JP2016129948A - Printing apparatus carrying out multicolor printing on metallic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly precise positioning with a simple structure.SOLUTION: A printing apparatus 1 carries out multicolor printing while conveying a metallic sheet S. The printing apparatus 1 includes, between the printing apparatus 1 and an adjacent off-set printing machine 120, a first table 10 and a second table 20 which convey the sheet S while positioning the sheet S. The first table 10 has a first conveyor belt 14 running in a high speed. The second table 20 has a second conveyor belt 23 running in a low speed, and a pusher 133 which pushes a rear end of the sheet S from the middle of conveyance. The first conveyor belt 14 has a larger friction resistance than that of the second conveyor belt 23.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a printing apparatus that performs multicolor printing while conveying a metal sheet.

  FIG. 1 shows an example of this type of printing apparatus. The illustrated printing apparatus 100 includes a feed apparatus 110, an offset printing machine 120, a transport apparatus 130, a UV dryer 140, and the like. The offset printing press 120 is arranged at intervals in the direction in which the sheet S is conveyed.

  Sheets S before printing (rectangular sheets processed to a certain size) made of thin plates such as tin and aluminum are set in the feed device 110 in a stacked state. The sheet S is taken out one by one from the feed device 110 and is continuously supplied to the first-stage offset printing press 120 by the feed conveyor 111 at a constant interval.

  In the offset printing machine 120, a horizontally long cylindrical plate cylinder 121, a blanket cylinder 122, and an impression cylinder 123 are arranged side by side with their outer peripheral surfaces in contact with each other. During printing, the cylinders 121, 122, and 123 are driven to rotate in synchronization with the direction indicated by the arrow. Above the plate cylinder 121, a liquid supply system 124 for supplying ink and dampening water to the plate cylinder 121 is provided.

  A plate is mounted on the outer peripheral surface of the plate cylinder 121, and ink is transferred to the image portion while the non-image portion of the plate is covered with dampening water. The ink transferred to the plate cylinder 121 is once transferred to the blanket cylinder 122 and then transferred to the sheet S, whereby printing (single color) is performed.

  FIG. 2 shows the printing process. A blanket 122 a corresponding to the printing surface of the printing plate is mounted on the outer peripheral surface of the blanket cylinder 122 in a cross-sectional arc shape. The impression cylinder 123 is provided with a plurality of grippers 123a arranged in parallel in the axial direction.

  The blanket cylinder 122 and the impression cylinder 123 are such contact portions (printing portion P, this position is also referred to as a printing position) so that the outer peripheral surfaces of the blanket cylinder 122 and the impression cylinder 123 run synchronously in the traveling direction of the sheet S. Driven by rotation. Each offset printing machine 120 is installed so that the printing positions are at the same height.

  As shown in FIG. 2A, the metal sheet S having a high rigidity is conveyed along a tangent passing through the printing position when viewed from the side, and the leading end of the sheet S Is inserted into the printing region P. Then, as shown in FIG. 2 (b), the edge of the leading edge is sandwiched by the gripper 123a at the printing position, so that the sheet S is held in a state of being positioned on the impression cylinder 123. The

  When the leading edge of the sheet S passes through the printing position and the sheet S is sandwiched between the printing parts, the gripper 123a is opened to remove the leading edge of the sheet S, as shown in FIG. Restraint is released. This release position is located below the printing position.

  The sheet S printed by the first-stage offset printing machine 120 is supplied to the second-stage offset printing machine 120 by the transport device 130. As shown in detail in FIG. 3, the conveyance device 130 includes a first conveyor 131 and a second conveyor 132.

  The first conveyor 131 plays a role of smoothly receiving the sheet S from the offset printer 120 and returning it to the printing position. The first conveyor 131 is provided with a plurality of preceding belts 131a that circulate in parallel at the same speed, and the single sheet S travels along the flat upper surface of the first conveyor 131. It is carried on the top.

  The upstream end of the upper surface of the first conveyor 131 is positioned below the printing position in order to smoothly receive the sheet S. Then, the upper surface of the first conveyor 131 is inclined upward toward the downstream side so that the downstream end is located at the printing position.

  The traveling speed of the front belt 131a is set to be higher (a few percent increase) than the printing speed of the offset printing machine 120 (speed at which the sheet S passes through the offset printing machine 120) so that the sheet S does not stick. Has been.

  Further, the conveyance distance of the first conveyor 131 is set to be sufficiently large so that the sheet S is completely transferred to the first conveyor 131.

  Accordingly, it is possible to smoothly transfer the sheet S from the offset printing machine 120 onto the first conveyor 131.

  The second conveyor 132 has a role of feeding the sheet S to the offset printing machine 120 by decelerating the conveying speed of the sheet S and then gradually increasing the printing speed while accurately positioning the sheet. The second conveyor 132 is provided with a plurality of rear belts 132a, pushers 133, attachments 134, and the like.

  The rear belt 132a is configured to run in parallel at the same speed along the upper surface of the substantially horizontal second conveyor 132. The running speed of the rear belt 132a is set to be lower (several percent reduction) than the printing speed.

  The attachment 134 is composed of a pair of left and right, and is disposed opposite to the second conveyor 132 in the width direction. Each of the attachments 134 is attached to a chain 134c spanned between the upstream sprocket 134a and the downstream sprocket 134b, and circulates at a constant speed.

  Each of the attachments 134 travels along the upper surface of the second conveyor 132 in a state where the region (upstream boosting region) extending from the intermediate portion of the second conveyor 132 to the upstream side protrudes from the upper surface of the second conveyor 132. It is configured.

  The traveling speed of the attachment 134 is set to be lower than the printing speed and higher than the speed of the rear belt 132a.

  The pushers 133 are also a pair of left and right, and are arranged facing each other in the width direction of the second conveyor 132. Each pusher 133 is attached to a chain 133c spanned between the upstream sprocket 133a and the downstream sprocket 133b, and circulates at a constant speed.

  Each pusher 133 travels along the upper surface of the second conveyor 132 in a state where the region (downstream boosting region) extending from the intermediate portion of the second conveyor 132 to the downstream side protrudes from the upper surface of the second conveyor 132. It is configured. In the intermediate portion of the second conveyor 132, a region (transition region) where the downstream boost region and the upstream boost region overlap each other is set.

  The traveling speed of the pusher 133 is set to the same speed as the printing speed or slightly lower (substantially the same) so as to synchronize with the printing speed.

  When the sheet S is transferred from the first conveyor 131 to the second conveyor 132, the sheet S is conveyed by the rear belt 132a, so that the conveyance speed is reduced more than the printing speed.

  Then, as shown in FIG. 4A, when the trailing edge of the sheet S reaches the upstream boosting region, each attach 134 comes into contact with the trailing edge of the sheet S, and the sheet The sheet S is pushed. Thereby, the conveyance speed of the sheet S is increased.

  Further, as shown in FIG. 4B, when the trailing edge of the sheet S reaches the transition region, each pusher 133 comes into contact with the trailing edge of the sheet S, and FIG. As shown, each attachment 134 is replaced and the sheet S is pushed. Thereby, the conveyance speed of the sheet S is further increased, and becomes substantially the same as the printing speed.

  Then, as shown in FIG. 4D, each pusher 133 in a state where the sheet S is positioned in the lateral width direction by a positioning guide (not shown) provided in the conveying device 130. And the gripper 123a position the sheet S in the vertical direction, and the sheet S is inserted into the print site P.

  The ink printed on the sheet S is dried by the UV dryer 140 during conveyance.

  In this way, the sheet S printed by the first-stage offset printer 120 is supplied to the second-stage offset printer 120. In the second-stage offset printing machine 120, printing is performed on the sheet S with another color ink in the same manner as the first-stage offset printing machine 120.

  On the downstream side in the transport direction from the second-stage offset printing machine 120, a third-stage and subsequent offset printing machine 120, a dryer, and the like are installed. By using this printing apparatus 100, a metal sheet Multi-color printing can be performed while the sheet S is conveyed at high speed.

  An example of the pusher 133 is disclosed in Patent Document 1, for example.

  Regarding the present invention, Patent Document 2 discloses a technique for assisting positioning by attracting a metal sheet being conveyed by aerodynamic force or magnetic force.

JP-A-64-61248 Japanese Patent Laid-Open No. 9-174814

  In multi-color printing, unlike simple coating or single-color printing, it is necessary to highly position during printing. Therefore, in the printing apparatus 100 as described above, in addition to the function of conveying the sheet S at high speed, the conveying apparatus 130 is also required to have a function of positioning the sheet S with high accuracy.

  Therefore, in the conveying device 130, complicated control for increasing / decreasing the conveying speed of the sheet S is performed by combining complicated mechanisms.

  In order to stably deliver the sheet between the mechanisms, a long conveyance distance is required, and there is a problem that a large space must be secured between the adjacent offset printing presses.

  SUMMARY OF THE INVENTION An object of the present invention is to make it possible to position a sheet with high accuracy while conveying a sheet at a high speed with a simple structure in this type of printing apparatus.

  The disclosed printing apparatus performs multicolor printing while conveying a metal sheet. The printing apparatus is continuously arranged between two or more offset printing presses arranged adjacent to each other in the conveying direction and passing the sheet at a synchronized printing speed and the adjacent offset printing presses. And a first table and a second table for conveying the sheet while positioning the sheet.

  The first table has a first conveyor belt that travels on the upper surface of the first table at a speed higher than the printing speed and receives the sheet from the preceding offset printing press.

  The second table travels on the upper surface of the second table at a speed lower than the printing speed, receives the sheet from the first table, and delivers it to the offset printing machine in the subsequent stage, A pusher that travels on the upper surface of the second table in synchronization with the printing speed and presses the rear end of the sheet. The first conveyance belt has a higher frictional resistance than the second conveyance belt.

  That is, according to this printing apparatus, a first table having a high-speed first conveyance belt and a second table having a low-speed second conveyance belt and a pusher are arranged between adjacent offset printing machines. In addition, since the first conveyance belt has a higher frictional resistance than the second conveyance belt, the sheet can be smoothly transferred from the offset printing machine to the first table. The sheet can be smoothly transferred from the first table to the second table. In addition, it is possible to smoothly position the final sheet before the delivery to the subsequent offset printing press.

  In particular, the second transport belt includes a center belt located at a center portion in the width direction of the second table, and side belts located on both sides of the center belt, and the center belt is the side belt. It is preferable to set the speed higher than that.

  If it does so, since it will become difficult to shake a sheet | seat sheet right and left, a sheet | seat sheet | seat can be conveyed more smoothly.

  In this case, the center belt is formed so as to be ventilated, and a suction device that sucks the single sheet through the center belt is provided on the upstream side in the transport direction of the second table. Good.

  Then, the speed adjustment of the sheet on the second table can be stably performed with a simple structure. The speed can be increased smoothly and quickly to near the speed of the pusher, and the suction device can suppress fluttering of the sheet that can occur during delivery to the pusher, so even if there is no mechanism equivalent to attachment, each pusher can be received. Thus, it is possible to achieve stable alignment, and a significant reduction in the transport distance of the second table can be realized.

  Furthermore, it is preferable that a non-suction region for transporting the single sheet is provided downstream of the second table in the transport direction in a state where the suction force of the suction device does not act.

  Ultimately, each pusher and the gripper of the offset printing machine in the subsequent stage position the sheet in the vertical direction. At this time, the sheet is located in the non-suction area and becomes slippery. The final positioning can be performed smoothly. Therefore, the sheet can be transferred to the subsequent offset printing machine with the sheet positioned with high accuracy.

  Furthermore, it is preferable to provide a second suction device that sucks the single sheet and attracts it to the upper surface of the first table on the downstream side in the transport direction of the first table.

  If it does so, the positioning accuracy of a sheet | seat sheet can be hold | maintained highly in the stage before delivery to a 2nd table. When transferring from the first table to the second table, the sheet is held by both tables, so that the positional deviation of the sheet can be suppressed.

  Therefore, it is possible to more stably deliver the sheet to the pusher on the second table, and it is possible to feed the sheet into the subsequent offset printing machine in a highly positioned state.

  In particular, the upstream end in the transport direction on the upper surface of the first table is located below the printing position of the preceding offset printing press, and the upper surface of the first table faces the downstream side in the transport direction. It is preferable that the curved portion bends while gradually rising so that the downstream end portion is substantially horizontal at the printing position.

  Then, the sheet can be pulled out from the offset printing machine without being stuck and smoothly transferred to the first table. Moreover, even if the upper surface of the first table bulges upward due to the suction of the sheet, the sheet can be prevented from floating and rattling, so that the sheet can be conveyed stably while preventing misalignment. it can. As a result, the sheet can be guided to the second table in a horizontal state while returning to the printing position at a short distance.

  According to the printing apparatus of the present invention, the sheet can be positioned with high accuracy while being conveyed at high speed while having a simple structure.

It is the schematic which shows an example of the printing apparatus which this invention makes object. (A)-(c) is the schematic explaining the printing process with an offset printing machine. It is the schematic which shows the conveying apparatus of the printing apparatus of FIG. (A) is the figure seen from the upper part, (b) is the figure seen from the side. (A)-(d) is the schematic explaining the operation | movement of a conveying apparatus. It is the schematic which looked at the principal part of the printing apparatus to which this invention is applied from the side. It is the schematic which looked at the 1st table and the 2nd table from the upper part. (A)-(c) is the schematic which shows operation | movement of the 1st table at the time of printing. (A) And (b) is the schematic which shows operation | movement of the 2nd table at the time of printing. (A) And (b) is the schematic which shows operation | movement of the 2nd table at the time of printing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following description is merely illustrative in nature and does not limit the present invention, its application, or its use.

  FIG. 5 shows a main part of the printing apparatus 1 to which the present invention is applied. Since the basic configuration of the printing apparatus 1 such as the offset printing press 120 is the same as that of the printing apparatus 100 described above, the same reference numerals are used for the same configuration and the description thereof is omitted.

  Also in this printing apparatus 1, two or more offset printing machines 120 that allow the sheet S to pass at a synchronized printing speed are transported in the transport direction (the direction in which the sheet S is transported as indicated by the white arrow in FIG. 5). ) Are arranged at intervals. A first table 10 and a second table 20 that convey the sheet S while positioning the sheet S between the adjacent upstream offset printing machine 120 and the subsequent offset printing machine 120 are continuous in the conveyance direction. Installed.

  In the printing apparatus 1, the structures of the first table 10 and the second table 20 are devised to realize high-precision positioning and high-speed conveyance of the sheet S with a simple structure.

  That is, the first half vacuum device 11 (an example of a second suction device) is installed at the downstream end of the first table 10 in the transport direction, and the upstream side of the second table 20 in the transport direction is A second half vacuum device 25 (an example of a suction device) is installed. In the second table 20, the attach 134 is omitted.

  And the conveyance distance of both the 1st table 10 and the 2nd table 20 is shortened, and the space between the front and back offset printing machines 120 is narrower than the conventional printing apparatus 100. FIG.

  FIG. 6 shows details of the first table 10 and the second table 20.

(First table)
Similar to the first conveyor 131, the first table 10 plays a role of smoothly receiving the sheet S from the offset printing press 120 and returning it to the printing position. In addition, the first table 10 has a function of delivering the sheet S to the second table 20 while suppressing positional deviation.

  The first table 10 is provided with a first vacuum unit 11, a first upstream shaft 12, a first downstream shaft 13, a plurality of first conveyor belts 14, a guide table 15, and the like.

  The first upstream shaft portion 12 is disposed obliquely below the impression cylinder 123 of the preceding offset printing press 120. The first upstream shaft portion 12 extends in parallel with the impression cylinder 123, and both ends thereof are supported by the first table 10.

  The first downstream shaft portion 13 is disposed at a position away from the first upstream shaft portion 12 on the downstream side in the transport direction. The first downstream shaft portion 13 extends in parallel with the first upstream shaft portion 12, and both ends thereof are supported by the first table 10.

  A plurality of pulleys 16 are attached to the first upstream shaft portion 12 in a rotatable state. A plurality of pulleys 16 are also rotatably attached to the first downstream shaft 13 so as to face the pulleys 16 of the first upstream shaft 12.

  Each first transport belt 14 is an annular flat belt, and is wound around each pulley 16 of the first upstream shaft portion 12 and the first downstream shaft portion 13. By being rotationally driven by a device (not shown), each first transport belt 14 travels in the same direction and at the same speed.

  Each first conveyor belt 14 has a surface with a large frictional resistance so that the sheet S is difficult to slip. Each first conveyor belt 14 is set to run at a higher speed (for example, several percent increase) than the printing speed.

  The first transport belt 14 is symmetrically disposed on both the left and right sides of the first center belt 14a and the first center belt 14a at the center of the first table 10 in the width direction (the direction orthogonal to the transport direction). The first side belt 14b.

  Unlike the first side belt 14b, the first center belt 14a has a plurality of air holes 17 penetrating the belt. The vent holes 17 are arranged in a line at equal intervals in the longitudinal direction of the first center belt 14a.

  Between the first upstream shaft portion 12 and the first downstream shaft portion 13, a guide table 15 that supports the lower surface of the traveling first conveyor belt 14 is installed. The guide table 15 has a top surface that extends uniformly in the width direction and is curved in an arc shape while gradually rising toward the downstream side in the transport direction (see FIG. 7). Of the upper surface of the guide table 15, the downstream side in the transport direction is substantially horizontal and is located at the height of the printing position.

  The first half vacuum device 11 is installed along the lower side of the travel path of the first center belt 14a at the end of the guide table 15 (downstream part in the transport direction).

  The first-half vacuum device 11 is installed on the guide table 15 so as to communicate with the intake port 11a and an intake port 11a that opens on the upper surface of the guide table 15 so as to overlap the vent hole 17 of the first center belt 14a. And a box-shaped intake duct 11b.

  The intake port 11a is formed to extend from the central portion of the guide table 15 (the portion where the top of the curved upper surface is located) to the downstream side region (suction region) in the transport direction. A vacuum pump (not shown) is connected to the intake duct 11b, and the inside of the intake duct 11b is depressurized during conveyance.

  A plurality of guide plates 18 are installed at the edge of the end of the guide table 15 (upstream end in the transport direction). These guide plates 18 protrude toward the impression cylinder 123, and a sheet guide portion 18a that is recessed in an arc shape in cross section is provided on the upper edge portion (see FIG. 7).

  At the time of printing, each first conveyor belt 14 travels along the upper surface of the guide table 15 and receives and conveys the sheet S from the preceding offset printing press 120.

  FIG. 7 shows the operation of the first table 10 during printing.

  As shown in FIG. 7A, the leading end of the sheet S coming out from the offset printing press 120 is smoothly guided by the sheet guiding portion 18 a of the guide plate 18 and is transferred to the upper surface of the first table 10. . On the upper surface of the first table 10, the first conveying belt 14 having a large frictional resistance is traveling at a speed higher than the printing speed. Therefore, the sheet S is pulled by the first conveying belt 14 without being struck. Are smoothly pulled out from the offset printing press 120.

  Then, as shown in FIG. 7B, when the leading end of the sheet S reaches the intake area, the leading half of the sheet S is sucked by the first half vacuum device 11 and the top surface of the first table 10 is sucked. Therefore, it is possible to prevent the sheet S from being lifted and rattling, and to prevent the sheet S from being displaced.

  Since the upper surface on the upstream side in the conveyance direction of the guide table 15 is curved upward, the sheet S can be smoothly received even if the leading edge of the sheet S coming out of the offset printing machine 120 is lifted. it can. Accordingly, as shown in FIG. 7C, the sheet S can be guided to the second table 20 in a horizontal state while being returned to the printing position at a short distance.

  In a state where the rear end portion of the sheet S is sandwiched between the printing parts P, the sheet S is positioned with high accuracy. Therefore, if the leading end of the sheet S is sucked by the first half vacuum device 11 in this state, it is possible to carry the sheet in a highly accurately positioned state.

(Second table)
Similar to the second conveyor 132, the second table 20 reduces the conveyance speed of the sheet S, gradually increases the printing speed to the printing speed, and accurately positions the sheet S to the offset printing press 120. Have a role to send.

  As shown in FIG. 6, the second table 20 includes a second upstream shaft portion 21, a second downstream shaft portion 22, a plurality of second transport belts 23, a pusher 133, a second half vacuum device 25, and the like. Yes.

  The second upstream shaft portion 21 is disposed in the vicinity of the first downstream shaft portion 13. The second upstream shaft portion 21 extends in parallel with the first downstream shaft portion 13, and both ends thereof are supported by the second table 20.

  The second downstream shaft portion 22 is disposed in the vicinity of the printing portion P of the subsequent offset printing press 120. The second downstream shaft portion 22 extends in parallel with the second upstream shaft portion 21, and both ends thereof are supported by the second table 20.

  A plurality of pulleys 26 are attached to the second upstream shaft portion 21 in a rotatable state. A plurality of pulleys 26 are also attached to the second downstream shaft portion 22 so as to face each pulley 26 of the second upstream shaft portion 21 in a rotatable state. The second upstream shaft portion 21 and the second downstream shaft portion 22 are located at substantially the same height as the printing position.

  Each second transport belt 23 is an annular flat belt and is wound around each pulley 26 of the second upstream shaft portion 21 and the second downstream shaft portion 22. Each second transport belt 23 is supported by a guide member (not shown) so that the upper travel path thereof is substantially horizontal at the printing position. Each second transport belt 23 is rotationally driven by a device (not shown) during transport.

  The second transport belt 23 includes a second center belt 23a located at the center in the width direction of the second table 20, and a plurality of second side belts 23b located on the left and right sides of the second center belt 23a. Yes. Unlike the first transport belt 14, the second center belt 23a and the second side belts 23b have surfaces with small frictional resistance so that the sheet S is easy to slip.

  The second center belt 23a and each second side belt 23b are set so as to run at a lower speed (for example, several percent reduction) than the printing speed. The traveling speed is different between the second center belt 23a and the second side belt 23b.

  Specifically, each second side belt 23b is set to the same traveling speed, and the second center belt 23a is set to a higher speed (for example, several percent increase) than these second side belts 23b.

  The 2nd center belt 23a is formed so that ventilation is possible, and has a plurality of ventilation holes 27 penetrated in the thickness direction. The vent holes 27 are arranged in a line at equal intervals in the longitudinal direction of the second center belt 23a.

  In the traveling path on the upper side of the second center belt 23a, the rear half vacuum device 25 is installed along the lower side of the upstream portion of the second table 20 in the transport direction. The latter half vacuum device 25 has a box-shaped second intake duct 25a and a plurality of slit-like intake ports 25b opened on the upper surface thereof. Each intake port 25b is disposed along the travel route of the second center belt 23a so as to overlap the vent hole 27 vertically.

  A vacuum pump (not shown) is connected to the second intake duct 25a, and the inside of the second intake duct 25a is depressurized during conveyance. As a result, the sheet S passing above the second half vacuum device 25 passes through the second center belt 23a, is sucked into the second half vacuum device 25, and is crimped to the second center belt 23a.

  The pusher 133 is configured so that a region (protrusion region r1) extending from the vicinity of the inside of the second upstream shaft portion 21 to the vicinity of the inside of the second downstream shaft portion 22 protrudes from the upper surface of the second table 20. It is comprised so that it may run along the upper surface of 20. The traveling speed of the pusher 133 is set to a speed synchronized with the printing speed.

  On the upstream side of the protruding region r1, there is provided a transition region where a delivery position PP where the pusher 133 starts pressing the sheet S is present. An area where the suction force of the latter half vacuum device 25 acts is set on the downstream side of the transfer position PP in the transition area (suction area r2).

  Then, on the downstream side of the second table 20 in the transport direction with respect to the suction region r2, the second transport belt 23 transports the single sheet S in a state where the suction force of the latter half vacuum device 25 does not act (non-suction). Region r3) is provided. That is, the conveyance distance of the non-suction area r3 is set to be larger than the front-rear dimension (length in the conveyance direction) of the sheet S.

  8 and 9 show the operation of the second table 20 during printing.

  As shown in FIG. 8A, the sheet S is received from the first table 10 by the second transport belt 23. At this time, the front part of the sheet S enters the transition area of the second table 20 in a state where the rear part is held by the first half vacuum device 11 of the first table 10.

  Therefore, when transferring from the first table 10 to the second table 20, the sheet S is securely held by the first half vacuum device 11 and the displacement is suppressed.

  Although the second conveyor belt 23 is slower than the first conveyor belt 14, the second conveyor belt 23 has a lower frictional resistance than the first conveyor belt 14. 2 A portion on the conveyor belt 23 slips, and the sticking of the sheet S is suppressed.

  Even if the second conveyor belt 23 is slippery, as the sheet S is advanced, the holding force of the sheet S by the second conveyor belt 23 increases, and the portion of the sheet S on the first conveyor belt 14 increases. The sheet S is smoothly decelerated.

  In addition, at this time, the second center belt 23a located at the center in the width direction has a higher holding force than the second side belts 23b on both sides. The sheet S is less likely to swing left and right, and the sheet S can be smoothly and appropriately conveyed. The bumping of the sheet S can also be effectively suppressed.

  As shown in FIG. 8B, when the sheet S is transferred to the second table 20, the speed difference between the second center belt 23a and the second side belt 23b, even if the second transport belt 23 is slippery. Therefore, it can be stably conveyed.

  Then, as shown in FIG. 9A, after the trailing edge of the sheet S reaches the delivery position PP, each pusher 133 contacts the trailing edge of the sheet S, and the sheet The sheet S is pushed in the transport direction. At the delivery position PP, the speed of the sheet S is increased to near the speed of the pusher 133, so that it can be smoothly delivered to each pusher 133.

  Furthermore, at the delivery position PP, the rear part of the sheet S is in the suction region r2 and is sucked by the latter half vacuum device 25, so even if each pusher 133 having a speed difference comes into contact, there is no fluttering. It can be delivered smoothly.

  As a result, there is no need to provide a mechanism corresponding to the attach 134, and the transport distance of the second table 20 can be significantly shortened.

  By being pushed by each pusher 133, the sheet S is increased to the printing speed.

  As shown in FIG. 9B, the sheet S is inserted into the printing region P in a state in which final positioning in the width direction is performed by a positioning guide (not shown). Each pusher 133 and the gripper 123a perform final positioning of the sheet S in the vertical direction, and the sheet S is delivered to the offset printing machine 120 at the subsequent stage.

  At this time, since the sheet S is located in the non-suction region r3 and is easy to slip, the final positioning can be performed smoothly. Therefore, the sheet S can be transferred to the subsequent offset printing machine 120 in a state where the sheet S is positioned with high accuracy.

  Therefore, according to the printing apparatus 1, it is possible to realize highly accurate positioning and high-speed conveyance of the sheet S with a simple structure, and the overall length of the printing apparatus 1 can be shortened.

  The printing apparatus according to the present invention is not limited to the above-described embodiment, and includes various other configurations.

  For example, each suction device is not limited to aerodynamic suction, and may be attracted by a magnetic force such as an electromagnet. The suction device of the first table may suck from between adjacent belts. The first table may have the same structure as the conventional first conveyor. The second center belt may be meshed, for example, so that it can be ventilated.

1 Printing Device 10 First Table 11 First Half Vacuum Device (Second Suction Device)
14 1st conveyance belt 15 Guide table 20 2nd table 23 2nd conveyance belt 23a 2nd center belt 23b 2nd side belt 25 Late vacuum device (suction device)
120 Offset Printing Machine 121 Plate Cylinder 122 Blanket Cylinder 123 Impression Cylinder 123a Gripper
124 Liquid supply system 133 Pusher 133a Upstream sprocket 133b Downstream sprocket 133c Chain 140 UV dryer

Claims (6)

A printing apparatus that performs multicolor printing while conveying a metal sheet,
Two or more offset printing presses arranged at intervals in the transport direction and passing the sheet at a synchronized printing speed;
A first table and a second table, which are continuously arranged between the adjacent offset printing presses, and convey the sheet while positioning;
With
The first table is:
A first conveyor belt that travels on the upper surface of the first table at a speed higher than the printing speed and receives the sheet from the offset printing machine in the previous stage;
The second table is:
A second conveyor belt that travels on the upper surface of the second table at a speed lower than the printing speed, receives the sheet from the first table, and delivers it to the offset printing machine at a later stage;
A pusher that runs on the upper surface of the second table in synchronization with the printing speed, and that pushes the rear end of the sheet from the middle of conveyance;
Have
A printing apparatus in which the first conveyance belt has a higher frictional resistance than the second conveyance belt. The printing apparatus according to claim 1,
The second transport belt is
A center belt located at the center in the width direction of the second table;
Side belts located on both sides of the center belt;
Have
A printing apparatus in which the center belt is set at a higher speed than the side belt. The printing apparatus according to claim 2,
The center belt is formed to be breathable,
A printing apparatus provided with a suction device that sucks the sheet by passing through the center belt on the upstream side in the transport direction of the second table. The printing apparatus according to claim 3.
A printing apparatus in which a non-suction region for transporting the sheet is provided in a state where the suction force of the suction device does not act on the downstream side of the transport direction of the second table. In the printing apparatus as described in any one of Claims 1-4,
A printing apparatus provided with a second suction device that sucks the single sheet and attracts it to the upper surface of the first table on the downstream side in the transport direction of the first table. The printing apparatus according to claim 5, wherein
The upstream end portion in the transport direction on the upper surface of the first table is located below the printing position of the offset printing machine in the preceding stage,
The upper surface of the first table is curved while gradually rising toward the downstream side in the transport direction,
The printing apparatus in which the downstream end portion is substantially horizontal at the printing position.

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