JP5662748B2 - Paper feed roller - Google Patents

Description

  The present invention relates to a paper feed roller, and more particularly to a paper feed roller suitable as a pick-up roller, a feed roller, a retard roller, a transport roller, and the like used in devices such as a copying machine, a printer, and a facsimile machine.

  A paper feed roller used in a copying machine or the like generally has a shaft body and an elastic layer formed on the outer periphery of the shaft body. This type of paper feed roller is required to maintain a coefficient of friction over a long period of time. For example, when using so-called bad paper containing a large amount of calcium carbonate or the like in a copying machine, the paper component (paper dust) accumulates on the surface of the paper feed roller, thereby reducing the coefficient of friction and paper feed failure. There was a problem that (non-feed, double feed, etc) occurred.

  In order to prevent this problem, conventionally, the surface of the elastic layer has been subjected to graining to form fine irregularities, or a plurality of concave grooves extending in the roller axis direction are formed, and paper is applied to the fine concave or concave grooves. A paper feed roller has been proposed in which powder is induced and deposited (see, for example, Patent Document 1).

  Although it is not a technology related to paper feeding rollers used in devices such as copying machines, printers, facsimiles, etc., Patent Document 2 describes the occurrence of meandering and wrinkling of continuous strips such as aluminum foil and synthetic resin films. A roller that can feed while preventing is disclosed. In this roller, grooves are formed at predetermined intervals along the circumferential direction of the core body part, and an outer layer part having a polygonal outer peripheral surface corresponding to the groove part is elastically deformed outside the core body part. Is formed.

Patent No. 4042806 JP-A-6-271163

  However, the conventionally known paper feed rollers have the following problems. In other words, when forming fine irregularities on the surface of the elastic layer by embossing, there is a limit to the size of the fine irregularities due to problems such as a processing method of a roller molding die and demoldability at the time of molding. In order to overcome this limitation, a method of forming a plurality of concave grooves on the surface of the elastic layer is effective.

  However, from the viewpoint of demolding at the time of molding, the present situation is that the groove direction must be arranged parallel to the roller axis direction. In this case, since the groove direction is perpendicular to the sheet passing direction, there is a problem that the paper is dammed by the groove when the paper passes, and a paper feeding problem is likely to occur.

  As described above, in the conventional paper feeding roller, it has been difficult to achieve both reduction in paper feeding performance due to adhesion of paper dust and suppression of paper feeding problems.

  The present invention has been made in view of the above circumstances, and the problem to be solved by the present invention is that it is possible to achieve both reduction in paper feed performance due to adhesion of paper dust and suppression of paper feed faults. It is to provide a paper feeding roller.

  In order to solve the above problems, a paper feeding roller according to the present invention is a paper feeding roller having a shaft body and an elastic layer formed on an outer periphery of the shaft body, and is provided on a peripheral surface of the elastic layer. The gist is that the elastic layer side surface irregularities having no corners are formed along the roller axial direction.

  Here, the shaft body side surface unevenness is formed on the peripheral surface of the shaft body along the roller axial direction, and the elastic layer side surface unevenness is formed corresponding to the shaft body side surface unevenness. preferable.

  Moreover, it is preferable that the convex part which comprises the said shaft-body-side surface unevenness | corrugation does not have a corner | angular.

  In addition, the radius of the circumscribed circle that circumscribes the convex portion constituting the elastic layer side surface irregularities with the roller axis as the center is r1, and the inscribed inscribed in the concave portion that constitutes the elastic layer side surface irregularities with the roller axis as the center. When the radius of the circle is r2, it is preferable that the value of r1-r2 is in the range of 0.05 to 0.45 mm.

  Moreover, it is preferable that the thickness of the said elastic layer exists in the range of 1.60 times-13.33 times the height of the convex part which comprises a part of said shaft body side surface unevenness | corrugation.

  Further, the surface of the elastic layer is preferably subjected to a textured process.

  The paper feed roller according to the present invention has a shaft body and an elastic layer formed on the outer periphery of the shaft body, and the peripheral surface of the elastic layer has no corners along the roller axial direction. Elastic layer side surface irregularities are formed.

  For this reason, even if paper dust adheres to the peripheral surface of the elastic layer, the paper dust is guided to the concave portion of the surface irregularities on the elastic layer side and is deposited on that portion. Therefore, it is possible to suppress a decrease in paper feeding performance due to adhesion of paper powder. Further, since the surface irregularities on the elastic layer side have no corners, the irregular shape on the surface becomes gentle, and paper catching can be prevented. Therefore, it is possible to suppress a paper feeding problem.

  Therefore, when the paper feed roller according to the present invention is applied to a pickup roller, a feed roller, a retard roller, a transport roller, etc., paper feed performance can be maintained over a long period of time while reducing paper feed problems. In particular, when the paper feed roller according to the present invention is applied to a retard roller that easily causes a paper feed failure, the effect of the present invention is enhanced.

  Here, the shaft body side surface irregularities are formed along the roller axis direction on the peripheral surface of the shaft body, and the elastic layer side surface irregularities are formed by elastic deformation of the elastic layer corresponding to the shaft body side surface irregularities. If it is formed, it becomes easy to obtain a gentle and uniform surface irregularity on the elastic layer side. Therefore, it is advantageous to achieve both the suppression of the decrease in paper feeding performance due to the adhesion of paper dust and the suppression of paper feeding defects. Moreover, since the surface irregularities can be easily formed on the surface of the elastic layer by press-fitting an elastic layer having no surface irregularities into the shaft body, it is possible to contribute to productivity and cost reduction.

  At this time, if the projections constituting the shaft-side surface irregularities are not cornered, it becomes easier to obtain gentle and uniform elastic layer-side surface irregularities, and the paper feed performance is prevented from being lowered due to the adhesion of paper dust. This is advantageous for achieving both feeding failure suppression.

  In addition, when the value of r1-r2 is in the range of 0.05 to 0.45 mm, the paper powder adhering to the surface of the elastic layer is easily induced and deposited in the concave portions of the surface irregularities on the elastic layer side. Since it is difficult to inhibit paper, it is excellent in balance between suppression of paper feed performance reduction due to adhesion of paper dust and suppression of paper feed failure.

  Further, when the thickness of the elastic layer is in the range of 1.60 times to 13.33 times the height of the convex portion constituting a part of the surface unevenness on the shaft body side, the peripheral surface of the shaft body When the shaft body side surface irregularities are formed along the roller axis direction, the elastic layer side surface irregularities corresponding to the shaft body side surface irregularities are easily formed on the elastic layer surface.

  In addition, when the surface of the elastic layer is subjected to a graining process, paper dust accumulates in the concaves and convexes of the fine irregularities caused by the graining process, so that the effect of suppressing a decrease in paper feeding performance due to the adhesion of the paper powder is increased.

It is a front view of the paper feed roller according to the present embodiment. It is AA sectional drawing of the paper feed roller which concerns on this embodiment shown in FIG. It is a front view of the other paper feed roller according to the present embodiment. FIG. 4 is a cross-sectional view of the paper feeding roller according to the present embodiment shown in FIG. 3 taken along the line BB. FIG. 6 is a diagram illustrating a cross-sectional shape of an elastic layer of a paper feeding roller according to a third embodiment. It is a figure which shows the cross-sectional shape of the elastic layer of the paper feed roller which concerns on the comparative example 1. FIG.

  Hereinafter, the paper feed roller according to the present embodiment will be described.

  FIG. 1 is a front view of a paper feed roller according to the present embodiment. FIG. 2 is a cross-sectional view of the paper feed roller according to the present embodiment shown in FIG. FIG. 3 is a front view of another paper feeding roller according to the present embodiment. FIG. 4 is a cross-sectional view taken along the line B-B of another paper feeding roller according to the present embodiment shown in FIG. 3. As shown in these drawings, the paper feed roller 10 includes a shaft body 12 and an elastic layer 14 formed along the outer peripheral surface of the shaft body 12.

  Examples of the material of the shaft body 12 include polyacetal (POM), acrylonitrile butadiene styrene copolymer (ABS), synthetic resin such as polycarbonate and nylon, or metal material such as iron, stainless steel, and aluminum. . The shaft body 12 may be either conductive or non-conductive, but preferably has conductivity. This is because static electricity generated on the roller surface during energization can be easily removed, and there is an advantage in suppressing the accumulation of paper dust.

  The shaft body 12 may be formed in a hollow shape as shown in FIGS. 2 and 4 or may be a solid body. Preferably, it is hollow from the viewpoints of weight reduction, rotation, and the like. The dimension of the shaft body 12 is usually set within the range of the outer diameter of 7 to 30 mm and the thickness of 0.5 to 3.0 mm (in the case of a hollow shape) from the viewpoint of making it suitable as a paper feed roller. Good.

  Moreover, as a material of the elastic layer 14, a urethane type polymer, ethylene-propylene-diene rubber (EPDM), norbornene rubber (NOR) etc. can be illustrated, for example. In particular, urethane-based polymers are preferable from the viewpoints of obtaining a suitable hardness for improving the paper feeding function and durability, and being excellent in reliability and durability. The elastic layer 14 may be made of two or more materials.

  The dimension of the elastic layer 14 is preferably set within a range of an axial length of 5 to 60 mm and an outer diameter of 10 to 40 mm from the viewpoint of making it suitable as a paper feed roller. Further, the hardness of the elastic layer 14 is preferably set in the range of JIS-A hardness 30 to 90 degrees, more preferably JIS-A hardness 40 to 40, from the viewpoint of excellent paper feeding function and durability. It should be within a range of 75 degrees.

  Here, in the paper feeding roller 10, the elastic layer 14 has the elastic layer side surface irregularities 16 formed on the circumferential surface thereof. The elastic layer-side surface irregularities 16 are composed of concave portions 16a and convex portions 16b. The elastic layer side surface irregularities 16 are formed along the roller axial direction. That is, the groove portion of the recess 16a extends along the roller axis direction, and paper dust is induced and accumulated in this groove portion. On the other hand, the protruding portion of the convex portion 16b also extends along the roller axis direction in the same manner.

  Here, the elastic layer-side surface irregularities 16 are in a state having no corners. Since the elastic layer-side surface irregularities 16 are formed along the roller axis direction, if there are corners, the paper will be caught, but if there are no corners, the surface irregularities on the elastic layer 14 will be loose, It becomes possible to prevent catching.

  The number of the concave portions 16a and the convex portions 16b in the elastic layer-side surface irregularities 16 is not particularly limited. FIG. 2 schematically shows an example in which eight concave portions 16a and eight convex portions 16b are formed. FIG. 4 schematically shows an example in which six concave portions 16a and six convex portions 16b are formed. In addition, the concave portions 16a may be formed at four locations and ten locations, and the convex portions 16b may be formed at four locations and ten locations. The number of the concave portions 16a and the convex portions 16b is preferably such that the concave portions 16a and 16b are formed as shown in FIG. 8 and 8 convex portions 16b are alternately formed. Alternatively, as shown in FIG. 4, 6 concave portions 16a and 6 convex portions 16b are alternately formed. .

  2 and 4, the recesses 16a and the protrusions 16b in the elastic layer-side surface unevenness 16 are each separated by a predetermined distance (in FIG. 2, a line connecting the center of the roller shaft and the bottom of the adjacent recess 16a. The angle formed by the line connecting the center of the roller shaft and the apex of the adjacent convex portion 16b is 45 °. In FIG. 4, the line connecting the center of the roller shaft and the bottom of the adjacent concave portion 16a The angle formed is 60 °, and the angle formed by the line connecting the center of the roller shaft and the apex of the adjacent convex portion 16b is 60 °). The distance between the convex portions 16b does not necessarily need to be completely matched.

  As shown in FIGS. 2 and 4, the elastic layer 14 is elastic with the roller axis as the center, the radius of the circumscribed circle circumscribing the convex portion 16b constituting the elastic layer side surface unevenness 16 as r1, and the roller axis as the center. When the radius of the inscribed circle inscribed in the concave portion 16a constituting the layer-side surface unevenness 16 is defined as r2, the value of r1-r2 is preferably in the range of 0.05 to 0.45 mm. Paper dust attached to the surface of the elastic layer 14 is easily deposited and deposited in the recess 16a, and it is difficult to inhibit paper passing. Therefore, it is excellent in balance between suppression of paper feeding performance reduction due to adhesion of paper dust and suppression of paper feeding failure. Because. The value of r1-r2 is more preferably in the range of 0.10 to 0.40 mm, and still more preferably in the range of 0.12 to 0.25 mm.

  In addition, the surface of the elastic layer 14 is preferably subjected to graining. This is because paper dust accumulates also in the concave and convex portions (not shown) of the fine irregularities due to the texture processing, and thus the effect of suppressing the decrease in paper feeding performance due to the adhesion of the paper dust is increased.

  The elastic layer-side surface irregularities 16 described above can be formed by polishing the elastic layer 14 or by mold transfer or the like. In addition, since the surface uneven | corrugated shape of the elastic layer side surface unevenness | corrugation 16 is loose, there is no particular concern about the problem of demoldability at the time of molding.

  The elastic layer side surface irregularities 16 are preferably formed by elastic deformation of the elastic layer 14 due to the shaft body side surface irregularities 18 formed in the shaft body 12. This is because the elastic layer-side surface irregularities 16 can be easily formed corresponding to the shaft-body-side surface irregularities 18 by press-fitting an elastic layer having no surface irregularities into the shaft body 12. This will be described below.

  The shaft body 12 shown in FIGS. 2 and 4 has a shaft body-side surface irregularity 18 formed on the circumferential surface thereof. The shaft-body-side surface unevenness 18 is composed of a concave portion 18a and a convex portion 18b. The shaft body side surface irregularities 18 are formed along the roller axial direction. That is, the groove portion of the recess 18a extends along the roller axis direction. On the other hand, the protruding portion of the protrusion 18b extends in the same manner along the roller axis direction. Here, protrusions 18b are formed on the surface of the main body 12a of the shaft body 12 by forming protrusions along the roller axis direction, and a recess 18a is formed between the protrusions 18b. Yes. The shaft-body-side surface irregularities 18 are preferably formed to be the same as or longer than the axial length of the elastic layer 14. This is because the uniform elastic layer side surface irregularities 16 can be easily obtained.

  Of the shaft body-side surface irregularities 18, the convex portions 18b preferably have no corners. This is because it becomes easier to obtain the gentle and uniform elastic layer-side surface irregularities 16 and is advantageous in achieving both the suppression of the paper feeding performance deterioration due to the adhesion of paper dust and the suppression of paper feeding defects. Specifically, the shape of the convex portion 18b is preferably a semicircular cross section (including an elliptical shape). Although not shown, the convex portion 18b of the shaft-body-side surface unevenness 18 may have a substantially semi-hexagonal cross-section, a substantially semi-octagonal cross-sectional shape, or the like as long as the elastic layer-side surface unevenness 16 is within a range where no corners can be formed.

  The number of the concave portions 18a and the convex portions 18b in the shaft body side surface irregularities 18 is not particularly limited. FIG. 2 schematically shows an example in which eight concave portions 18a and eight convex portions 18b are formed. FIG. 4 schematically shows an example in which six concave portions 18a and six convex portions 18b are formed. In addition, the concave portions 18a may be formed at four places, ten places, the convex portions 18b may be formed at four places, ten places, and the like. The number of the concave portions 18a and the convex portions 18b is preferably such that the concave portions 18a and 18b are formed as shown in FIG. 8 and 8 convex portions 16b are alternately formed. Alternatively, as shown in FIG. 4, 6 concave portions 18a and 6 convex portions 16b are alternately formed. .

  2 and 4, the concave portion 18a and the convex portion 18b in the shaft-body-side surface irregularity 18 are connected to each other at a predetermined interval (in FIG. 2, the center of the roller shaft and the bottom center of the adjacent concave portion 18a are connected. The angle formed by the line is 45 °, the angle formed by the line connecting the center of the roller shaft and the apex of the adjacent convex portion 18b is 45 °, and in FIG. 4, the center of the roller shaft and the bottom center of the adjacent concave portion 18a are The angle formed by the connecting line is 60 °, and the angle formed by the line connecting the center of the roller shaft and the apex of the adjacent convex portion 18b is 60 °. The distance between the adjacent concave portions 18a and the adjacent convex portions 18b is preferably set at a constant interval. This is because it becomes easier to obtain uniform elastic layer side surface irregularities 16.

  The shaft body side surface irregularities 18 of the shaft body 12 described above can be formed by grinding a solid shaft body, mold transfer in mold forming, or the like.

  When the shaft body-side surface irregularities 18 are formed on the shaft body 12, the thickness of the elastic layer 14 is in the range of 1.60 times to 13.33 times, where H is the height of the convex portion 18b of the shaft body side surface irregularities 18. It is preferable that it exists in. This is because the elastic layer side surface irregularities 16 corresponding to the shaft body side surface irregularities 18 are easily formed on the surface of the elastic layer 14. The height H is more preferably in the range of 1.70 times to 7.11 times, and still more preferably in the range of 2.76 times to 5.89 times. Specifically, the thickness of the elastic layer 14 is preferably set in the range of 1.0 to 7.0 mm, more preferably in the range of 1.5 to 5.0 mm.

  The paper feed roller 10 described above can be suitably manufactured as follows, for example. In the following, the case where the shaft body 12 having the shaft body side surface irregularities 18 is used will be described.

  First, a molding die having a through-hole having a circular cross section without a gentle surface irregularity on the inner peripheral surface is prepared. At this time, if it is desired to apply a texture to the surface of the elastic layer, a texture shape for transfer can be formed by performing electrical discharge machining on the inner peripheral surface of the through hole.

  Next, the core metal is coaxially set in the through hole of the prepared molding die. After filling the forming space between the cored bar and the inner peripheral surface of the through hole with the elastic layer forming material, it is heated at a temperature suitable for the elastic layer forming material, and the outer peripheral surface of the cored bar is elastically Form the body. Thereafter, the mold is removed and the elastic body is extracted from the core bar and cut into a predetermined length. In this way, an elastic body 14 ′ in which the elastic layer side surface irregularities 16 are not yet formed is produced. A textured shape is introduced on the surface of the elastic body 14 '.

  Next, the shaft body in which the shaft body side surface irregularities 18 are formed at a predetermined pitch is press-fitted into the hollow portion of the elastic body 14 ′. Thereby, the paper feeding roller 10 can be obtained. When using a smooth shaft body 12 'in which the shaft body side surface irregularities 18 are not formed, the surface of the elastic body formed on the outer peripheral surface of the core metal is polished and ground, or the through hole of the molding die is used. A surface unevenness corresponding to the elastic layer side surface unevenness may be formed in advance on the inner peripheral surface of the elastic member and transferred to the surface of the elastic body.

  The paper feeding roller described above is suitable as a pick-up roller, a feed roller, a retard roller (separation roller) used for a paper feeding device in a copying machine or the like, and a transport roller for sequentially transporting paper fed from the paper feeding device to an outlet. It is. In addition, it can also be used as a paper feeding roller for vending machines, automatic ticket gates, automatic cash collection devices, money changers, counting machines, cash dispensers, and the like.

  Hereinafter, the present invention will be described in detail using examples.

1. Production of Paper Feeding Roller According to Example and Comparative Example (Example 1)
<Preparation of elastic layer forming material>
80 parts by mass of polytetramethylene ether glycol (PTMG) [Mn = 2000], 20 parts by mass of polypropylene glycol (PPG) [Mn = 5000] (specifically, a mixture of PTMG and PPG “PREMINOL S3005” (Asahi Glass Co., Ltd.)) Was degassed and dehydrated at 80 ° C. for 1 hour, and then 48 parts by mass of MDI was mixed and reacted at 80 ° C. for 3 hours in a nitrogen atmosphere to prepare a urethane prepolymer. And after defoaming this urethane prepolymer at 90 ° C. for 30 minutes, 65 parts by mass of a plasticizer [dioctyl phthalate] and 3 parts by mass of a chain extender [1,4-butanediol (1,4-BD)] Then, 2 parts by mass of a chain extender [trimethylolpropane (TMP)] was blended and stirred and mixed for 2 minutes under reduced pressure to prepare an uncrosslinked thermosetting urethane-based polymer as a material for forming an elastic layer.

<Production of elastic layer molding die>
A mold provided with a through-hole having a circular cross section (inner diameter φ20 mm) was prepared. Electric discharge machining with an electric discharge machine (“DIAX VX10” manufactured by Mitsubishi Electric Corporation) was performed on the inner peripheral surface of the through hole of the prepared mold. The electric discharge machining is performed in order to impart a textured shape to the surface of the elastic body to be molded, and the height of the ridges of the textured shape is about 30 to 60 μm, and the distance between the tops is about 50 to 80 μm. It was made to become. This mold is referred to as a mold A.

(Production of paper feed roller)
A cored bar (outer diameter φ10 mm) is coaxially set in the through hole of the molding die A, and both end openings are closed with cap molds, and the above-mentioned uncrosslinked material forming the elastic layer is formed in the molding space. After filling with the thermosetting urethane-based polymer, the molding die A was put in an oven and crosslinked (150 ° C. × 60 minutes). And on the outer peripheral surface of the core metal, an elastic body (JIS-A hardness 30 degrees) made of a thermosetting urethane-based polymer that has been crosslinked and cured is formed, and then the elastic body is removed from the core metal while being demolded. Cut to a length of 25 mm. Each obtained elastic body is tube-shaped (outer diameter φ20 mm, inner diameter φ10 mm, length 25 mm), and the surface thereof is subjected to graining.

  Next, a shaft body (length 27 mm, outer diameter φ10 mm) made of polyacetal (POM) was prepared. In this shaft body, six convex portions extending along the axial direction are formed around the main body portion. The shape of the convex portion is semicircular in cross section, and the angle formed by the line connecting the axis and the top of the adjacent convex portion is set to 60 °. Further, the height H of the convex portion is 0.1 mm.

  Next, the shaft body was press-fitted into the hollow portion of the tubular elastic body. In this way, a paper feeding roller according to Example 1 having the cross-sectional shape shown in FIG. 4 was obtained.

(Example 2)
A paper feed roller according to Example 2 was obtained in the same manner as Example 1 except that a shaft body having a height H of the convex portion of 0.3 mm was prepared.

Example 3
A paper feeding roller according to Example 3 was obtained in the same manner as in Example 1 except that a shaft body having a height H of the convex portion of 1.0 mm was prepared.

Example 4
A molding die B was prepared separately on the inner peripheral surface of the through hole, in which the outer shape of the elastic layer in FIG. In Example 1, a molding die B is used in place of the molding die A, it is a tube shape (outer diameter φ20 mm, inner diameter φ10 mm, length 25 mm), and the surface is loosened by embossing and mold transfer. An elastic body having surface irregularities was produced. Next, a shaft body (length 27 mm, outer diameter φ10 mm) made of polyacetal (POM) having no surface irregularities on the shaft body side was press-fitted into the hollow portion of the tubular elastic body. In this way, a paper feeding roller according to Example 4 having the cross-sectional shape illustrated in FIG. 4 was obtained.

(Example 5)
A paper feeding roller according to Example 5 was obtained in the same manner as Example 1 except that a shaft body having a height H of the convex portion of 1.60 mm was prepared.

(Example 6)
A paper feeding roller according to Example 6 was obtained in the same manner as in Example 1 except that a shaft body having a height H of the convex portion of 1.33 mm was prepared.

(Comparative Example 1)
A shaft body (length 27 mm, outer diameter φ10 mm) made of polyacetal (POM) having no shaft surface unevenness was prepared. The shaft body was press-fitted into the hollow portion of the tubular elastic body produced in Example 1. As a result, a paper feeding roller according to Comparative Example 1 in which the cross section of the elastic layer was almost a perfect circle was obtained.

(Comparative Example 2)
It is tube-shaped (outer diameter φ20 mm, inner diameter φ10 mm, length 25 mm), and has a textured surface, and eight square grooves with a width of 0.2 mm are formed along the axis. An elastic body was produced. In addition, this elastic body was produced by performing a square groove process on the surface of the elastic body produced in Example 1 with a router. Next, a shaft body (length 27 mm, outer diameter φ10 mm) made of polyacetal (POM) having no surface irregularities on the shaft body side was press-fitted into the hollow portion of the tubular elastic body. As a result, a paper feeding roller according to Comparative Example 2 in which angular surface irregularities were formed on the surface of the elastic layer was obtained.

2. The shape of the elastic layer of the produced paper feed roller The surface shape of the elastic layer was measured for each produced paper feed roller. Specifically, each paper feed roller is set on a roundness measuring device (“RONDCOM 60A” manufactured by Tokyo Seimitsu Co., Ltd.). After aligning along the reference axis, the contour of the circumference is rotated while rotating the roll. Then, the difference r1-r2 between the radius r1 of the minimum circumscribed circle and the radius r2 of the maximum inscribed circle of the measured contour shape is obtained with the measurement rotation axis as the center, and this is calculated as the convexity of the surface irregularity of the elastic layer. It was a club height.

  FIG. 5 shows a cross-sectional shape of the elastic layer of the paper feed roller according to the third embodiment as a representative example of the paper feed roller according to the first to sixth embodiments. As shown in FIG. 5, it was confirmed that the paper feeding roller according to Example 3 had elastic layer side surface irregularities without corners along the roller axial direction on the peripheral surface of the elastic layer. Although not shown, any of the paper feeding rollers according to the other embodiments is gently loose with no corners along the roller axial direction on the peripheral surface of the elastic layer, similarly to the paper feeding roller according to the third embodiment. Uneven surface irregularities on the elastic layer were formed.

  On the other hand, FIG. 6 shows a cross-sectional shape of the paper feed roller according to Comparative Example 1. As shown in FIG. 6, it can be seen that the paper feeding roller according to Comparative Example 1 does not have the gentle elastic layer side surface irregularities without corners along the roller axial direction on the peripheral surface of the elastic layer. In addition, the fine unevenness | corrugation of the elastic layer surface is a surface unevenness | corrugation by embossing.

(Evaluation of paper feed performance)
Each paper feed roller is incorporated in the paper feed section (feed section and retard section) of a commercially available color printer (manufactured by KYOCERA, “KM-8030”), and 300,000 sheets of paper (manufactured by INTERNATIONAL PAPER, “REY”) A durability test for passing paper was conducted. In the above durability test, the case where there was no paper feed failure due to feed roller abrasion or paper dust adhesion was determined as “A”. A case where the paper feeding failure occurred less than 5 times was determined as “B”. A case where the paper feeding failure occurred 5 times or more and less than 10 times was determined as “C”. The case where the paper feeding failure occurred 10 times or more and less than 30 times was determined as “D”. The case where the paper feeding failure occurred 30 times or more was determined as “E”.

(Evaluation of paper feed defects)
Each paper feed roller is incorporated in the paper feed section (feed section and retard section) of a commercially available color printer (manufactured by KYOCERA, “KM-8030”), and 300,000 sheets of paper (manufactured by INTERNATIONAL PAPER, “REY”) A durability test for passing paper was conducted. In the endurance test, a case where no paper passage failure occurred at the retard roller portion was determined as “A”. A case where the paper passage failure occurred less than 5 times was determined as “B”. A case where the paper passage failure occurred 5 times or more and less than 10 times was determined as “C”. A case where the above paper passing defect occurred 10 times or more and less than 30 times was determined as “D”. A case where the paper passage defect occurred 30 times or more was determined as “E”.

  Table 1 summarizes the detailed configuration and evaluation results of the elastic layer and the shaft body.

  A relative comparison of Table 1 shows the following. In other words, the paper feeding roller according to Comparative Example 1 has only the outer shape of the elastic layer that is close to a perfect circle and has a texture on the surface. For this reason, the ability to deposit paper dust on the fine concave portions of the texture is low, and the paper feeding performance due to adhesion of paper dust is poor.

  In the paper feeding roller according to Comparative Example 2, surface irregularities having corners along the roller axis are formed on the surface of the elastic layer. For this reason, the paper is dammed by the grooves when the paper passes, and a paper feeding defect is likely to occur.

  On the other hand, any of the paper feed rollers according to Examples 1 to 6 has the configuration of the present invention. Therefore, it can be seen that it is possible to achieve both the suppression of the decrease in paper feeding performance and the suppression of paper feeding defects. In particular, the paper feeding roller according to Examples 2 to 5 in which the height (r1-r2) of the convex portion of the surface irregularities on the elastic layer side is in the range of 0.05 to 0.45 mm is obtained by paper dust adhesion. It was confirmed that the balance between the suppression of the decrease in feeding performance and the suppression of paper feeding defects was excellent.

  Further, by forming the shaft body side surface irregularities on the surface of the shaft body, it is possible to easily impart the elastic layer side surface irregularities using an elastic body having a perfectly circular cross section. Therefore, it was also confirmed that there is an advantage that a molding die for forming the elastic layer can be simplified and can contribute to cost reduction.

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

DESCRIPTION OF SYMBOLS 10 Paper feed roller 12 Shaft body 12a Main body part 14 Elastic layer 16 Elastic layer side surface unevenness 16a Concave part 16b Convex part 18 Shaft body side surface uneven part 18a Concave part 18b Convex part

Claims (3)

A paper feed roller having a shaft body and an elastic layer formed on an outer periphery of the shaft body,
On the peripheral surface of the shaft body, the shaft body side surface unevenness is formed along the roller axis direction, and the convex portion constituting the shaft body side surface unevenness has no corners,
By forming the elastic layer along the outer peripheral surface of the shaft body, the elastic layer side surface having no corners along the roller axis direction on the peripheral surface of the elastic layer is formed on the peripheral surface of the elastic layer. Irregularities are formed ,
The paper feeding roller, wherein the elastic layer has a thickness in a range of 2.76 times to 5.89 times a height of a convex portion constituting a part of the surface irregularities on the shaft body side . The radius of the circumscribed circle that circumscribes the convex portion constituting the elastic layer side surface irregularities with the roller axis as the center is r1, and the inscribed circle that is inscribed in the concave portion that constitutes the elastic layer side surface irregularities with the roller axis as the center. When the radius is r2,
2. The paper feed roller according to claim 1 , wherein a value of r1-r2 is in a range of 0.05 to 0.45 mm. The elastic layer surface, the paper feed roller according to claim 1 or 2, characterized in that the embossing is applied.

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