WO2021085365A1

WO2021085365A1 - Paper feeder, paper feed roll, and separation roll

Info

Publication number: WO2021085365A1
Application number: PCT/JP2020/040059
Authority: WO
Inventors: 和志山口; 淳洋河野; 和宏土井
Original assignee: 住友理工株式会社
Priority date: 2019-10-30
Filing date: 2020-10-26
Publication date: 2021-05-06
Also published as: JP2021070557A

Abstract

Provided are a paper feeder, paper feed roll, and separation roll that suppress paper jams after long-term use. The paper feeder 10 comprises a paper feed roll 12 that is rotationally driven and conveys paper P, and a separation roll 14 that is pressed against the paper feed roll 12 and has a built-in torque limiter to suppress double feed of the paper P. The paper feed roll 12 and the separation roll 14 each have a surface comprising an elastic body containing polyurethane, each have a surface roughness Rz of 20 μm or more, and have a difference in JIS-A hardness of 5 degrees or more on the surfaces. The coefficient of friction between the paper feed roll 12 and the separation roll 14 is in the range of 1.0-3.0.

Description

Paper feed device, paper feed roll and separation roll

The present invention relates to a paper feed device, a paper feed roll, and a separation roll that are suitably used in electrophotographic equipment such as copiers, printers, and facsimiles that employ an electrophotographic method.

In electrophotographic equipment such as copiers, printers, and facsimiles that employ the electrophotographic method, the paper feed roll is formed in a cylindrical shape by an elastic material such as a rubber crosslinked body, and its peripheral surface serves as a contact surface with paper. .. Paper dust generated from the paper may adhere to the peripheral surface of the paper feed roll. Then, during repeated contact with the paper, paper dust may accumulate on the peripheral surface of the paper feed roll. When the paper dust accumulates, the contact area of the peripheral surface with respect to the paper decreases, and the friction coefficient of the contact surface with the paper decreases. As a result, poor paper transfer may occur.

It is known that the peripheral surface of the paper feed roll is formed with irregularities in order to suppress paper transport defects (Patent Document 1). For example, Patent Document 1 describes a paper feed roll in which a plurality of ridges and grooves are formed in parallel with the axial direction.

Japanese Unexamined Patent Publication No. 2017-065907 Japanese Unexamined Patent Publication No. 2001-151371

In Patent Document 1, the coefficient of friction between the paper feed roll alone and the paper is a problem. On the other hand, Patent Document 2 proposes an invention of a sheet feeding device including a feeding roll and a separating roll. The feed roll is a roll that is rotationally driven in the sheet transport direction, and the separation roll is a roll that is driven to rotate in the same direction as the feed roll and suppresses double feed of the sheet by a built-in torque limiter. .. In Patent Document 2, the hardness of the feeding roll is set to be lower than the hardness of the separating roll so that a minute slip occurs between the separating roll and the feeding roll at the pressure welding portion between the separating roll and the feeding roll. , The feeding roll cleans the paper dust adhering to the surface of the separation roll, and suppresses the decrease in the friction coefficient of the separation roll due to the paper dust. However, the configuration of Patent Document 2 alone does not have a sufficient function of suppressing double feeding of sheets after long-term use, and there is a problem that paper jams after long-term use cannot be eliminated.

An object to be solved by the present invention is to provide a paper feed device, a paper feed roll, and a separation roll that can suppress a paper jam after long-term use.

In order to solve the above problems, the paper feed device according to the present invention is separated into a paper feed roll that is rotationally driven to convey paper and a torque limiter that is pressed against the paper feed roll and has a built-in torque limiter to suppress double feed of paper. Each of the paper feed roll and the separation roll is composed of an elastic body containing polyurethane on the surface, has a surface roughness Rz of 20 μm or more, and has a difference in JIS-A hardness of 5 degrees on the surface. The gist of the above is that the coefficient of friction between the paper feed roll and the separation roll is 1.0 or more and 3.0 or less.

It is preferable that the paper feed roll and the separation roll each have a convex portion having a height of 20 to 300 μm on the surface. The separation roll preferably has a larger surface roughness Rz than the paper feed roll. The separation roll preferably has a smaller surface friction coefficient than the paper feed roll.

The paper feed roll according to the present invention is the paper feed roll used in the paper feed device. Further, the separation roll according to the present invention is a separation roll used in the above-mentioned paper feeding device.

According to the paper feeding device according to the present invention, the paper feed roll and the separation roll are each composed of an elastic body containing polyurethane on the surface, each having a surface roughness Rz of 20 μm or more, and a difference in JIS-A hardness of the surfaces. Is 5 degrees or more, and the friction coefficient between the paper feed roll and the separation roll is 1.0 or more and 3.0 or less, so that a paper jam after long-term use can be suppressed.

It is a schematic diagram of the paper feed device which concerns on one Embodiment of this invention. It is a figure of the paper feed operation of the paper feed device shown in FIG. FIG. 2A shows a state before one sheet of paper arrives between rolls, and FIG. 2B shows an operation when one sheet of paper arrives between rolls. It is a thing. It is a figure of the paper feed operation of the paper feed device shown in FIG. FIG. 3A shows a state before the two sheets of paper arrive between the rolls, and FIG. 3B shows an operation when the two sheets of paper arrive between the rolls. It is a thing. FIG. 4A is a schematic external view of the paper feed roll according to the embodiment. FIG. 4B is a schematic external view according to an embodiment of the separation roll. FIG. 5A is an enlarged view showing the meshing state of the paper feed roll and the separation roll. FIG. 5B is an enlarged view showing a state in which the paper is conveyed between the paper feed roll and the separation roll that mesh with each other. FIG. 6A is an enlarged view showing a state in which the separation roll bites into the surface of the paper feed roll. FIG. 6B is an enlarged view showing a state in which the paper is conveyed between the paper feed roll and the separation roll in which the separation roll bites. FIG. 7A is a schematic view showing an example in which the surface unevenness is composed of a plurality of convex portions. FIG. 7B is a schematic view showing an example in which the surface unevenness is composed of a plurality of concave portions. FIG. 7C is a schematic view showing an example in which the surface unevenness is composed of a plurality of convex portions and a plurality of concave portions. It is a figure which showed the measuring method of the friction coefficient between a paper feed roll and a separation roll.

The paper feeding device according to the present invention will be described in detail.

As shown in FIG. 1, the paper feeding device 10 according to the embodiment of the present invention includes a paper feed roll 12 (feed roll) and a separation roll 14 (retard roll). The paper feed roll 12 has a shaft body 12a and an elastic body layer 12b formed on the outer periphery of the shaft body 12a. The separation roll 14 has a shaft body 14a and an elastic body layer 14b formed on the outer periphery of the shaft body 14a. The paper feed roll 12 is rotationally driven by receiving power from a drive source (motor) (not shown), and has a function of transporting the paper P. The separation roll 14 is pressed against the paper feed roll 12 at a predetermined pressure by an urging member (spring or the like) (not shown). Further, the separation roll 14 has a built-in torque limiter (not shown), and is configured so that the brake torque is applied in the direction opposite to the transport direction (direction of the arrow) of the paper P.

The paper to be conveyed is loaded in the paper feed cassette 16. The surface of the pull-in roll 18 (pickup roll) is in frictional contact with the upper surface of the loaded paper P, so that the pull-in roll 18 sequentially feeds the paper P from the paper feed cassette 16 toward the paper feed roll 12. It is configured. The retractable roll 18 has a shaft body 18a and an elastic body layer 18b formed on the outer periphery of the shaft body 18a. The pull-in roll 18 is configured to rotate in conjunction with the drive of the paper feed roll 12 by a connecting member (gear, timing belt, etc.) (not shown).

Along with the rotational drive of the paper feed roll 12, the pull-in roll 18 rotates, and the paper P is fed one by one from the paper feed cassette 16 toward the paper feed roll 12. As shown in FIG. 2A, the paper feed roll 12 is rotationally driven before the paper P arrives. The separation roll 14 press-contacted with the paper feed roll 12 is driven to rotate against the brake torque due to the frictional force between the paper feed roll 12 and the separation roll 14 (between the rolls) as the paper feed roll 12 rotates. When one sheet of paper P that has been fed out arrives between the rolls, the paper P is carried out through the rolls as shown in FIG. 2 (b).

When two sheets of paper P are fed from the paper feed cassette 16 toward the paper feed roll 12, as shown in FIG. 3A, the paper feed roll 12 is rotationally driven before the papers P1 and P2 arrive. Then, the separation roll 14 is driven to rotate against the brake torque as the paper feed roll 12 rotates. When the two sheets of paper P1 and P2 that have been fed out arrive between the rolls, the separation roll 14 comes into contact with the paper feed roll 12 via the two sheets of paper P1 and P2, as shown in FIG. 3 (b). Become. Since the frictional force acting between the two sheets P1 and P2 is small, the separation roll 14 does not follow the rotation of the paper feed roll 12 due to the brake torque and stops. As a result, the paper P1 in contact with the paper feed roll 12 is carried out through the rolls as the paper feed roll 12 rotates, while the paper P2 in contact with the separation roll 14 is not carried out. As a result, double feeding of the paper P is suppressed.

The paper feed roll 12 has surface irregularities on the outer peripheral surface of the elastic layer 12b. Due to this surface unevenness, the paper feed roll 12 is configured to have a surface roughness Rz of 20 μm or more. The surface roughness Rz of the paper feed roll 12 is the surface roughness Rz on the outer peripheral surface of the elastic body layer 12b of the paper feed roll 12. The surface roughness Rz of the paper feed roll 12 is a ten-point average roughness, and is measured according to JIS B0601 (1994). The surface unevenness can be formed by any unevenness. The surface unevenness may be formed by a plurality of convex portions, may be formed by a plurality of concave portions, or may be formed by a plurality of convex portions and a plurality of concave portions such as a textured shape. It may be formed.

Similarly, the separation roll 14 has surface irregularities on the outer peripheral surface of the elastic layer 14b. Due to this surface unevenness, the separation roll 14 is configured to have a surface roughness Rz of 20 μm or more. The surface roughness Rz of the separation roll 14 is the surface roughness Rz on the outer peripheral surface of the elastic layer 14b of the separation roll 14. The surface roughness Rz of the separation roll 14 is a ten-point average roughness, and is measured according to JIS B0601 (1994). The surface unevenness can be formed by any unevenness. The surface unevenness may be formed by a plurality of convex portions, may be formed by a plurality of concave portions, or may be formed by a plurality of convex portions and a plurality of concave portions such as a textured shape. It may be formed.

FIG. 4A shows a schematic external view of the paper feed roll 12 according to the embodiment. As shown in FIG. 4A, the paper feed roll 12 has a plurality of convex portions 12c on the outer peripheral surface of the elastic body layer 12b. The outer peripheral surface of the paper feed roll 12 is provided with surface irregularities by a plurality of convex portions 12c.

In FIG. 4A, the plurality of convex portions 12c are composed of hemispherical convex portions. Further, in FIG. 4A, the plurality of convex portions 12c are regularly arranged in a staggered manner on the outer peripheral surface of the elastic body layer 12b. A second row of convex portions 12c arranged in the axial direction X of the paper feed roll 12 is arranged between the convex portions 12c and the convex portions 12c of the first row arranged in the axial direction X of the paper feed roll 12, and the shaft of the paper feed roll 12 is arranged. A third row of convex portions 12c arranged in the axial direction X of the paper feed roll 12 is arranged between the convex portions 12c of the second row arranged in the direction X and the convex portions 12c of the third row arranged in the axial direction X of the paper feed roll 12. The convex portions 12c of the fourth row arranged in the axial direction X of the paper feed roll 12 are arranged between the convex portions 12c of the row and the convex portions 12c, and the convex portions 12c are arranged alternately. The plurality of convex portions 12c are arranged in the axial direction X of the paper feed roll 12 on the peripheral surface of the elastic body layer 12b, but are also arranged in a direction at an angle of 45 ° with respect to the axial direction X of the paper feed roll 12. Has been done. The plurality of convex portions 12c are not limited to the hemispherical convex portions. Further, the plurality of convex portions 12c may not be regularly arranged or may not be arranged.

The paper feed roll 12 is configured to have a surface roughness Rz of 20 μm or more. When the surface roughness Rz is 20 μm or more, the biting of the paper feed roll 12 and the separation roll 14 can be increased. Further, from the viewpoint of increasing the bite between the paper feed roll 12 and the separation roll 14, the surface roughness Rz of the paper feed roll 12 is more preferably 30 μm or more, still more preferably 50 μm or more. On the other hand, the surface roughness Rz of the paper feed roll 12 is preferably 300 μm or less from the viewpoint of preventing the paper feed roll 12 and the separation roll 14 from being caught too much. It is more preferably 200 μm or less, still more preferably 150 μm or less.

In the paper feed roll 12, the height of the convex portion 12c is 20 μm or more from the viewpoint of increasing the surface roughness Rz of the paper feed roll 12, increasing the engagement between the paper feed roll 12 and the separation roll 14. Is preferable. It is more preferably 30 μm or more, still more preferably 50 μm or more. Further, the height of the convex portion 12c is preferably 300 μm or less from the viewpoint of preventing the paper feed roll 12 and the separation roll 14 from being caught too much. It is more preferably 200 μm or less, still more preferably 150 μm or less.

The paper feed roll 12 is preferably configured with a surface friction coefficient in the range of 0.8 to 3.0. More preferably, it is in the range of 1.0 to 2.5. The surface of the paper feed roll 12 is the outer peripheral surface of the elastic layer 12b. The coefficient of friction on the surface of the paper feed roll 12 can be measured using a commercially available friction coefficient meter. The coefficient of friction of the surface of the paper feed roll 12 can be adjusted by the material composition of the elastic body layer 12b, the thickness of the elastic body layer 12b, the composition of the convex portion 12c, and the like. When the friction coefficient of the surface of the paper feed roll 12 is 0.8 or more, slippage of the paper during paper feed is likely to be suppressed. When the friction coefficient of the surface of the paper feed roll 12 is 3.0 or less, sticking of the paper during paper feed can be suppressed. Moreover, it is easy to manufacture.

It is preferable that the paper feed roll 12 has a surface JIS-A hardness in the range of 20 to 80 degrees. More preferably, it is in the range of 30 to 70 degrees. The surface of the paper feed roll 12 is the outer peripheral surface of the elastic layer 12b. The surface hardness of the paper feed roll 12 can be adjusted by adjusting the material composition of the elastic body layer 12b, the thickness of the elastic body layer 12b, and the like. When the JIS-A hardness of the surface of the paper feed roll 12 is 20 degrees or more, wear is easily suppressed. When the JIS-A hardness of the surface of the paper feed roll 12 is 80 degrees or less, damage to the paper (shaving of the paper, etc.) is likely to be suppressed, and deterioration of image quality is likely to be suppressed.

The paper feed roll 12 has an elastic body layer 12b made of an elastic body containing polyurethane. Since the elastic layer 12b of the paper feed roll 12 contains polyurethane, it has excellent wear resistance during durability, and it is easy to maintain surface roughness and uneven shape even during durability.

The elastic layer 12b of the paper feed roll 12 may be conductive or semi-conductive, or may not be conductive or semi-conductive. The volume resistivity of the elastic layer having conductivity or semiconductivity is in the range of 10 ² to 10 ¹⁰ Ω · cm, 10 ³ to 10 ⁹ Ω · cm, 10 ⁴ to 10 ⁸ Ω · cm, and the like. When the elastic layer 12b of the paper feed roll 12 has conductivity or semiconductivity, the surface residual charge of the elastic layer 12b of the paper feed roll 12 can be suppressed to a low level, and the adhesion of paper dust can be easily suppressed.

The elastic layer 12b of the paper feed roll 12 may contain a conductive agent from the viewpoint of reducing electrical resistance. Examples of the conductive agent include an electron conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black, graphite, c-TiO ₂ , c-ZnO, c-SnO ₂ (c- means conductivity) and the like. Examples of the ionic conductive agent include a quaternary ammonium salt, a borate, and a surfactant.

Various additives may be appropriately added to the elastic layer 12b of the paper feed roll 12, if necessary. Additives include lubricants, vulture accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoamers, pigments, mold release agents, etc. Can be mentioned.

The thickness of the elastic layer 12b of the paper feed roll 12 is not particularly limited, and may be appropriately set within the range of 0.1 to 10 mm or the like.

The elastic layer 12b of the paper feed roll 12 can be formed by using a urethane composition and molding with a molding die. For example, the shaft body 12a is coaxially installed in the hollow portion of the roll molding die, the uncrosslinked urethane composition is injected, heated / cured (crosslinked), and then demolded. An elastic body layer 12b can be formed on the outer periphery of the body. As the molding die, a mold having a concave portion having a shape corresponding to the convex portion 12c formed on the inner peripheral surface thereof can be used. The convex portion 12c of the elastic body layer 12b can be formed, for example, by mold transfer using a molding die.

Examples of the material of the shaft body 12a of the paper feed roll 12 include synthetic resins such as polyacetal (POM), acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate and nylon, and metal materials such as iron, stainless steel and aluminum. Can be done. The shaft body 12a may be formed in a hollow shape or may be a medium substance.

FIG. 4B shows a schematic external view according to an embodiment of the separation roll 14. As shown in FIG. 4B, the separation roll 14 has a plurality of convex portions 14c on the outer peripheral surface of the elastic body layer 14b. The outer peripheral surface of the separation roll 14 is provided with surface irregularities by a plurality of convex portions 14c.

In FIG. 4B, the plurality of convex portions 14c are composed of hemispherical convex portions. Further, in FIG. 4B, the plurality of convex portions 14c are regularly arranged in a staggered manner on the outer peripheral surface of the elastic body layer 14b. Specifically, the convex portion 14c of the second row arranged in the axial direction X of the separation roll 14 is arranged between the convex portion 14c of the first row arranged in the axial direction X of the separation roll 14 and the convex portion 14c, and the separation roll 14 is arranged. A third row of convex portions 14c arranged in the axial direction X of the separation roll 14 is arranged between the convex portions 14c of the second row arranged in the axial direction X of the separation roll 14 and arranged in the axial direction X of the separation roll 14. The convex portions 14c of the fourth row arranged in the axial direction X of the separation roll 14 are arranged between the convex portions 14c of the row and the convex portions 14c, and the convex portions 14c are arranged alternately. The plurality of convex portions 14c are arranged in the axial direction X of the separation roll 14 on the peripheral surface of the elastic body layer 14b, but are also arranged in a direction at an angle of 45 ° with respect to the axial direction X of the separation roll 14. There is. The plurality of convex portions 14c are not limited to the hemispherical convex portions. Further, the plurality of convex portions 14c may not be regularly arranged or may not be arranged.

The separation roll 14 is configured to have a surface roughness Rz of 20 μm or more. When the surface roughness Rz is 20 μm or more, the biting of the paper feed roll 12 and the separation roll 14 can be increased. Further, from the viewpoint of increasing the bite between the paper feed roll 12 and the separation roll 14, the surface roughness Rz of the separation roll 14 is more preferably 30 μm or more, still more preferably 50 μm or more. On the other hand, the surface roughness Rz of the separation roll 14 is preferably 300 μm or less from the viewpoint of preventing the paper feed roll 12 and the separation roll 14 from being caught too much. It is more preferably 200 μm or less, still more preferably 150 μm or less.

In the separation roll 14, the height of the convex portion 14c is 20 μm or more from the viewpoint of increasing the surface roughness Rz of the separation roll 14 and increasing the bite between the paper feed roll 12 and the separation roll 14. preferable. It is more preferably 30 μm or more, still more preferably 50 μm or more. Further, the height of the convex portion 14c is preferably 300 μm or less from the viewpoint of preventing the paper feed roll 12 and the separation roll 14 from being caught too much. It is more preferably 200 μm or less, still more preferably 150 μm or less.

The separation roll 14 is preferably configured with a surface friction coefficient in the range of 0.8 to 3.0. More preferably, it is in the range of 1.0 to 2.5. The surface of the separation roll 14 is the outer peripheral surface of the elastic layer 14b. The coefficient of friction on the surface of the separation roll 14 can be measured using a commercially available friction coefficient meter. The coefficient of friction on the surface of the separation roll 14 can be adjusted by the material composition of the elastic body layer 14b, the thickness of the elastic body layer 14b, the composition of the convex portion 14c, and the like. When the friction coefficient of the surface of the separation roll 14 is 0.8 or more, slippage of the paper during paper feeding is likely to be suppressed. When the friction coefficient of the surface of the separation roll 14 is 3.0 or less, the sticking of the paper at the time of feeding the paper is suppressed. Moreover, it is easy to manufacture.

It is preferable that the separation roll 14 has a surface JIS-A hardness in the range of 20 to 80 degrees. More preferably, it is in the range of 30 to 70 degrees. The surface of the separation roll 14 is the outer peripheral surface of the elastic layer 14b. The surface hardness of the separation roll 14 can be adjusted by the material composition of the elastic body layer 14b, the thickness of the elastic body layer 14b, and the like. When the JIS-A hardness of the surface of the separation roll 14 is 20 degrees or more, wear is easily suppressed. When the JIS-A hardness of the surface of the separation roll 14 is 80 degrees or less, damage to the paper (such as scraping of the paper) is likely to be suppressed, and deterioration of image quality is likely to be suppressed.

In the separation roll 14, the elastic body layer 14b is made of an elastic body containing polyurethane. Since the elastic layer 14b of the separation roll 14 contains polyurethane, it has excellent wear resistance during durability, and it is easy to maintain surface roughness and uneven shape even during durability.

The elastic layer 12b of the paper feed roll 12 may be conductive or semi-conductive, or may not be conductive or semi-conductive. The volume resistivity of the elastic layer having conductivity or semiconductivity is in the range of 10 ² to 10 ¹⁰ Ω · cm, 10 ³ to 10 ⁹ Ω · cm, 10 ⁴ to 10 ⁸ Ω · cm, and the like. When the elastic layer 14b of the separation roll 14 is conductive or semi-conductive, the surface residual charge of the elastic layer 14b of the separation roll 14 can be suppressed to a low level, and the adhesion of paper dust can be easily suppressed.

The elastic layer 14b of the separation roll 14 may contain a conductive agent from the viewpoint of reducing electrical resistance. Examples of the conductive agent include an electron conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black, graphite, c-TiO ₂ , c-ZnO, c-SnO ₂ (c- means conductivity) and the like. Examples of the ionic conductive agent include a quaternary ammonium salt, a borate, and a surfactant.

Various additives may be appropriately added to the elastic layer 14b of the separation roll 14, if necessary. Additives include lubricants, vulture accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoamers, pigments, mold release agents, etc. Can be mentioned.

The thickness of the elastic layer 14b of the separation roll 14 is not particularly limited, and may be appropriately set within the range of 0.1 to 10 mm or the like.

The elastic layer 14b of the separation roll 14 can be formed by using a urethane composition and molding with a molding die. For example, the shaft body 14a is coaxially installed in the hollow portion of the roll molding die, the uncrosslinked urethane composition is injected, heated / cured (crosslinked), and then demolded. An elastic body layer 14b can be formed on the outer periphery of the surface. As the molding die, a mold having a concave portion having a shape corresponding to the convex portion 14c formed on the inner peripheral surface thereof can be used. The convex portion 14c of the elastic body layer 14b can be formed, for example, by mold transfer using a molding die.

Examples of the material of the shaft body 14a of the separation roll 14 include synthetic resins such as polyacetal (POM), acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate and nylon, and metal materials such as iron, stainless steel and aluminum. it can. The shaft body 14a may be formed in a hollow shape or may be a medium substance.

As described above, the paper feed roll 12 and the separation roll 14 have a plurality of

convex portions

12c and 14c on the outer peripheral surfaces of the elastic body layers 12b and 14b, respectively. Therefore, in the paper feed roll 12 and the separation roll 14, as shown in FIG. 5A, the outer peripheral surface of the elastic body layer 12b of the paper feed roll 12 and the outer peripheral surface of the elastic body layer 14b of the separation roll 14 are paper. The convex portion 12c of the feed roll 12 and the convex portion 14c of the separation roll 14 mesh with each other. The paper feed roll 12 and the separation roll 14 each have a surface roughness Rz of 20 μm or more. Therefore, the biting of the paper feed roll 12 and the separation roll 14 becomes large. Then, as shown in FIG. 5B, when the paper P is conveyed, the paper P is arranged between the paper feed roll 12 and the biting of the separation roll 14, and the convex portion 12c of the paper feed roll 12 is placed on the paper P. Deformation occurs by receiving pressing force from the convex portion 14c of the separation roll 14 and the separation roll 14. Due to this anchor effect, the transportability of the paper P (the propulsive force of the paper P in the transport direction) is improved. Further, if the paper feed roll 12 and the separation roll 14 are largely bitten, even if paper dust adheres to the surfaces of the paper feed roll 12 and the separation roll 14, due to the influence of the bite, the paper feed roll 12 and the separation roll 14 are caught. The coefficient of friction between them is unlikely to decrease.

The paper feed roll 12 and the separation roll 14 are configured so that the difference in JIS-A hardness on the surface is 5 degrees or more. The surface hardness of the paper feed roll 12 and the separation roll 14 are different, and the separation roll 14 is pressed against the paper feed roll 12, so that one bites into the surface of the other as shown in FIG. 6A (a). In FIG. 6A, the separation roll 14 bites into the surface of the paper feed roll 12). As a result, the nip area (contact area) between the paper feed roll 12 and the separation roll 14 becomes large, and the friction coefficient between the paper feed roll 12 and the separation roll 14 becomes large. Then, as shown in FIG. 6B, since the paper P is arranged between the paper feed roll 12 and the separation roll 14 in which one bites into the surface of the other, the paper feed roll 12 and the paper P The contact area between the sheets and the contact area between the separation roll 14 and the paper P are also increased. As a result, the transportability of the paper P (the propulsive force of the paper P in the transport direction) is improved. Such an effect is exhibited when the hardness difference is 5 degrees or more.

The difference in surface hardness between the paper feed roll 12 and the separation roll 14 is more preferably 10 degrees or more, still more preferably 15 degrees or more, from the viewpoint of improving the transportability of the paper P. On the other hand, the difference in surface hardness between the paper feed roll 12 and the separation roll 14 is more preferably 50 degrees or less, still more preferably 40 degrees or less, from the viewpoint that wear of the paper feed roll 12 and the separation roll 14 can be easily suppressed. ..

The paper feed roll 12 and the separation roll 14 may have a higher surface hardness than any of the rolls, but the separation roll 14 has a higher surface hardness than the paper feed roll 12 from the viewpoint that double feeding of paper can be easily suppressed. Is preferable.

The coefficient of friction between the paper feed roll 12 and the separation roll 14 is 1.0 or more and 3.0 or less. When the friction coefficient is 1.0 or more, the transportability of the paper P (the propulsive force of the paper P in the transport direction) is improved. From this point of view, the coefficient of friction is more preferably 1.2 or more, still more preferably 1.5 or more. On the other hand, if the friction coefficient is more than 3.0, the friction coefficient is too large and the paper P tends to be clogged between the paper feed roll 12 and the separation roll 14. From the viewpoint of suppressing the friction coefficient to a small value, the friction coefficient is more preferably 2.7 or less, still more preferably 2.5 or less.

The friction coefficient between the paper feed roll 12 and the separation roll 14 is the material composition of the elastic body layer 12b of the paper feed roll 12, the thickness of the elastic body layer 12b of the paper feed roll 12, and the elastic body layer 12b of the paper feed roll 12. The composition of the convex portion 12c, the surface roughness Rz of the paper feed roll 12, the material composition of the elastic body layer 14b of the separation roll 14, the thickness of the elastic body layer 14b of the separation roll 14, and the convex portion of the elastic body layer 14b of the separation roll 14. It can be set in a desired range by adjusting the configuration of 14c, the surface roughness Rz of the separation roll 14, the hardness difference between the paper feed roll 12 and the separation roll 14, and the like.

In the paper feed device 10, the separation roll 14 preferably has a larger surface roughness Rz than the paper feed roll 12 from the viewpoint of improving the overall durability. Further, the separation roll 14 preferably has a smaller surface friction coefficient than the paper feed roll 12 from the viewpoint that double feeding of paper can be easily suppressed.

In the paper feed device 10 shown above, since the paper feed roll 12 and the separation roll 14 each have a surface roughness Rz of 20 μm or more, the paper feed roll 12 and the separation roll 14 are greatly engaged with each other, and the paper P can be transported. (Propulsive force of paper P in the transport direction) is improved. Further, even if paper dust adheres to the surface of the paper feed roll 12 or the separation roll 14, the friction coefficient between the paper feed roll 12 and the separation roll 14 is unlikely to decrease due to the influence of large biting. Then, since the friction coefficient between the paper feed roll 12 and the separation roll 14 is unlikely to decrease, it becomes difficult for the paper feed roll 12 and the separation roll 14 to slip. Further, when the JIS-A hardness difference between the paper feed roll 12 and the separation roll 14 is 5 degrees or more, the nip area (contact area) between the paper feed roll 12 and the separation roll 14 becomes large, and the paper P becomes large. Transportability (propulsive force of paper P in the transport direction) is improved. Further, since the friction coefficient between the paper feed roll 12 and the separation roll 14 becomes large, it becomes difficult for the paper feed roll 12 and the separation roll 14 to slip. Further, when the friction coefficient between the paper feed roll 12 and the separation roll 14 is 1.0 or more and 3.0 or less, the slip between the paper feed roll 12 and the separation roll 14 becomes difficult to slip. By interacting with each other, the transportability of the paper P (the propulsive force of the paper P in the transport direction) is improved, and as a result, the paper feed roll 12 and the separation roll 14 are less likely to slip, resulting in a paper jam after long-term use. Is suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

The paper feed roll 12 of FIG. 4A is provided with surface irregularities on the outer peripheral surface of the elastic body layer 12b by a plurality of convex portions 12c, and the surface irregularities can be formed by any irregularities. The surface unevenness may be formed by a plurality of convex portions 21 as shown in FIG. 7 (a), or may be formed by a plurality of concave portions 22 as shown in FIG. 7 (b). As shown in FIG. 7 (c), it may be formed by a plurality of convex portions 23 and a plurality of concave portions 24 such as a textured shape. The wrinkle shape means a wrinkle pattern. The textured shape can be formed by using a molding die whose inner surface is machined by electric discharge machining or the like. Examples of the grain shape include leather (scales), satin finish, wood grain, rock grain, sand grain, cloth grain, silk grain, streak (hairline), and geometric pattern.

Similarly, in the separation roll 14 of FIG. 4B, surface irregularities are provided on the outer peripheral surface of the elastic body layer 14b by the plurality of convex portions 14c, but the surface irregularities may be formed by arbitrary irregularities. it can. The surface unevenness may be formed by a plurality of convex portions 21 as shown in FIG. 7 (a), or may be formed by a plurality of concave portions 22 as shown in FIG. 7 (b). As shown in FIG. 7 (c), it may be formed by a plurality of convex portions 23 and a plurality of concave portions 24 such as a textured shape.

Further, in the above embodiment, the plurality of

convex portions

12c and 14c of the paper feed roll 12 and the separation roll 14 are hemispherical, but the shapes of the plurality of

convex portions

12c and 14c are limited to the hemispherical convex portions. However, it may have various shapes. The spherical shape may be substantially spherical and may have a shape close to a spherical surface having a curved surface. The spherical shape includes a true spherical shape and an elliptical spherical shape. A hemisphere is a half shape of a sphere cut on a surface passing through the center of the sphere, a shape larger than half a sphere cut on a surface not passing through the center of the sphere, or a half shape of a sphere. Also includes small shapes. When the

convex portions

12c and 14c are hemispherical, the contact surface with the paper P is a curved surface, so that the generation of paper dust is relatively suppressed and the paper feed performance is also excellent.

Examples of the shapes of the

convex portions

12c and 14c include an amorphous shape, a pillar body, a cone, a spherical segment, and a wedge shape. Examples of the pillars include cylinders, elliptical pillars, prisms (square pillars, pentagonal pillars, etc.), fan-shaped pillars, D-shaped pillars, gear-shaped pillars, and the like. Further, the head of the pillar may be a head pillar having a shape cut out in a slanted shape or a curved shape (a head cylinder, a head prism, etc.). Examples of the pyramid include a cone, an elliptical pyramid, and a pyramid (square pyramid, pentagonal pyramid, etc.). Further, the head of the cone may be a truncated cone (frustum), a truncated cone, or a truncated pyramid (such as a truncated cone or a truncated pyramid) having a shape such that it is cut into a slanted or curved shape. A spherical segment is a solid shaped like a sphere cut out by two parallel planes. When a sphere intersects two parallel planes, the part of the sphere sandwiched between these two planes is a sphere, and the sphere and the solid surrounded by these two planes are a spherical segment. One of the two planes of the sphere may be a plane that passes through the center of the sphere, or both of the two planes of the sphere may be a plane that does not pass through the center of the sphere. The two planes of the spherical segment may be any plane close to the plane, and may be, for example, a curved surface having a radius of curvature larger than that of the sphere. Further, each upper base (upper plane) of a cylinder, an elliptical pillar, a prism, a fan-shaped pillar, a D-shaped pillar, a gear-shaped pillar, a frustum, and a spherical segment may be a polished surface. The polished surface can be formed by polishing each upper bottom.

Further, in the above embodiment, the plurality of

convex portions

12c and 14c of the paper feed roll 12 and the separation roll 14 are arranged in a staggered manner on the peripheral surfaces of the elastic body layers 12b and 14b, but the plurality of convex portions 12c, The 14c may be uniformly distributed and arranged on the peripheral surfaces of the

elastic layers

12b and 14b, or may be randomly arranged. Further, they may be arranged so as to be arranged. When the

convex portions

12c and 14c are arranged along the peripheral surfaces of the elastic body layers 12b and 14b, a groove is formed between the rows, which serves as an escape route for the generated paper dust and facilitates discharge of the paper dust. .. The

convex portions

12c and 14c may be arranged in the circumferential direction along the peripheral surfaces of the elastic body layers 12b and 14b, or may be arranged in a direction different from the circumferential direction. The direction different from the circumferential direction means a form in which the elastic body layers 12b and 14b are arranged along the peripheral surface at a predetermined angle with respect to the circumferential direction. Further, the

convex portions

12c and 14c may be arranged spirally along the peripheral surfaces of the elastic body layers 12b and 14b.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

(Examples 1 to 6, 9 to 14, Comparative Examples 1 to 4)
(Adjustment of molding mold)
A molding die having a through hole (outer diameter φ12 mm) having a circular cross section was prepared. An electric discharge machine (“DIAX VX10” manufactured by Mitsubishi Electric Corporation) was used to perform electric discharge machining on the inner peripheral surface of the through hole of the prepared molding die. The electric discharge machining was performed in order to give a textured shape (arbitrary unevenness) to the surface of the elastic body to be molded. The surface roughness Rz of the elastic body to be molded was adjusted according to the above electric discharge machining conditions.

(Making a paper feed roll)
A core metal (outer diameter φ6 mm) is coaxially set in the through hole of the electric discharge machine, and the openings at both ends are closed with a cap mold, which is a material for forming an elastic layer in the molding space. After filling with an uncrosslinked thermosetting urethane polymer, the molding die was placed in an oven and crosslinked (150 ° C. × 60 minutes). Then, an elastic body made of a thermosetting urethane polymer crosslinked and cured was formed on the outer peripheral surface of the core metal, and then the elastic body was removed from the core metal while being demolded and cut into a length of 25 mm. The obtained elastic body has a tubular shape (outer diameter φ12 mm, inner diameter φ6 mm, length 25 mm), and its surface is textured. Next, a shaft body made of polyacetal (POM) (length 27 mm, outer diameter φ6 mm) was prepared. Next, the shaft body was press-fitted into the hollow portion of the tubular elastic body. From the above, a paper feed roll was produced. The surface roughness Rz of the paper feed roll was adjusted according to the above-mentioned electric discharge machining conditions. The coefficient of friction of the paper feed roll was adjusted by the material composition and the surface roughness Rz.

(Preparation of separation roll)
A separation roll was produced in the same manner as the paper feed roll. The surface roughness Rz of the separation roll was adjusted according to the above-mentioned electric discharge machining conditions. The coefficient of friction of the separation roll was adjusted by the material composition and the surface roughness Rz.

(Examples 7 and 8, Comparative Example 5)
The electric discharge machining conditions were adjusted so that the heights of the convex portions of the elastic body to be molded were 20 μm (Example 7), 200 μm (Example 8), and 15 μm (Comparative Example 5), respectively. From the above, a paper feed roll was produced. Separation rolls were also prepared in the same manner.

Durability was evaluated using the prepared paper feed roll and separation roll. The results are shown in the table together with the role configuration.

(Measurement of coefficient of friction)
The friction coefficient of the paper feed roll was measured by using a commercially available friction coefficient meter, applying a linear indenter and a load of 50 g, and sliding it in the longitudinal direction of the surface of the elastic body layer at a speed of 2.5 mm / s. Similarly, the friction coefficient of the separation roll was measured by using a commercially available friction coefficient meter, applying a linear indenter and a load of 50 g, and sliding it in the longitudinal direction of the surface of the elastic body layer at a speed of 2.5 mm / s. As shown in FIG. 8, the friction coefficient between rolls is different from that of the rotatably provided paper feed roll 1 (shaft radius r1 = 3 mm, roll radius r2 = 6 mm) and the separation roll 2 (shaft radius 3 mm, roll). The load cell 4 is attached to the end of the string 3 wound around the shaft body 1a of the paper feed roll 1 by pressing the string 3) with a load N = 200 gf so that the string 3 is horizontal and the string is at a speed of 50 mm / sec. It was calculated by pulling 3 and measuring its tensile force F. The coefficient of friction between rolls μ was calculated from the following equation (1).
μ = (F × r1 / r2) / N ・・・ (1)

(Measurement of surface hardness)
The surface hardness of the paper feed roll was the JIS-A hardness of the surface of the elastic layer of the paper feed roll. Similarly, the surface hardness of the separation roll was the JIS-A hardness of the surface of the elastic layer of the separation roll. The difference in hardness between rolls was expressed by the difference between the JIS-A hardness on the surface of the elastic layer of the separation roll and the JIS-A hardness on the surface of the elastic layer of the paper feed roll.

(Measurement of surface roughness)
The surface roughness Rz of the paper feed roll was defined as the surface roughness Rz of the surface of the elastic layer of the paper feed roll. Similarly, the surface roughness Rz of the separation roll was defined as the surface roughness Rz of the surface of the elastic layer of the separation roll. The surface roughness Rz is a ten-point average roughness, and was measured according to JIS B0601 (1994).

(Evaluation of durability)
The paper feed roll and the separation roll were incorporated into a commercially available copier equipped with an FRR type paper feed system, and the paper feed performance was evaluated. Commercially available PPC paper was used as the paper, 300,000 sheets were passed, and the number of paper jams was measured. "A" for paper jams that occur once or less, "B" for paper jams that occur 2 or more and 4 times or less, and paper jams that occur 5 or more and 6 times or less. “C” was defined as “D” when the number of times the paper jam occurred 7 times or more and 10 times or less, and “E” when the number of times the paper jam occurred 11 times or more.

In Comparative Example 1, the friction coefficient between the rolls of the paper feed roll and the separation roll was less than 1.0, and there were many paper jams in the durability test of 300,000 sheets. In Comparative Example 2, the coefficient of friction between the paper feed roll and the separation roll is more than 3.0, the paper feed roll and the separation roll are strongly engaged, and there are many paper jams in the durability test of 300,000 sheets. It was. In Comparative Example 3, the hardness difference between the rolls of the paper feed roll and the separation roll was small at less than 5 degrees, and there were many paper jams in the durability test of 300,000 sheets. In Comparative Examples 4 and 5, the surface roughness Rz of the paper feed roll and the separation roll was small at less than 20 μm, and there were many paper jams in the durability test of 300,000 sheets.

According to Examples and Comparative Examples, the paper feed roll and the separation roll are each composed of an elastic body containing polyurethane on the surface, each has a surface roughness Rz of 20 μm or more, and the difference in JIS-A hardness of the surfaces is 5. If the degree or more and the coefficient of friction between the paper feed roll and the separation roll is 1.0 or more and 3.0 or less, the paper jam is suppressed in the durability test of 300,000 sheets, and the paper jam after long-term use is suppressed. Can be seen to be suppressed.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. ..

Claims

A paper feed roll that is rotationally driven to convey paper,
It is equipped with a separate roll that is pressed against the paper feed roll and has a built-in torque limiter to suppress double feed of paper.
The paper feed roll and the separation roll are each composed of an elastic body containing polyurethane on the surface, each having a surface roughness Rz of 20 μm or more, and a difference in JIS-A hardness of the surfaces of 5 degrees or more.
A paper feeding device characterized in that the friction coefficient between the paper feed roll and the separation roll is 1.0 or more and 3.0 or less.
The paper feeding device according to claim 1, wherein the paper feed roll and the separation roll each have a convex portion having a height of 20 to 300 μm on the surface thereof.
The paper feeding device according to claim 1 or 2, wherein the separation roll has a surface roughness Rz larger than that of the paper feed roll.
The paper feeding device according to any one of claims 1 to 3, wherein the separation roll has a smaller surface friction coefficient than the paper feed roll.
The paper feed roll according to any one of claims 1 to 4.
The separation roll according to any one of claims 1 to 4.