Paper feed roll

Abstract

To provide a paper feed roll in which determination of roll life is facilitated.SOLUTION: A paper feed roll 10 comprises an axial body 12, and an elastic body layer 14 formed on an outer peripheral face of the axial body 12. The elastic body layer 14 has an outer diameter of 10 mm or more and 50 mm or less. The outer peripheral face of the elastic body layer 14 is formed in a circumferential direction with 1 more to 8 or less grooves 16 extending in an axial direction. The grooves 16 are grooves each having a fixed groove width W along a depth direction, or having the groove width W that gradually becomes smaller along the depth direction. The grooves 16 each have a groove width W of 0.2 mm or more and 1.0 mm or less. The grooves 16 each have a groove depth D of 0.2 mm or more and 1.0 mm or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a paper feed roll that is suitably used in electrophotographic devices such as copying machines, printers, and facsimiles that employ an electrophotographic system. [Background technology]

[0002] The paper feed roll is formed into a roll shape from an elastic material such as rubber. The paper is transported by the frictional force generated between the outer circumferential surface of this paper feed roll and the paper. When a large amount of paper is transported by the paper feed roll, paper transport problems are more likely to occur. When paper transport problems become frequent, the user contacts a service technician. The service technician then determines the lifespan (replacement time) of the paper feed roll. In reality, it is difficult for the user to determine the lifespan (replacement time) of the paper feed roll.

[0003] In response to this situation, for example, Patent Document 1 proposes a paper feed roll in which grooves are provided on the roll surface and the time when the grooves disappear due to wear on the roll surface is used as an indicator of the roll's lifespan. This allows users to determine when the roll needs to be replaced when the grooves on the roll surface disappear. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 07-172614 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the lifespan of a roll (time to replace it) cannot be determined solely by the amount of wear on the roll surface. For example, if the coefficient of friction on the roll surface decreases due to the accumulation of paper dust generated by the paper on the roll surface, paper transport problems may occur even if the roll surface is only slightly worn.

[0006] The problem to be solved by the present invention is to provide a paper feed roll that makes it easy to determine the end of the roll's life. [Means for solving the problem]

[0007] As a result of extensive research, the inventors have discovered that the amount of wear on a roll is not necessarily related to the roll's lifespan, that the amount of paper dust adhering to the roll surface is more likely to indicate a relationship with the roll's lifespan than the amount of wear on the roll, and that by providing grooves of a specific shape on the roll surface, the roll's lifespan can be determined from the relationship between the grooves of that specific shape and the amount of paper dust that accumulates in those grooves, and have completed the present invention.

[0008] In other words, the paper feed roll of the present invention comprises a shaft body and an elastic layer formed on the outer peripheral surface of the shaft body, the outer diameter of the elastic layer being 10 mm or more and 50 mm or less, and the outer peripheral surface of the elastic layer having grooves extending in the axial direction formed circumferentially in a number of 1 to 8, the grooves having a constant groove width along the depth direction, or grooves having a groove width that gradually decreases along the depth direction, the groove width of the grooves being 0.2 mm or more and 1.0 mm or less, and the groove depth of the grooves being 0.2 mm or more and 1.0 mm or less.

[0009] It is particularly preferable that the grooves have a groove width that gradually decreases along the depth direction. The number of grooves in the circumferential direction is preferably 2 to 6. The surface roughness Sp, which is expressed as the maximum value of the height of the bottom surface of the groove from the average plane, is preferably 20 μm to 150 μm. [Effects of the Invention]

[0010] According to the paper feed roll of the present invention, it comprises a shaft body and an elastic layer formed on the outer peripheral surface of the shaft body, the outer diameter of the elastic layer being 10 mm or more and 50 mm or less, and the outer peripheral surface of the elastic layer has grooves extending in the axial direction formed circumferentially in a number of 1 to 8 grooves, the grooves having a constant groove width along the depth direction, or grooves having a groove width that gradually decreases along the depth direction, the groove width of the grooves being 0.2 mm or more and 1.0 mm or less, and the groove depth of the grooves being 0.2 mm or more and 1.0 mm or less, and the life of the roll can be determined from the relationship with the amount of paper dust accumulated in the grooves, making it easy to determine the life of the roll.

[0011] If the groove has a groove width that gradually decreases along the depth direction, it is a shape that makes it easy for paper dust to accumulate, and also makes it easy to visually see that paper dust has accumulated, making it particularly easy to determine the lifespan of the roll in relation to the amount of paper dust accumulated in the groove.

[0012] When the number of grooves in the circumferential direction is between 2 and 6, it becomes particularly easy to determine the life of the roll in relation to the amount of paper dust accumulated in the grooves.

[0013] Furthermore, when the surface roughness Sp, which is expressed as the maximum height of the bottom surface of the groove from the mean plane, is 20 μm or more and 150 μm or less, the grooves are highly effective in retaining paper dust, making it difficult for the paper dust to move from the grooves to other parts of the roll surface. This prevents the paper dust from decreasing the coefficient of friction of the roll surface, improving the accuracy of determining the end of the roll life due to the accumulation of paper dust in the grooves. [Brief explanation of the drawings]

[0014] [Figure 1] 1A is a schematic view of the appearance of a paper feed roll according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA thereof. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the outer peripheral surface side of the elastic layer of the paper feed roll. DETAILED DESCRIPTION OF THE INVENTION

[0015] The paper feed roll according to the present invention will be described in detail. Fig. 1 is a schematic diagram of the appearance of the paper feed roll according to one embodiment of the present invention (a) and a cross-sectional view taken along line AA (b). Fig. 2 is an enlarged cross-sectional view of the outer peripheral surface side of the elastic layer of the paper feed roll.

[0016] The paper feed roll 10 according to one embodiment of the present invention includes a shaft 12 and an elastic layer 14 formed on the outer peripheral surface of the shaft 12. The elastic layer 14 is a layer (base layer) that serves as the base of the paper feed roll 10. The elastic layer 14 is a layer that appears on the surface of the paper feed roll 10.

[0017] The shaft 12 may be a solid body or a hollow body (cylinder) made of metal or resin. Examples of metal materials include iron, stainless steel, and aluminum. The elastic layer 14 may be adhered to the shaft 12 via an adhesive layer (primer layer). The adhesive, primer, etc. may be made conductive as necessary.

[0018] The elastic layer 14 is made of an elastic material and formed in a roll shape on the outer circumferential surface of the shaft 12. The outer circumferential surface of the elastic layer 14 has axially extending grooves 16 formed therein in a number ranging from one to eight. The grooves 16 have a specific shape, and the roll's lifespan can be determined based on the amount of paper dust accumulated in the grooves 16. The grooves 16 may be formed continuously from end to end in the axial direction on the outer circumferential surface of the elastic layer 14, or may be formed only partially in the axial direction. The paper dust referred to here refers to dust, debris, fibers, etc. discharged from paper, including calcium carbonate and kaolin, which are incorporated into paper. Paper dust is particularly likely to occur with paper produced overseas. Calcium carbonate and kaolin are irregular in shape and have particle diameters of approximately 1 to 3 μm.

[0019] FIG. 2 shows an example of the shape of the groove 16. FIG. 2 shows a portion of the outer peripheral surface of a radial cross section of the elastic layer 14. The groove 16 in FIG. 2(a) has a U-shaped cross section and a constant groove width W along the depth direction. The groove 16 in FIG. 2(b) has a U-shaped cross section and a constant groove width W along the depth direction. The groove 16 in FIG. 2(b) has rounded corners at the bottom. The groove 16 in FIG. 2(c) has a V-shaped cross section and a groove width W that gradually decreases along the depth direction. The bottom surface of the groove 16 is flat. The groove 16 in FIG. 2(c) may have rounded corners at the bottom, as in the groove 16 in FIG. 2(b).

[0020] As shown in Figure 2, the grooves 16 formed in the outer peripheral surface of the elastic layer 14 are grooves with a constant groove width W along the depth direction, or grooves with a groove width W that gradually decreases along the depth direction, making it easy for paper dust to accumulate and easy to visually see that paper dust has accumulated. This makes it easy to determine the lifespan of the roll in relation to the amount of paper dust accumulated in the grooves 16. In particular, when the grooves 16 formed in the outer peripheral surface of the elastic layer 14 have a groove width that gradually decreases along the depth direction, it is easy to determine the lifespan of the roll in relation to the amount of paper dust accumulated in the grooves 16, based on the ease with which paper dust accumulates and the ease of visually seeing the amount of paper dust.

[0021] The groove width W of the groove 16 is 0.2 mm or more and 1.0 mm or less, and the groove depth D of the groove 16 is 0.2 mm or more and 1.0 mm or less. If either the groove width W or the groove depth D is less than 0.2 mm, the capacity of the groove 16 for collecting paper dust is too small, so that the groove fills with paper dust before paper transport problems occur, and the roll life cannot be determined based on the amount of paper dust accumulated in the groove 16. If either the groove width W or the groove depth D is more than 1.0 mm, the capacity of the groove 16 for collecting paper dust is too large, making it difficult to visually determine whether there is enough paper dust accumulated in the groove 16 even when frequent paper transport problems occur, and the roll life cannot be determined based on the amount of paper dust accumulated in the groove 16. If both the groove width W and the groove depth D are 0.2 mm or more and 1.0 mm or less, the roll life can be determined based on the amount of paper dust accumulated in the groove 16.

[0022] The groove width W of the groove 16 is more preferably 0.3 mm or more, and even more preferably 0.4 mm or more. Also, it is more preferably 0.9 mm or less, and even more preferably 0.8 mm or less. The groove depth D of the groove 16 is more preferably 0.3 mm or more, and even more preferably 0.4 mm or more. Also, it is more preferably 0.9 mm or less, and even more preferably 0.8 mm or less.

[0023] The grooves 16 are formed in a number between 1 and 8 in the circumferential direction. If the number of grooves 16 exceeds 8, the grooves 16 have a significant effect on the paper transportability, resulting in a deterioration of transportability. In particular, if the outer diameter φ of the elastic layer 14 is small, the roll may bounce and flutter (band) when rotating, making it impossible to transport paper. Furthermore, from the viewpoint of making it particularly easy to determine the lifespan of the roll in relation to the amount of paper dust accumulated in the grooves 16, it is preferable that the number of grooves 16 be between 2 and 6 in the circumferential direction. If multiple grooves 16 are formed in the circumferential direction, it is preferable that the grooves 16 be formed at equal intervals and at equal positions in the circumferential direction.

[0024] The bottom surface of the groove 16 preferably has a moderate roughness, such as by forming convex protrusions on the radially outward side or by forming minute concave recesses on the radially inward side. This effectively retains paper dust in the groove 16, making it difficult for the paper dust to move from the groove 16 to other parts of the roll surface. This prevents the paper dust from decreasing the friction coefficient of the roll surface, thereby improving the accuracy of determining the end of the roll's life due to the accumulation of paper dust in the groove 16. The roughness of the bottom surface of the groove 16 can be expressed as a surface roughness Sp, which is the maximum height of the bottom surface of the groove 16 from the average plane. The surface roughness Sp of the bottom surface of the groove 16 is preferably 20 μm or more and 150 μm or less. The surface roughness Sp of the bottom surface of the groove 16 is more preferably 30 μm or more, and even more preferably 50 μm or more. The surface roughness Sp of the bottom surface of the groove 16 is more preferably 120 μm or less, and even more preferably 100 μm or less.

[0025] The outer diameter φ of the elastic layer 14 is 10 mm or more and 50 mm or less. If the outer diameter of the elastic layer 14 is less than 10 mm, the nip with the paper is small and the amount of paper dust generated is small, resulting in less paper dust entering the grooves 16. Even when paper transport failures frequently occur, it is difficult to visually determine whether sufficient paper dust has accumulated in the grooves 16, making it impossible to determine the roll's lifespan in relation to the amount of paper dust accumulated in the grooves 16. If the outer diameter of the elastic layer 14 is greater than 50 mm, the nip with the paper is large and the amount of paper dust generated is large, resulting in a large amount of paper dust entering the grooves 16. The grooves are filled with paper dust before paper transport failures occur, making it impossible to determine the roll's lifespan in relation to the amount of paper dust accumulated in the grooves 16. The outer diameter of the elastic layer 14 is more preferably 15 mm or more, and even more preferably 20 mm or more. The outer diameter of the elastic layer 14 is more preferably 45 mm or less, and even more preferably 40 mm or less.

[0026] From the viewpoint of the nip with the paper, the elastic layer 14 preferably has a JIS-A hardness of 25 degrees or more and 85 degrees or less, more preferably 30 degrees or more and 80 degrees or less.

[0027] The elastic layer 14 is made of an elastic material such as rubber, elastomer, or resin. The material is not particularly limited as long as it is a rubber-like elastic material. For example, known materials such as urethane rubber, hydrin rubber, silicone rubber, and EPDM can be used.

[0028] If necessary, various additives may be added appropriately to the elastic layer 14. Examples of additives include lubricants, vulcanization accelerators, antioxidants, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, antifoaming agents, pigments, and mold release agents.

[0029] The thickness of the elastic layer 14 is not particularly limited and may be set appropriately within the range of 2 to 25 mm.

[0030] The elastic layer 14 can be formed by molding using a mold. For example, a core material is coaxially placed in the hollow portion of a roll molding mold, an uncrosslinked rubber composition is injected, and the composition is heated and cured (crosslinked), followed by demolding to form a tubular elastic layer 14. A molding mold having convex portions formed on its inner circumferential surface in a shape corresponding to the grooves 16 can be used. The grooves 16 in the elastic layer 14 can be formed, for example, by mold transfer using a molding mold. The concave and convex portions on the inner circumferential surface of the molding mold can be formed by various concave and convex forming methods such as electric discharge machining, etching, shot blasting, and polishing. The paper feed roll 10 can be formed by inserting a shaft 12 into a cylindrically formed elastic layer 14.

[0031] In the paper feed roll 10 configured as described above, the grooves 16 formed in the outer peripheral surface of the elastic layer 14 extend in the axial direction and have a constant groove width W along the depth direction, or have a groove width W that gradually decreases along the depth direction. This makes it easy for paper dust to accumulate and makes it easy to visually detect the accumulation of paper dust. Furthermore, because the groove width W of the grooves 16 is between 0.2 mm and 1.0 mm and the groove depth D of the grooves 16 is between 0.2 mm and 1.0 mm, the capacity of the grooves 16 to accumulate paper dust is appropriate, and the roll life can be determined based on the amount of paper dust accumulated in the grooves 16. Furthermore, because the grooves 16 are formed in a number between 1 and 8 along the circumferential direction of the outer peripheral surface of the elastic layer 14, the grooves 16 have little effect on paper transportability and do not impair transportability. Furthermore, by setting the outer diameter of the elastic layer 14 to 10 mm or more and 50 mm or less, the nip with the paper becomes appropriate, and the amount of paper dust that enters the grooves 16 becomes appropriate, so that the life of the roll can be determined in relation to the amount of paper dust that accumulates in the grooves 16. As described above, the life of the roll can be determined in relation to the amount of paper dust that accumulates in the grooves 16, making it easy to determine the life of the roll.

[0032] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention. [Example]

[0033] The present invention will be described in detail below using examples and comparative examples.

[0034] Using a cylindrical molding die having axially extending ridges on the inner peripheral surface, an elastic layer of a urethane rubber composition was formed on the outer periphery of a core material (φ6, made of SUS304). This resulted in a paper feed roll having a predetermined groove on the outer peripheral surface of the elastic layer. The shape of the groove was as follows: Figure 2(c)As shown in Figure 1, the groove width gradually decreases along the depth direction. In the table, φ is the outer diameter of the elastic layer, n is the number of grooves, W is the groove width, and D is the groove depth. The groove width W and groove depth D were measured by observing the radial cross section of the elastic layer of the fabricated paper feed roll.

[0035] Using the fabricated paper feed roll, printing was repeated until a paper feed failure occurred. When a paper feed failure occurred, the radial cross section of the elastic layer of the paper feed roll was observed and the amount of paper dust accumulated in the grooves was measured. In the table, the numbers 10 to 90 represent the amount of paper dust in the groove volume (filling rate). A filling rate of over 100% before a paper feed failure occurred was evaluated as "-". Furthermore, a filling rate of 50% or more but less than 100% at the point where a paper feed failure occurred was evaluated as good (◯), a filling rate of over 20% but less than 50% was evaluated as poor (△), and a filling rate of 20% or less was evaluated as poor (×). The experimental results are shown in Tables 1 to 8 below.

[0036] [Table 1]

[0037] [Table 2]

[0038] [Table 3]

[0039] [Table 4]

[0040] [Table 5]

[0041] [Table 6]

[0042] [Table 7]

[0043] [Table 8]

[0044] From Tables 2, 3, 6 and 7, we can see that when n=1 to 8, in the range of φ10 mm or more and φ50 mm or less, the groove width W is 0.2 mm or more and 1.0 mm or less, and the groove depth D is 0.2 mm or more and 1.0 mm or less, the filling rate of paper dust in the groove when a paper feed failure occurs is 50% or more and 100% or less, and when a paper feed failure occurs, the accumulation of paper dust can be clearly confirmed visually, and it can be seen that the lifespan of the roll can be judged from the amount of paper dust accumulated in the groove.

[0045] As shown in Table 1, with a diameter of 5 mm, the nip with the paper is small, so even when the groove width W or groove depth D is changed, the amount of paper dust that gets into the groove is small. When paper feed problems occur, the filling rate of the groove with paper dust is less than 50%, so it is difficult to visually determine whether there is enough paper dust accumulated in the groove. Therefore, it was not possible to determine the roll life in relation to the amount of paper dust accumulated in the groove. Furthermore, as shown in Table 4, with a diameter of 60 mm, the nip with the paper is large, so even when the groove width W or groove depth D is changed, the amount of paper dust that gets into the groove is large. The groove fills up with paper dust before paper feed problems occur. Therefore, it was not possible to determine the roll life in relation to the amount of paper dust accumulated in the groove.

[0046] From Table 5, when n=9 and φ5mm, the roll bounced and flapped when feeding paper, making it impossible to feed paper (NG). Also, from Table 8, when n=9 and φ60mm, the nip with the paper was large, so even if the groove width W and groove depth D were changed in various ways, the amount of paper dust that entered the groove increased, and the groove filled with paper dust before paper feeding problems occurred, making it impossible to determine the roll life in relation to the amount of paper dust accumulated in the groove.

[0047] Furthermore, from Tables 2, 3, 6 and 7, it can be seen that even if n=1 to 8 and φ10 mm or greater and φ50 mm or less, if the groove width W is outside the range of 0.2 mm or greater and 1.0 mm or less and the groove depth D is outside the range of 0.2 mm or greater and 1.0 mm or less, the filling rate will exceed 100% before a paper feed failure occurs, or the filling rate of paper dust in the grooves will be less than 50% when a paper feed failure occurs, and the life of the roll cannot be determined in relation to the amount of paper dust accumulated in the grooves.

[0048] Although the above example shows the implementation using the groove shape shown in FIG. 2(d), similar results were obtained with the groove shapes shown in FIGS. 2(a) and 2(b).

[0049] 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 are possible within the scope of the invention. [Explanation of symbols]

[0050] 10 Paper feed roll 12 shaft body 14 Elastic layer 16 groove W groove width D Groove depth

Claims

1. a shaft body; and an elastic layer formed on an outer peripheral surface of the shaft body, The outer diameter of the elastic layer is 10 mm or more and 50 mm or less, The elastic layer has an outer peripheral surface on which grooves extending in an axial direction are formed, the number of which is 1 to 8 in the circumferential direction, The groove has a V-shaped cross section, a flat bottom surface, and a groove width that gradually decreases along a depth direction, The groove width on the roll surface is 0.2 mm or more and 1.0 mm or less, A paper feed roll, wherein the groove has a depth of 0.2 mm or more and 1.0 mm or less.

2. The paper feed roll according to claim 1 , wherein the number of grooves in the circumferential direction is 2 or more and 6 or less.

3. 3. The paper feed roll according to claim 1, wherein a surface roughness Sp, expressed as a maximum value of the height of the bottom surface of the groove from the average plane, is 20 μm or more and 150 μm or less.

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