Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F15/00—Screen printers
  • B41F15/08—Machines
  • B41F15/0804—Machines for printing sheets
  • B41F15/0809—Machines for printing sheets with cylindrical or belt-like screens
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M1/00—Inking and printing with a printer's forme
  • B41M1/12—Stencil printing; Silk-screen printing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
  • B41P2215/00—Screen printing machines
  • B41P2215/10—Screen printing machines characterised by their constructional features
  • B41P2215/11—Registering devices

Definitions

• the invention relates to a method and its application, and a device for coating sheets or sections by means of coordinated rotating screens, the sheets or sections being removed from a stack and forcibly fed to the coating.
• the inventors have recognized that at least screen printing, painting and applying special materials such as glue / adhesive are not only related techniques, but there is also a real need for a single processor to be able to use these different techniques.
• Screen printing has the great advantage that relatively small forces between the circular screen and the arches are required.
• the main problem with rotary screen printing is that the movement between the rotary screen and an opposing printing cylinder must be synchronized with the highest accuracy during printing so that the job can be applied precisely to the sheets or sections.
• the beginning and end of the sheets to be printed must also exactly match the template as it results from the movement of the circular screen.
• the targeted screen printing is mostly a finishing process, often on an already printed sheet.
• the sheets are held by means of grippers which are arranged at a mutual distance and attached to chains.
• the grippers are precisely guided during the printing process.
• the counter-pressure rollers have a recess in the circumference for the grippers to pass through. Proper positioning of the objects relative to the platen roller and holding it while pressing is one of the main difficulties. It must be avoided that the printed image is placed inaccurately or even deformed.
• DE-PS 693 00 644 was based on the object of developing a device which allows precise positioning in terms of location and time along at least part of the path on which the objects are printed. It is proposed to do so within a mechanical endless conveyor to arrange a short Fuhrungsem ⁇ chtung with the highest precision, so that the individual sheets are moved absolutely synchronously with the printing cylinder - 3 -
• DE-OS 1 97 03 31 2 also relates to screen printing cylinder machines with a printing cylinder which receives the printing material and is driven by a drive motor.
• the machine has a rotary screen arranged at a distance parallel to the axis and independently driven by a drive motor, and a device for synchronizing the Movement of the printing cylinder and the rotary screen during the printing process
• the older printing method has disadvantages with regard to the acceleration of the printing cylinders, since these can lead to vibrations of the entire machine.
• the printing cylinder with a circumference which is greater than or equal to the circumference of the rotary screen, rotates at an essentially constant speed.
• a major advantage of the document is that the essentially constant rotational speed means that the control effort for synchronizing sation of screen movement and impression cylinder can be kept low
• the object of the invention was now to improve the coating of sheets and sections in such a way that the qualitative standard of flat screen printing can also be achieved by means of rotary screens with the greatest possible performance, in particular also inexpensive and rational for smaller series - 4 -
• the method according to the invention is characterized in that the circulation of the circular screen can be adjusted or regulated, in particular corrected, with respect to the forcibly fed sheets or sections, for a precisely coordinated run during the printing process
• the device according to the invention is characterized in that it has a precision workstation with a constant feeder and the circular screen has a control or regulable drive for referencing the circular screen in relation to the printing length and / or printing position of the sheets or sections
• the new invention further relates to the application of the method and use of the device and is characterized in that for screen printing as color printing or varnishing of sheets or sections or for the application of special application media such as glue etc. with a corresponding design of the screen cylinder as a quick change cylinder e.g. is designed as a screen printing cylinder, screen coating cylinder or as a special screen application cylinder, wherein one or more screen cylinders can be used in a precision work station or in several precision work stations
• the influence of heat changes. This can even occur while a batch is being processed.
• the first batch is often worked on, while the subsequent batches are still outside the warm production room, e.g. store at a lower or higher temperature or other humidity.
• the length difference can be 0.5 to 1 millimeter.
• a tolerance of the order of plus / minus one tenth of a millimeter is required for printing accuracy.
• the sole requirement of synchronizing the circulation of the rotary screen and the impression cylinder does not solve the problem presented.
• a common source of disruption is that multiple sub-items are used for an identical order, or that these are split up. Even if there are no dimensional differences within an item, there may be differences with regard to the sheets or sections of various items that are processed at longer intervals, especially due to the influencing factors mentioned.
• the new invention opens up a completely new process technology.
• the transfer of the sheets from the stack to the forced guide for the coating is done as well as possible by mechanical means.
• the highest possible accuracy is still in a gripper solution.
• the sheets are guided through the coating section by means of grippers.
• the disadvantage of the gripper solution is that it requires considerable expenditure in terms of manufacturing costs.
• a tape solution is much simpler, but physically less precise.
• the accuracy of the coating required above can be achieved by adjusting / regulating or correcting the rotary screen circulation. In very many applications, there is no need to transport the gripper because the exact positioning of the sheets for the coating is achieved using the rotary screen.
• control / regulation of the circulation of the rotary screen is based on a reference axis and takes place via a control-regulating unit, which allows operation with position correction and operation without position correction. Position errors of individual, positively fed sheets or sections can be corrected by adjusting the print start position via the control / regulation of the circulation of the rotary screen.
• the speed of rotation of the screen drum is controlled or regulated in relation to the longitudinal repeat of the sheets, the referencing being carried out by accelerating and / or decelerating the speed of screen rotation.
• the screen cylinder is preferably driven by a controllable servo motor and controlled by a computer, the position of the respectively fed sheet or section relative to the Screen cylinder movement is monitored by sensor means at a distance before contact with the screen cylinder. It has also been shown that the entire handling of the sheets or sections is more optimal if the sheets or sections are transported to and from the coating in a horizontal working plane and the sheets or sections are transferred during the transfer from a feed transport to the coordinated pass the printing process can be accelerated to the precise processing speed.
• the screen printing cylinder preferably has a regulated servo drive and the impression cylinder and the sheet transport through the printing unit has a regulated drive, in particular a regulated vector drive, to which one or one local control unit is assigned.
• a regulated drive in particular a regulated vector drive, to which one or one local control unit is assigned.
• the entire system is mastered to a very high degree if the settings or corrections required according to the invention are literally on-site. be coordinated between the elements involved. It is therefore proposed that, in addition to a machine control, an on-site control module with the individual control units is provided, the setpoints being specified by the machine control and the control corrections being made directly by the on-site control module.
• FIG. 1 shows schematically the production of the screen cylinder printing form for rotary screen printing according to the prior art
• FIG. 2 shows a precision work station with a screen cylinder for processing in one plane
• 3 shows an entire system for the coating of sheets
• Figure 4 shows the precision workstation on a larger scale with an inlet and outlet table and a calender
• FIG. 5 shows a preferred control scheme with an on-site control module
• Figures 6 and 7 schematically show the control / regulation of the screening drum with a control ramp
• 8 shows the gripper insert in a position close to the rotary screen and the transfer from a feeder to the precision work station with a sheet acceleration
• Figures 9 and 10 view and Grund ⁇ ss the precision workstation
• Figures 1 1 and 1 2 view and Grund ⁇ ss of a system from a feeder to a precision workstation
• Figure 1 shows schematically the workflow from a print template "A” to a ready-to-use screen printing cylinder 10 (“E"). The process is illustrated with six figures “A” to “E”.
• the print template 1 is exposed after a preliminary film production.
• the desired screen openings are washed out, so that a flat printing form 2 is obtained.
• the flat printing form 2 is then combined into a cylinder and placed as a cylindrical printing form 3 on a prepared form support 4 .
• the mold carrier 4 not only gives the cylindrical shape but also has a central axis 5, so that the position of the axis of rotation is exactly determined.
• a stencil ring 6 is placed from above into the cylindrical printing form 3 and onto the axis 5 (“C”).
• the printing form is then glued to the carrier elements ("D") and the sieve cylinder which has now been produced is equipped with the necessary auxiliary elements 7, 8 ("E") and can be used in the machine.
• the whole process takes about half an hour. Since the screen cylinder has a large opening 9 on one side, the material feed 11 for the coating medium and a doctor blade 12 can be inserted through the opening 9 into the screen cylinder.
• This structure allows a very quick change of a screen cylinder 10, from a first printing form to a second screen cylinder with a second printing form, etc.
• the production of a rotary screen printing cylinder is state of the art for the printing of continuous webs.
• the sheet or section is processed on a horizontal working plane, which forms a working table level 20 from the feeder to the deposit.
• the sheet is fed to the calendering via an alignment station 1 8 and a vibrating system 19.
• a precision work station 21 has a chain or toothed belt 22 which is stretched over the entire precision work area PAL by means of deflection rollers 23, 23 ', 23 ", 23'" becomes.
• the transport by means of chain or toothed belts 22 is driven by a motor 24, which can be controlled via a machine control 25.
• the sieve cylinder is indicated by 1 0.
• an application unit 26 can also be swiveled in (st ⁇ ch ert indicated), so that either screen printing or painting can be carried out at the same workstation, for example Precision working length PAL further procedural steps - 8th -
• a counter-pressure roller 29 is arranged at the precision work station, directly opposite the screen cylinder 1 0.
• the number 27 only indicates that one or more further identical or different stations can be arranged after or before a precision work station 21.
• Mechanical precision guidance is important for the precision workstation over the entire work area PAL. In addition to the chain or toothed belt, this is ensured by a mechanical gripper station 30 at the beginning and a sheet release point for the mechanical grippers. In FIG. 2, the sheet is forcibly fed via chains and grippers 31.
• FIG. 3 shows an entire system 40 for the treatment of sheets or sections 41.
• a feeder 43 On the right is a feeder 43, followed by a belt conveyor 44 and the precision work station 21. Following the latter is a station 45 for drying, hardening and stabilizing the processed sheets, followed by a deposit 46.
• a control box 32 for the feeder In FIG. 3 there is also a control box 32 for the feeder, a main control box 33, a controller 34 for the dryer and a controller 35 shown for the offshoot.
• FIG. 4 shows the system in a modular design, a precision workstation 25 comprising a machine control 25 with the inclusion of a high-performance computer R.
• the precision work station 21 is a screen printing station, on which an inlet table 47 and then an outlet table 48 are arranged beforehand.
• a calender 28 is located in front of the infeed table.
• FIGS. 3 and 4 show a solution with suction belt transport in the area of the precision work station.
• FIG. 50 designates a machine control system by means of which all system elements are coordinated and controlled, or are supplied with power.
• the reference numeral 51 denotes a bus system.
• the part of the figure below the thick line for the BUS system is the actual control and regulation 61 for the coating process, including the drive system for everyone Transport elements.
• the drive system consists of three drive units, which communicate with each other and with the machine control via serial data lines.
• This drive unit serves as a reference axis for the speed of the complete system, it communicates with the screen printing unit via a serial data interface.
• the digital speed setpoint is specified by the machine controller M-ST via the data bus 51 and sent to the screen printing unit via a serial data interface. From there, the setpoint is sent to the drive unit via the aforementioned data interface.
• the screen printing cylinder 10 is driven with the drive unit 53 for the screen printing cylinder 10.
• the drive unit obtains the effective system speed or the position from the reference axis via the pulse chain. In operation without position correction, the speed of this drive unit corresponds exactly to that of the reference axis. In correction mode (operation with position correction), the speed only corresponds to that of the reference axis at the intersection points. This means that the speed in the pressure range from 0 mm - 720 mm is lower or higher than that of the reference axis. In the travel range of 720 - 820 mm, the speed for travel compensation or position correction is higher or lower than that of the reference axis.
• the position is corrected by means of sinusoidal positive and negative acceleration of the screen printing cylinder. The position is assessed using the pulse chain. A correction is calculated on the drive unit, the machine control is not loaded with the drive control, or the machine control and the BUS system do not inhibit the control speed for corrections.
• the removal is e.g. driven by UV dryer and sheet deposit. It is an unregulated asynchronous drive 57.
• the drive unit receives the setpoint value for the speed via a data interface from the screen printing unit. The speed is proportionally greater than the system speed.
• All three drive motors 55, 56 and 57 are each a local controller 58 and. 59 resp. 60 assigned, with a direct data exchange via pulse chains taking place between the on-site controllers 58 and 59.
• the two control engineering key pieces are combined as a on-site control module 61 with a dash-dotted line, this module preferably also containing the on-site controller 60.
• other servo systems e.g. Control over - l ü ⁇
• the speed input of the servo motor can be selected for one, two or all three motors. All described control functions that are directly related to the coating are preferably combined on site, so that the corresponding functions are ensured locally autonomously.For example, it is possible in this way to coat a sheet only with the means of on-site control / regulation for a whole Setpoints required in the recipe are managed by the machine computer in normal operation and, if required, transferred to the on-site control module as setpoints.This means that all sensor means in the area of the precision workstation are also used in the on-site control module.
• the servo motor 56 and the motor 55 are controlled via power electronics have the necessary interfaces and can also be operated directly via a keyboard 62
• FIGS 6 and 7 show schematically the referencing of circular screen and bow.
• a single sheet can be accelerated, for example by means of a traveling stop 65, 65 ', from the speed V1 to the precision transport speed V2 over the distance shown, and is subsequently with a precise, constant speed V2 on the constant conveyor 66 to the screen cylinder guided.
• a photocell arrangement is indicated with which the front end of the sheet is detected on the running conveyor.
• the photocells 67 are arranged at a regular distance RA in front of a theoretical screen printing line SD.
• the screen cylinder 10 rotates at a speed Vx at the point in time X (T1) at which the leading edge of the sheet triggers the arrival signal at the photocell 85.
• the computer has additional sensor and storage means, so that the exact position Px or Px 'of the corresponding reference point P on the sieve cylinder 1 0 is recognized.
• the computer R immediately begins to calculate the orbital movement and subsequently controls the circulation or the rotational speed of the sieve cylinder within milliseconds in such a way that the reference point P at the same time (or at the time Z or T2) arrives at the theoretical screen printing line SD with the leading edge Vk of the sheet, in such a way that the possibly corrected rotational speed V3 is reached before the front edge Vk meets the reference point P and exactly corresponds either with the precision transport speed V2 or with a Speed circulation, which corrects by the amount of the bow distortion i st.
• FIG. 8 schematically shows a compilation of a transfer station from a feeder to the coating station, the transfer station including a gentle acceleration of the sheets. A gripper solution is indicated at the coating station. This combination is suitable for the highest requirements with large, thin sheets. However, the gentle acceleration can be very advantageous when transporting a suction belt as a precision work station. In practical operation, it is not expedient to control the feeder sequence in such a way that an attempt is made to accelerate the sheets directly onto the coating station with the corresponding feeder.
• An alignment station is therefore arranged between the feeder and the precision workstation.
• a centerpiece of the alignment station 49 is an acceleration roller 70 with pinch rollers 71 that can be pushed in and out, and a controllable stop 72.
• the sheets 41 are fed by the feeder 43 via a conveyor belt and slide unhindered at the feed speed VA over the acceleration roller 70 No traces of pressing, clamping or rubbing are made, as these would otherwise jeopardize the quality of the printing sheet.
• a particular difficulty is that the line speed V1 is based on the criteria of the coating and the sheets can have any length dimension L.
• With 73 a pair of guide rollers is designated.
• the basic control functions of the alignment station 49 are shown in FIG.
• a computer C 1 is connected to an incremental encoder JG of the subsequent processing system, drive means 74, not shown schematically, being able to drive a feed belt 34 at the speed V 1 of the processing system.
• the acceleration roller 70 can be directly connected to a mechanical overdrive, center line 80 to the drives 74 on the processing side.
• the stop 72, a clutch lever 91 and a push-in and push-out mechanism 82 for the guide rollers 71 can be controlled directly by a drive unit 84 of the feeder 43, or on the feeder side, via corresponding overdrive means 83.
• a common control shaft 85 is provided, on which three cams 86, 87 and 88 are arranged corresponding to the three functions.
• the cam disc 86 is in direct engagement with a tapping roller 89, a lever joint 90 and a clutch lever 91 for the clutch 81.
• the cam plate 87 controls the engagement and disengagement mechanism 82 via a lever 92 and a connecting rod 93.
• the third cam plate 88 controls a rotary arm 95 of the stop 72 via a lever 94.
• Figures 9 and 10 show an example of a quick-change circular screen 10 on a larger scale.
• the rotary screen 1 0 is driven on both sides by a common servo motor 56, which can be controlled via on-site controller 59.
• On the side of the inlet 68 several sensors are, for. B. arranged as light sensors or photocells 67, the signals of which are used in the on-site controller 59 for referencing.
• the screen cylinder 1 0 can be lowered and raised in the vertical direction A - A, this movement also being coordinated via the drive unit 53 or the on-site module 61
• the screen cylinder 1 0 can also, as indicated by the letters P and DR, be adjusted for the diagonal repeat and with the letter LR for the longitudinal repeat
• FIGS. 1 1 and 1 2 show a view and basic view of a plant from right to left, one with a feeder 43, an alignment station and the precision work station, which as a belt transport with mechanical transport aids for constant demand or with a chain or toothed belt transport with mechanical grippers can be trained. From the feeder to the left there is a shingled system, acceleration, sheet cleaning and a smoothing calender 28.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Screen Printers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Coating With Molten Metal (AREA)
• Printing Methods (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=4192850

Family Applications (1)

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• 1999
  • 1999-03-23 DE DE59901634T patent/DE59901634D1/de not_active Expired - Lifetime
  • 1999-03-23 CN CN99804353.2A patent/CN1213863C/zh not_active Expired - Fee Related
  • 1999-03-23 AU AU27097/99A patent/AU2709799A/en not_active Abandoned
  • 1999-03-23 WO PCT/CH1999/000124 patent/WO1999048690A1/fr active IP Right Grant
  • 1999-03-23 US US09/646,795 patent/US6485777B1/en not_active Expired - Fee Related
  • 1999-03-23 JP JP2000537711A patent/JP2002507506A/ja active Pending
  • 1999-03-23 AT AT99907225T patent/ATE218439T1/de not_active IP Right Cessation
  • 1999-03-23 EP EP99907225A patent/EP1066159B1/fr not_active Expired - Lifetime

Non-Patent Citations (1)

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