JP2004268297A - Printing drum and stencil process printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing drum capable of preventing an ink leakage from the rear end side, in the rotating direction, of the printing drum from occurring. <P>SOLUTION: This printing drum comprises a cylindrical porous support 1A having an ink-passable porous perforated region 1b and an ink non-passable unperforated region 1a; an ink leakage-proof member 7 having an open part 7a bonded to the unperforated region 1a so as to let the open part 7a face toward the perforated region 1b, on the outer peripheral surface and at the rear, in the rotating direction, of a porous support 1A; and a porous elastic body 2 which is wound around the outer peripheral surface and has a part, corresponding to the rear end part of the perforated region 1b, which is formed of an ink non-passable part 10. A folded-back part 10a is formed by folding back a side 10d in contact with the outer peripheral surface of the ink non-passable part 10 and the ink is guided into the perforated region 1b by engaging the folded-back part 10a with the ink leakage-proof member 7 so as to position the front end 10b of the folded-back part 10a facing forward in the rotating direction of the porous support 1A. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printing drum having an ink leakage preventing function for preventing ink leakage from a rear end side, and a stencil printing apparatus using the same.
[0002]
[Prior art]
In general, a stencil printing apparatus includes a plate cylinder as a printing drum around which a stencil sheet is wound, and a printing pressure member that comes into contact with the outer peripheral surface of the plate cylinder via a printing sheet. As shown in FIGS. 4 and 5, this plate cylinder has a mesh screen provided with an ink-impermeable portion 2a and an ink-permeable mesh portion 2b on the outer peripheral surface of a cylindrical porous support 1A. 2 is wound and mounted. On the outer periphery of the mesh screen 2, a stencil sheet Ma (hereinafter, “master Ma”) perforated and made with its tip held by an openable / closable clamper 3 provided along one generatrix of the outer periphery of the plate cylinder 1. Is written).
[0003]
As shown in FIGS. 6 and 7, the porous support 1A has a porous open area 1b in which a large number of ink-permeable holes are formed, and a non-open area 1a that is impermeable to ink. are doing. Inside the plate cylinder 1, an ink roller 5 for supplying a predetermined amount of ink supplied in the form of a film on the outer peripheral surface to the inner peripheral surface of the plate cylinder 1 while rotating in the same direction as the rotation direction A of the plate cylinder 1 is provided. Is provided. In the vicinity of the outer peripheral surface of the plate cylinder 1 facing the ink roller 5, a pressing roller 6 as a pressing member that swings up and down and presses the printing paper P against the master Ma on the plate cylinder 1 is arranged.
[0004]
In the stencil printing apparatus, the printing paper P is sent between the printing drum 1 and the pressing roller 6 at a predetermined timing, and the fed printing paper P is transmitted via the printing drum 1 and the master Ma wound thereon. To press the ink between the ink roller 5 and the pressing roller 6 to supply the ink supplied to the inner peripheral surface of the plate cylinder 1 to the opening 1c in the opening area 1b of the plate cylinder 1, the mesh portion 2b of the mesh screen 2 and the master. The desired print image is formed by exuding through the perforated portion of Ma and transferring to the printing paper P.
[0005]
The pressing roller 6 sequentially presses the plate cylinder 1 from the front end (downstream end) to the rear end (upstream end) in the rotation direction A of the plate cylinder 1 with the rotation of the plate cylinder 1. A part of the ink not used for printing is pushed to the rear end side of the plate cylinder 1. The ink thus extruded enters between the outer peripheral surface of the plate cylinder 1 and the ink non-passing portion 2a of the mesh screen 2, and finally leaks from the rear end (upstream end) side of the ink non-passing portion 2a of the mesh screen 2. The printing paper P and the inside of the stencil printing apparatus are thereby contaminated with the leaked ink.
[0006]
For this reason, conventionally, as shown in FIG. 7, in order to prevent the above-mentioned ink leakage from the rear end side of the plate cylinder 1, the porous support 1A is located behind (upstream) the rotation direction A of the plate cylinder 1. The three sides are adhered to the rear end portion (upstream end portion) of the opening region 1b by using a double-sided adhesive tape 18 to adhere the three sides thereof to the non-opening region 1a of the plate cylinder 1. An ink leakage preventing member 7 provided toward the opening area 1b of the cylinder 1 and made of an ink impermeable member is provided in a pocket shape. The ink non-passing portion 2a is formed by providing a belt cloth 10 serving as an ink impermeable member at the rear end 2c of the mesh screen 2 and folding the belt cloth 10 to open the front end 10b of the ink leakage preventing member 7. The mesh screen 2 is elastically mounted on the outer peripheral surface of the plate cylinder 1 by inserting the mesh screen 2 into the plate cylinder 1 by inserting the mesh screen 2 into the opening 7a. The hole 1c has a function of guiding.
[0007]
[Problems to be solved by the invention]
In the case where the ink impermeable member 10 of the mesh screen 2 is folded back and mounted on the plate cylinder as in the prior art, no particular consideration is given to the manner of folding, and the inventor of the present application has proposed the folding method shown in FIG. Observation of the plate cylinder 1 using revealed that buttocks leakage occurred. The reason for this is that the ink accumulated in the space 20 formed between the outer peripheral surface of the plate cylinder 1 and the mesh screen 2 is only caused by the opening 1c of the opening area 1b due to the bent back portion 10a. In other words, it is presumed that they are also guided to the mesh screen 2 side as indicated by reference symbol R2. In addition, depending on the method of folding, it is supposed that the thickness of the folded portion 10a, the space 20 is increased, and the amount of accumulated ink is increased.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing drum and a stencil printing apparatus that can prevent the occurrence of ink leakage from the rear end side in the rotation direction of the printing drum (commonly referred to as "ink leakage").
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a cylindrical porous support having an ink-permeable porous open area and an ink-impermeable non-open area, and an outer periphery of the porous support. An ink leakage preventing member which is in close contact with a non-opening area so that its open part faces the open area, and an ink leakage preventing member which is wound around the outer peripheral surface and is provided behind the porous area. A portion corresponding to the end portion has a porous elastic body composed of an ink non-passing portion, and a side in contact with the outer peripheral surface of the ink non-passing portion is bent to form a folded portion, and a tip of the folded portion is a porous support. A printing drum having an ink guiding portion for guiding the ink to the opening region by engaging the folded portion with the ink leakage preventing member so as to be positioned forward in the rotation direction of the printing drum.
[0010]
In this manner, when the folded portion is engaged with the ink leakage preventing member such that the tip of the folded portion formed by folding the ink non-passing portion is located forward in the rotation direction of the porous support, the opening area is reduced. Since the thickness of the bent portion of the ink non-passing portion on the side is reduced, the space for storing the ink is reduced.
[0011]
If the shape of the end surface at the end of the folded portion is a flat surface, preferably a plane substantially perpendicular to the outer peripheral surface of the porous support, the ink accumulated in the space is not guided to the porous elastic body, and the porous support It was observed that it was guided to the open area of the.
[0012]
The ink impervious portion is easy to manufacture if it is configured by attaching an ink impervious member to the rear end of the porous elastic body. Examples of the form of attachment include a form of pressing and welding to the porous elastic body.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The overall configuration and operation of the thermal digital stencil printing apparatus will be described with reference to FIG. In FIG. 3, reference numeral 65 indicates an apparatus main body. A document reading section 60 for reading document information is arranged at an upper portion of the apparatus main body 65. Inside the apparatus main body 65, the plate cylinder 1 as a printing drum is disposed at the center thereof, and on the left side thereof, a plate discharge section 70 for discarding the master Ma wound on the outer peripheral surface of the plate cylinder 1, and on the right side thereof On the other hand, a stencil feeding section 80 for making a stencil image corresponding to the image read by the document reading section 60 into an unprinted master and sending it out toward the plate cylinder 1 is provided. At the lower right of the apparatus main body 65, a printing pressure unit disposed under the plate cylinder 1 by separating the printing paper P stacked on the paper feeding tray 66 one by one by a paper feeding roller 111 and a separation roller pair 112. A paper feed unit 110 that feeds paper toward 120 is provided. Between the separation roller pair 112 and the printing unit 120, a registration roller pair 113 for sending the fed printing paper P to the printing unit 120 at a predetermined timing is arranged. The printing unit 120 is provided with a pressing roller 6 as a printing member having the same configuration as that of the related art. At the lower left of the apparatus main body 65, a porous transport belt 117 around which a pair of rollers 115 and 116 that rotate the printing paper P that has passed through the printing unit 120 and that rotates counterclockwise is provided below. A paper discharge unit 130 is provided, which is attracted to the conveyor belt 117 by the suction force of the suction fan 118 and is discharged to the paper discharge tray 67.
[0014]
In the stencil printing apparatus having such a configuration, when a stencil making start key on an operation panel (not shown) is operated, the plate cylinder 1 is rotated in a counterclockwise direction opposite to the rotation direction A indicated by an arrow in FIG. The rear end portion of the used master Mb on the outer peripheral surface of the plate cylinder 1 is picked up and peeled off by a pair of plate discharging roller (not shown) in the plate discharging section 70 and peeled off from the outer peripheral surface of the plate cylinder 1.
[0015]
In parallel with the plate discharge, the document reading unit 60 reads an image of the document, and an electric signal photoelectrically converted by an image sensor (not shown) is sent to an analog / digital (A / D) converter (not shown) in the apparatus main body 65. It is input and converted to a digital image signal. In parallel with the image reading, a plate making and plate supplying process is performed in the plate making and supplying section 90 based on the digitalized image information to form a plate-making master Ma. The leading end of the master Ma is sent toward the outer peripheral side of the plate cylinder 1 and hangs down toward the expanded clamper 3 (shown by a two-dot chain line) of the plate cylinder 1 in the plate feeding position shown in FIG. When the leading end of the master Ma is clamped by the clamper 3 at a predetermined timing and the plate cylinder 1 rotates in the rotation direction A, the master Ma is wound around the outer peripheral surface thereof and is not shown if it is fed out by a predetermined length. It is cut to a certain length by a cutter.
[0016]
When the master Ma of one plate is wound around the outer peripheral surface of the plate cylinder 1, plate making and plate feeding are completed, and printing is started. First, the uppermost one of the printing papers P stacked on the paper feeding table 66 is sent out to the registration roller pair 113 by the paper feeding roller 111 and the separation roller pair 112, and further sent out by the registration roller pair 113. It is sent to the printing pressure unit 120 at a predetermined timing synchronized with the rotation of the plate cylinder 1. When the sent printing paper P comes between the plate cylinder 1 and the pressing roller 6, the pressing roller 6 indicated by a solid line in FIG. By being displaced upward as described above, it is pressed against the master Ma wound on the outer peripheral surface of the plate cylinder 1. In this way, the ink oozes out from the opening 1c of the plate cylinder 1 and the perforation (not shown) of the plate-making master Ma, and the oozed ink is transferred to the surface of the printing paper P to form a print image. Is done.
[0017]
At this time, on the inner peripheral side of the plate cylinder 1, ink drops from a plurality of ink supply holes 24 a formed in the ink supply pipe 24 to an ink pool 27 formed between the ink roller 5 and the doctor roller 26. The ink is supplied to the inner peripheral surface of the plate cylinder 1 by the ink roller 5 which rotates in the same direction as the rotational direction A of the plate cylinder 1 and rotates in synchronization with the rotational speed of the plate cylinder 1 to contact the inner peripheral surface. Supplied to In addition, as the ink, for example, a W / O emulsion ink is preferably used, but is not limited to this.
[0018]
The printing paper P on which the print image has been formed in the printing pressure unit 120 is peeled off from the plate cylinder 1 by the paper discharge peeling claw 114 in the paper discharge unit 130, and is sucked by the suction fan 118 while the counterclockwise rotation of the transport belt 117. Due to the rotation in the direction, the sheet is conveyed toward the discharge tray 67 and is sequentially discharged and stacked on the discharge tray 67. In this way, the so-called test printing (also called plate printing) is completed.
After the trial printing, the number of prints is set using a numeric keypad (not shown) arranged on the operation panel (not shown), and a print start key (not shown) arranged on the operation panel is pressed to set the trial printing. In the same process, each process of paper feeding, printing, and paper discharging is repeatedly performed for the set number of prints, and all the processes of stencil printing are completed.
[0019]
Next, the configuration of the printing drum, which is a feature of the present invention, will be described. Including FIG. 7 described above and FIGS. 1 and 2 described later, the thickness of the plate cylinder 1 and the size of the opening 1c, the ink impermeable member 2a of the mesh screen 2, the ink guide member 8, the double-sided adhesive tape 18, and the like. The thickness is illustrated in an enlarged and exaggerated manner, and the dimensional ratios of the respective components are illustrated while ignoring each other.
[0020]
As shown in FIG. 2, the plate cylinder 1 has a porous support 1A and is made of stainless steel in which a large number of openings 1c are formed by, for example, an etching method (chemical corrosion method) or the like to form an opening region 1b. Is made by bending a thin plate into a cylindrical shape. The plate cylinder 1 has a predetermined elastic restoring property. End plates (not shown) are attached and fixed to both ends of the plate cylinder 1, respectively, and both end edges of the plate cylinder 1 are fixed to the outer periphery of the both end plates by fastening means such as screws. The plate cylinder 1 is rotatable together with the both end plates around a drum support shaft 24 also serving as an ink supply tube 24 shown in FIG. 3 via a rolling bearing (not shown) disposed at the center of the both end plates. Supported. The non-opening area 1a of the plate cylinder 1 is also provided at each side edge.
[0021]
As schematically shown in FIG. 4, a member called a clamper base portion 17 for holding the clamper 3 via a shaft is partially provided on the outer peripheral surface of the plate cylinder 1 in the non-perforated region 1a. It is arranged along one bus of the outer periphery. The plate cylinder 1 is driven to rotate in a rotation direction A (clockwise) and a counterclockwise direction by, for example, a main motor (not shown).
As shown in FIG. 3, the ink supply device 4 is provided with the ink roller 5 and an ink pool 27 having a wedge-shaped cross section between the ink roller 5 and the ink roller 5. It mainly comprises a doctor roller 26 to be formed, and an ink supply pipe 24 for supplying ink to the ink reservoir 27.
The ink roller 5 is formed of metal such as aluminum or stainless steel, rubber, or the like, and rotates in the rotation direction A together with the plate cylinder 1 by a gear train (not shown). The doctor roller 26 is formed of metal such as iron or stainless steel, and rotates counterclockwise by a gear train (not shown). The ink roller 5 and the doctor roller 26 are rotatably supported by an ink side plate (not shown) which is vertically provided to the ink supply pipe 24.
[0022]
As shown in FIG. 6, the ink leakage preventing member 7 has a substantially rectangular shape in plan view. As shown in FIG. 6, the double-sided adhesive tape 18 has a U-shape having three sides projecting from the outer peripheral surface of the plate cylinder 1 in plan view. The ink leakage preventing member 7 is provided with a double-sided adhesive from the front end (downstream end) in the rotation direction A of the plate cylinder 1 in the non-opening area 1a to the rear end (upstream end) of the opening area 1b. It is closely adhered with a tape 18.
[0023]
As shown in FIG. 5, the mesh screen 2 has a configuration and function as a porous elastic body including an ink-permeable mesh portion 2b and an ink-impermeable ink non-passage portion 2a. As shown in FIG. 1, the ink non-passing portion 2a is configured by attaching a belt cloth 10 as an ink non-passing member to the rear end 2c of the mesh portion 2b. The belt cloth 10 is crimped to the rear end 2c so as to sandwich the rear end 2c of the mesh portion from both sides thereof. For this reason, in the present embodiment, the rear end 2c of the mesh portion and the end 2d of the mesh portion are ink non-passing portions.
[0024]
The belt cloth 10 has a folded portion 10a formed by bending a side 10d of the porous support 1Aa that contacts the outer peripheral surface 1B. Then, the folded portion 10a is inserted into the ink leakage prevention member 7 so that the tip 10b of the folded portion 10a is positioned forward in the rotation direction of the porous support 1A, and the ink that guides the ink to the opening region 1b. An induction part is formed. The end face 10c of the tip 10b is a flat face, and in the present embodiment, is a flat face substantially perpendicular to the outer peripheral face 1B of the porous support 1A.
[0025]
The belt cloth 10 is integrally formed of, for example, a vinyl chloride (PVC) -based resin as a resin that is a material having resistance to ink infiltration. The thickness of the belt cloth 10 is preferably about 0.1 mm to 0.3 mm from the viewpoint of its functionality and assemblability. If it is less than 0.1 mm, there is a problem that the belt cloth 10 is liable to be broken or wrinkled during assembly. If it exceeds 3 mm, the members will be too strong (strength) and will rise from the plate cylinder 1 to cause so-called assail leakage, respectively. Therefore, the above range is appropriate.
[0026]
In FIG. 1 (FIG. 7), reference numeral 15 indicates a pressing range in which the pressing force of the pressing roller 6 acts. The pressing range 15 is, as shown in FIG. 1, from the vicinity of the rear end of the front margin of the master Ma whose front end is held by the clamper 3 shown in FIG. 3 or FIG. The pressing force of the pressing roller 6 does not act on the rear end of the opening region 1b of the plate cylinder 1 existing on the lower surface 10d of the ink non-passing portion 2a in this embodiment. Is configured.
[0027]
In mounting and assembling the mesh screen 2 on the plate cylinder 1, the belt cloth 10 shown in FIG. 1 is bent and folded, the leading end 10b is positioned on the opening area 1b side, and the folded part 10a is turned into an ink leakage preventing member. 7, a space 20 is formed between the front end 10b, the mesh screen 2, and the aperture area 1b of the porous support 1A by inserting the inner side of the substantially bag-shaped opening 7a into the inner side (right side in the figure). You. Accordingly, the tip 10b serving as an ink guiding portion is configured to prevent the ink that leaks out from between the plate cylinder 1 and the mesh screen 2 from leaking backward from the portion where the tip 10b is disposed.
[0028]
In the printing drum 1 having such a configuration, at the time of printing, the printing drum 1 is pressed in the radial direction by the pressing roller 6 while rotating in the rotation direction A in FIG. A part of the ink extruded from the inside of the plate cylinder 1 by the pressing of the pressing roller 6 is diffused by the mesh portion 2b of the mesh screen 2, oozes uniformly from the perforated portion of the master Ma, and is transferred to the printing paper P. A part of the surplus ink which is used for printing but is not used for printing is squeezed out between the plate cylinder 1 and the mesh screen 2 by the rotation of the plate cylinder 1 to the rear thereof and enters the space 20. Accumulate.
[0029]
As shown in FIG. 1, excess ink accumulated in the space 20 is caused to flow by the plate cylinder 1 due to its own fluid pressure from the opening 1c at the rear end of the opening area 1b by the end face 10c of the front end 10b of the belt cloth 10. Is prevented from leaking from the rear end 2c of the mesh portion 2b of the mesh screen 2 to the downstream side. Thus, even when the stencil printing apparatus is used for a long period of time, it is possible to prevent the ink from leaking from the rear end side in the rotation direction of the plate cylinder 1, and to prevent the inside of the apparatus and the printed matter from being stained.
[0030]
The stencil printing apparatus to which the present invention is applied is not limited to the stencil printing integrated type thermosensitive digital type shown in FIG. 3, but is of the type that supplies ink from the inside of the plate cylinder to the stencil master on the plate cylinder. If it is provided, it goes without saying that the present invention can be applied to various stencil printing apparatuses such as a stencil printing apparatus dedicated to the A4 size, a multicolor stencil printing apparatus, or a double-sided stencil printing apparatus.
[0031]
【The invention's effect】
According to the present invention, when the folded portion is engaged with the ink leakage preventing member so that the tip of the folded portion formed by folding the ink non-passing portion is located forward in the rotation direction of the porous support, Since the thickness of the bent portion of the ink non-passing portion on the hole region side is reduced, the space for storing the ink is reduced, and the ink accumulated in the space by the tip of the folded portion can be returned to the inside of the printing drum, Ink tail leakage can be prevented. In particular, by making the shape of the tip of the folded portion a flat surface, the ink accumulated in the space is not guided to the mesh screen as the porous support, but is guided to the open area of the porous support, Ink tail leakage can be prevented.
[Brief description of the drawings]
FIG. 1 is an enlarged view showing a configuration of a bent portion of a porous elastic body having an ink non-passing portion according to an embodiment of the present invention.
FIG. 2 is a partially broken plan view when the printing drum according to the present invention is developed.
FIG. 3 is an overall configuration diagram of a stencil printing apparatus to which the present invention is applied.
FIG. 4 is a perspective view of a main part around a printing drum and a printing pressure member in FIG. 3;
FIG. 5 is a perspective view of a main part around a printing drum and a mesh screen in FIG. 3;
FIG. 6 is a perspective view of a main part showing an arrangement state of an ink leakage preventing member and a double-sided adhesive tape in FIG. 3 with respect to a printing drum.
FIG. 7 is an enlarged view showing a configuration of a bent portion of a conventional porous elastic body having an ink non-passing portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printing drum 1a Non-open area 1b Open area 1A Porous support 2 Porous elastic body (mesh screen)
2a Ink non-passing portion 2c Rear end 6 of porous elastic body Printing pressure member 7 Ink leakage preventing member 7a Opening portion 10 Ink non-passing member (belt cloth)
10a folded portion 10b tip 10c of folded portion end face A rotation direction Ma stencil sheet P printing paper

Claims (5)

A cylindrical porous support having an ink-permeable porous open area and an ink-impermeable non-open area; and a rotation of the porous support on the outer peripheral surface of the porous support. In the rear of the direction, an ink leakage prevention member closely contacted with the non-opening area so that the open side faces the open area, and a portion corresponding to the rear end of the open area wound around the outer peripheral surface. In a printing drum provided with a porous elastic body comprising an ink non-passing portion,
The side of the ink non-passing portion that is in contact with the outer peripheral surface is bent to form a folded portion, and the folded portion is formed with the ink so that the tip of the folded portion is located forward in the rotation direction of the porous support. A printing drum, wherein an ink guide portion is formed to engage the leak prevention member to guide ink to the opening area. The printing drum according to claim 1,
A printing drum, wherein an end face of a tip of the folded portion is flat. The printing drum according to claim 1 or 2,
The printing drum, wherein the ink non-passing part is configured by mounting an ink non-passing member at a rear end of the porous elastic body. The printing drum according to claim 1, 2 or 3,
The printing drum, wherein the porous elastic body is a mesh screen. In a stencil printing apparatus comprising: a printing drum around which a stencil sheet is wound around its outer peripheral surface;
A stencil printing apparatus comprising the printing drum according to any one of claims 1 to 4 as the printing drum.

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