JP2009190833A - Decurling roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decurling roller which is fitted to an electrophotographical type OA apparatus such as a copier, an image recording device, a printer, and a facsimile, and capable of demonstrating the superior decurling effect to curled paper sheets, and has small compressive permanent set of an elastic body, and superior heat resistance. <P>SOLUTION: The decurling roller has an elastic body 21 on an outer circumference of a shaft 11, and mitigates or eliminates curls of the paper sheets by pressing the curled paper sheets to the roller harder than the elastic body 21 with the elastic body 21. In the elastic body 21, an outer circumferential surface of an extruded cylindrical silicon foam is polished, and cells 26 are exposed on the outer circumferential surface 25, and a skin 23a is provided on an inner circumferential surface 23 of a center hole 22 in which the shaft is inserted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a decurling roller attached to an electrophotographic OA apparatus such as a copying apparatus, an image recording apparatus, a printer, and a facsimile.

  Some OA devices such as a copying apparatus, an image recording apparatus, a printer, and a facsimile are of an electrophotographic system in which toner is attached to paper sheets (copy paper or print paper) with static electricity and the toner is fixed by heating. In the electrophotographic OA apparatus, since paper sheets are easily curled by heat, some apparatuses are used to reduce or eliminate curl of the paper sheets by providing a curl removing roller.

  As shown in FIG. 4, the conventional decurling roller 50 is composed of a shaft 51 and an elastic body 53 provided on the outer periphery thereof. As shown in FIG. 5, a conveying roller 61 in the paper sheet conveying path of the OA device. The surface of the elastic body 53 is pressed and deformed by pressing the elastic body 53 against the surface of the elastic body 53. The conveying roller 61 is made of a material harder than the elastic body 53, for example, a metal. When the curled paper sheet 80 passes between the conveying roller 61 and the curl removing roller 50, the curled paper sheet 80 is wound around a part of the outer periphery of the conveying roller 61 and bent to the side opposite to the curled side, thereby removing the curl. It is. Reference numeral 65 is a fixing roller for fixing the toner attached to the paper sheet 80 by heating, and 67 is a pressure roller. It should be noted that the conveying roller 61 combined with the curl removing roller 50 is not limited to one as described above, and may be combined with two conveying rollers 71 and 72 as shown in FIG.

  The curl removal roller 50 is made of a material whose elastic body 53 can be pressure-deformed such as rubber or polyurethane foam. However, in recent years, with the downsizing of OA equipment, the curl removing roller is often provided close to the toner fixing roller. As a result, during the period of use of the OA device, the elastic body of the curl removal roller may be plastically deformed or deteriorated by heat, and the curl removal effect may not be obtained. In particular, the decurling roller needs to be made of a material whose elastic body can be deformed by pressure and has a small compression set.

  In order to improve heat resistance, it is conceivable to use an extruded cylindrical silicone foam as the elastic body. Silicone foam is superior to polyurethane foam in heat resistance, and can be expected to improve the heat resistance of the decurling roller. Moreover, according to extrusion molding, a cylindrical body (tube) can be obtained continuously, and then an elastic body of a desired size can be obtained simply by cutting to a predetermined length according to the dimensions of the curl removal roller. Excellent productivity. Furthermore, since extrusion does not require a mold, the cost of the product can be reduced.

  Therefore, the present inventor made an extruded cylindrical silicone foam on the outer periphery of the shaft to produce a curl removal roller and used it. The compression set of the elastic body is large and needs to be improved. There was found.

JP 2003-165661 A Japanese Examined Patent Publication No. 6-55457

  The present invention has been made in view of the above points, and an object of the present invention is to provide a decurling roller that has a small compression set of an elastic body, exhibits a good decurling effect, and is excellent in heat resistance.

  The invention according to claim 1 has an elastic body on the outer periphery of the shaft, and curls the curled paper sheet against the roller harder than the elastic body by the elastic body to reduce or eliminate curling of the paper sheet. In the take-off roller, the elastic body is characterized in that an outer peripheral surface of an extruded cylindrical silicone foam is polished and cells are exposed on the outer peripheral surface.

  According to a second aspect of the present invention, in the first aspect, a skin is provided on an inner peripheral surface of a central hole through which the shaft of the elastic body is inserted, and an average cell size on the polished outer peripheral surface is 250 μm to 350 μm. It is characterized by.

  According to the decurling roller of the present invention, since the elastic body provided on the outer periphery of the shaft is made of a silicone foam, the heat resistance is better than that of the conventional decurling roller. In addition, since the decurling roller of the present invention is made by extruding the silicone foam constituting the elastic body, the cost of the product can be reduced.

  Further, when the silicone foam is extruded into a cylindrical shape, a dense skin (film) is formed on the outer peripheral surface and the inner peripheral surface of the center hole, and the cells are covered with the skin. In the curl removing roller, the outer peripheral surface of the extruded cylindrical silicone foam is polished and the elastic body is formed by exposing the cells, and there is no skin on the outer peripheral surface of the elastic body. At the time of compression and release of air, air can easily flow between the inside and the outside of the elastic body, the resilience of the elastic body is increased, and the compression set is reduced. In addition, the decurling roller of the present invention has an elastic body with a skin remaining on the inner peripheral surface of the central hole through which the shaft is inserted, so that the strength of the inner peripheral surface of the elastic body in contact with the shaft can be increased. The risk of the elastic body being damaged at the interface with the shaft can be eliminated.

  Instead of the extruded silicone foam as in the present invention, a cylindrical silicone foam having a predetermined size is formed by casting using a mold, and then the outer peripheral surface is polished to remove the curl removing roller. When obtaining an elastic body, the molded cylindrical silicone foam has skins not only on the outer peripheral surface and inner peripheral surface but also on both end surfaces in the length direction. May be reduced. Therefore, in addition to the outer peripheral surface of the cylindrical silicone foam, the skin must be removed by polishing or cutting on both end faces, and a product having a predetermined length can be obtained without cutting the length. The advantages of cast molding are impaired, and not only are there advantages compared to extrusion molding, but also the disadvantage of increased costs due to the use of the mold becomes a major problem.

  FIG. 1 is a front view and a sectional view of a curl removing roller according to an embodiment of the present invention. A decurling roller 10 shown in FIG. 1 is used for decurling paper sheets in electrophotographic OA equipment such as a copying machine, an image recording apparatus, a printer, and a facsimile machine. The OA shown in FIGS. It is used in place of the conventional decurling roller 50 in the paper sheet conveyance path of the apparatus.

  The decurling roller 10 includes a shaft 11 and an elastic body 21 provided on the outer periphery thereof. The shaft 11 serves as an attachment and rotation shaft for the curl removing roller 10 and is made of metal.

  The elastic body 21 is pressed against the conveying rollers 61, 71, 72 shown in FIGS. 5 and 6 and the surface thereof is pressure-deformable. The outer peripheral surface of the extruded cylindrical silicone foam is Made of polished one. The elastic body 21 has a center hole 22 through which a shaft is inserted, and has a skin 23 a on an inner peripheral surface 23 of the center hole 22. The skin 23a is formed as a film when the silicone foam is formed into a cylindrical shape by extrusion, and covers the cells (pores) inside the silicone foam. The outer diameter and thickness of the elastic body 21 are set to appropriate dimensions according to the OA equipment to which the decurling roller is attached, and examples include an outer diameter of 16 to 24 mm and a thickness of 3 to 8 mm.

  The outer peripheral surface 25 after polishing in the elastic body 21 has a skin (coating film) formed on the outer peripheral surface of the silicone foam when the cylindrical silicone foam is extruded to be removed by polishing. The internal cells (pores) 26 are exposed. Since the elastic body 21 has exposed cells (pores) on the outer peripheral surface 25 after polishing, the air flow between the inside and the outside of the silicone foam is good during compression and compression release, and the elastic body 21 Restoration is good and compression set is reduced.

  The elastic body 21 preferably has an average cell size of 250 μm to 350 μm on the outer peripheral surface 24 after the polishing. By setting the average cell size in the above range, the compression set of the elastic body 21 can be reduced, and the deformability required for the elastic body 21 when the elastic body 21 is pressed against another roller for curling. Can be secured. In the present example, the average cell size value was determined by measuring the cell diameters of 10 adjacent cells. Further, the elastic body 21 preferably has a compression set (JIS K 6401) of 5% or less in order to make the restorability better.

  As shown in FIG. 2, the extruded cylindrical silicone foam 21A, that is, the cylindrical silicone foam 21A before being polished, has a skin (coating) 24a having a predetermined thickness on the outer peripheral surface 24. In addition, the cell size of the cell inside the silicone foam is small at the portion close to the skin 24a. Therefore, the average size of the cells exposed on the outer peripheral surface after polishing can be adjusted by adjusting the removal thickness of the outer peripheral surface 24 in the extruded cylindrical silicone foam 21A. The elastic body 21 has a removal thickness by polishing of 1.25 mm to 6.25 mm, whereby the average cell size on the outer peripheral surface after polishing can be 100 μm to 350 μm, and particularly preferably, removal by polishing. By setting the thickness to 1.5 mm to 4 mm, the average cell size on the outer peripheral surface after polishing is set to 250 μm to 350 μm. Furthermore, it is more preferable as the elastic body 21 that the average cell size on the outer peripheral surface after polishing is 250 μm to 350 μm and the compression set (JIS K 6401) is 5% or less.

  Polishing of the outer peripheral surface 24 of the extruded cylindrical silicone foam 21A can be performed by an appropriate method. For example, as shown in FIG. 3, the temporary shaft 110 or the shaft 11 is inserted into the center hole 22 of the extruded cylindrical silicone foam 21A, and the temporary shaft 110 or the shaft 11 is rotatably supported. In this state, the polishing machine holding the ceramic grindstone 41 can be pressed against the outer peripheral surface 24 of the silicone foam 21A. At that time, by adjusting the removal thickness of the outer peripheral surface by polishing as described above, the average size of the cells on the outer peripheral surface of the elastic body 21 after polishing is from 100 μm to 350 μm, particularly preferably from 250 μm to 350 μm. Therefore, the compression set (JIS K 6401) can be 5% or less.

  Further, both end surfaces 21a, 21a in the length direction of the elastic body 21 are cut surfaces, and there is no skin and the cells are exposed.

  The silicone foam was formed into two types of cylindrical silicone foams having an inner diameter of 7 mm, an outer diameter of 28.0 mm, and 26.0 m by extrusion molding, and the cylindrical silicone foam was cut to a length of 300 mm. Then, a temporary shaft having a diameter of 8 mm and a length of 350 mm is inserted into the center hole of the cylindrical silicone foam obtained as described above, and both ends of the temporary shaft are rotatably supported. A grinder (product name: polishing machine) LG-70 (manufactured by Mizuguchi Seisakusho) was applied to the outer peripheral surface of the cylindrical silicone foam and polished to remove the skin on the outer peripheral surface. At that time, the removal amount (polishing amount) of the outer peripheral surface was changed to form 10 types of elastic bodies each.

  The average cell size was magnified and observed at a magnification of 100 using a Keyence microscope VH-8000 on the outer peripheral surface of the elastic body thus obtained, and the average of 10 adjacent cells was determined. However, small cells of 50 μm or less were not judged as cells and were not counted. The compression set of the elastic body was measured based on JIS K 6401. The measurement results are shown in Tables 1 and 2. In addition, a measurement result is an average value of 10 elastic bodies, respectively. For comparison, the compression set was measured in the same manner for the elastic body whose outer peripheral surface of the extruded silicone foam was not polished, and the average value was calculated. In addition, the outer diameter after grinding | polishing of Table 1 and Table 2 is a value in a shaft press-fit state.

  As shown in Tables 1 and 2, the outer peripheral surface is not polished, and the skin on the outer peripheral surface is removed by polishing, compared to the experimental example (experiment No. 1) having the skin on the outer peripheral surface. In other experimental examples, the distortion is small. In particular, the experiment No. in Table 1 in which the average cell size of the outer peripheral surface from which the skin was removed was 250 μm to 350 μm. 4-13, Experiment No. 2 in Table 2. Nos. 4 to 8 have a small distortion of 5% or less, and are found to be suitable as an elastic body of the curl removing roller.

It is the front view and sectional view of a curl removal roller concerning one embodiment of the present invention. It is sectional drawing of the cylindrical silicone foam before the skin of an outer peripheral surface is removed. It is sectional drawing which shows the example at the time of removing the outer peripheral surface of a cylindrical silicone foam. It is the front view and sectional drawing of the conventional decurling roller. It is the schematic which shows the use condition of a decurling roller. It is the schematic which shows the other use condition of a decurling roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Curling roller 11 Shaft 21 Elastic body 23 Inner peripheral surface 23a Skin of inner peripheral surface 25 Outer peripheral surface after skin removal 26 Cell 61, 71, 72 Roller for conveyance

Claims (2)

In the decurling roller that has an elastic body on the outer periphery of the shaft, presses curled paper sheets against the roller that is harder than the elastic body, and reduces or eliminates curling of the paper sheets by pressing the elastic body,
The curling roller is characterized in that the elastic body is formed by polishing an outer peripheral surface of an extruded cylindrical silicone foam and exposing cells on the outer peripheral surface.   2. The curl according to claim 1, wherein the elastic body has a skin on an inner peripheral surface of a central hole through which a shaft is inserted, and an average cell size on the polished outer peripheral surface is 250 μm to 350 μm. Roller.

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