Offset printing system and temperature control device

Abstract

To provide an offset printing system which can adjust a plate surface temperature without using damping water.SOLUTION: An offset printing system 100 includes an offset printing machine 3, and a temperature control device 2, wherein the offset printing machine 3 includes a plate cylinder 31, and a blanket cylinder 32. The temperature control device 2 includes a temperature control machine 6 for generating temperature control air A, a blowout duct 7 provided with a slit, and a connection duct 8 for supplying the temperature control air A generated by the temperature control machine to the blowout duct 7. The temperature control air A supplied to the blowout duct 7 is blown out toward an opposite position to the plate cylinder 31 and the blanket cylinder 32. A plurality of partition plates arranged at intervals in a predetermined direction are provided in the blowout duct, and a surface area of the plurality of partition plates gradually increases toward the other end face from the end face connected with the connection duct 8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an offset printing system and a temperature control device used therein. [Background technology]

[0002] Conventionally, offset printing involves transferring ink from a plate to a blanket cylinder, which then transfers it to paper for printing. This type of offset printing can be divided into water-based printing, which uses dampening water, and waterless printing, which does not. Dampening water contains harmful substances such as etching solutions, and must be disposed of as industrial waste. Therefore, from an environmental conservation perspective, it is preferable to use waterless printing, which does not use dampening water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2017 / 077825 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the amount of DG (dot gain) affects the color quality of printed materials, and the Japan Society of Printing Science and Technology (Japan Color), a general incorporated association, requires that the tolerance for DG amount be within ±3%. In order to control the color reproduction of color printing, the amount of DG must be kept within a certain tolerance range, but if the plate surface temperature (ink temperature) is too high, the amount of DG will be too thick, and if the plate surface temperature is too low, the amount of DG will be too thin, leading to a decrease in color quality.

[0005] More specifically, when an offset printing machine is operated, the temperature of the plate surface rises, and as the temperature of the plate surface rises, the amount of DG also increases. Furthermore, the faster the printing speed, the higher the plate surface temperature. In water-based printing, dampening water cools the plate, so the cooling effect of dampening water can be used to suppress increases in the amount of DG. However, in waterless printing, the cooling effect of dampening water cannot be obtained.

[0006] In particular, with waterless UV printing using UV ink, even at printing speeds of 10,000 / rph or less, after printing around 3,000 sheets, the amount of DG increases due to a rise in plate surface temperature, causing color unevenness and background scumming, among other problems at high temperatures.

[0007] On the other hand, during winter or when the machine is stopped for an extended period of time, if the plate surface temperature falls below the lower limit of the optimum temperature range, the GD amount decreases, and problems such as peeling of the printing paper, poor ink transfer adhesion, and edge picking occur.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an offset printing system capable of adjusting the plate surface temperature without using dampening water, and a temperature adjusting device used therein. [Means for solving the problem]

[0009] The offset printing system according to the present invention comprises an offset printing press for printing on a printing medium transported in a predetermined direction, and a temperature control device, the offset printing press comprising a plate cylinder having a printing plate on its circumferential surface, and a blanket cylinder disposed opposite the plate cylinder, the temperature control device comprising a temperature control device that generates temperature-controlled air for cooling or heating the offset printing press, an outlet duct provided with a slit, and a connection duct for supplying the temperature-controlled air generated by the temperature control device to the outlet duct, and the temperature-controlled air supplied to the outlet duct The temperature-controlled air is blown out from the slit toward a position facing the plate cylinder and the blanket cylinder, the blow-out duct has a first end face and a second end face facing each other in a predetermined direction, and a side face extending in the predetermined direction, the first end face has a connection hole to which the connection duct connects, the slit is provided in the side face, the blow-out duct is provided with a plurality of partition plates arranged at intervals in the predetermined direction, and the surface areas of the plurality of partition plates gradually increase from the first end face toward the second end face.

[0010] Furthermore, the temperature control device of the present invention is a temperature control device used in the above-mentioned offset printing system, and comprises: a temperature controller for generating temperature-controlled air; an outlet duct provided with a slit for blowing out the temperature-controlled air supplied from the temperature controller; and a connection duct for supplying the temperature-controlled air generated by the temperature controller to the outlet duct, wherein the outlet duct has a first end face and a second end face facing each other in a predetermined direction, and a side face extending in the predetermined direction, wherein the first end face has a connection hole to which the connection duct connects, and the slit is provided in the side face, and the outlet duct is provided with a plurality of partition plates arranged at intervals in the predetermined direction, and the surface area of ​​the plurality of partition plates gradually increases from the first end face to the second end face. [Effects of the Invention]

[0011] According to the offset printing system and temperature control device of the present invention, the plate cylinder can be cooled by the temperature-controlled air generated by the temperature control machine, eliminating the need for dampening water. In addition, since the blow-out duct is provided with multiple partition plates, the volume of the temperature-controlled air blown out from the slit can be made uniform in the longitudinal direction of the slit, allowing the plate cylinder to be cooled or heated uniformly without unevenness. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an offset printing system according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of a main part of the offset printing system shown in FIG. [Figure 3] 2A and 2B are diagrams showing an air outlet duct provided in the offset printing system shown in FIG. 1, in which (a) is an external perspective view and (b) is a see-through perspective view. [Figure 4] FIG. 4 is a plan view of the outlet duct shown in FIG. 3. [Figure 5] Table showing the results of the demonstration experiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An offset printing system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0014] 1, an offset printing system 100 according to this embodiment includes a printing apparatus 1 and a temperature control apparatus 2. The printing apparatus 1 includes four offset printing machines 3 corresponding to the four colors CMYK, a paper feed unit 4 that supplies a printing substrate (not shown) to the offset printing machines 3, and a paper discharge unit 5 from which the printing substrate is discharged after printing, and the printing substrate is transported from the paper feed unit 4 toward the paper discharge unit 5 in a predetermined transport direction D1.

[0015] Each offset printing press 3 includes a plate cylinder 31 with a printing plate mounted on its peripheral surface, a blanket cylinder 32 arranged opposite the plate cylinder 31, an impression cylinder 33 for bringing the material to be printed into contact with the blanket cylinder 32 at a nip, a transfer cylinder 34 for transporting the material to be printed, drive means (not shown) for driving the plate cylinder 31, blanket cylinder 32, impression cylinder 33, and transfer cylinder 34 to rotate in the directions of the arrows, and an ink supply device (not shown) for supplying ink to the plate cylinder 31. The plate cylinder 31, blanket cylinder 32, impression cylinder 33, and transfer cylinder 34 are each configured as a cylinder with a rotation axis in a predetermined direction D2 (a direction perpendicular to the plane of the paper in FIG. 1 / see FIG. 3) perpendicular to the transport direction D1.

[0016] Ink supplied to plate cylinder 31 from an ink supply device (not shown) is transferred to blanket cylinder 32 at a position where plate cylinder 31 and blanket cylinder 32 face each other. The printing substrate is a sheet-like material such as paper or a resin sheet, and the ink transferred to blanket cylinder 32 is transferred to the printing substrate at the nip between blanket cylinder 32 and impression cylinder 33, where it is printed.

[0017] Each offset printing press 3 further has a frame 35, which rotatably supports the plate cylinder 31, blanket cylinder 32, impression cylinder 33, and transfer cylinder 34. As shown in Figure 2, the frame 35 is provided with an air intake 35a and ventilation holes 35b. The air intake 35a is located upstream of the opposing position of the plate cylinder 31 and blanket cylinder 32 in the conveying direction D1, and extends along the predetermined direction D2 (Figure 3). The ventilation hole 35b is located above the air intake 35a.

[0018] Referring to Figure 1, the temperature control device 2 includes a temperature control machine 6 for generating temperature-controlled air (cool air or hot air), four blow-out ducts 7 provided corresponding to the four offset printing machines 3, and a connection duct 8 for supplying the temperature-controlled air generated by the temperature control machine 6 to each blow-out duct 7.

[0019] The temperature controller 6 has a cooling mode, a heating mode, and a standby mode. In the cooling mode, it takes in air from outside (air inside the factory where the temperature controller 6 is installed, hereinafter referred to as "ambient air") and cools it to a predetermined lowering temperature to generate cool air, which is then supplied as temperature-controlled air to the outlet duct 7 via the connecting duct 8. In the heating mode, it takes in ambient air and heats it to a predetermined raising temperature to generate warm air, which is then supplied as temperature-controlled air to the outlet duct 7 via the connecting duct 8. In the standby mode, the generation of temperature-controlled air is stopped.

[0020] In this embodiment, the lowering temperature in the cooling mode is set to 10°C or less. That is, the temperature difference between the ambient air and the cool air is set to 10°C or less. For example, if the ambient air is 25°C and the lowering temperature is 10°C, the temperature controller 6 generates cool air of 15°C. Also, the raising temperature in the heating mode is set to 10°C or more, so that the temperature difference between the ambient air and the warm air is 10°C or more. For example, if the ambient air is 15°C and the raising temperature is 10°C, the temperature controller 6 generates warm air of 25°C.

[0021] There is no limitation on the method of mode switching of the temperature regulator 6, and for example, it may be automatically switched in response to the plate surface temperature (surface temperature of the plate cylinder 31) or the air temperature, or it may be manually switched by an operator based on the plate surface temperature, DG amount, etc. The structure of the temperature regulator 6 is well known, so a detailed description will be omitted.

[0022] The connecting duct 8 has a main duct 81 connected to the temperature controller 6 and multiple branch ducts 82 branching off from the main duct 81 toward each blow-out duct 7, and it is preferable to use a flexible duct for each branch duct 82.

[0023] 3 and 4, each blowout duct 7 is box-shaped and elongated in a predetermined direction D2, and has a side surface 71 extending in the predetermined direction D2 and facing the corresponding offset printing press 3, a first end surface 72 and a second end surface 73 facing each other in the predetermined direction D2, an upper surface 74, and a lower surface 75. The side surface 71 is provided with a slit 70 extending along the predetermined direction D2. The side surface 71 is also provided with a recessed step 71a above the slit 70, giving the blowout duct 7 an L-shaped vertical cross section. The upper surface 74 is provided with a pair of grips 76.

[0024] The first end surface 72 is provided with a connection hole 72a to which the branch duct 82 of the connection duct 8 is connected, thereby allowing the internal space of the connection duct 8 and the internal space S of the blow-out duct 7 to communicate with each other via the connection hole 72a.

[0025] The internal space S of the discharge duct 7 is provided with a plurality of partition plates 9 (four partition plates 91, 92, 93, and 94 in this embodiment) spaced apart in a predetermined direction D2, and the lower edge 9a and both side edges 9b and 9c of each partition plate 9 abut the internal surface of the discharge duct 7 that defines the internal space S. The surface areas of these partition plates 9 gradually increase from the first end face 72 to the second end face 73. That is, the surface areas of the partition plates 9 increase in the order of 91, 92, 93, and 94. In other words, the height of the partition plates 9 gradually increases from the first end face 72 to the second end face 73 (the heights of the partition plates 91, 92, 93, and 94 increase in the order of 91, 92, 93, and 94).

[0026] Such an air outlet duct 7 is disposed so that the side surface 71 faces the air intake port 35a of the corresponding offset printing machine 3.

[0027] In this configuration, the ambient air taken in by the temperature regulator 6 is cooled or heated as described above depending on the mode of the temperature regulator 6, sent to each blow-out duct 7, and blown out as temperature-controlled air A (FIG. 2) from slits 70 of the blow-out duct 7 toward the opposing positions of the plate cylinder 31 and blanket cylinder 32. The temperature-controlled air A blown out in this manner enters the inside of the offset printing press 3 through the air intake port 35a and cools or heats the plate cylinder 31 and blanket cylinder 32.

[0028] Here, because the above-mentioned partition plate 9 is provided in the blowout duct 7, the volume of the temperature-controlled air A blown out from the slit 70 is uniform throughout the entire area in the predetermined direction D2. In other words, if the partition plate 9 were not used, the volume of the temperature-controlled air A blown out from the slit 70 would increase as it approaches the second end face 73 from the first end face 72 (connection hole 72a to which the branch duct 82 is connected), and the plate cylinder 31 and the blanket cylinder 32 would not be cooled or heated uniformly.

[0029] In contrast to this, in this embodiment, by providing partition plates 9 with different surface areas in the blow-out duct 7, the air volume of the temperature-controlled air A blown out from the slit 70 is made uniform throughout the entire area in the specified direction D2, so that the plate cylinder 31 and blanket cylinder 32 can be cooled or heated uniformly and evenly throughout the entire area in the specified direction D2.

[0030] Furthermore, if the temperature to which the air is lowered by the temperature regulator 6 (i.e., the temperature difference before and after cooling the air) exceeds 10°C, the temperature difference between the ambient air and the cooled air (cold air) becomes large, causing dew to form, and the temperature regulator 6 cannot be used while the dew is being removed. However, in this embodiment, the temperature to which the air is lowered by the temperature regulator 6 is set to within 10°C, so the formation of dew can be prevented. Furthermore, even if the temperature-controlled air (cold air) A is only 10°C lower than the ambient air, a sufficient cooling effect can be obtained for the plate cylinder 31 and the blanket cylinder 32.

[0031] On the other hand, the temperature of the air raised by the temperature regulator 6 is set to 10° C. or higher, so the plate surface temperature can be raised efficiently.

[0032] Furthermore, since the side surface 71 of the blow-out duct 7 is provided with the recessed step 71a, the blow-out duct 7 can be prevented from blocking the vent opening 35b.

[0033] Furthermore, in this embodiment, the temperature-controlled airflow A is blown from the upstream side in the conveyance direction D1 (along the conveyance direction), preventing damage to the substrate. Specifically, thin paper with a thickness of 0.05 mm to 0.8 mm is typically used as the substrate. Especially when thin paper is used as the substrate, blowing the temperature-controlled airflow A from the downstream side in the conveyance direction D1 can cause the substrate to flutter, potentially resulting in damage. In contrast, blowing the temperature-controlled airflow A from the upstream side in the conveyance direction D1 can prevent such fluttering of the substrate. Furthermore, because the opposing positions of the plate cylinder 31 and blanket cylinder 32 are a certain distance from the conveyance path of the substrate, the temperature-controlled airflow A does not directly hit the substrate, thereby preventing fluttering of the substrate.

[0034] [Example] A demonstration experiment was conducted to confirm the effects of the offset printing system according to the above embodiment. The results of the demonstration experiment are shown in FIG.

[0035] In this demonstration experiment, an offset printing system equipped with eight offset printing presses 3 capable of double-sided printing was used, and the DG amount was measured for each offset printing press 3 when cooling was performed using temperature-controlled air (cool air) A (cool air) as described above (Example) and when cooling with temperature-controlled air (cool air) A was not performed (Comparative Example). The printing substrate used was high-quality paper, which is easily affected by temperature changes. The temperature inside the factory during the experiment was 25°C, and the temperature reduced by the temperature controller 6 was 10°C (i.e., the temperature of temperature-controlled air A was 15°C).

[0036] In the example, the DG amount was measured after printing 18,000 sheets at a printing speed of 14,000 / rph, and in the comparative example, the DG amount was measured after printing 3,000 sheets at a printing speed of 10,000 / rph.

[0037] As a result, in the comparative example, the DG amount exceeded the allowable range of ±3% in all eight offset printing presses 3, but in the example, despite the printing speed being faster than in the comparative example, a DG amount within ±3% was achieved in all eight offset printing presses 3. If a printing substrate that is less susceptible to temperature changes (for example, coated paper) is used, further stability in quality (DG amount) can be expected.

[0038] The offset printing system according to an embodiment of the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such an embodiment, and various modifications and alterations are possible without departing from the scope of the present invention.

[0039] For example, in the above embodiment, the offset printing system 1 includes four offset printing presses 3, but the number of offset printing presses 3 is not limited to this. Also, in the above embodiment, four partition plates 9 are provided in each air outlet duct 7, but the number of partition plates 9 is not limited to this. The surface area (height dimension) of each partition plate 9 may be set using, for example, an air flow meter, or may be determined by simulation, so that the air volume from the slit 70 is constant in the predetermined direction D2.

[0040] Furthermore, in the above embodiment, the blow-out duct 7 has a step portion 71a on the side surface 71 and has an L-shaped vertical cross section, but the cross-sectional shape of the blow-out duct 7 is not limited to this and can be a shape that corresponds to the configuration of the offset printing machine 3 to be used.

[0041] In the above embodiment, the temperature to be lowered by the temperature regulator 6 is set to 10°C, but the temperature to be lowered is not limited to 10°C and may be any temperature below 10°C. [Explanation of symbols]

[0042] 1 Printing device 2 Temperature control device 3. Offset printing press 6 Temperature controller 7. Air outlet duct 8 Connecting duct 9 Partition 31 Printing cylinder 32 Blanket Torso 70 slit 71 Side 72 1st end face 73 Second end face 100 offset printing system

Claims

1. an offset printing machine for printing on a printing medium transported in a predetermined transport direction; A temperature control device, The offset printing press includes a plate cylinder having a printing plate on its peripheral surface, and a blanket cylinder disposed opposite the plate cylinder, The temperature control device includes a temperature control machine that generates temperature-controlled air for cooling or heating the offset printing machine, a blowing duct having a slit, and a connecting duct that supplies the temperature-controlled air generated by the temperature control machine to the blowing duct, the temperature-controlled air supplied to the blowing duct is blown out from the slit toward a position where the plate cylinder and the blanket cylinder face each other, The air outlet duct includes a first end surface and a second end surface opposed to each other in a predetermined direction, and a side surface extending in the predetermined direction, a connection hole to which the connection duct is connected is provided on the first end surface; The slit is provided on the side surface, An offset printing system in which the blowing duct is provided with a plurality of partition plates arranged at intervals in the specified direction, and the surface areas of the plurality of partition plates gradually increase from the first end face toward the second end face.

2. The temperature controller has a cooling mode and a heating mode, In the cooling mode, the temperature controller cools the surrounding air to a lowering temperature of 10° or less to generate the temperature-controlled air. The offset printing system according to claim 1 , wherein in the warming mode, the temperature regulator generates the temperature-regulated air by heating the surrounding air to an elevated temperature of 10° C. or more.

3. The offset printing system according to claim 1 , wherein the blowing duct is located upstream of the opposing position in the transport direction.

4. A temperature control device for use in the offset printing system according to any one of claims 1 to 3, A temperature controller for generating temperature-controlled air; A blowing duct having a slit for blowing out the temperature-controlled air supplied from the temperature controller; a connection duct for supplying the temperature-controlled air generated by the temperature regulator to the blow-out duct; The air outlet duct includes a first end surface and a second end surface opposed to each other in a predetermined direction, and a side surface extending in the predetermined direction, a connection hole to which the connection duct is connected is provided on the first end surface; The slit is provided on the side surface, A temperature control device in which the blowing duct is provided with a plurality of partition plates arranged at intervals in the specified direction, and the surface area of ​​the plurality of partition plates gradually increases from the first end face toward the second end face.

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