inner peripheral portion of the rubber layer 13 of the charging roll 10 or the like is adhered to the outer peripheral portion of the cored bar 11 by the adhesive layer 12 over the entire surface, the outer peripheral portion of the rubber layer 13 is exposed to light during the contact. Even if pressed by the drum 17 or the like, the rubber layer 13 causes the core metal 11
12 does not move outward along the outer peripheral surface of the rubber layer 13, and as shown in FIG. 12, only the outermost portions of the large diameter portions 13a at both ends of the rubber layer 13 are slightly pushed outward (in FIG.
3b shows this pressed portion). Therefore, both ends of the rubber layer 13 still have a large diameter, and the outer diameter of the rubber layer 13 is not uniform.
A gap 18 is formed between the two and the uniform nip width (pressing width) cannot be obtained. Therefore, many problems occur as an electrophotographic copying machine that requires high functionality. To give a few examples, the charging roll has a problem that the photosensitive drum is worn and the image quality is deteriorated due to non-uniform charging, and the fixing roll has a disorder of a fixed image and a paper wrinkle.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a roll for an electrophotographic copying machine, which is inexpensive and does not cause deterioration in image quality.

[0006]

In order to achieve the above object, an electrophotographic copying machine roll according to the present invention comprises a cored bar having small diameter portions projecting from both end surfaces of a cored bar main body, and the above-mentioned cores. An elastic layer formed on the outer peripheral portion of the core metal so as to cover the outer peripheral portion of the core metal in a state where at least the tip side portion of the small diameter portion is exposed, and the inner peripheral portion of the elastic layer is the adhesive layer on the outer peripheral portion of the core metal body. The entire inner peripheral portion of the elastic layer corresponding to the outer peripheral portion or a portion of the elastic layer end face side is directly adhered to the outer peripheral portions of both the small diameter portions to be in a non-adhered state. Take

That is, according to the roll for an electrophotographic copying machine of the present invention, the inner peripheral part of the elastic layer is formed on the outer peripheral part of the cored bar main body of the cored bar in which the small diameter parts are projected from both end surfaces of the cored bar main body. Although it is adhered by the adhesive layer,
The entire inner peripheral portion of the elastic layer or a part of the elastic layer end face side is directly adhered to the non-adhered state. Therefore, in the roll of the present invention, the outer diameter is non-uniform, and even if a rising portion (large diameter portion) is formed at both ends, when it is pressed against the photosensitive drum or the like, The elastic layer not only elastically deforms in the radial direction, but also moves outward along the outer peripheral surface of the small-diameter portion that is in a non-bonded state with the elastic layer. Therefore, the amount of deformation of the large-diameter portions at both ends of the elastic layer at the time of contact is large, and the large-diameter portions at both ends are bent until they become the same as the outer diameters of other portions such as the central portion, so that the outer diameter of the roll is in the longitudinal direction. Becomes the same (uniform). Further, since the elastically deformable portion is a small-diameter portion (smaller in diameter than the core metal body), the unit volume of the elastic layer in the small-diameter portion is larger than the unit volume of the elastic layer in the core metal body. , The influence on the total volume of the total deformation becomes small, and the amount of strain becomes small, such as the distance at which the large-diameter portion at both ends of the elastic layer moves outward along the outer peripheral surface of the small-diameter portion due to the contact, etc. . Then, as a result of these, in the roll of the present invention, a uniform nip width is obtained in the length direction. Such actions and effects can be obtained without performing a polishing step or the like on the formed base roll, or even by forming a coating layer on the outer peripheral portion of the base roll. Therefore, the roll for an electrophotographic copying machine of the present invention can be manufactured at low cost, and even when the roll is used as a charging roll, deterioration of image quality due to abrasion of the photosensitive drum and uneven charging does not occur, and the roll is used as a fixing roll. However, the fixed image is not disturbed and paper wrinkles do not occur. In the present invention, the diameter ratio R (D ₂ / D ₁ ) of the diameter D ₂ of the small diameter portion to the diameter D ₁ of the core metal body is 1>R> 0.3.
When set to 1, the thickness of the elastic layer in the core metal body can be sufficiently ensured, and when the small diameter portion is used as the shaft portion, it has sufficient strength against the load applied thereto. Further, the hardness H of the elastic layer is JIS A hardness, 5 ° ≦ H
When it is set to ≦ 70 °, the elastic layer is highly deformed and a uniform nip width is obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail.

According to the present invention, a cored bar having a small diameter portion projecting from both end surfaces of the cored bar main body, and an outer peripheral portion of the cored bar main body of the cored bar (or an outer peripheral portion of the cored bar main body and a small diameter). Part of the part), and an elastic layer formed on the outer peripheral part of the core metal.

The cored bar is not particularly limited, and a cylindrical one made of metal or a cylindrical one is used. The diameter ratio R (D ₂ / D ₁ ) of the diameter D ₂ of the small diameter portion to the diameter D ₁ (see FIG. 4) of the core metal body of such a core metal is 1>
R> 0.3, preferably 0.9> R
It is set within the range of> 0.4. The diameter ratio R is 1
When it is set within the range of>R> 0.3, the load applied to the core metal body when the small diameter portion is used as the shaft portion while the thickness of the elastic layer in the main body is sufficiently secured. Has sufficient strength against. On the other hand, when the diameter ratio R is 0.3 or less, the core metal body becomes too thick and the elastic layer becomes too thin, and the small diameter portion becomes too thin, resulting in insufficient strength. . In addition, there is a drawback that a contraction of the elastic layer causes a gap between the core metal small-diameter portion and the elastic layer.
Further, when the diameter ratio R is set within the range of 0.9>R> 0.4, the amount of strain due to elastic deformation at the large diameter portions at both ends of the elastic layer becomes very small, and the nip width Is very uniform and excellent image quality is obtained.

As the adhesive constituting the above-mentioned adhesive layer,
A one-component or two-component vulcanizing adhesive or the like is used.

As the material of the elastic layer, natural rubber or
Examples thereof include synthetic rubbers such as fluororubber, fluorosilicone rubber, silicone rubber, ethylene propylene rubber (EPDM), acrylic rubber and blended rubbers thereof, and thermoplastic elastomers. Also, the hardness H of the elastic layer
Is set in the range of 5 ° ≦ H ≦ 70 °, preferably 10 ° ≦ H ≦ 40 ° in JIS A hardness. When the hardness H is set within the range of 5 ° ≦ H ≦ 70 °, the elastic layer is highly deformed and a uniform nip width is obtained. On the other hand, the hardness H is 5
If it is smaller than 70 °, the deformation recovery force is lowered, and if it is larger than 70 °, the elastic layer is not sufficiently deformed. Further, the hardness H is 10 ° ≦ H ≦ 40 °
When it is set within the range of, the nip width becomes very uniform and excellent image quality is obtained.

[0013] Preferred height range of the rising portion of the opposite ends of the roll (the large-diameter portion), the roll outer diameter phi ₁ of the core body portion relative (see FIG. 4), the roll outer diameter of the small-diameter portion phi ₂ The outer diameter ratio X (φ ₂ / φ ₁ ) is set within the range of 1 <X <1.3, and preferably within the range of 1.1 <X <1.2. When the outer diameter ratio X is set within the range of 1 <X <1.3, the large diameter portions at both ends become equal to the outer diameters of other portions due to elastic deformation at the time of contact with the photosensitive drum or the like. Prone. On the other hand, when the outer diameter ratio X is 1.3 or more, the large diameter portions at both ends rise too high, and the outer peripheral portion does not become uniform at the time of contact. Further, when the outer diameter ratio X is set within the range of 1.1 <X <1.2, the nip width becomes extremely uniform and excellent image quality is obtained. Also, the length Y of the non-bonded portion of the elastic layer (see FIG. 4)
Is set to 1 to 5 mm, preferably 2 to 4 mm. This is because if the length Y of the non-bonded portion is less than 1 mm, the elastic layer is insufficiently deformed in the axial direction and uniform contact properties cannot be obtained, and if it exceeds 5 mm, the elastic layer is likely to be turned over.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the roll of the present invention. In this embodiment, the roll is composed of a base roll in which the large-diameter portions at both ends (rising portions at both ends) 3a are not polished. In the figure, reference numeral 1 denotes a cored bar made of a stainless steel columnar body, and as shown in FIGS. 2 and 3, a cored bar main body 1a and a thin bar coaxially protruding from both left and right side surfaces of the cored bar main body 1a. It consists of the diameter part 1b. Reference numeral 2 is an adhesive layer formed on the outer peripheral surface of the core metal body 1a of the core metal 1. Reference numeral 3 denotes an EPDM rubber layer formed on the outer peripheral portion of the core metal 1 by extrusion molding or the like. As shown in FIG. 4, the inner peripheral portion of the rubber layer 3 is different from the outer peripheral portion of the core metal body 1a. Are adhered by the adhesive layer 2 and are in a non-adhered state by directly adhering to the outer peripheral portions of the small diameter portions 1b.

When the above roll is used as a charging roll and brought into contact with the photosensitive drum 5 as shown in FIG. 5, the outer peripheral portions of the large diameter portions 3a at both ends of the rubber layer 3 are pressed against the photosensitive drum 5 and the like. At the same time as elastically deforming in the radial direction, both small diameter parts 1
It moves outward along the outer peripheral surface of b (in the figure, 3b
Indicates the moved portion), so the deformation amount becomes large. Therefore, the outer diameter of the charging roll becomes the same (uniform) in the longitudinal direction, and a uniform nip width can be obtained (in FIG. 5, the dotted line shows the rubber layer 3 not in contact with the photosensitive drum 5 or the like). The shape of the large diameter portions 3a at both ends is shown).

As described above, when the roll of this embodiment is used as a charging roll, a uniform nip width is obtained when the roll is pressed against the photosensitive drum 5 or the like, and the photosensitive drum is worn or worn. Image quality does not deteriorate due to uneven charging.
Also, when using this roll as a fixing roll,
The same operation is performed, and a fixed image is not disturbed and paper wrinkles do not occur.

FIG. 6 shows another embodiment of the present invention. In this embodiment, not only the adhesive layer 2 is formed on the outer peripheral portion of the core metal body 1a of the core metal 1, but also the small diameter portions 1b (only one small diameter portion 1b is shown in the drawing. Not)
The adhesive layer 2a is provided on the outer peripheral surface of the core metal body 1a over a predetermined width from the end surface 1c. For this reason, the inner peripheral portion of the rubber layer 3 is in direct contact with the portion of the outer peripheral surface of the small-diameter portion 1b outside the adhesive layer 2a and is in a non-adhered state. The other parts are the same as those in the above embodiment, and the same parts are denoted by the same reference numerals.

Also in this embodiment, the same effects as the above-described embodiment are exerted.

In each of the above embodiments, the case where the base roll is used as a roll has been described, but a coating layer may be provided on the outer peripheral surface of the base roll.
In this case as well, the same operation and the same effect as those of the above-described respective embodiments are achieved.

Next, examples of the present invention will be described.

[0022]

EXAMPLE In this example, the roll is shown in FIGS.
It has the same structure as the rolled roll. That is, the roll is
Of core metal 1 (total length 250 mm) made of Tenres cylinder
EPDM rubber layer 3 on the outer circumference (total length: roll surface length L₁Two
20mm, hardness H25 °)
There is. The core metal 1 is formed in a bilaterally symmetrical shape.
Body 1a (width 214 mm, diameter D₁8 mm), left and right
A pair of small diameter parts 1b (width 18 mm, diameter D₂6 mm)
Consists of. The core metal 1 has an outer peripheral surface of the core metal body 1a.
The adhesive layer 2 is formed only on the. Therefore glued
Part length L ₂Is the same as the width 214mm of the core metal body 1a
become. In addition, the roll outer diameter φ of the core metal body 1a₁Is 1
4 mm, outer diameter of roll of small diameter part 1b φ₂Is 14.2 mm
Are set respectively. At this time, the adhesive layer is formed
The part that is not attached (non-adhesive part Y) is formed on both ends,
Both lengths were 3 mm.

The roll of this example was used as a charging roll in an electrophotographic copying machine. As a result, the same excellent image quality as that obtained by using a roll having a large outer diameter on both ends of the base roll and having a uniform outer diameter was obtained.

[0024]

As described above, according to the roll for an electrophotographic copying machine of the present invention, the cored bar is composed of the cored bar main body and the small-diameter portions projecting from both end surfaces of the cored bar main body. Configure and
The inner peripheral portion of the elastic layer is bonded to the outer peripheral portion of the core metal body with an adhesive layer, but the outer peripheral portions of the both small diameter portions are:
The entire inner peripheral portion of the elastic layer or a part of the elastic layer end face side is directly adhered to be in a non-adhesive state. Therefore, in the roll of the present invention, the outer diameter is non-uniform, and even if a rising portion (large diameter portion) is formed at both ends, when it is pressed against the photosensitive drum or the like, The elastic layer not only elastically deforms in the radial direction, but also moves outward along the outer peripheral surface of the small-diameter portion that is in a non-bonded state with the elastic layer. Therefore, the amount of deformation of the large-diameter portions at both ends of the elastic layer at the time of contact is large, and the large-diameter portions at both ends are bent until they become the same as the outer diameters of other portions such as the central portion, so that the outer diameter of the roll is in the longitudinal direction. Becomes the same (uniform). Further, since the elastically deformable portion is a small-diameter portion (smaller in diameter than the core metal body), the unit volume of the elastic layer in the small-diameter portion is larger than the unit volume of the elastic layer in the core metal body. , The influence on the total volume of the total deformation becomes small, and the amount of strain becomes small, such as the distance at which the large-diameter portion at both ends of the elastic layer moves outward along the outer peripheral surface of the small-diameter portion due to the contact, etc. . Then, as a result of these, in the roll of the present invention, a uniform nip width is obtained in the length direction. Such actions and effects can be obtained without performing a polishing step or the like on the formed base roll, or even by forming a coating layer on the outer peripheral portion of the base roll. Therefore, the roll for an electrophotographic copying machine of the present invention can be manufactured at low cost, and even when the roll is used as a charging roll, deterioration of image quality due to abrasion of the photosensitive drum and uneven charging does not occur, and the roll is used as a fixing roll. Even
Distorted fixed images and paper wrinkles do not occur. In the present invention, the diameter ratio R (D ₂ / D ₁ ) of the diameter D ₂ of the small diameter portion to the diameter D ₁ of the core metal body is 1>R>.
When it is set to 0.3, the thickness of the elastic layer in the core metal body can be sufficiently secured, and when the small diameter portion is used as the shaft portion, sufficient strength is exerted against the load applied thereto. Have. The hardness H of the elastic layer is 5 according to JIS A hardness.
When it is set to ° ≦ H ≦ 70 °, the elastic layer is deformed to a high degree and a uniform nip width can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of a roll showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of the roll.

FIG. 3 is a cross-sectional view of the roll.

FIG. 4 is a partially enlarged sectional view of the roll.

FIG. 5 is a partial enlarged cross-sectional view showing the action of the roll.

FIG. 6 is a partially enlarged sectional view of a roll showing another embodiment of the present invention.

FIG. 7 is an explanatory view of a roll showing a conventional example.

FIG. 8 is a vertical cross-sectional view of the roll of the conventional example.

FIG. 9 is a cross-sectional view of the roll of the conventional example.

FIG. 10 is an explanatory diagram of a base roll.

FIG. 11 is an explanatory diagram showing a flow of a coating liquid flowing down a base roll.

FIG. 12 is a partially enlarged cross-sectional view showing the action of the roll of the conventional example.

[Explanation of symbols]

1 core 1a core metal body 1b small diameter part 2 Adhesive layer 3 rubber layers

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/08 G03G 15/09 G03G 15/20 G03G 21/00

Claims (3)

(57) [Claims] 1. A cored bar having small-diameter portions protruding from both end surfaces of a cored bar main body, and an outer peripheral portion of the cored bar with at least distal end portions of the two small-diameter parts exposed. The elastic layer is formed, and the inner peripheral portion of the elastic layer is adhered to the outer peripheral portion of the core metal body by an adhesive layer, and the outer peripheral portions of both small-diameter portions of the elastic layer corresponding to the outer peripheral portion. A roll for an electrophotographic copying machine, characterized in that the entire inner peripheral portion or a part of the end surface side of the elastic layer is directly adhered to be in a non-adhesive state. _2. The diameter ratio R (D ₂ / D ₁ ) of the diameter D ₂ of the small diameter portion to the diameter D _{1 of the} core metal body is 1>R>.
The roll for an electrophotographic copying machine according to claim 1, wherein the roll is set to 0.3. 3. The roll for an electrophotographic copying machine according to claim 1, wherein the hardness H of the elastic layer is set to 5 ° ≦ H ≦ 70 ° according to JIS A hardness.