JP2011057427A - Sheet feeding shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding shaft capable of accurately feeding paper in the object direction while holding the paper in an accurate position, when a characteristic of the paper is changed by improving a projection shape, when forming a projection by plastic working to a metallic round bar peripheral surface. <P>SOLUTION: This sheet feeding shaft is formed by the plastic working out of a plurality of projections of rising in the rotational direction on a circumferential surface of a metallic round bar opposed by sandwiching a sheet between a feed roller and itself. The projections are formed in a pair by a center punching work tool in opposed two places of the metallic round bar peripheral surface, and are composed of a plurality of spike-shaped projections contrary to each other in the rising direction, and are formed so that an apex angle of the projection shape when viewed from the direction of the work tool becomes 70 degrees to 120 degrees, and a plurality of projections contrary to each other in the rising direction are also arranged in a row along the circumferential direction and the axial direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet feeding shaft used for feeding a sheet of a printing machine or a printer for an office machine, or feeding a sheet such as a film used in an overhead projector.

  Conventionally, for paper feeding such as printers for office machines, a sheet is sandwiched between feeding rollers, and a plurality of protrusions rising in the rotational direction are plastically processed on the circumferential surface of a metal round bar facing it. Sheet feed shafts formed by have been used.

  As the shape of the protrusion, the apex angle of the protrusion when viewed from the direction of the processing tool was formed at an angle of about 38 to less than 60 degrees when forming a protrusion with a height of 30 to 200 μm. . With such a height of the protrusion, uneven feeding due to slip during paper feeding hardly occurs, and paper feeding can be performed efficiently.

  Specifically, for example, Japanese Patent Application Laid-Open No. 10-109777 discloses a projection shape and a processing method thereof in detail. Such a shaft is used as a roller for a multi-color printer because there is little slip or the like during paper feeding and unevenness in paper feeding is not noticeable.

Japanese Patent Laid-Open No. 10-109777 (see FIG. 8)

  However, with the recent increase in printing speed of printers and office machine printers, the paper feed force applied to the print paper and the pressure contact force applied from the feed roller to the sheet feed shaft are increased. Due to the demand for lower prices, changes have occurred in the characteristics of the print paper itself.

  Specifically, there are products that have not been surface-treated on the back side that is not the print side of the paper, or products that have been made flexible. Such paper has low strength in the paper thickness direction, and the protrusions are on the paper. It becomes easy to bite into. For this reason, there is a difference between the biting of the protrusion when feeding the paper and the biting of the protrusion when returning the paper.

  By the way, when performing color printing on a predetermined paper, a color ink jet method in which fine particles of liquid color ink are mainly blown onto the paper, a sublimation type in which the color ink ribbon is vaporized (sublimated) by heat and fixed on the paper, Furthermore, there are three types of color laser systems that use color toner.

  Among them, a printer that uses a sublimation printing method because it can be printed with just a digital video printer without using a personal computer, a digital camera, still images of TV images can be easily printed in full color, sticker printing, etc. There are many.

  In a printer that employs a sublimation printing method, a color ink ribbon is sublimated and fixed on paper, and the three colors of the ink ribbon are stacked in response to a color signal to obtain a predetermined color. . In this case, complete color development cannot be obtained if a positional shift occurs at the three-color stacking position. For this reason, it is necessary to strictly manage and control the sheet misalignment tolerance as compared with other methods.

  That is, the operation of repeatedly feeding or pulling the paper back and forth is repeatedly performed, and each time the three colors of the ink ribbon are laminated in correspondence with the color signal at the position corresponding to the print image signal. If a positional shift is caused at this time, a color image is blurred or blurred, and a high-quality image cannot be obtained.

  In addition, in the case of the color ink jet method, ink particles are ejected from the ink jet head onto the paper. For fine color printing, the ink particles are made fine and the paper is sent out, and the print image signal is supported each time. Ink particles are ejected at the position of the inkjet head. In this case, the protrusions bite into the paper, so that the feeding is fine and sure without causing uneven feeding due to slip or the like.

  However, the load applied to the paper may be different between the leading edge and the trailing edge of the paper, and the amount of protrusions that bite into the paper may change. Specifically, when continuous printing is performed with multiple sheets of paper loaded, the paper load is applied directly to the paper, leading to the leading edge and trailing edge of the paper, or the initial paper and the end of the multiple sheets. The load on the paper may differ depending on the paper size. In particular, in a printer employing a sublimation printing method, pressure from the head is applied as a load to the paper when printing, but this load is not applied when pulling back. As a result, the amount of protrusions that bite into the paper changes, resulting in a phenomenon in which the radius of the paper feed roller changes substantially, resulting in a difference in the paper feed amount, resulting in “paper feed misalignment”. .

  Under such circumstances, a paper feed error occurs in the conventional sheet feed shaft, resulting in a “blurred” image due to printing misalignment, which tends to be an undesirable product.

  The present invention solves the above-described problems, and when forming protrusions by plastic working on the metal round bar circumferential surface, even when the characteristics of the paper are changed by improving the protrusion shape, It is an object of the present invention to provide a sheet feeding shaft that can accurately feed a sheet in an intended direction while holding a sheet at an accurate position.

  In order to achieve the above object, according to the present invention, a plurality of protrusions that rise in the rotational direction on the circumferential surface of a metal round bar facing each other with a sheet sandwiched between the feed rollers are formed by plastic working. In the sheet feed shaft, the protrusion is formed by a pair of perforating tools at two opposing portions of the metal round bar circumferential surface and includes a plurality of spike-like protrusions whose rising directions are opposite to each other, Formed so that the apex angle of the projection shape seen from the direction of the processing tool is 70 to 120 degrees, and a plurality of projections whose rising directions are opposite to each other are arranged along the circumferential direction and the axial direction It is possible to provide a sheet feed shaft characterized by the following.

  According to the first aspect of the present invention, the apex angle of the protrusion shape seen from the direction of the processing tool is formed to be 70 degrees to 120 degrees, and the amount of advance of the sheet when the sheet is fed, and the sheet A sheet feed shaft that can accurately stack or discharge ink while holding the paper in the correct position even when the paper characteristics change so that there is no difference in the return amount of the paper when pulling back. Can be provided.

It is a perspective view of the principal part which shows the paper feeding apparatus which has a sheet feeding shaft by one Embodiment of this invention. It is a perspective view which expands and shows the sheet | seat feed shaft in FIG. It is a perspective view which expands and shows the protrusion shape in FIG. It is sectional drawing which shows a mode that protrusion protruded into the paper. It is the figure which looked at the protrusion in FIG. 4 from the direction of the perforation member. It is a side view which shows the concept of the method of measuring the paper feed amount of this invention. It is a top view of the trace of the protrusion which measured the paper feed of this invention. It is a perspective view of the apparatus which manufactures the sheet | seat feed shaft by one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a principal part of a paper feeding device having a sheet feeding shaft according to the present invention. In FIG. 1, a sheet feeding shaft S composed of a metal round bar 1 is interposed between a hard rubber feeding roller 2. The sheet 3 is fed in the arrow direction by sandwiching the sheet 3 to be fed and rotating the sheet feeding shaft S in the arrow direction.

  In addition, as shown in FIG. 2 in an enlarged manner, the metal round bar 1 has a plurality of spikes that rise at an obtuse angle in the rotation direction of the metal round bar 1 on a circumference divided into three regions. The projections A and B are formed along the circumferential direction and the axial direction by plastic working.

  That is, in the sheet feeding shaft S according to the present invention, the protrusions A and B are formed in pairs at opposite locations on the circumferential surface of the metal round bar by a pair of punching processes, and the rising directions are opposite to each other. And a plurality of protrusions A and B whose rising directions are opposite to each other are formed in a line along the circumferential direction and the axial direction.

  3 and 4, each protrusion A, B is formed in a spike shape that rises at an obtuse angle in the rotational direction of the metal round bar 1 by a perforated cutting blade that is a conventional method shown in FIG. ing. Moreover, when viewed from the machining direction by the perforated cutting blade, the protrusions are formed in mutually opposite directions so that the apex angle θ of the projection is 70 degrees or more and 120 degrees or less. Then, the protrusions A and B adjacent in the circumferential direction on the circumferential surface have their rising directions opposite to each other as shown in FIG.

  That is, the projections A and B arranged in the circumferential direction on the circumferential surface are provided in a plurality of rows along the axial direction, and the rising directions of the projections A and B in the rows adjacent to each other in the axial direction are opposite to each other. Further, the protrusions A and B in the rows adjacent in the axial direction are alternately arranged adjacent to each other while being shifted by a half pitch along the axial direction.

  Here, the protrusion is formed so that the apex angle θ is not less than 70 degrees and not more than 120 degrees, for example, in the case of a product in which the surface processing is not performed on the back surface other than the print surface of the paper, This corresponds to a difference between the biting of the protrusions and the biting of the protrusions when returning the paper. That is, if the protrusion is formed so that this angle is less than 60 degrees as in the prior art, the protrusion pierces the paper even with a relatively weak force, so that the amount of protrusion of the protrusion when feeding the paper and the protrusion when returning the paper A difference is likely to occur in the amount of bite.

  Specifically, the amount of biting is small in the direction where the paper is not loaded, but when it is pulled in the direction of loading, the amount of biting is increased, and the diameter of the sheet feed shaft is apparently reduced. Paper feed amount decreases. That is, in FIG. 4, the amount of biting is small in the direction where the load is not applied to the sheet as indicated by the arc a, but the amount of biting is increased when the sheet is pulled in the direction of applying the load as indicated by the arc b. The diameter D of the sheet feed shaft changes from Da to Db and acts as if it appears to be small, thereby reducing the paper feed amount. As a result, there is a difference between the paper advance amount when the paper is sent out and the paper return amount when the paper is pulled back, and ink is not stacked or ejected at an accurate position.

  Therefore, the inventor has focused on this point, and pursued a protrusion shape in which the difference between the amount of protrusion of the protrusion when feeding the paper and the amount of protrusion of the protrusion when returning the paper is less likely to occur. As a result, it has been found that a numerical value in which the apex angle of the protrusion shape is 70 degrees or more and 120 degrees or less when viewed from the processing direction by the perforated cutting blade is appropriate.

  That is, if the apex angle is 70 degrees, compared to the conventional case of less than 60 degrees, it becomes difficult to pierce the paper, while if it exceeds 120 degrees, it interferes with the adjacent protrusion formed in the axial direction, and the unit area As a result, the number of projections per contact decreases, and as a result, the conveying force for feeding and pulling out the paper decreases, which is not preferable.

  By the way, the background that the inventor has reached such a conclusion as a result of trial and error will be described in detail based on the drawings showing the outline of the apparatus used in the experiment. FIG. 6 schematically shows a main part of a paper feeding apparatus having a feeding roller 2 for pressing the paper 3 and a sheet feeding shaft S. Here, the paper 3 and the weight F can be removed by the attachment 4 so that the paper can be appropriately changed and measurement can be performed. In principle, a method of measuring the amount of protrusion of the shaft S that bites into the sheet when the load F applied to the sheet 3 changes when the sheet 3 is fed out or pulled back is shown.

  That is, a constant pressure P is always applied to the feed roller 2, the weight F corresponding to the load applied to the paper 3 is changed, the shaft S is rotated in the direction of arrow A, and the paper 3 is sent in the left direction B. In this case, the feed roller 2 turns in the direction of arrow C via the paper 3. Next, after changing the paper 3 to another one and changing the weight of the weight F, the shaft S is similarly rotated in the direction of arrow A, and the paper 3 is sent out in the left direction B.

  Since the paper 3 obtained in this way has traces of the protrusions A and B being left, if the distance (distance) L between these traces is measured, the paper 3 has taken into the protrusions A and B. The depth can be assumed from the state shown in FIG. FIG. 7 shows a trace of protrusions A and B biting into the paper 3. The protrusion A represents the trace shape of each protrusion, assuming that the protrusion A is in the forward direction and the protrusion B is in the reverse direction. What is necessary is just to measure the space | interval L of the trace of this protrusion row | line | column.

  That is, in FIG. 4, if the sheet has bitten to the depth of the arc a, the sheet 3 is conveyed along the cylinder with the diameter Da, and the trace is measured at the protrusion pitch on the circumference of the cylinder with the diameter Da. On the other hand, if the paper bites into the depth of the arc b, the paper 3 is conveyed along the cylinder having the diameter Db, and the trace is measured at the protrusion pitch of the circumference of the cylinder having the diameter Db.

If the distance L between the traces thus measured is within a predetermined limit even when the weight F is changed, it may be determined that “feed unevenness” of the paper 3 can be tolerated. Become. Specifically, the weight F is assumed to be about 1.0 to 1.8 kg, and by changing this, the difference δL between the distance L ₁ corresponding to the weight F ₁ and the distance L ₂ corresponding to the weight F ₂ is changed. Is within 10 μm, it is determined that the value of the printed image is acceptable.

  In the sheet feed shaft having such a configuration, when the tips of the protrusions A and B formed on the outer periphery of the metal round bar 1 are viewed from the machining direction by the perforated cutting blade, the apex angle of the protrusion is 70 degrees or more and 120 degrees or less. In addition to being formed so that it is sharp and sharply pointed, it is possible to ensure that any of the above-mentioned problematic printing papers or relatively flexible printing papers can be used regardless of the rotation direction of the metal rod 1 , And can smoothly feed out to the specified direction and the specified position smoothly within the allowable range by the interaction with the feed roller 2. Therefore, if this is used for multicolored color printing or the like, it is possible to realize beautiful multicolored printing in which a specific paper or film is not permanently deformed and color misregistration is not noticeable.

  In addition, this invention is not limited to the said embodiment, Embodiment can be changed suitably and implemented within the range of the technical idea of this invention.

1 Metal Round Bar 2 Feed Roller 3 Paper S Shaft F Weight A, B Protrusion

Claims (1)

In the sheet feed shaft formed by plastic working a plurality of protrusions rising in the rotation direction on the circumferential surface of the metal round bar facing each other with the sheet sandwiched between the feed rollers,
The protrusions are formed by a pair of perforating tools at opposite locations on the circumferential surface of the metal round bar and include a plurality of spike-like protrusions whose rising directions are opposite to each other, as viewed from the direction of the processing tool. Sheet feeding characterized in that the apex angle of the protrusion shape is 70 degrees or more and 120 degrees or less, and a plurality of protrusions whose rising directions are opposite to each other are arranged along the circumferential direction and the axial direction shaft.

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