JP5878782B2 - Image forming system - Google Patents

Description

  The present invention relates to an image forming system.

  Printing provided with digital printing means for discharging ink onto the surface of the offset blanket to form an ink image on the surface of the blanket and for the transfer image of the ink image to cover the entire circumference of the printing target surface of the cylindrical print medium An apparatus is known (see, for example, Patent Document 1).

Special table 2010-502489 gazette

Here, after forming an image using the first color material on the outer peripheral surface of the can rotating in the circumferential direction, when forming an image using the second color material, the first color material In some cases, the formed image and the image formed by the second color material are aligned. At this time, for example, if the image formation of the first color is performed from a predetermined origin position and the image formation of the second color is performed from this origin position, the alignment can be performed. It takes time to arrange the cans, and the number of cans that can form an image per unit time is reduced.
An object of the present invention is to provide an image forming system capable of increasing the number of cans capable of forming an image per unit time.

  In an image forming system to which the present invention is applied, a first image forming unit that forms an image on an outer peripheral surface of a can rotating in a circumferential direction, and image formation by the first image forming unit are started. A first acquisition means for acquiring information relating to the rotation angle of the can body during rotation, and the can body rotating in a circumferential direction after an image is formed on the can body by the first image forming unit A second image forming unit that forms an image on the screen, a second acquisition unit that acquires information on a rotation angle of the can when the image formation by the second image forming unit is started, A data storage unit that stores image data of the image formed by two image forming units, information about the rotation angle acquired by the first acquisition unit, and the rotation acquired by the second acquisition unit Based on the information about the angle, Determining means for determining a reading start position of the image data used by the image forming section from the data storage section, and the second image forming section sequentially starts from the reading start position determined by the determining means. In the image forming system, the image data to be read is used to form an image on the outer peripheral surface of the can rotating in the circumferential direction.

Here, the determination means is specified by the rotation angle specified by the information on the rotation angle acquired by the first acquisition means and the information on the rotation angle acquired by the second acquisition means. The read start position may be determined based on an angle difference that is a difference from a rotation angle. In this case, the reading start position can be determined more easily.
The rotating unit further rotates the can body in the circumferential direction, and the rotating unit finishes image formation by the second image forming unit after image formation by the first image forming unit is started. In the meantime, the can body can be rotated at a constant speed without increasing or decreasing the rotation speed of the can body. In this case, it is possible to suppress a decrease in the accuracy of the image forming position that may occur with an increase or decrease in the rotation speed of the can body.
Further, the first image forming unit and the second image forming unit form an image on an outer peripheral surface of the can body by discharging ink from above the can body in a lying state. can do. In this case, the ink arrival position can be controlled with higher accuracy than when ink is ejected from the side of the standing can body or when ink is ejected from below the can body.

  From another point of view, an image forming system to which the present invention is applied includes a plurality of image forming units that are arranged at different locations and that form images on the outer peripheral surface of a can rotating in the circumferential direction, Moving means for moving the can body through each of the plurality of image forming units while rotating the can body in the circumferential direction, and each of the plurality of image forming units being rotated in the circumferential direction. The can body that moves via the image forming system is an image forming system that performs the movement while rotating at a constant speed without increasing or decreasing the rotation speed. In this case, it is possible to suppress a decrease in the accuracy of the image forming position that may occur with an increase or decrease in the rotation speed of the can body.

  According to the present invention, it is possible to provide an image forming system capable of increasing the number of cans capable of forming an image per unit time.

1 is a diagram when an image forming system according to an exemplary embodiment is viewed from above. FIG. It is a figure for demonstrating an image forming apparatus. It is a figure showing a comparative example of an image forming apparatus. It is the figure which showed the image formation process by an inkjet head. It is a figure for demonstrating reading of the image data from a page memory. It is the figure which showed an example of the image formed in a can. It is the figure which showed the process example of the image formation process with respect to a can. It is the figure which showed the image formation process of this embodiment. It is a figure at the time of seeing the image forming system shown in FIG. 1 from the arrow IX direction. It is a figure for demonstrating a can body supply mechanism.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a view of an image forming system 100 according to the present embodiment as viewed from above.
The image forming system 100 in the present embodiment forms an image based on digital image information on a can body 10 used for a beverage can or the like. Here, the image forming system 100 includes a plurality of image forming apparatuses 200 that perform image formation on the can body 10 using an inkjet method, and the can body 10 manufactured in a can body manufacturing process (not shown). The can body supply mechanism 300 that sequentially supplies the plurality of image forming apparatuses 200 and the can body discharge mechanism 400 that discharges the can body 10 on which an image is formed by the image forming apparatus 200 are configured.

  In addition, the image forming system 100 includes a CPU that executes digital arithmetic processing according to a predetermined processing program, and a control unit 500 that controls each device and each mechanism unit provided in the image forming system 100. It has been. The image forming system 100 also includes a page memory 600 that stores image data of an image formed on the can 10 and supplied to an inkjet head (described later) provided in the image forming apparatus 200. Is provided.

Here, in the present embodiment, three image forming apparatuses 200 are provided, and each of the image forming apparatuses 200 forms an image on the can 10. For this reason, in this embodiment, compared with the case where image formation to the can 10 is performed using the single image forming apparatus 200, the number of cans 10 that can perform image formation per unit time is large. It has become.
Here, the three image forming apparatuses 200 are respectively provided at locations corresponding to the vertices of a regular triangle (not shown). More specifically, the three image forming apparatuses 200 are arranged radially with a predetermined location (location indicated by reference numeral 1A in the figure) as the center. More specifically, the three image forming apparatuses 200 are arranged so that the central portions thereof are placed on the circular virtual line 1B.

  Each of the image forming apparatuses 200 is supplied from the can supply mechanism 300 at a predetermined receiving location (location indicated by reference numeral 1C in the drawing, hereinafter may be referred to as “can receiving location 1C”). The can body 10 is received. In addition, each of the image forming apparatuses 200 includes a can body 10 on which an image is formed at a predetermined discharge position (a position indicated by reference numeral 1D in the drawing, hereinafter may be referred to as a “can discharge position 1D”). Is discharged. Here, the can receiving part 1C and the can discharging part 1D are arranged inside the virtual line 1B.

  Here, the image forming apparatus 200 will be described in detail with reference to FIG. 2 (a diagram for explaining the image forming apparatus 200). 2A is a view when the image forming apparatus 200 is viewed from above, and FIG. 2B is a view when the image forming apparatus 200 is viewed from the direction of arrow IIB in FIG. FIG.

  As shown in FIG. 1A, each of the image forming apparatuses 200 includes a rotating member 210 that is formed in a columnar shape and is driven by a motor (not shown) to rotate in a direction indicated by an arrow in the drawing. Further, the image forming apparatus 200 is provided with a support base 220 that supports the rotating member 210 as shown in FIG. Further, as shown in FIG. 5A, the image forming apparatus 200 is provided so as to protrude from the outer peripheral surface of the rotating member 210 and is provided every 45 ° in the rotating direction of the rotating member 210. A plurality (eight in this embodiment) of holding mechanisms 230 that hold the can body 10 supplied by the supply mechanism 300 are provided.

  In addition, each of the image forming apparatuses 200 is provided with the can body 10 that is provided so as to protrude from the outer peripheral surface of the rotating member 210 and that is radially arranged around the rotating member 210 and that is supplied by the can body supplying mechanism 300. A plurality of holding mechanisms 230 for holding are provided. In addition, the image forming apparatus 200 is provided with four inkjet heads 240 that form an image by discharging ultraviolet curable ink onto the outer peripheral surface of the can body 10 held by the holding mechanism 230. Here, in the present embodiment, the can body 10 moves so as to pass through the four inkjet heads 240, and an image formed of four colors of ink is formed on the outer peripheral surface of the can body 10.

  Furthermore, in the present embodiment, UVLED that irradiates the outer peripheral surface of the can 10 that is provided on the downstream side of the four inkjet heads 240 and is held by the holding mechanism 230 in the rotation direction of the rotating member 210. (Ultraviolet Light Emitting Diode) lamp 250 is provided. Further, a plurality of head cleaners (not shown) are provided to correspond to each of the four ink jet heads 240 and clean the ink jet heads 240.

  Here, each inkjet head 240 ejects ink of different colors to the can 10. Further, the four inkjet heads 240 and the UVLED lamp 250 are provided so as to be adjacent to each other in the rotation direction of the rotation member 210. The four inkjet heads 240 and the UVLED lamps 250 are arranged radially around the rotating member 210 and are arranged at 45 ° intervals in the rotating direction of the rotating member 210. The four inkjet heads 240 and the UVLED lamps 250 are fixed and stationary with respect to the installation surface on which the image forming system 100 is installed (see FIG. 9).

  As the inkjet head 240, one belonging to a classification called on-demand type can be adopted. Specifically, a piezo method in which ink is ejected from a minute hole by pressure generated by deforming a piezo element (piezoelectric element) or a thermal method in which ink is ejected from a minute hole by vapor pressure may be employed. it can. In addition, it is also possible to employ a method of ejecting ink by an electric force or the like belonging to a classification called a continuous type.

  Here, as shown in FIG. 2B, each of the holding mechanisms 230 is provided with a fixing member 231 provided so as to protrude from the outer peripheral surface of the rotating member 210 and arranged substantially horizontally and fixed to the rotating member 210. I have. Furthermore, it has the support cylinder (mandrel) 232 inserted in the can body 10 and supporting the can body 10. Here, the support tube (mandrel) 232 includes a base portion 232-1 and a rotating portion 232-2. Here, in the present embodiment, the rotation unit 232-2 is mounted on the base 232-1, and the rotation shaft of a motor (not shown) installed on the base 232-1 is connected to the rotation unit 232-2. . Further, the base 232-1 is coupled to the disk-like member 233.

  Here, the support cylinder 232 is formed in a cylindrical shape. Further, the support cylinder 232 has one end 232A and the other end 232B, as shown at the center in FIG. In the present embodiment, when the support cylinder 232 is inserted into the can body 10, the support cylinder 232 is inserted into the can body 10 with the one end 232A of the support cylinder 232 at the top. Further, in the present embodiment, a disk-shaped member 233 attached to the other end 232B of the support cylinder 232 is provided, and the disk-shaped member 233 is provided so as to penetrate both the disk-shaped member 233 and the fixing member 231. A shaft 234 that is fixed to the fixing member 231 is provided.

  Here, in this embodiment, the disk-shaped member 233 rotates around the shaft 234. Although not shown, in the present embodiment, a rotation mechanism that rotates the disk-shaped member 233 around the shaft 234 is provided. In addition, this rotation mechanism can be comprised by arrange | positioning a worm wheel (not shown) inside the disk shaped member 233, and arrange | positioning a worm (not shown) inside the fixing member 231, for example. In this case, the disk-shaped member 233 can be rotated by rotating the worm inside the fixed member 231 with a motor (not shown).

  In the present embodiment, the servo motor (not configured) is housed in the base portion 232-1 and the rotation shaft is connected to the rotation portion 232-2 to rotate the rotation portion 232-2 (can body 10) in the circumferential direction. (Shown) is provided. Here, in this embodiment, the rotational position (phase) of the rotation shaft of the servo motor is detected by a rotary encoder (not shown), and the ink in each inkjet head 240 is detected based on the detection result by the rotary encoder. The discharge start timing is controlled. Accordingly, the images formed on the can 10 by the respective ink jet heads 240 are suppressed from shifting from each other.

Here, the operation of the image forming apparatus 200 will be described with reference to FIG.
First, the image forming apparatus 200 receives the can body 10 conveyed by the can body supply mechanism 300 at the can body receiving portion 1C shown in FIGS. 2 (A) and 2 (B).
Specifically, the can body 10 is conveyed to the can receiving portion 1C by the can supplying mechanism 300 shown in FIG. 1, and the support provided in the image forming apparatus 200 is provided at the can receiving portion 1C. The tube 232 is waiting. Thereafter, the can body 10 is dropped from the can body supply mechanism 300, and the can body 10 is sucked by the support cylinder 232. Thereby, the can 10 is received by the image forming apparatus 200.

  In the present embodiment, when the disc-shaped member 233 is rotated by the rotating mechanism and the can body 10 is received by the support cylinder 232, the axis of the support cylinder 232 is along the vertical direction (vertical direction). A support cylinder 232 is arranged as described above. And reception of the can 10 by the support cylinder 232 is performed by the support cylinder 232 entering the inside of the can 10 that has moved from above.

  In the present embodiment, a vent hole (not shown) that communicates with the inside of the support cylinder 232 is formed at the tip of the one end 232 </ b> A of the support cylinder 232. Further, a suction device that sucks air inside the support cylinder 232 and a feeding device that feeds air into the support cylinder 232 are provided, and suction inside the support cylinder 232 causes the inside of the support cylinder 232 to The negative pressure is applied, and the can 10 is sucked through the ventilation hole. Moreover, the pressure inside the support cylinder 232 increases by the air being fed by the feeding device, and the pressure inside the can 10 is increased through the ventilation holes. Thereby, the force in the direction away from the support cylinder 232 acts on the can body 10, and the can body 10 is removed from the support cylinder 232 (described later).

  In addition, the can 10 in the present embodiment is formed in a cylindrical shape. Moreover, the can 10 is in a state in which a bottom is formed at one end in the longitudinal direction and the one end is closed. On the other hand, the other end portion of the can 10 is not closed and opened. The can 10 is supported by the support cylinder 232 by the support cylinder 232 entering the inside of the can 10 from the opened side.

  After the can body 10 is supported by the support cylinder 232, the rotation member 210 that functions as a part of the moving means is rotated. Thereby, the can 10 moves in the counterclockwise direction in FIG. In other words, the rotation of the rotating member 210 causes the support cylinder 232 to move, and the can body 10 moves in the counterclockwise direction in the figure as the support cylinder 232 moves.

  Further, in the present embodiment, after the can body 10 is supported by the support cylinder 232, the rotation of the rotating unit 232-2 that is a part of the support cylinder 232 is started, and the can body 10 in the circumferential direction of the can body 10 is started. The rotation of the body 10 is started (rotation of the can body 10). In the present embodiment, the support cylinder 232 is accelerated (increased rotational speed) in a region located between the can receiving place 1C and the first inkjet head 240, and the first inkjet head By the time it reaches 240, the rotational speed of the support cylinder 232 becomes a predetermined rotational speed.

  In the present specification, the ink jet head 240 (the first ink jet head 240) located on the most upstream side in the rotation direction of the rotating member 210 is hereinafter referred to as a first ink jet head 240. In addition, another ink jet head 240 positioned downstream of the first ink jet head 240 and adjacent to the first ink jet head 240 is referred to as a second ink jet head 240. Further, another inkjet head 240 positioned next to the second inkjet head 240 is referred to as a third inkjet head 240, and another inkjet head 240 positioned next to the third inkjet head 240 is referred to as a fourth inkjet head 240. Called. In addition, when each of the first inkjet head 240 to the fourth inkjet head 240 is not particularly distinguished, it may be simply referred to as an inkjet head 240.

  Here, in the present embodiment, after the can body 10 is supported by the support cylinder 232, a motor (not shown) housed in the fixing member 231 is driven, and the disk-like member 233 is centered on the shaft 234. Rotate to. Thereby, in this embodiment, as shown to 2D of FIG.2 (B), the support cylinder 232 comes along a horizontal direction (it comes along the direction which cross | intersects an up-down direction), and the can 10 is made. Go to sleep. Thereafter, the can 10 reaches below the first inkjet head 240 that functions as the first image forming unit, and the movement of the can 10 (rotation of the rotating member 210) is stopped.

  Next, ink is ejected from the first inkjet head 240 toward the can body 10 positioned below and rotating (spinning) at a predetermined speed, and the first color with respect to the outer peripheral surface of the can body 10. An ink image is formed. Here, in the present embodiment, ink is ejected from above the can body 10 toward the can body 10 in this way. In this case, the action direction of gravity coincides with the ink ejection direction, the behavior of the ejected ink is stabilized, and the ink arrival position can be controlled with higher accuracy.

  Thereafter, in the present embodiment, the rotation of the rotating member 210 is resumed, and the can body 10 on which an image is formed by the first inkjet head 240 reaches below the second inkjet head 240. When the can 10 reaches the lower side of the second inkjet head 240, the rotation of the rotating member 210 is stopped again. Next, the second inkjet head 240 forms an image with the second color ink.

  Thereafter, in the present embodiment, movement of the can body 10 to the third inkjet head 240, formation of an image by the third inkjet head 240, movement of the can body 10 to the fourth inkjet head 240, and image by the fourth inkjet head 240 Is formed. Thereafter, the can body 10 moves to below the UVLED lamp 250 and the outer peripheral surface of the can body 10 is irradiated with ultraviolet rays. Thereby, the ink adhering to the outer peripheral surface of the can 10 is cured. Here, although the case where the UVLED lamp 250 is used has been described in the present embodiment, a lamp such as a metal halide lamp can be used instead of the UVLED lamp 250. However, the UVLED lamp 250 is more compact and consumes less power.

  In addition, while the can body 10 sequentially passes below the first ink jet head 240 to the fourth ink jet head 240, the can body 10 continues to rotate without rotating and the can body 10 is kept constant. It is preferable to rotate at a speed of In addition, it is preferable to move (revolve) the can body 10 while maintaining a constant rotation speed without changing the rotation speed (spinning speed) of the can body 10. When changing the rotation speed (spinning speed) of the can 10, the control of the can 10 is complicated, and the size of the apparatus is increased (details will be described later).

In the present embodiment, the case where the UVLED lamp 250 is arranged in each image forming apparatus 200 has been described. However, when it is difficult to provide the UVLED lamp 250 in each image forming apparatus 200 due to space or the like, there are three. One UV LED lamp 250 can be provided on the downstream side of the image forming apparatus 200.
In the present embodiment, the case of using ultraviolet curable ink has been described. However, thermosetting ink can also be used, and in this case, for example, a can body is formed by a heater indicated by reference numeral 1E in FIG. 10 is heated and the ink on the surface of the can 10 is cured.

  In this embodiment, after the UV LED lamp 250 irradiates the can body 10 with ultraviolet rays, the can body 10 stands up as shown by reference numeral 2E in FIG. 2B. More specifically, the disk-shaped member 233 is rotated about the shaft 234 by the rotation mechanism, and the support cylinder 232 is erected. And the can 10 also stands up with this standing up. Thereafter, in the present embodiment, the can body 10 is removed from the support cylinder 232 at the can body discharge location 1D, and the removed can body 10 is held by the can body discharge mechanism 400. Thereafter, the can body 10 is conveyed by the can body discharge mechanism 400.

  Here, in the present embodiment, as described above, when the can body 10 is received by the support cylinder 232, the support cylinder 232 is disposed so that the axis of the support cylinder 232 is along the vertical direction. In addition, when the can 10 is removed from the support cylinder 232, the support cylinder 232 is arranged so that the axis of the support cylinder 232 is along the vertical direction.

  Here, when the can 10 is received by the support cylinder 232, the support cylinder 232 can be laid as shown by reference numeral 3 </ b> A in FIG. 3 (a diagram showing a comparative example of the image forming apparatus 200). . In this case, a supply device for supplying the can 10 to the support cylinder 232 needs to be provided on the side of the support cylinder 232, and the area occupied by the image forming system 100 tends to increase. Further, when the can body 10 is removed from the support cylinder 232, the support cylinder 232 can be laid as shown by reference numeral 3B in FIG. 3, but in this case also, the removed can body 10 is conveyed. It is necessary to provide a conveying device or the like on the side of the support cylinder 232, and the occupation area of the image forming system is likely to increase.

  On the other hand, in the case of the configuration of this embodiment, the apparatus (can supply mechanism 300) for supplying the can body 10 can be positioned above the support cylinder 232, and has been removed above the support cylinder 232. The apparatus (can body discharge mechanism 400) which conveys the can body 10 can be located. For this reason, in the configuration of the present embodiment, an increase in the occupied area of the image forming system 100 is unlikely to occur. This can be easily inferred from the fact that the can receiving part 1C and the can discharging part 1D are arranged in the region indicated by the circular virtual line 1B shown in FIG.

  By the way, although image formation on the outer peripheral surface of the can 10 is often performed by color multicolor printing, monochromatic ink is ejected from each of the inkjet heads 240 provided in each image forming apparatus 200. For this reason, image formation on the can 10 is overprinting using a plurality of inkjet heads 240. More specifically, the can 10 put into the image forming apparatus 200 first reaches the first inkjet head 240, and the first inkjet head 240 forms an image on the outer peripheral surface of the can 10.

  Thereafter, the rotating member 210 rotates 45 ° counterclockwise, and the can 10 reaches the second inkjet head 240. Then, the second ink jet head 240 ejects the second color ink toward the outer peripheral surface of the can body 10. Thereafter, similarly, the can body 10 reaches the third ink jet head 240 and the fourth ink jet head 240, and the image formation on the can body 10 is further performed by these ink jet heads 240.

Hereinafter, the image forming process by the inkjet head 240 will be described in detail.
FIG. 4 is a diagram illustrating image forming processing by the inkjet head 240. 2A is a diagram showing the inkjet head 240 and the can body 10 when an image is formed by the first inkjet head 240, and FIG. 2B is an image by the second inkjet head 240. FIG. It is the figure which showed the inkjet head 240 and can 10 at the time of formation.

  Here, in the present embodiment, as described above, the movement of the can body 10 (revolution of the can body 10 and rotation of the rotating member 210) is stopped at a position where the first inkjet head 240 and the can body 10 face each other. Then, as shown in FIG. 4A, ink is ejected from the first inkjet head 240 to the can 10 that is rotating. As a result, an image of the first color ink is formed on the outer peripheral surface of the can 10.

Here, in the present embodiment, when the ejection of ink by the first inkjet head 240 is started, the output from the rotary encoder is grasped by the control unit 500 (see FIG. 1), and the first inkjet is performed by the control unit 500. The rotation angle of the can 10 when the ink is ejected by the head 240 (the rotation angle of the rotation shaft of the servo motor) is grasped. In the present specification, the grasped rotation angle is hereinafter referred to as “reference angle”. In addition, in the present embodiment, when the discharge of ink by the first inkjet head 240 is started, the output from the rotary encoder is grasped, and the rotation angle when the first inkjet head 240 starts printing on the can 10. Is acquired by the control unit 500 functioning as a first acquisition unit. At this time, the first inkjet head 240 reads the image data from the origin of the image data stored in the page memory 600 (the location where the angle difference Δθ shown in FIG. 5 is 0 °), and the read image data is the first. By supplying the ink to the inkjet head 240, ink is ejected to the can body 10, and an image of the first color ink is formed on the outer peripheral surface of the can body 10. At this time, the control unit 500 acquires the rotation angle of the can 10 corresponding to the origin of the image of the first color ink formed on the can 10 (the origin of the image data). This acquired angle becomes the reference angle.
Although not described above, four page memories 600 are provided so as to correspond to each of the first inkjet head 240 to the fourth inkjet head 240, and the first page memory 600 includes the first page memory 600. Image data of an image formed by one inkjet head 240 is stored. When an image is formed by the first inkjet head 240, image data is supplied from the first page memory 600 to the first inkjet head 240. The image data of the image formed by the second inkjet head 240 is stored in the second page memory 600, and the image data of the image formed by the third inkjet head 240 is stored in the third page memory 600. The fourth page memory 600 stores image data of an image formed by the fourth inkjet head 240.

  Thereafter, the rotation of the rotating member 210 is resumed, and the can 10 reaches the second inkjet head 240 that functions as the second image forming unit. Then, as shown in FIG. 4B, ink is ejected from the second inkjet head 240 to the outer peripheral surface of the can body 10. As a result, an image of the second color ink is formed on the outer peripheral surface of the can 10.

Here, in the present embodiment, even when the ejection of ink from the second inkjet head 240 is started, the output from the rotary encoder is grasped by the control unit 500 functioning as the second acquisition unit, and the can body 10 is obtained (information on the rotation angle of the can 10 is acquired). Next, the controller 500 subtracts the reference angle from the grasped rotation angle (hereinafter referred to as “grasping angle”) to obtain an angle difference. Thereafter, the control unit 500 starts reading from the image data corresponding to the angle difference among the image data stored in the page memory 600 (the second page memory 600) functioning as the data storage unit. Image data is sequentially supplied to the second inkjet head 240.
More specifically, the second inkjet head 240 starts discharging the second color ink to the can 10 based on the grasp angle, but the image data that the second inkjet head 240 discharges to the can 10 is: Not the image data read from the origin of the image data, but the image data from the read position corresponding to the angle difference. From the left image data, the ink discharge to the can 10 is started, and the image of the second color ink is It is formed on the outer peripheral surface of the can 10.

  Specifically, referring to FIG. 5 (a diagram for explaining reading of image data from the page memory 600), an angle difference Δθ obtained by subtracting the reference angle from the grasp angle is, for example, Δθ1. In this case, reading is started from image data corresponding to Δθ1 among the image data stored in the page memory 600, and the read image data is supplied to the second inkjet head 240.

  In other words, the control unit 500 that also functions as a determination unit determines the reading start position of the image data from the page memory 600 based on Δθ1, and starts reading from the image data at the determined reading start position. More specifically, the image data is divided into segments according to the angle, and image data for one segment corresponding to Δθ1 (image data for one line or images for a plurality of lines by the second inkjet head 240 are obtained. If it can be formed simultaneously, it is determined that the image data for a plurality of lines) is read first, and the image data for one segment is read first. Next, the control unit 500 supplies the read image data to the second inkjet head 240.

  Thereafter, as indicated by the arrow 7A, the image data of the segments adjacent to the image data corresponding to Δθ1 are sequentially read, and this image data is supplied to the second inkjet head 240. Thereafter, as indicated by an arrow 7B, image data corresponding to an angle difference of 0 ° is read out, image data of segments adjacent to the image data is read out sequentially, and the read image data is sequentially supplied to the second inkjet head 240. To do. Thereby, in this embodiment, as a means for aligning the position of the image formed by the first inkjet head 240 and the position of the image formed by the second inkjet head 240, the can 10 by the mechanical drive system of the apparatus is used. The position of the image formed by the first ink jet head 240 and the second ink jet head are changed by changing the start position of the image data read by the second ink jet head 240 by performing arithmetic processing inside the control unit 500 instead of performing position control. By aligning the position of the image formed at 240, image formation on the can 10 can be performed.

  Although not described above, there is a time lag between the time when the rotation angle of the can 10 is grasped and the time when ink is actually ejected when the ink is ejected by the second inkjet head 240. . In this case, the image forming position may be shifted. For this reason, for example, an angle difference obtained by subtracting the reference angle from the grasp angle is added to an angle corresponding to the time lag as a new angle difference, and an image is obtained based on the new angle difference. The reading start position of the data from the page memory 600 can also be determined.

  Here, the alignment of the image formed by the first inkjet head 240 and the image formed by the second inkjet head 240 is performed, for example, after the can body 10 is once arranged so as to have the reference angle. Can also be performed by supplying image data to the second inkjet head 240 in order from the image data corresponding to the reference angle in the image data.

  In addition, when image formation is performed by the second inkjet head 240, the support cylinder 232 is rotated so that the rotation angle of the can 10 becomes the reference angle, and then the image data stored in the page memory 600 is stored. By supplying image data to the second inkjet head 240 from image data corresponding to the reference angle (for example, image data corresponding to 0 ° (angle difference Δθ is 0 °) of the image data), The image formed by the first inkjet head 240 and the image formed by the second inkjet head 240 can be aligned.

  In this case, in order to set the rotation angle of the can 10 to the reference angle, rotation control (position control) of the support cylinder 232 is required, and it takes time until image formation by the second inkjet head 240 is started. It becomes like this. In this case, the number of cans 10 that can form an image per unit time is reduced.

  Further, when the rotation angle of the support cylinder 232 is set to the reference angle, the rotation control of the support cylinder 232 is necessary, and the control becomes complicated. In addition, when the rotation of the support cylinder 232 is controlled, it is necessary to control an object having a certain weight such as the support cylinder 232, and the accuracy of the stop position of the support cylinder 232 is likely to be lowered due to the influence of inertia. Further, since the support cylinder 232 has a certain weight, it is necessary to select a motor with a large output in order to control in a short time, which may increase power consumption and cost. In addition, when a motor with a large output is used, the size of the apparatus tends to increase.

On the other hand, in the present embodiment, the position of the can body 10 is not controlled (the can body 10 is rotated so as to have a reference angle), but the state of the can body 10 is grasped, Depending on the state, the image data to start reading is varied. In addition, the position control of the can body 10 is not performed, but the reading start position of the image data of the formed image is made different according to the rotation angle of the can body 10. Thereby, since it performs by the arithmetic processing inside the control part 500, without applying a burden to the mechanical drive system of an apparatus, position control of the can 10 becomes unnecessary and it becomes difficult to produce the malfunction demonstrated above. In the present embodiment, the state in which the can body 10 is rotated at a constant speed (the state in which the can body 10 rotates at a constant speed) can be maintained, which results from the rotation control of the can body 10. Decrease in accuracy is less likely to occur.
On the other hand, when the rotation of the can 10 is not rotated at a constant speed, the control of the second inkjet head 240 is complicated, such as changing the ejection frequency of the ink ejected from the second inkjet head 240 according to the rotational speed. Therefore, the accuracy is likely to be lowered due to the rotation control of the can 10.

  In the present embodiment, the image data is stored in the page memory 600, and the image data is stored in the page memory 600 in a state where the angle difference and the image data for one segment correspond to each other. In such a case, the image data can be read immediately according to the angle difference, and the processing speed of image formation can be increased.

  In addition to the method of associating the angle difference with the image data for one segment and storing the image data in the page memory 600, the position along the circumferential direction of the can 10 (the position specified by the distance) It is also possible to store image data in the page memory 600 in association with image data for one segment. In this case, a conversion table for converting the angle difference into a position along the circumferential direction of the can 10 is prepared in advance, and the angle difference is converted into a distance using this table. Based on the distance obtained by this conversion, image data is read from the page memory 600.

  In the above description, the processing when an image is formed on the can 10 by the second inkjet head 240 has been described. However, when an image is formed by the third inkjet head 240 (the same applies to the fourth inkjet head 240). The same processing is performed. That is, when the ejection of ink from the third inkjet head 240 is started, the control unit 500 grasps the output from the rotary encoder and grasps the rotation angle of the can body 10. Next, the reference angle is subtracted from the grasp angle, and the angle difference is acquired. Thereafter, reading is started from image data corresponding to the angle difference among the image data stored in the page memory 600, and the image data is sequentially supplied to the third inkjet head 240.

  In the above description, the angle at which image formation is started by the first inkjet head 240 is the reference angle (in this case, the reference angle is different for each can 10), but an image is captured by the first inkjet head 240. It is also possible to control the position of the can body 10 when it is formed and set a predetermined angle as a reference angle. In this case, the reference angle for each can 10 is the same.

  For example, the angle difference when the can body 10 reaches the third ink jet head 240 can be predicted based on the angle difference obtained when the can body 10 reaches the second ink jet head 240. More specifically, in the present embodiment, the distance (arrangement interval) between the first inkjet head 240 and the second inkjet head 240 and the distance (arrangement interval) between the second inkjet head 240 and the third inkjet head 240. ) Are equal, and the can 10 rotates at a constant speed. For this reason, in this embodiment, the angle at which the can 10 reaches the third inkjet head 240 is doubled by doubling the angle difference obtained when the can 10 reaches the second inkjet head 240. The difference can be predicted. In addition, the angle difference when the can 10 reaches the fourth inkjet head 240 can be predicted by triple the angle difference obtained when the can 10 reaches the second inkjet head 240. it can.

  In addition, the process which correct | amends the said angle difference obtained by prediction can also be performed. More specifically, for example, when one can body 10 (the preceding can body 10) is transported, if the predicted angle difference is different from the angle difference obtained by actual measurement, two cans When the body 10 (following can body 10) is transported, a correction process for the predicted angle difference can be performed. More specifically, the predicted angle difference for the first can body 10 and the actual measurement for the first can body 10 with respect to the predicted angle difference (the predicted angle difference for the second can body 10). The predicted angle difference for the second can 10 can be corrected by adding the difference with the angle difference. In this case, the prediction accuracy of the angle difference is improved. In this case, the correction can be performed by delaying or speeding up the timing of starting the ejection of ink from the inkjet head 240 in addition to the method of changing the reading position of the image data.

This will be described in more detail with reference to specific examples shown in FIGS.
In this specific example, four characters “A”, “B”, “C”, and “D” shown in FIG. 6 (a diagram showing an example of an image formed on the can 10) are sequentially displayed. An example in which the cans 10 are formed on the can 10 is an image in which each character is arranged in a plurality of colors. Here, FIG. 3A is a front view of the can body 10, and FIG. 4B is a rear view of the can body 10.

  In this specific example, as shown in FIG. 7 (a diagram showing an example of the image forming process performed on the can 10), a process when the second inkjet head 240 forms an image will be described. 7A is a diagram showing a processing example (comparative example) in the case where an image is formed on the can body 10 after the position control of the can body 10 is performed, and FIG. FIG. 5 is a diagram illustrating a processing example of the present embodiment.

  In the case of the comparative example shown in FIG. 7A, the rotation of the can body 10 is controlled as described above, and image formation by the second inkjet head 240 is performed from the state where the can body 10 is arranged at the reference angle. Be started. For example, when the image formation by the first inkjet head 240 is started from the position where the end of the letter “A” starts, as shown by the symbol A1 in FIG. The image formation is started from the position that becomes the end of the character “”.

  On the other hand, in the present embodiment, image formation is started even if the can 10 is disposed at a position other than the reference angle. Referring to the specific example of FIG. 7B, for example, even when the image formation by the first inkjet head 240 is started from a position that becomes the end of the letter “A”, the second inkjet When the character “A” is directed in the other direction when the can body 10 reaches the head 240, the character “C” is used instead of the character “A”, as indicated by reference numeral B 1 in FIG. The image formation starts from the characters “”.

  In the example shown in FIG. 7A, an image is formed from the character “A”, and characters “B”, “C”, and “D” are further formed before the can 10 rotates 360 °. Is done. In the example shown in FIG. 7B, an image is formed from the character “C”, and characters “D”, “A”, and “B” are further formed before the can 10 rotates 360 °. Is done. In addition, although the case where the can body 10 is rotated 360 ° has been described in this example, the can body 10 can also be rotated to a position exceeding 360 °. In this case, one end portion and the other end portion of the formed image overlap each other.

  Here, in this embodiment, image formation is not performed so that a sheet-like image in a range of W (length in the height direction) × L (length in the circumferential direction) is wrapped around the can body 10, but a cylinder In other words, image formation is performed so that the sleeve 10 is covered with a sleeve-shaped image in a range of W (length in the height direction) × θ (rotation angle (rotation position)). For this reason, in the present embodiment, the image data is not converted into W × L planar image data, but is converted into W × θ cylindrical image data in advance. It is also preferable to prepare in advance a conversion program that automatically converts W × L planar image data into W × θ cylindrical image data when the diameter of the can 10 is input. In this case, preparation time can be shortened.

  Further, in this embodiment, the can body 10 is rotated independently of the ink jet head 240, and the ink jet head 240 is rotated when the can body 10 is rotated 360 ° after the ink discharge from the ink jet head 240 is started. Ink ejection is stopped and printing is terminated. For this reason, in this embodiment, the overlap of the image resulting from the difference in the perimeter of the can 10 does not occur. Generally, there is a variation in the outer diameter of the can body 10, and there is also a variation in the circumference of the can body 10 according to this. At present, image formation on the can 10 is often performed by plate printing. Here, there is a variation in the circumferential length, and when image formation is performed by printing plate printing, the circumferential length from the printing start portion to the printing end portion is longer than the circumferential length of the can 10. In this case, the image at the print start portion and the image at the print end portion overlap each other. By the way, in this case, there is a possibility that the appearance of the can 10 may be damaged.

  On the other hand, in the present embodiment, as described above, the can body 10 is rotated 360 ° independently of the inkjet head 240 and the rotation of the can body 10 is terminated when the can body 10 is rotated 360 °. For this reason, an image is not formed at a portion exceeding 360 °, and the image at the print start portion and the image at the print end portion do not overlap. In this case, it is possible to suppress a decrease in the appearance of the can 10. Further, when the image at the print start portion and the image at the print end portion overlap, the consumed ink increases. However, in the case of this embodiment, since no overlap occurs, the amount of ink used is reduced. .

Here, the image forming process performed in the present embodiment will be further described with reference to FIG. 8 (a diagram showing the image forming process of the present embodiment).
Here, the frame indicated by the alternate long and short dash line in FIG. 8A indicates the original image, and the frame indicated by the solid line indicates the formed image (printed image) formed on the can 10. In addition, “W” in FIG. 4A indicates the length of the can 10 in the height direction. In addition, “L” in the figure indicates the circumference of the can 10.

  There is a variation in the circumferential length of the can body 10, and in the case of printing plate printing and when the circumferential length of the can body 10 is large, a gap may be formed between the formed image at the printing start portion and the formed image at the printing end portion. There is. Therefore, in the case of plate printing, a surplus length (α) (not shown) is provided, and the length of the formed image is made larger than the length of the original image, that is, the length of “L” in FIG. It is set as “L + α”. In this case, as described above, the end of the formed image at the print start portion and the end of the formed image at the print end portion overlap each other, which may impair the appearance of the can 10. In this case, the ink consumption also increases.

  Next, this embodiment will be described with reference to FIG. In FIG. 8B, (I) shows the original image and the actually formed image as described above. Further, (II) shows a state in which only the formed image is extracted. Also, (IV) shows a modeled result of converting the planar formed image extracted in (II) into a cylindrical formed image. In addition, FIG. (III) shows the process from FIG. (II) to FIG. (IV).

  Further, FIG. 4 (V) shows image data output to the inkjet head 240. Here, the position in an arbitrary rotation direction is set to 0 point (origin), and the rotation angle when the can 10 in the state rotated by θ1 (radian) is rotated to θ2 (radian) is Δθ1 (radian), Furthermore, when the radius of the can body 10 is R, an image (ΔP1) formed on the outer peripheral surface of the can body 10 when the can body 10 is rotated by this Δθ1 is an area of R × Δθ1 × W. It becomes the inside image.

  In the image forming process of the present embodiment, since image formation can be started from an arbitrary rotational position, it is also possible to start image formation from the position θ2 in FIG. Further, in the present embodiment, as described above, the printing end position is a position rotated once (360 °) from the position where the can body 10 starts to rotate, so that the overlapping of images does not occur. When the circumference of the can body 10 is large, the distance between the image for one segment formed by the inkjet head 240 and the image of the segment adjacent to the image is large, and the circumference of the can body 10 is small. The distance between the image of one segment formed by the inkjet head 240 and the image of the segment adjacent to this image is reduced, and more specifically, the ink droplets ejected from the inkjet head 240 arrive at the can body surface. With respect to the ink dots thus formed, when the perimeter of the can body 10 is large, the distance between the dots in the circumferential direction of the adjacent ink increases, and when the perimeter of the can body 10 is small, the distance becomes smaller. However, this describes a case when viewed microscopically, and it is difficult to distinguish it with the naked eye. As described above, the image density increases or decreases in accordance with the circumference of the can 10, but in any case, the image overlap does not occur.

Next, the can body supply mechanism 300 and the can body discharge mechanism 400 shown in FIG. 1 will be described in detail.
FIG. 9 is a view of the image forming system 100 shown in FIG. 1 as viewed from the direction of the arrow IX. FIG. 10 is a diagram for explaining the can supply mechanism 300. In FIG. 9, two image forming apparatuses 200 positioned below in FIG. 1 among the three image forming apparatuses 200 provided are not shown.

  As shown in FIG. 9, the can body supply mechanism 300 is disposed on the upper portion of the image forming apparatus 200 and supplies the can body 10 to the image forming apparatus 200 from the upper portion of the image forming apparatus 200. Here, the can body supply mechanism 300 includes a duct 310 disposed so as to be directed downward from above, and supplies the can body 10 to the image forming apparatus 200 using the duct 310. As shown in FIG. 10, the duct 310 is formed in a state of being twisted by 90 °, and the can body 10 that has been conveyed in a lying state is supplied to the image forming apparatus 200 in an upright state. To do.

  As shown in FIG. 1, a plurality of ducts 310 are provided so as to correspond to each of the image forming apparatuses 200. Further, each of the ducts 310 is disposed inside the image forming apparatus 200 as shown in FIG. If it adds, each of the duct 310 is arrange | positioned inside the said circular virtual line 1B (refer FIG. 1). Further, in order to prevent the ducts 310 from interfering with each other, the respective ducts 310 are not directed toward the central portion (the portion indicated by reference numeral 1A) of the circular imaginary line 1B, but are inclined with respect to a straight line toward the central portion. Arranged in a state. In other words, each duct 310 is arranged in an inclined state with respect to an imaginary line going from the can receiving part 1C to the central portion (a part indicated by reference numeral 1A).

Next, the can body discharging mechanism 400 will be described.
As shown in FIG. 9, the can body discharge mechanism 400 includes a first transport mechanism 410 that is disposed above the image forming apparatus 200 and transports the can body 10 on which an image is formed by the image forming apparatus 200. A protective layer forming device 440 that forms a protective layer on the outer peripheral surface of the can body 10 that has been transported by the first transport mechanism 410, and a second transport that transports the can body 10 on which the protective layer is formed by the protective layer forming device 440. A third transport mechanism 430 that receives the can 10 from the mechanism 420 and the second transport mechanism 420 and transports the can 10 is provided.

  Here, as shown in FIG. 9, the first transport mechanism 410 has a plurality of holding pads 411 that suck and hold the can body 10, and is disposed above the holding pads 411 and supports the holding pads 411 from above. And an upper support member 412. Here, as shown in FIG. 1, the upper support member 412 is provided so as to circulate and move along a predetermined route. Further, as shown in FIG. 1, the upper support member 412 is provided so as to pass through can body discharge locations 1 </ b> D provided in each of the three image forming apparatuses 200. Further, as shown in FIG. 1, the upper support member 412 is provided so as to pass through the inside of the circular imaginary line 1B.

Here, in the present embodiment, the can body 10 on which image formation has been performed by the image forming apparatus 200 is held by the holding pad 411 when reaching the can body discharge location 1D (see FIG. 9).
Specifically, when the can body 10 reaches the can body discharge point 1D, air is increased in pressure with respect to the space inside the support cylinder 232 in place of suction to fix the can body 10 to the support cylinder 232. Is supplied. And the air by which the pressure was increased flows into the space | gap of the support cylinder 232 and the can body 10 by the ventilation hole which penetrates the inside and outer surface of the support cylinder 232, the pressure of this space is raised, and the can body 10 is supported by the support cylinder A force for detaching from the 232 acts on the can body 10. Thereby, the can 10 supported by the support cylinder 232 moves upward. On the other hand, the holding pad 411 also starts sucking. Thereby, the can 10 is held by the holding pad 411.

  Here, the holding pad 411 can be lowered to the support cylinder 232 by providing a function (not shown) for moving the holding pad 411 up and down. In this case, similarly to the above, the holding pad 411 starts suction, while the support cylinder 232 destroys the suction of the can body 10, so that the movement of the can body 10 from the support cylinder 232 to the holding pad 411 is performed. Prompted. In this case, after the suction of the can 10 by the holding pad 411 is started, the holding pad 411 is raised. Thereby, the can 10 is removed from the support cylinder 232 and moves upward. The can body 10 held by the holding pad 411 moves with the movement of the upper support member 412 and reaches the protective layer forming apparatus 440.

Next, the protective layer forming apparatus 440 will be described.
As shown in FIG. 1, a part of the protective layer forming apparatus 440 is provided below the first transport mechanism 410. First, the can body 10 transported by the first transport mechanism 410 is supported from below. To do. Next, the supported can body 10 is laid down, and a roll-shaped member is brought into contact with the outer peripheral surface of the can body 10, and a coating material that serves as a protective layer is applied to the outer peripheral surface. Thereafter, the protective layer forming apparatus 440 transports the can 10 to the second transport mechanism 420.

With reference to FIG. 9, the protective layer formation apparatus 440 is demonstrated concretely.
Similarly to the image forming apparatus 200, the protective layer forming apparatus 440 of the present embodiment is driven by a motor (not shown) in the counterclockwise direction (the rotation direction indicated by the arrow positioned below the reference numeral 440 in FIG. 1). A rotating member 441 that rotates, and a support base 442 that supports the rotating member 441 are provided. Furthermore, it has a plurality of holding mechanisms 443 that are provided so as to protrude from the outer peripheral surface of the rotating member 441 and hold the can 10 that has been transferred by the first transfer mechanism 410.

  Furthermore, an applicator 444 that applies paint to the outer peripheral surface of the can 10 held by the holding mechanism 443 is provided. Here, the coating device 444 includes a storage container 444A containing paint, a coating roll 444B that contacts the outer peripheral surface of the can body 10 from below the can body 10 and applies the paint to the outer peripheral surface, and a coating roll from the storage container 444A. It is comprised from the supply roll 444C which supplies a coating material to 444B.

  Here, each of the holding mechanisms 443 has the same configuration as the holding mechanism 230 provided in the image forming apparatus 200. Specifically, as shown in FIG. 9, each of the holding mechanisms 443 includes a fixing member 443 </ b> A that is provided so as to protrude from the outer peripheral surface of the rotating member 441 and that is disposed substantially horizontally and fixed to the rotating member 441. I have. Furthermore, it has a cylindrical support cylinder (mandrel) 443B which is formed in a cylindrical shape and is inserted into the can body 10 and supports the can body 10. Here, in the present embodiment, like the support tube (mandrel) 232, the support tube (mandrel) 443B includes a base portion 443B-1 and a rotation portion 443B-2. Each of the holding mechanisms 443 is provided so as to penetrate both the disk-shaped member 443C, the disk-shaped member 443C, and the fixing member 443A attached to one end of the support cylinder 443B, and the disk-shaped member 443C and the fixing member 443A. Has a shaft 443D for fixing.

  Further, the disk-like member 443C is provided with a rotation mechanism (not shown) that rotates around the shaft 443D. Here, in this rotation mechanism, similarly to the rotation mechanism provided in the image forming apparatus 200, a worm wheel (not shown) is arranged inside the disk-shaped member 443C, and a worm (not shown) is placed inside the fixing member 443A. It can be configured by arranging. In this case, the disk-like member 443C can be rotated by rotating the worm inside the fixed member 443A with a motor (not shown). Further, in the present embodiment, each holding mechanism 443 is housed in the base portion 443B-1, the rotation shaft thereof is connected to the rotation portion 443B-2, and the rotation portion 443B-2 (can body 10) is surrounded. A motor (not shown) that rotates in the direction is provided.

  Here, when the protective layer is formed by the protective layer forming apparatus 440, first, the can body 10 transported by the first transport mechanism 410 at the position indicated by reference numeral 4E in FIG. Delivered. More specifically, when the holding pad 411 breaks the suction at the position indicated by reference numeral 4E, the can body 10 that has been sucked and transported until then falls downward, and waits at the bottom. The can 10 is sucked by the supporting cylinder 443B. Thereby, the support cylinder 443B enters the inside of the can body 10, and the can body 10 is held by the support cylinder 443B.

  In addition, the holding pad 411 holding the can 10 can be lowered by providing a function (not shown) for moving the holding pad 411 up and down. In this case, when the holding pad 411 breaks the suction, the suction of the can body 10 is finished, and the holding pad 411 releases the can body 10. On the other hand, the suction from the ventilation hole (not shown) installed in the support cylinder 443B is started. Thereby, the can 10 moves from the holding pad 411 to the support cylinder 443B, and the can 10 is held by the support cylinder 443B.

  After the can body 10 is held by the support cylinder 443B, a motor provided in a rotation mechanism (not shown) is driven to rotate the disk-shaped member 443C around the shaft 443D, so that the can body 10 Go to sleep. Next, the can body 10 reaches the application roll 444B, and the coating roll 444B applies the paint to the outer peripheral surface of the can body 10. Thereby, a protective layer is formed on the outer peripheral surface of the can 10.

  Thereafter, in the present embodiment, when the motor provided in the rotation mechanism is driven again, the disk-shaped member 443C rotates around the shaft 443D, and the can 10 stands. Thereafter, the can 10 is delivered to the second transport mechanism 420. In addition, when application | coating of the coating material by the application roll 444B is performed, the rotation part 443B-2 rotates to the circumferential direction by the motor accommodated in the inside of base 443B-1, and the can 10 rotates. In the present embodiment, the application roll 444B and the supply roll 444C are rotated using other motors.

Next, the second transport mechanism 420 will be described.
The second transport mechanism 420 has the same configuration as the first transport mechanism 410. That is, as shown in FIG. 9, a plurality of holding pads 421 for sucking and holding the can body 10 and an upper support member 422 arranged above the holding pad 421 and supporting the holding pad 421 from above are provided. ing. Here, as shown in FIG. 1, the upper support member 422 in the second transport mechanism 420 is formed in a disk shape and rotates around the center. In this embodiment, the holding pad 421 is attached to the lower surface of the disk-like upper support member 422.

  Here, the can body 10 on which the protective layer is formed by the protective layer forming apparatus 440 is sucked and held by the holding pad 421 when reaching the lower portion of the second transport mechanism 420. More specifically, when the can body 10 reaches the position indicated by reference numeral 4F in FIG. 9, the can body 10 is replaced with the suction that has been fixed to the support cylinder 443B, and the space inside the support cylinder 443B is changed. Air with increased pressure is supplied, and air with increased pressure flows into the space between the support cylinder 443B and the can body 10 through the ventilation holes penetrating the inside and the outer surface of the support cylinder 443B, and the pressure in this space is increased. The force that causes the can body 10 to be detached from the support cylinder 443B acts on the can body 10, and the can body 10 moves upward. On the other hand, a holding pad 421 is located above the can body 10. Thereby, the can 10 moved upward is sucked and held by the holding pad 421.

  Note that a function (not shown) for moving the holding pad 421 up and down may be provided. In this case, the holding pad 421 moves down to the support cylinder 443B, and the holding pad 421 starts suction. On the other hand, the support cylinder 443B prompts the can 10 to move from the support cylinder 443B to the holding pad 421 by destroying the suction of the can 10. Further, after the holding pad 421 adsorbs the can 10, the holding pad 421 is raised. Accordingly, the can body 10 is detached from the support cylinder 443B, and the holding of the can body 10 by the holding pad 421 is started. The can 10 held by the holding pad 421 moves with the rotation of the upper support member 422 and reaches the third transport mechanism 430.

Next, the third transport mechanism 430 will be described.
As shown in FIG. 9, the third transport mechanism 430 includes a metal chain 431 that circulates and moves along a predetermined path, and a plurality of pins that are attached to the chain 431 and provided upward. 432. Here, in the present embodiment, when the can body 10 transported by the second transport mechanism 420 reaches the upper side of the third transport mechanism 430, the suction of the can body 10 by the holding pad 421 is destroyed, whereby the can body 10 Is released. Thereby, the can body 10 falls downward and the pins 432 are inserted into the can body 10. Thereafter, the can 10 moves along with the movement of the chain 431.

  Note that the holding pad 421 can be lowered to the pin 432 by providing a function (not shown) for moving the holding pad 421 up and down. In this case, after the pins 432 are inserted into the can 10, the holding pad 421 breaks the suction of the can 10. Thereby, the holding of the can body 10 is released, and the holding of the can body 10 by the pins 432 is started. Thereafter, the holding pad 421 is raised. Although illustration is omitted, a drying device for heating and drying the paint applied by the protective layer forming device 440 is provided on the downstream side of the third transport mechanism 430. The third transport mechanism 430 includes a can The body 10 is conveyed to this drying device.

  Here, when an image is formed on the can 10 based on digital image information as in the present embodiment, a flexible response such as multi-product small-lot production is possible compared to offset printing that is currently widely used. It becomes possible. Here, in the present embodiment, since a plate called a printing plate used at the time of offset printing is not used, a printing plate manufacturing process, an alignment operation between the printing plate and the printing machine, and a cleaning operation of the printing plate are not required. For this reason, in this embodiment, an operation called “setup” when changing lots is simplified, and it is possible to flexibly cope with multi-product small-lot production. In addition, there are not a few factors related to printing in defects that occur in the manufacturing process of cans. When digital printing is performed as in the present embodiment, there is a possibility that a part of the cause of the failure can be solved.

DESCRIPTION OF SYMBOLS 10 ... Can body, 100 ... Image forming system, 210 ... Rotating member, 240 ... 1st inkjet head, 500 ... Control part, 600 ... Page memory

Claims (5)

A first image forming unit that forms an image on the outer peripheral surface of the can rotating in the circumferential direction;
First acquisition means for acquiring information related to the rotation angle of the can when the image formation by the first image forming unit is started;
A second image forming unit that forms an image on the can rotating in a circumferential direction after an image is formed on the can by the first image forming unit;
Second acquisition means for acquiring information related to the rotation angle of the can when the image formation by the second image forming unit is started;
A data storage unit for storing image data of the image formed by the second image forming unit;
The data storage unit for image data used by the second image forming unit based on the information on the rotation angle acquired by the first acquisition unit and the information on the rotation angle acquired by the second acquisition unit Determining means for determining a reading start position from:
With
The second image forming unit forms an image on the outer peripheral surface of the can rotating in the circumferential direction using the image data sequentially read from the reading start position determined by the determining unit. A featured image forming system.   The determination means includes a rotation angle specified by information about the rotation angle acquired by the first acquisition means, and a rotation angle specified by information about the rotation angle acquired by the second acquisition means. The image forming system according to claim 1, wherein the reading start position is determined based on an angle difference that is a difference between the two. Rotating means for rotating the can body in the circumferential direction,
The rotating means is constant without increasing or decreasing the rotational speed of the can body from the start of image formation by the first image forming unit to the end of image formation by the second image forming unit. The image forming system according to claim 1, wherein the can body is rotated at a speed.   The first image forming unit and the second image forming unit form an image on an outer peripheral surface of the can body by discharging ink from above the can body in a lying state. Item 4. The image forming system according to any one of Items 1 to 3. The first image forming unit and the second image forming unit are arranged at different locations,
A moving means for moving the can through the first image forming unit and the second image forming unit while rotating the can in the circumferential direction;
The can that moves through each of the first image forming unit and the second image forming unit while rotating in the circumferential direction rotates at a constant speed without increasing or decreasing the rotation speed. The image forming system according to claim 1 , wherein the movement is performed.

Images