Stencil printer

Abstract

To prevent overflowing without generating any ink waste.SOLUTION: A stencil printer comprises: a squeezee roller 21 inscribed in a print drum 20 and rotated to supply ink; a doctor roller 22 disposed so as to form a prescribed gap from a peripheral surface of the squeezee roller 21; ink supply means 24 for supplying ink to an ink supply position of the squeezee roller 21; and an ink drive rod 25 disposed in parallel with the squeezee roller 21 in an ink reservoir formed between the squeezee roller 21 and the doctor roller 22 to be rotary-driven. The ink drive rod 25 is driven to be able to increase / decrease a distance to the squeezee roller 21. When a leaving period of the print drum 21 is equal to or longer than a prescribed time, the ink drive rod 25 is brought close to the print drum 20, and thickening ink stuck to an outer peripheral part of the ink drive rod 25 is removed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a stencil printing machine that prevents ink from being wasted and prevents overflow. [Background technology]

[0002] In a stencil printing machine, a sheet of paper is pressed against a master wound around a drum by a press roller, and ink in the drum is transferred through the perforations in the master to the sheet of paper, thereby printing an image.

[0003] Ink is supplied to the ink supply position of the ink supply roller, and a drive rod that is arranged parallel to the ink supply roller and is driven to rotate is provided in an ink reservoir formed between the ink supply roller and the ink control roller.

[0004] When ink is left for a long period of time, the water content evaporates and the ink thickens. This thickened ink clings to the outer surface of the drive rod. Because the thickened ink is difficult to mix with newly supplied ink, the ink dispersion effect caused by the rotation of the drive rod is hindered.

[0005] As a result, the supplied ink accumulates near the ink supply section of the distributor, causing the distribution of the ink volume in the ink pool to be uneven along the central axis. When this difference in ink vortex diameter occurs, if the vortex diameter of the ink sensor, which detects the ink vortex diameter and controls whether or not ink is supplied, is small, it will be determined that there is an ink shortage, resulting in an oversupply of ink. In this case, there is a possibility that some of the ink will not pass through the gap between the ink supply roller and ink control roller and will spill over the top of the ink control roller, a phenomenon known as overflow.

[0006] If overflow occurs, the uniform supply of ink to the inner peripheral surface of the printing drum by the ink layer is hindered, resulting in a decrease in print quality.

[0007] The technology described in Patent Document 1 discloses a stencil printing device equipped with an ink equalization means that can move between a retracted position where it is retracted from the ink receiving section and an advanced position where it is advanced into the ink receiving section, and that equalizes the distribution of ink volume in the ink pool in the direction of the rotation axis of the printing drum by moving from the retracted position to the advanced position. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-84300 Summary of the Invention [Problem to be solved by the invention]

[0009] However, with the technology described in Patent Document 1, ink adheres to the end face of the ink equalization means, resulting in wasted ink, and it is difficult to adequately remove thickened ink that adheres to the outer periphery of the drive rod after being left unused for a long period of time.

[0010] SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stencil printing machine which can prevent ink overflow without causing ink waste. [Means for solving the problem]

[0011] In order to achieve the above object, the stencil printing apparatus according to the present invention is characterized by: an ink supply roller that is in contact with the printing drum and rotates to supply ink; an ink control roller disposed parallel to the ink supply roller so as to form a predetermined gap between the ink control roller and the circumferential surface of the ink supply roller; an ink supply unit that supplies ink to an ink supply position of the ink supply roller; a drive rod disposed in an ink reservoir formed between the ink supply roller and the ink control roller and rotated in parallel with the ink supply roller, The drive rod can be driven to increase or decrease the distance from the ink supply roller, and when the printing drum has been left unused for a predetermined period of time or longer, the drive rod is moved closer to the ink supply roller to remove thickened ink adhering to the outer periphery of the drive rod. [Effects of the Invention]

[0012] According to the features of the stencil printing machine of the present invention, overflow can be prevented without causing waste of ink. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of a stencil printing apparatus according to an embodiment of the present invention; [Figure 2] (a) is a plan view of the vicinity of a squeegee roller provided in a stencil printing apparatus according to one embodiment of the present invention, and (b) is a side view of the vicinity of a squeegee roller provided in a stencil printing apparatus according to one embodiment of the present invention. [Figure 3] FIG. 1(a) is an explanatory diagram illustrating the state of ink around the ink drive rod under normal conditions, and FIG. 1(b) is an explanatory diagram illustrating the state of ink around the ink drive rod after long-term unused use. [Figure 4] 5(a) to 5(c) are explanatory views for explaining the removal of thickened ink adhering to the outer periphery of an ink drive rod in a stencil printing machine according to one embodiment of the present invention. [Figure 5] 1 is an explanatory diagram illustrating a driving mechanism for an ink driving rod provided in a stencil printing machine according to an embodiment of the present invention; [Figure 6] 1 is an explanatory diagram illustrating a driving mechanism for an ink driving rod provided in a stencil printing machine according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual product. Furthermore, the drawings may include parts with different dimensional relationships and ratios.

[0015] Furthermore, the embodiments shown below are merely examples of devices that embody the technical concept of the present invention, and the technical concept of the present invention does not limit the arrangement of each component to that shown below. Various modifications can be made to the technical concept of the present invention within the scope of the claims.

[0016] FIG. 1 is a schematic diagram of a stencil printing machine according to one embodiment of the present invention.

[0017] As shown in Fig. 1, the stencil printing machine 10 has a control unit 11 and a printing unit 13. Printing paper is fed from a paper feed unit 14 to the printing unit 13, and printing paper printed in the printing unit 13 is discharged to a paper discharge unit 15. Each unit of the stencil printing machine 10 is controlled collectively by the control unit 11.

[0018] The printing unit 13 has a cylindrical printing drum 20, a squeegee roller (ink supply roller) 21 provided inside the printing drum 20, and a doctor roller (ink control roller) 22 arranged adjacent to the squeegee roller 21.

[0019] The printing drum 20 is supported rotatably about a rotation axis extending in its axial direction (a direction perpendicular to the plane of the paper in FIG. 1), and is driven to rotate by the driving force of a drum drive unit (not shown). The printing drum 20 is ink permeable, and a stencil paper (not shown) made in a stencil making unit (not shown) is wound around the outer circumferential surface of the printing drum 20.

[0020] The squeegee roller 21 and the doctor roller 22 are each cylindrical members extending in the direction of the rotation axis of the printing drum 20. The squeegee roller 21 is supported so as to be rotatable about a rotation axis parallel to the rotation axis of the printing drum 20. The doctor roller 22 is fixed to the squeegee roller 21 with a specified gap therebetween.

[0021] An ink receiving section 23 extending in the direction of the rotation axis of the print drum 20 is formed between the squeegee roller 21 and the doctor roller 22. Ink is supplied to the ink receiving section 23 from ink supply means 24. The ink supply means 24 has an ink bottle 24a filled with ink, and an ink discharge section 24b that discharges ink from the ink bottle 24a into the ink receiving section 23. The ink supplied from the ink supply means 24 is stored in the ink receiving section 23 and forms an ink pool IR extending in the direction of the rotation axis of the print drum 20.

[0022] The ink stored in the ink pool IR forms an ink film on the outer peripheral surface of the squeegee roller 21, with the amount of ink supplied being adjusted by the gap between the squeegee roller 21 and the doctor roller 22. The squeegee roller 21 is positioned with a small gap from the inner peripheral surface of the printing drum 20, and is inscribed on the inner peripheral surface of the printing drum 20 via the ink film on the outer peripheral surface of the squeegee roller 21. During printing, the printing drum 20 rotates in the direction F1 in Figure 2, and the squeegee roller 21 rotates in the direction F2 accordingly. When the squeegee roller 21 rotates in the direction F2, ink is drawn out of the ink pool IR and supplied to the portion of the squeegee roller 21 that is inscribed on the printing drum 20.

[0023] An ink drive rod 25 is provided in the ink receiver 23. The ink drive rod 25 extends in the direction of the rotation axis of the print drum 20 and is driven to rotate by a drive means, which will be described later. The rotation of the squeegee roller 21 and the ink drive rod 25 causes the ink in the ink reservoir IR to flow, and the ink is extended in the direction of the rotation axis of the print drum 20. As will be described later, the ink drive rod 25 is provided so as to be driveable to increase or decrease the distance from the squeegee roller (ink supply roller) 21.

[0024] A press roller 29 is provided on the outside of the printing drum 20. In synchronization with the rotation of the printing drum 20, printing paper P transported from the paper feed section 14 is supplied between the printing drum 20 and the press roller 29. The press roller 29 presses the printing paper P against the stencil paper on the outer peripheral surface of the printing drum 20. This pressure causes ink from the printing drum 20 to pass through the holes in the stencil paper and transfer to the printing paper P, thereby performing stencil printing. The printing drum 20 rotates a predetermined amount in the direction F1, and when printing on one sheet of printing paper P is completed, the printed printing paper P is peeled off from the printing drum 20 and discharged to the paper discharge section 15.

[0025] When printing is performed by the printing unit 13, ink in the ink reservoir IR is supplied to the print drum 20 via the squeegee roller 21 and consumed. An ink sensor 27 that detects the amount of ink in the ink reservoir IR is provided near the ink receiver 23. When the ink sensor 27 detects a decrease in the ink in the ink reservoir IR, the control unit 11 causes ink to be supplied from the ink supply means 24 to replenish the consumed ink.

[0026] Figure 2(a) is a plan view of the vicinity of the squeegee roller 21 provided in a stencil printing apparatus 10 according to one embodiment of the present invention, and Figure 2(b) is a side view of the vicinity of the squeegee roller 21 provided in a stencil printing apparatus according to one embodiment of the present invention.

[0027] As shown in FIGS. 2(a) and 2(b), the ink drive rod 25 is supported by an ink drive rod support member 26.

[0028] When the rotary shaft 36 is rotated by driving means such as a motor (not shown), the transmission gear 33 fixed to the rotary shaft 36 rotates in accordance with the rotation of the rotary shaft 36. The drive force transmitted by the transmission gear 33 rotates the fulcrum shaft 34 to which the pulley 37 is fixed.

[0029] An endless belt 32 is stretched between the pulleys 37 and 38, and when the pulley 37 rotates, the ink drive rod 25 to which the pulley 38 is fixed is driven to rotate.

[0030] Further, the squeegee roller 21 is rotationally driven by the drive transmission of the transmission gear 33 via the endless belt 31 .

[0031] Here, the cause of overflow from the ink pool IR will be described in detail.

[0032] FIG. 3(a) is an explanatory diagram that schematically illustrates the state of ink around the ink drive rod 25 under normal conditions, and FIG. 3(b) is an explanatory diagram that schematically illustrates the state of ink around the ink drive rod 25 after long-term use.

[0033] As shown in Figure 3(a), under normal conditions where the ink has not been left unused for a long period of time, old ink IR1 around the ink drive rod 25 and new ink IR2 newly ejected from the ink ejection section 24b onto the ink IR1 are mixed together, and the rotation of the ink drive rod 25 disperses the ink in the direction of the rotation axis, making the vortex diameter uniform.

[0034] On the other hand, as shown in Figure 3(b), if the ink sensor 27 is left unused for a long period of time, the old ink IR1 around the ink drive rod 25 becomes thickened ink IR11, which has a high viscosity. This thickened ink IR11 does not easily mix with new ink IR2 newly ejected from the ink ejection unit 24b onto the thickened ink IR1. Therefore, even if the ink drive rod 25 is rotated, the ink does not easily disperse in the direction of the rotation axis, and the vortex diameter does not become uniform, causing the ink IR2 to accumulate near the ink ejection unit 24b. As a result, new ink IR2 is ejected from the ink ejection unit 24b without the ink sensor 27 detecting a decrease in ink, and the ejected new ink IR2 overflows.

[0035] Therefore, in the stencil printing apparatus 10 according to one embodiment of the present invention, the thickened ink IR11 adhering to the outer periphery of the ink drive rod 25 is removed. Specifically, when the printing drum 20 has been left unused for a predetermined time or longer, the control unit 11 moves the ink drive rod 25 closer to the squeegee roller (ink supply roller) 21, and removes the thickened ink IR11 adhering to the outer periphery of the ink drive rod 25.

[0036] 4(a) to 4(c) are explanatory diagrams that schematically explain the removal of thickened ink adhering to the outer periphery of the ink drive rod 25 in the stencil printing machine 10 according to one embodiment of the present invention.

[0037] As shown in FIG. 4(a), when the print drum 20 is left unused for a predetermined period of time or longer, the old ink IR1 around the ink drive rod 25 may become thickened ink IR11 with increased viscosity.

[0038] Therefore, in order to prevent overflow, the control unit 11 moves the ink drive rod 25 in the direction F3 so as to bring the ink drive rod 25 closer to the squeegee roller (ink supply roller) 21, as shown in FIG. 4(b).

[0039] This causes the squeegee roller 21 to scrape off the thickened ink IR11 around the ink drive rod 25, which has become more viscous.

[0040] Then, after the squeegee roller 21 has scraped off the thickened ink IR11, the ink drive rod 25 is moved in the direction F4 so as to move away from the squeegee roller (ink supply roller) 21 to the printing position, as shown in Figure 4(c).

[0041] As a result, the amount of thickened ink IR11 decreases, and new ink IR2 newly ejected from the ink ejection unit 24b mixes with the ink IR1, and the rotation of the ink drive rod 25 disperses the ink in the direction of the rotation axis, making the vortex diameter uniform, thereby preventing ink overflow.

[0042] 5 and 6 are explanatory diagrams illustrating the drive mechanism of the ink drive rod 25 provided in the stencil printing machine 10 according to one embodiment of the present invention. Fig. 5 shows the state during normal printing, and Fig. 6 shows the state during ink scraping.

[0043] As shown in Figures 5(a) and (b), the ink drive rod 25 is supported by one end of the ink drive rod support member 26, and a spring 44 is attached to the other end of the ink drive rod support member 26 as a biasing means.

[0044] A cam 42 is provided near the ink drive rod support member 26 so as to come into contact with the ink drive rod support member 26. The cam 42 has an eccentric rotation shaft 42a, and when rotational drive is transmitted via the transmission gear 33, the cam 42 rotates about the rotation shaft 42a, and this rotation, together with the biasing force of the spring 44, moves the ink drive rod support member 26 in the vertical direction.

[0045] In the example shown in Figures 5(a) and (b), during normal printing, the control unit 11 rotates the cam 42 to a predetermined first rotation angle, thereby moving the ink drive rod 25 in the F4 direction so as to move the ink drive rod 25 away from the squeegee roller (ink supply roller) 21 to the printing position.

[0046] 6(a) and 6(b), when scraping off ink, the control unit 11 rotates the cam 42 to a predetermined second rotation angle, thereby moving the ink drive rod 25 in the direction F3 so as to bring the ink drive rod 25 closer to the squeegee roller (ink supply roller) 21. This causes the squeegee roller 21 to scrape off the thickened ink IR11 around the ink drive rod 25, which has become more viscous.

[0047] (Addendum) The present application discloses the following inventions.

[0048] (Appendix 1) an ink supply roller that is in contact with the printing drum and rotates to supply ink; an ink control roller disposed parallel to the ink supply roller so as to form a predetermined gap between the ink control roller and the circumferential surface of the ink supply roller; an ink supply unit that supplies ink to an ink supply position of the ink supply roller; a drive rod disposed in an ink reservoir formed between the ink supply roller and the ink control roller and rotated in parallel with the ink supply roller, a driving rod that can be driven to increase or decrease the distance from the ink supply roller, and when the printing drum has been left unused for a predetermined time or longer, the driving rod is moved closer to the ink supply roller to remove thickened ink adhering to the outer periphery of the driving rod.

[0049] This allows the ink supply roller to scrape off and remove the thickened ink adhering to the outer periphery of the drive rod, so that new ink ejected from the ink supply unit is dispersed in the direction of the rotation axis by the rotation of the ink drive rod, making the vortex diameter uniform, thereby preventing overflow without wasting ink. [Explanation of symbols]

[0050] 10 Stencil printing device 11 Control section 13 Printing Department 14 Paper feed section 15 Paper output section 20 printing drums 21 Squeegee roller (ink supply roller) 22 Doctor roller (ink control roller) 23 Ink receiver 24 Ink supply means 24a ink bottle 24b Ink ejection section 25 Ink Drive Rod 26 Ink drive rod support member 27 Ink sensor 29 Press roller 31,32 Endless belt 33 Transmission gear 34 Fulcrum Axis 36 Rotation axis 37,38 Pulley 42 Cam 42a Rotation axis 44 Spring

Claims

[Claim 1] an ink supply roller that is in contact with the printing drum and rotates to supply ink; an ink control roller disposed parallel to the ink supply roller so as to form a predetermined gap between the ink control roller and the circumferential surface of the ink supply roller; an ink supply unit that supplies ink to an ink supply position of the ink supply roller; a drive rod disposed in an ink reservoir formed between the ink supply roller and the ink control roller and rotated in parallel with the ink supply roller, a driving rod that can be driven to increase or decrease the distance from the ink supply roller, and when the printing drum has been left unused for a predetermined time or longer, the driving rod is moved closer to the ink supply roller to remove thickened ink adhering to the outer periphery of the driving rod.

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