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Abstract

This invention provides a paper feed roller that can suppress poor paper feeding over a long period of time. The paper feed roller 10 includes a shaft 12 and an elastomer layer 14 formed on the outer peripheral surface of the shaft 12. The portion having the elastomer layer 14 has a first outer diameter portion 10a with an outer diameter one size smaller and a second outer diameter portion 10b with an outer diameter larger than the first outer diameter portion 10a. An inclined portion 10c is provided between the first outer diameter portion 10a and the second outer diameter portion 10b to connect the first outer diameter portion 10a and the second outer diameter portion 10b, so that the outer diameter changes in the axial direction. The inclined portion 10c accounts for more than 3% and less than 80% of the portion having the elastomer layer 14. The difference in outer diameter between the first outer diameter portion 10a and the second outer diameter portion 10b is more than 50 μm and less than 1000 μm. A plurality of protrusions 14a forming surface irregularities are formed on the outer peripheral surface of the elastomer layer 14. The surface roughness Rz in the first outer diameter portion 10a is more than 50% and less than 200% of the height difference between the first outer diameter portion 10a and the second outer diameter portion 10b.

Description

Technical Field

[0001] This invention relates to a paper feed roller preferred for use in electrophotographic devices such as copiers, printers, and fax machines that employ electrophotographic methods. Background Technology

[0002] Paper feed rollers are cylindrical, formed from elastic materials such as rubber crosslinkers, with their circumferential surface serving as the contact surface with the paper. Paper dust generated by the paper sometimes adheres to the circumferential surface of the paper feed roller. Furthermore, during repeated contact with the paper, paper dust can sometimes accumulate on the circumferential surface of the paper feed roller. When paper dust accumulates, the contact area between the circumferential surface and the paper decreases, and the coefficient of friction between the contact surface and the paper decreases. As a result, poor paper feeding can sometimes occur.

[0003] To suppress poor paper feeding, it is known that a paper feed roller has an irregular shape formed on its circumferential surface (Patent Document 1). For example, Patent Document 1 describes a paper feed roller in which a plurality of grooves extending circumferentially are formed at predetermined intervals along the axial direction on the circumferential surface of the paper feed roller, and fine irregularities based on a fold shape are formed on the outer circumferential surface of the convex strip formed by the portion without the grooves and at the bottom of the grooves.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2008-290826 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Existing paper feed rollers are insufficient in suppressing paper dust accumulation and maintaining a good coefficient of friction from the initial stage of use. When unevenness forms on the roller's circumference, paper dust is discharged into the concave areas, thereby suppressing dust accumulation and maintaining a good coefficient of friction. However, when the unevenness on the roller's circumference wears down due to long-term use, paper dust cannot be discharged, adhering to the roller's circumference, reducing the coefficient of friction and potentially causing poor paper feeding. In particular, the use of low-quality paper in recent years has led to more paper dust generation, resulting in poor paper feeding at an earlier stage.

[0009] The problem to be solved by the present invention is to provide a paper feed roller that can suppress poor paper feeding over a long period of time.

[0010] means for solving problems

[0011] The paper feed roller of the present invention is a paper feed roller having a shaft and an elastomeric layer formed on the outer peripheral surface of the shaft. The paper feed roller has a first outer diameter portion with an outer diameter one size smaller and a second outer diameter portion with an outer diameter larger than the first outer diameter portion in the portion having the elastomeric layer. An inclined portion is provided between the first outer diameter portion and the second outer diameter portion to connect the first outer diameter portion and the second outer diameter portion so that the outer diameter changes in the axial direction. The inclined portion accounts for more than 3% and less than 80% of the portion having the elastomeric layer. The difference in outer diameter between the first outer diameter portion and the second outer diameter portion is more than 50 μm and less than 1000 μm. A plurality of protrusions forming surface irregularities are formed on the outer peripheral surface of the elastomeric layer. The surface roughness Rz in the first outer diameter portion is more than 50% and less than 200% of the height difference between the first outer diameter portion and the second outer diameter portion.

[0012] The protruding direction of the convex portion formed by the elastomeric layer in the inclined portion may be different from the protruding direction of the convex portion formed by the elastomeric layer in the first outer diameter portion and the protruding direction of the convex portion formed by the elastomeric layer in the second outer diameter portion. The proportion of the inclined portion to the portion having the elastomeric layer may be more than 10% and less than 50%. The second outer diameter portion may be located in a region including the center of the axial direction. The surface roughness Rz of the first outer diameter portion, the second outer diameter portion, and the inclined portion may be more than 25 μm and less than 500 μm. The shaft has a portion with a larger outer diameter at the second outer diameter portion, and the first outer diameter portion, the second outer diameter portion, and the inclined portion are formed according to the shape of the shaft.

[0013] Furthermore, the paper feed roller manufacturing method of the present invention is one of the above-described paper feed roller manufacturing methods, which is formed by inserting the shaft into the elastomer layer that is formed into a cylindrical shape.

[0014] Invention Effects

[0015] According to the present invention, a paper feed roller comprises a shaft and an elastomeric layer formed on the outer peripheral surface of the shaft. The paper feed roller has a first outer diameter portion having an outer diameter one size smaller than the first outer diameter portion and a second outer diameter portion having an outer diameter larger than the first outer diameter portion in the portion having the elastomeric layer. An inclined portion connecting the first outer diameter portion and the second outer diameter portion is provided between the first outer diameter portion and the second outer diameter portion to change the outer diameter in the axial direction. The inclined portion accounts for more than 3% and less than 80% of the portion having the elastomeric layer. The difference in outer diameter between the first outer diameter portion and the second outer diameter portion is more than 50 μm and less than 1000 μm. A plurality of protrusions forming surface irregularities are formed on the outer peripheral surface of the elastomeric layer. The surface roughness Rz in the first outer diameter portion is more than 50% and less than 200% of the height difference between the first outer diameter portion and the second outer diameter portion. The paper feed roller of this invention has a height difference between its first and second outer diameter portions. Therefore, even if the number of sheets of paper increases and the surface of the second outer diameter portion becomes worn due to unevenness, the friction coefficient can be maintained by the unevenness of the surface of the first outer diameter portion. At this time, the main contact area with the paper shifts from the second outer diameter portion to the first outer diameter portion, but by connecting the inclined portion between the first and second outer diameter portions, the decrease in the friction coefficient can be suppressed even during the transition from the second outer diameter portion to the first outer diameter portion. Thus, poor paper feeding can be suppressed for a long period. Attached Figure Description

[0016] Figure 1 This is an axial sectional view of a paper feed roller according to one embodiment of the present invention.

[0017] Figure 2 This is a diagram illustrating the durability process of the paper feed roller.

[0018] Figure 3 This is an axial cross-sectional view of the paper feed roller involved in other embodiments.

[0019] Figure 4 This is an axial cross-sectional view of the paper feed roller involved in other embodiments. Detailed Implementation

[0020] The paper feed roller involved in this invention will be described in detail. Figure 1 This is an axial sectional view of a paper feed roller according to one embodiment of the present invention.

[0021] One embodiment of the present invention includes a paper feed roller 10 comprising a shaft 12 and an elastomer layer 14 formed on the outer peripheral surface of the shaft 12.

[0022] The shaft body 12 is a solid body made of metal or resin. The shaft body 12 has a stepped shape with portions of different outer diameters. The two ends of the shaft body 12 along the axial direction form a small-diameter portion 12a with a smaller outer diameter, and the central portion along the axial direction forms a large-diameter portion 12b with a larger outer diameter. Both the small-diameter portion 12a and the large-diameter portion 12b have uniform outer diameters and are cylindrical in shape. The large-diameter portion 12b, including the central portion along the axial direction of the shaft body 12, is formed by a continuous and single structure. The small-diameter portions 12a are respectively disposed at both ends of the large-diameter portion 12b, forming a pair. The small-diameter portions 12a and the large-diameter portions 12b are integrally formed around the same axial center.

[0023] The difference in outer diameter between the minor diameter portion 12a and the major diameter portion 12b of the shaft can be 50 μm or more and 1000 μm or less. Therefore, the difference in outer diameter between the first outer diameter portion 10a and the second outer diameter portion 10b of the paper feed roller 10 (described later) can be set within a desired range. More preferably, the difference in outer diameter between the minor diameter portion 12a and the major diameter portion 12b is 100 μm or more and 700 μm or less, and even more preferably, 100 μm or more and 500 μm or less.

[0024] From the viewpoint of achieving an excellent balance between the ratio of the first outer diameter portion 10a to the second outer diameter portion 10b of the paper feed roller 10 (described later), the proportion of the large diameter portion 12b of the shaft to the length of the shaft body 12 is preferably 1.5% or more and 45% or less. The proportion of the large diameter portion 12b of the shaft to the length of the shaft body 12 is preferably 5% or more and 40% or less, and more preferably 10% or more and 30% or less.

[0025] The elastomer layer 14 is a cylindrical (tubular) seamless structure without seams along the circumference. The elastomer layer 14 is configured to fit around the outer periphery of the shaft 12. The elastomer layer 14 before fitting around the outer periphery of the shaft 12 is cylindrical, with uniform inner and outer diameters along the axial direction, and uniform thickness. Multiple protrusions 14a are formed on the outer peripheral surface of the elastomer layer 14, creating surface roughness. These protrusions 14a are uniformly distributed along both the circumferential and axial directions on the outer peripheral surface of the elastomer layer 14. Each protrusion 14a is composed of a cylinder extending in a direction orthogonal to the outer peripheral surface of the elastomer layer 14. The axial length of the elastomer layer 14 is shorter than the axial length of the shaft 12.

[0026] The elastomer layer 14 is fitted over the outer periphery of the stepped shaft 12, within a predetermined range exposed at both ends of the shaft 12. Due to the stepped shape of the shaft 12, the outer diameters of the two ends of the elastomer layer 14 covering the outer periphery of the shaft 12 are smaller diameters, and the outer diameter of the central portion is larger diameters.

[0027] The paper feed roller 10 is constructed by covering the outer periphery of a stepped shaft 12 with a cylindrical elastomer layer 14. Due to the shape of the shaft 12, the paper feed roller 10 has a first outer diameter portion 10a with a smaller outer diameter than the portion having the elastomer layer 14, and a second outer diameter portion 10b with a larger outer diameter than the first outer diameter portion 10a. Furthermore, due to the shape of the shaft 12, an inclined portion 10c is provided between the first outer diameter portion 10a and the second outer diameter portion 10b to change the outer diameter in the axial direction, thus forming the paper feed roller 10. The first outer diameter portion 10a is located at both ends of the portion having the elastomer layer 14 and has a smaller outer diameter. The second outer diameter portion 10b is located in the central portion of the portion having the elastomer layer 14 (including the axial center area) and has a larger outer diameter. The paper feed roller 10 thus has a predetermined height difference between the first outer diameter portion 10a and the second outer diameter portion 10b. Figure 1 In the diagram, D1 represents the outer diameter of the first outer diameter section 10a, and D2 represents the outer diameter of the second outer diameter section 10b. The height difference between the first outer diameter section 10a and the second outer diameter section 10b can be represented by half the difference in their outer diameters. For example... Figure 1 As shown, the outer diameters of the first outer diameter portion 10a and the second outer diameter portion 10b include the size of the surface irregularities.

[0028] Multiple protrusions 14a are formed on the outer peripheral surface of the elastomer layer 14 to create surface roughness, thus providing surface roughness at each of the first outer diameter portion 10a, the second outer diameter portion 10b, and the inclined portion 10c. The extending directions of the protrusions 14a formed in the first outer diameter portion 10a and the second outer diameter portion 10b are radially outward, and the protrusions 14a extend in a direction orthogonal to the outer peripheral surfaces of the elastomer layer 14 in the first outer diameter portion 10a and the second outer diameter portion 10b. On the other hand, regarding the extending direction of the protrusion 14a formed in the elastomeric layer 14 in the inclined portion 10c, since the protrusion 14a extends in a direction orthogonal to the outer peripheral surface of the elastomeric layer 14 in the inclined portion 10c, the extending direction of the protrusion 14a formed in the elastomeric layer 14 in the inclined portion 10c is located in a direction different from the extending direction of the protrusion 14a formed in the elastomeric layer 14 in the first outer diameter portion 10a and the extending direction of the protrusion 14a formed in the elastomeric layer 14 in the second outer diameter portion 10b.

[0029] In a paper feed roller 10 configured as shown, when paper is being fed, it becomes as follows. Figure 2 The durability process of the paper feed roller 10 is shown in the figure.

[0030] like Figure 2As shown in (a), in the initial stage of paper feeding, the paper feed roller 10 contacts the paper P at the elastomer layer 14 of the second outer diameter portion 10b, which has a larger outer diameter. The paper P does not contact the elastomer layer 14 of the first outer diameter portion 10a, which has a smaller outer diameter. Moreover, as... Figure 2 (b) Figure 2 As shown in (c), as the number of sheets of paper increases, the surface of the elastomer layer 14 of the second outer diameter portion 10b wears down and becomes smooth. When the surface becomes smooth at the second outer diameter portion 10b, paper dust becomes easier to adhere to the second outer diameter portion 10b, resulting in a decrease in the coefficient of friction.

[0031] Here, as Figure 2 As shown in (d), due to the height difference between the first outer diameter portion 10a and the second outer diameter portion 10b, when the second outer diameter portion 10b wears, the paper feed roller 10 contacts the paper P at the elastomer layer 14 of the first outer diameter portion 10a, which has a smaller outer diameter. Even if the number of sheets of paper increases and the surface of the second outer diameter portion 10b wears due to its unevenness, the paper feed roller 10 can maintain the coefficient of friction due to the unevenness of the surface of the first outer diameter portion 10a.

[0032] At this time, the main part in contact with the paper P switches from the second outer diameter portion 10b to the first outer diameter portion 10a. Furthermore, as... Figure 2 (b) Figure 2 As shown in (c), since the paper feed roller 10 has an inclined portion 10c connecting the first outer diameter portion 10a and the second outer diameter portion 10b, after the surface of the second outer diameter portion 10b is worn unevenly, the paper feed roller 10 comes into contact with the paper P at the elastomeric layer 14 of the inclined portion 10c. Therefore, the decrease in the coefficient of friction can be suppressed during the transition from the second outer diameter portion 10b to the first outer diameter portion 10a, allowing for a smooth transition. When the height difference between the first outer diameter portion 10a and the second outer diameter portion 10b increases, the decrease in the coefficient of friction becomes more likely to occur during the transition from the second outer diameter portion 10b to the first outer diameter portion 10a, but this method is particularly effective in such cases.

[0033] The proportion of the inclined portion 10c in the portion having the elastomer layer 14 can be 3% or more and 80% or less. The paper feed roller 10 achieves the above-mentioned effects by having the inclined portion 10c, and as the effective range of the above-mentioned effects, the proportion of the inclined portion 10c in the portion having the elastomer layer 14 is 3% or more. In addition, from this point of view, the proportion of the inclined portion 10c in the portion having the elastomer layer 14 is more preferably 5% or more, and even more preferably 10% or more. On the other hand, when the proportion of the inclined portion 10c in the portion having the elastomer layer 14 exceeds 80%, the ratio of the first outer diameter portion 10a to the second outer diameter portion 10b becomes relatively smaller, thereby weakening the advantage of setting the paper feed roller 10 as a stepped structure, and failing to suppress the decrease in the coefficient of friction. In addition, from this point of view, the proportion of the inclined portion 10c in the portion having the elastomer layer 14 is more preferably 70% or less, and even more preferably 50% or less. The proportion of the inclined portion 10c to the portion having the elastomer layer 14 can be expressed as the remaining length obtained by subtracting the lengths of the first outer diameter portion 10a and the second outer diameter portion 10b from the total length of the elastomer layer 14.

[0034] The difference in outer diameter between the first outer diameter portion 10a and the second outer diameter portion 10b can be 50 μm or more and 1000 μm or less. When the outer diameter difference is too small, the advantage of setting the paper feed roller 10 as a stepped structure is weakened, and the decrease in the coefficient of friction cannot be suppressed. From this point of view, the outer diameter difference is more preferably 100 μm or more, and even more preferably 150 μm or more. On the other hand, when the outer diameter difference is too large, the surface roughness of the elastomer layer 14 needs to be increased accordingly, and the size of the protrusion 14a used to form the surface unevenness also needs to be increased, which reduces the effect of the surface unevenness and makes it impossible to suppress the decrease in the coefficient of friction. From this point of view, the outer diameter difference is more preferably 700 μm or less, and even more preferably 500 μm or less.

[0035] The surface roughness Rz in the first outer diameter portion 10a can be 50% or more and 200% or less of the height difference between the first outer diameter portion 10a and the second outer diameter portion 10b. When the surface roughness Rz is too small relative to the height difference, after the surface of the second outer diameter portion 10b wears down, it cannot contact the paper at the elastomer layer 14 of the first outer diameter portion 10a, and it cannot suppress the decrease in the coefficient of friction during the switch from the second outer diameter portion 10b to the first outer diameter portion 10a. From this point of view, the surface roughness Rz is more preferably 60% or more, and more preferably 80% or more, relative to the height difference. On the other hand, when the surface roughness Rz is too large relative to the height difference, the switch from the second outer diameter portion 10b to the first outer diameter portion 10a occurs earlier, and therefore the decrease in the coefficient of friction occurs earlier, making it impossible to suppress poor paper feeding for a long time. From this point of view, the surface roughness Rz is more preferably 170% or less, and more preferably 150% or less, relative to the height difference.

[0036] The surface roughness Rz in the first outer diameter portion 10a, the second outer diameter portion 10b, and the inclined portion 10c can be 25 μm or more and 500 μm or less. When the surface roughness Rz is 25 μm or more, a sufficient coefficient of friction can be maintained in each of the first outer diameter portion 10a, the second outer diameter portion 10b, and the inclined portion 10c. Furthermore, from this viewpoint, the surface roughness Rz is more preferably 50 μm or more, and even more preferably 100 μm or more. Moreover, when the surface roughness Rz is 500 μm or less, it is a suitable surface roughness, and it is easy to control the difference in outer diameter between the first outer diameter portion 10a and the second outer diameter portion 10b within a suitable range. Furthermore, from this viewpoint, the surface roughness Rz is more preferably 400 μm or less, and even more preferably 300 μm or less. The surface roughness Rz is a ten-point average roughness, which is the average value of the values ​​measured at any five locations according to JIS B0601 (1994). The ten-point average roughness Rz can be measured by observation using a laser microscope (such as the Keyence "VK-9510").

[0037] Next, the material composition of the paper feed roller according to the present invention will be described.

[0038] The shaft 12 is a solid body made of metal or resin. Examples of metal materials include stainless steel, aluminum, and iron after electroplating. Examples of resin materials include polyoxymethylene (POM), acrylonitrile butadiene styrene copolymer (ABS), polycarbonate, nylon, and other synthetic resins. Furthermore, adhesives, primers, etc., can be applied to the shaft 12 as needed, and these adhesives and primers can also be made conductive as required.

[0039] The elastomer layer 14 is composed of elastic materials such as rubber, elastomer, and resin. There are no particular limitations on the material as long as it is a rubber-like elastic material. For example, known materials such as polyurethane rubber, chlorohydrin rubber, silicone rubber, and EPDM can be used.

[0040] The elastomer layer 14 can also be any of non-conductive, conductive, or semi-conductive. The elastomer layer 14 is particularly preferably non-conductive. As a non-conductive elastomer layer 14, its volume resistivity is 10⁻⁶. 12 ~10 14 The range of Ω·cm.

[0041] The elastomer layer 14 can also be appropriately supplemented with various additives as needed. Examples of additives include lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoamers, pigments, and release agents.

[0042] The thickness of the elastomer layer 14 is not particularly limited and can be appropriately set within the range of 0.1 to 10 mm. The thickness of the elastomer layer 14 includes the thickness of the protrusions 14a that form the surface unevenness.

[0043] The elastomeric layer 14 can be formed by molding based on a molding die. For example, a core material can be coaxially disposed in the hollow portion of a roll forming die, an uncrosslinked rubber composition can be injected, and after heating and curing (crosslinking), the material can be demolded to form a tubular elastomeric layer 14. The molding die can be a molding die with a recess on its inner circumferential surface that corresponds to the shape of the protrusion 14a. For example, the protrusion 14a of the elastomeric layer 14 can be formed by mold transfer based on the molding die.

[0044] The recesses on the inner circumferential surface of the forming mold can be formed by various recess-forming methods such as electrical discharge machining, etching, shot peening, grinding, eutectoid plating, and combinations thereof. In eutectoid plating, uniform resin particles are contained in the plating solution, causing the resin particles to precipitate together with the plating metal on the inner circumferential surface of the forming mold, and the resin particles appearing on the plating surface are removed, thereby forming a recess on the inner circumferential surface of the forming mold.

[0045] The paper feed roller 10 is formed by inserting the shaft 12 into the cylindrical elastomer layer 14.

[0046] The paper feed roller 10, configured as described above, has a height difference between the first outer diameter portion 10a and the second outer diameter portion 10b. Therefore, even if the number of sheets of paper increases and the surface of the second outer diameter portion 10b becomes worn, the surface unevenness of the first outer diameter portion 10a maintains the coefficient of friction. At this time, the main contact area with the paper shifts from the second outer diameter portion 10b to the first outer diameter portion 10a. However, by connecting the inclined portion 10c between the first and second outer diameter portions 10a and 10b, even during the transition from the second outer diameter portion 10b to the first outer diameter portion 10a, a decrease in the coefficient of friction can be suppressed. Thus, poor paper feeding can be suppressed over a long period.

[0047] The embodiments of the present invention have been described above, but the present invention is not limited to any of the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0048] For example, in the above embodiment, the shaft 12 is shown as a stepped shape with portions having different outer diameters, but the shaft may also be a cylindrical shape with a uniform outer diameter (a shape without steps).

[0049] exist Figure 3 In the middle, it represents the paper feed roller involved in other embodiments. Figure 3 The paper feed roller 30 shown includes a shaft 32 and an elastomer layer 34 formed on the outer circumferential surface of the shaft 32. The shaft 32 is a cylindrical shape (without steps) with a uniform outer diameter throughout the axial direction. The elastomer layer 34 consists of two layers: an inner elastomer layer 341 and an outer elastomer layer 342. The axial length of the inner elastomer layer 341 is relatively short, while the axial length of the outer elastomer layer 342 is longer than that of the inner elastomer layer 341.

[0050] The inner elastomer layer 341 and the outer elastomer layer 342 are both cylindrical (tubular) and seamless structures without circumferential joints. The inner elastomer layer 341 and the outer elastomer layer 342 are respectively composed of elastic materials such as rubber, elastomer, and resin. The inner elastomer layer 341 is positioned at the center of the shaft 32 along its axial direction, fitting around the outer periphery of the shaft 32. The outer elastomer layer 342 is positioned around the outer periphery of the shaft 32 and the inner elastomer layer 341, covering the inner elastomer layer 341. The inner elastomer layer 341 and the outer elastomer layer 342, before fitting around the outer periphery of the shaft 32, are both cylindrical, with uniform inner and outer diameters along the axial direction and uniform thickness. No protrusions forming surface roughness are formed on the outer peripheral surface of the inner elastomer layer 341. Multiple protrusions 34a forming surface roughness are formed on the outer peripheral surface of the outer elastomer layer 342. Multiple protrusions 34a are evenly distributed along the circumferential and axial directions on the outer peripheral surface of the outer elastomer layer 342. The multiple protrusions 34a are composed of cylinders extending in a direction orthogonal to the outer peripheral surface of the elastomer layer 34.

[0051] Because the inner elastomer layer 341 is fitted around the outer shape of the shaft 32, the outer diameters of the two ends of the outer elastomer layer 342, which covers the outer periphery of the shaft 32 and the inner elastomer layer 341, become smaller diameters, while the outer diameter of the central part becomes larger diameters.

[0052] The paper feed roller 30 is constructed by covering the outer periphery of the shaft 32 and the inner elastomer layer 341 with a cylindrical outer elastomer layer 342. Due to these shapes, it is a paper feed roller 30 with a first outer diameter portion 30a having a smaller outer diameter than the portion having the outer elastomer layer 342, and a second outer diameter portion 30b having a larger outer diameter than the first outer diameter portion 30a. Furthermore, due to these shapes, it is a paper feed roller 30 with an inclined portion 30c connecting the first outer diameter portion 30a and the second outer diameter portion 30b, thereby changing the outer diameter in the axial direction. The first outer diameter portion 30a is located at both ends of the portion having the outer elastomer layer 342 and has a smaller outer diameter. The second outer diameter portion 30b is located in the central portion of the portion having the outer elastomer layer 342 and has a larger outer diameter.

[0053] exist Figure 4 In the middle, it represents the paper feed roller involved in other embodiments. Figure 4 The paper feed roller 40 shown includes a shaft 42 and an elastomer layer 44 formed on the outer peripheral surface of the shaft 42. The shaft 42 is a cylindrical shape (without steps) with a uniform outer diameter throughout the axial direction.

[0054] The elastomer layer 44 is a cylindrical (tubular) seamless structure without any joints along its circumference. The elastomer layer 44 is composed of elastic materials such as rubber, elastomer, and resin. The elastomer layer 44 is configured to fit around the outer periphery of the shaft 42. The elastomer layer 44 before fitting around the outer periphery of the shaft 42 is cylindrical, but it has a stepped shape with a thicker wall portion in the central axial direction. The inner diameter of the elastomer layer 44 is uniform throughout the axial direction. The outer diameter of the elastomer layer 44 is one size smaller at both ends and one size larger in the central axial direction. The two ends of the elastomer layer 44 in the axial direction form a thin-walled portion 44a with a thinner wall thickness, and the central axial direction forms a thick-walled portion 44b with a thicker wall thickness. Furthermore, between the thin-walled portion 44a and the thick-walled portion 44b of the elastomer layer 44, there is a wall thickness inclined portion 44c where the wall thickness changes in the axial direction. Multiple protrusions 44d are formed on the outer peripheral surface of the elastomer layer 44 to create surface roughness. The multiple protrusions 44d are uniformly distributed along the circumferential and axial directions on the outer peripheral surface of the elastomer layer 44. The multiple protrusions 44d are composed of cylinders extending in a direction orthogonal to the outer peripheral surface of the elastomer layer 44.

[0055] The paper feed roller 40 is constructed by covering the outer periphery of the shaft 42 with an elastomer layer 44, thereby forming a paper feed roller 40 with a first outer diameter portion 40a having an outer diameter one size smaller than the first outer diameter portion 40a, and a second outer diameter portion 40b having an outer diameter larger than the first outer diameter portion 40a, depending on the shape of the elastomer layer 44. Furthermore, an inclined portion 40c is provided between the first outer diameter portion 40a and the second outer diameter portion 40b to connect them, thereby changing the outer diameter in the axial direction. The first outer diameter portion 40a is located at both ends of the portion having the elastomer layer 44 and has an outer diameter one size smaller. The second outer diameter portion 40b is located in the central portion of the portion having the elastomer layer 44 and has an outer diameter one size larger.

[0056] Furthermore, in the above embodiment, the second outer diameter portion 10b is located in the portion including the central portion of the portion having the elastomer layer 14, but the second outer diameter portion may also be located in the portion excluding the central portion of the portion having the elastomer layer. Additionally, in the above embodiment, the second outer diameter portion 10b is formed by a continuous and single configuration in the central portion of the portion having the elastomer layer 14 (exists in one location), but the second outer diameter portion may exist in two or more locations of the portion having the elastomer layer. For example, the shaft may have multiple small-diameter portions and large-diameter portions alternating along the axial direction, thereby allowing the second outer diameter portion to exist in two or more locations of the portion having the elastomer layer. Alternatively, multiple... Figure 3 The inner elastomeric layer shown here exists in two or more portions of the portion containing the elastomeric layer, thus the second outer diameter portion exists. Alternatively, multiple portions may exist along the axial direction. Figure 4The thick-walled portion shown means that the second outer diameter portion exists in more than two parts of the portion having the elastomer layer.

[0057] In addition, in the above embodiment, the paper feed roller 10 is a step consisting of two sections, the first outer diameter section 10a and the second outer diameter section 10b. However, it may also be configured to have a third outer diameter section with an outer diameter larger than the first outer diameter section and a outer diameter smaller than the second outer diameter section.

[0058] In addition, in the above embodiment, the first outer diameter portion 10a and the second outer diameter portion 10b are configured to be symmetrical in the axial direction, but they may also be configured in asymmetrical positions in the axial direction.

[0059] Furthermore, in the above embodiment, the plurality of protrusions 14a forming the uneven surface are cylindrical, but the plurality of protrusions are not limited to cylindrical shapes and can be protrusions of various shapes. Examples of protrusion shapes include hemispherical, irregular shapes, cylinders, cones, frustums, wedges, etc. Examples of cylinders include cylindrical, elliptical, prismatic (quadrilateral, pentagonal, etc.), sector-shaped, D-shaped, gear-shaped, etc. Additionally, the head of the cylinder can be cut into a truncated cylinder (truncated cylinder, truncated prism, etc.) to form a sloping or curved shape. Examples of cones include conical, elliptical, and pyramidal (quadrilateral, pentagonal, etc.). Additionally, the head of the cone can be cut into a flat (frustum), sloping, or curved shape to form a truncated cone (truncated cone, truncated pyramidal, etc.). A frustum is a solid shape formed by cutting a sphere into two parallel planes. When a sphere intersects two parallel planes, the portion of the sphere sandwiched between these two planes is called the spherical band, and the solid enclosed by the spherical band and the two planes is a table tennis table. One of the two planes of the table tennis table can be a plane that passes through the center of the sphere, or either of the two planes can be a plane that does not pass through the center of the sphere. The two planes of the table tennis table only need to be near-planar surfaces; for example, they can be curved surfaces with a radius of curvature larger than that of the spherical band. Furthermore, the upper bases (upper side planes) of cylinders, elliptical cylinders, prisms, sector-shaped cylinders, D-shaped cylinders, gear-shaped cylinders, frustums, and table tennis tables can be polished surfaces. Polished surfaces can be formed by polishing the upper bases.

[0060] In addition, in the above embodiments, the shaft 12 is made of a solid body of metal or resin, but the shaft 12 may also be made of a hollow body (cylindrical body) of metal or resin.

[0061] Example

[0062] The present invention will be described in detail below using examples.

[0063] (Example 1)

[0064] Prepare a device with the outer diameter and length of each part as described in Table 1. Figure 1 The structure shown has two stepped shafts, into which the stepped shafts are inserted. A 30mm long rubber tube (made of polyurethane) with a diameter of 10mm, a thickness of 5mm, and a surface roughness Rz of 150μm on its outer circumference was used to fabricate a product such as... Figure 1 The paper feed roller is shown. Furthermore, the rubber tube is manufactured by using a cylindrical forming mold with predetermined recesses on its inner circumferential surface, and forming an elastomeric layer of polyurethane rubber composition on the outer circumference of the core material. Multiple protrusions are formed on the outer circumferential surface of the rubber tube to create surface roughness. These protrusions are evenly distributed along both the circumferential and axial directions on the outer circumferential surface of the rubber tube. Each protrusion is composed of a cylinder extending in a direction orthogonal to the outer circumferential surface of the rubber tube.

[0065] (Examples 2 to 9, Comparative Examples 1 to 2)

[0066] Except for changing the ratio of the length of the major diameter portion to the minor diameter portion of the stepped shaft, and thus changing the ratio of the length of the first outer diameter portion, the second outer diameter portion, and the inclined portion, the paper feeding roller was manufactured in the same manner as in Example 1.

[0067] (Examples 10 to 13, Comparative Examples 3 to 4)

[0068] Except for changing the outer diameter of the major and minor diameters of the stepped shaft to alter the height difference between the first and second outer diameters, and changing the surface roughness Rz of the outer circumference of the rubber tube, the paper feeding roller was manufactured in the same manner as in Example 3.

[0069] (Comparative Examples 5 to 6)

[0070] Except for changing the surface roughness Rz of the outer circumference of the rubber tube, the paper feed roller was manufactured in the same manner as in Example 3.

[0071] (Comparative Example 7)

[0072] Except for changing the shaft from a stepped shaft to a non-stepped shaft, the paper feed roller was manufactured in the same manner as in Example 1.

[0073] The durability of the manufactured paper feed rollers was evaluated.

[0074] (Durability Evaluation)

[0075] The paper feed rollers were installed in a commercially available copier with an FRR (Free-Rate Response) paper feeding system to evaluate paper feeding performance. Commercially available PPC paper was used, and 600,000 sheets (600k sheets) were fed to determine the number of paper jams. Cases with fewer than one paper jam were categorized as "A", two to five as "B", six to ten as "C", and the durability test was terminated when the number of paper jams exceeded eleven. Cases where the number of sheets fed at this point was between 400,000 and 600,000 sheets (600k sheets) were categorized as "D", and cases where the number of sheets fed was less than 400,000 sheets (400k sheets) were categorized as "E".

[0076]

[0077] Table 2

[0078]

[0079] Comparative Example 7 uses a stepless shaft as its shaft body. In the portion containing the elastomer layer, it lacks a first outer diameter portion one size smaller and a second outer diameter portion larger than the first outer diameter portion, and it also lacks a height difference. Therefore, it cannot suppress the decrease in the coefficient of friction, and its durability evaluation is E. In contrast, the shafts in Examples 1 to 13 are stepped shafts. In the portion containing the elastomer layer, they have a first outer diameter portion one size smaller and a second outer diameter portion larger than the first outer diameter portion, and an inclined portion connecting the first and second outer diameter portions, so that the outer diameter changes in the axial direction. Therefore, they can suppress the decrease in the coefficient of friction, and their durability evaluation is C, B, or A.

[0080] In Comparative Example 1, the proportion of the inclined portion is small, therefore, the decrease in the coefficient of friction cannot be suppressed during the transition from the second outer diameter portion to the first outer diameter portion, resulting in a durability rating of D. Conversely, in Comparative Example 2, the proportion of the inclined portion is large, thus the ratio of the first outer diameter portion to the second outer diameter portion is relatively small, weakening the advantage of the stepped structure of the paper feed roller and failing to suppress the decrease in the coefficient of friction, resulting in a durability rating of D. In contrast, the proportions of the inclined portions in Examples 1 to 9 are appropriate, suppressing the decrease in the coefficient of friction, thus achieving durability ratings of B or A.

[0081] In Comparative Example 3, the difference in outer diameter between the second and first outer diameter portions is small, as is the difference in height. Therefore, the advantage of using a stepped structure for the paper feed roller is weakened, and the decrease in the coefficient of friction cannot be suppressed, resulting in a durability rating of D. Furthermore, the surface roughness Rz in Comparative Example 3 is also smaller, so the decrease in the coefficient of friction cannot be suppressed in this respect either, resulting in a durability rating of D. Moreover, in Comparative Example 4, the difference in outer diameter between the second and first outer diameter portions is large, as is the difference in height. Therefore, it is necessary to increase the surface roughness, and the width of the protrusion also increases. The effect of the uneven surface is reduced, and the decrease in the coefficient of friction cannot be suppressed, resulting in a durability rating of D. In contrast, in Examples 3, 10, and 13, the difference in outer diameter between the second and first outer diameter portions and the difference in height are moderate, and the surface roughness can also be set appropriately. Therefore, the decrease in the coefficient of friction can be suppressed, resulting in durability ratings of C, B, or A.

[0082] In Comparative Example 5, the surface roughness Rz of the elastomer layer is small, and the surface roughness Rz relative to the height difference between the second and first outer diameter portions is also small. Therefore, it cannot suppress the decrease in the coefficient of friction when the contact portion with the paper transfers from the second outer diameter portion to the first outer diameter portion, thus weakening the advantage of setting the paper feed roller as a stepped structure, and the durability evaluation is D. Furthermore, in Comparative Example 6, the surface roughness Rz of the elastomer layer is large, and the width of the protrusion is also large, reducing the effect of surface unevenness and failing to suppress the decrease in the coefficient of friction. Therefore, the advantage of setting the paper feed roller as a stepped structure is weakened, and the durability evaluation is D. In contrast, in Examples 3, 10 to 13, the outer diameter difference and height difference between the second and first outer diameter portions are moderate, and the surface roughness can also be set appropriately, thus suppressing the decrease in the coefficient of friction, and the durability evaluation is C, B, or A.

[0083] The embodiments and examples of the present invention have been described above, but the present invention is not limited to any of the above embodiments and examples, and various changes can be made without departing from the spirit of the present invention.

[0084] Explanation of reference numerals in the attached figures

[0085] 10: Paper feeding roller;

[0086] 10a: First outer diameter portion;

[0087] 10b: Second outer diameter portion;

[0088] 10c: Inclined portion;

[0089] 12: Shaft;

[0090] 12a: Minor diameter section of the shaft;

[0091] 12b: Major diameter section of the shaft;

[0092] 14: Elastomer layer;

[0093] 14a: convex part;

[0094] 30, 40: Paper feeding roller;

[0095] 30a, 40a: First outer diameter section;

[0096] 30b, 40b: Second outer diameter portion;

[0097] 30c, 40c: Inclined section;

[0098] 32, 42: Shaft;

[0099] 34, 44: Elastomer layers;

[0100] 34a, 44d: convex part;

[0101] 341: Inner elastomer layer;

[0102] 342: Outer elastomer layer;

[0103] 44a: Thin-walled portion;

[0104] 44b: Thick-walled section;

[0105] 44c: Inclined section of wall thickness.

Claims

1. A paper feed roller (10, 30, 40) comprising a shaft (12, 32, 42) and an elastomer layer (14, 34, 44) formed on the outer peripheral surface of the shaft (12, 32, 42), characterized in that, The paper feed rollers (10, 30, 40) have a first outer diameter portion (10a, 30a, 40a) with an outer diameter one size smaller than the elastomer layer (14, 34, 44), and a second outer diameter portion (10b, 30b, 40b) with an outer diameter larger than the first outer diameter portion (10a, 30a, 40a). An inclined portion (10c, 30c, 40c) is provided between the first outer diameter portion (10a, 30a, 40a) and the second outer diameter portion (10b, 30b, 40b) to connect the first outer diameter portion (10a, 30a, 40a) and the second outer diameter portion (10b, 30b, 40b), so that the outer diameter changes in the axial direction. The inclined portions (10c, 30c, 40c) constitute 3% to 80% of the portion having the elastomer layers (14, 34, 44). The difference in outer diameter between the first outer diameter portion (10a, 30a, 40a) and the second outer diameter portion (10b, 30b, 40b) is 50 μm or more and 1000 μm or less. Multiple protrusions (14a, 34a, 44a) forming surface irregularities are formed on the outer peripheral surface of the elastomer layers (14, 34, 44). The surface roughness Rz in the first outer diameter portion (10a, 30a, 40a) is more than 50% and less than 200% of the height difference between the first outer diameter portion (10a, 30a, 40a) and the second outer diameter portion (10b, 30b, 40b).

2. The paper feeding rollers (10, 30, 40) according to claim 1, characterized in that, The extending protruding direction of the protrusions (14a, 34a, 44a) formed by the elastomeric layers (14, 34, 44) in the inclined portions (10c, 30c, 40c) is located in a direction different from the extending protruding direction of the protrusions (14a, 34a, 44a) formed by the elastomeric layers (14, 34, 44) in the first outer diameter portions (10a, 30a, 40a) and the extending protruding direction of the protrusions (14a, 34a, 44a) formed by the elastomeric layers (14, 34, 44) in the second outer diameter portions (10b, 30b, 40b).

3. The paper feed roller (10, 30, 40) according to claim 1 or 2, characterized in that, The inclined portion (10c, 30c, 40c) accounts for more than 10% and less than 50% of the portion having the elastomer layer (14, 34, 44).

4. The paper feed roller (10, 30, 40) according to any one of claims 1 to 3, characterized in that, The second outer diameter portion (10b, 30b, 40b) is located in the region including the center of the axial direction.

5. The paper feed roller (10, 30, 40) according to any one of claims 1 to 4, characterized in that, The surface roughness Rz of the first outer diameter portion (10a, 30a, 40a), the second outer diameter portion (10b, 30b, 40b), and the inclined portion (10c, 30c, 40c) is 25 μm or more and 500 μm or less.

6. The paper feed roller (10) according to any one of claims 1 to 5, characterized in that, The shaft (12) has a portion with a larger outer diameter at the second outer diameter portion (10b), and the first outer diameter portion (10a), the second outer diameter portion (10b), and the inclined portion (10c) are formed due to the shape of the shaft (12).

7. A method for manufacturing paper feed rollers (10, 30, 40), which is the method for manufacturing paper feed rollers (10, 30, 40) as described in claim 6, characterized in that, It is formed by inserting the shaft (12, 32, 42) into the tubular elastomer layer (14, 34, 44).

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