Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F35/00—Cleaning arrangements or devices
  • B41F35/003—Cleaning arrangements or devices for screen printers or parts thereof
  • B41F35/005—Cleaning arrangements or devices for screen printers or parts thereof for flat screens

Definitions

• the invention relates to a method for cleaning the screen stencil of a screen printing device, in which a paper web for intermediate printing is placed under the screen stencil and printed by a doctor blade running over it.
• the invention also relates to a screen printing machine for performing this method.
• a cleaning method and a screen printing machine suitable for carrying out the cleaning method is known from DE 199 17 794 C2.
• the intermediate printing table is designed as a table which can be pivoted in parallel to the guideway of the printing table and which lies below the guide of the printing table during the printing process and is swung up under the screen template for the intermediate printing for the purpose of cleaning.
• Machines of this type work satisfactorily, but cannot prevent the disadvantage that the screen printing ink dries in part and clogs the screen fabric. In the case of screen printing devices, it is therefore necessary, despite the arrangement of an intermediate printing table used for screen cleaning, to stop production in order to clean the screen.
• the object of the present invention is to carry out such cleaning largely automatically, specifically in order to avoid a loss of production during operation. At the same time, better working conditions are to be created and incorrect production avoided.
• the underside of the screen template is wetted with a cleaning agent before the intermediate pressure is carried out. This measure also removes ink residues from the screen that have already dried up and therefore could not have been removed from the screen template by the measure of an intermediate pressure which is produced by the movement of the doctor blade mechanism on an intermediate printing paper which is then rolled up and removed.
• the wetting takes place by means of a rotating roller or brush which is brought into contact with the underside of the screen template and is immersed in a cleaning agent.
• the cleaning agent is conveyed out of the bath and brought to the underside of the screen stencil, where it can loosen dried-on paint residues, which can then be removed during intermediate printing.
• the invention also relates to a screen printing machine for carrying out the cleaning process, the screen printing machine being equipped with an intermediate printing device with which a paper web can be inserted under the screen template for the purpose of cleaning.
• the new screen printing machine is characterized by a rotary body assigned to the intermediate printing device and arranged transversely to the direction of movement of the intermediate printing direction, which can be coated with a cleaning agent and comes into contact with the underside of the screen stencil before the intermediate printing and can be guided along it.
• This configuration enables cleaning to be carried out automatically and in the screen printing machine.
• a roller can be provided as the rotating body, which plunges into a bath of the cleaning agent.
• this cleaning agent can be contained in a container surrounding the roller below and adapted to the shape of the roller, the surface of the roller being roughened in order to hold a sufficiently thick layer of the cleaning agent and to be able to bring it against the screen template.
• the roller is driven in rotation, and for this purpose it engages with a pinion arranged on the side in a toothed rack which is arranged next to the screen template on the printing unit.
• the intermediate pressure device itself can be lowered and raised and can thus be folded in and out, and a control device can be provided for determining the cleaning cycle, so that, for example, a cleaning printing process is carried out after every second, third or fifth print.
• the roller and the container assigned to it, to which the cleaning agent is supplied in a simple manner in a circuit are arranged on the end of the paper counter-pressure roller which is mounted so as to be displaceable in the direction of the squeegee movement.
• the roller with the container can expediently be arranged on a pair of swiveling levers which can be acted upon by pneumatic cylinders in such a way that the side pinions of the roller engage in the toothed rack which runs firmly next to the screen template ,
• the intermediate printing roller can be provided with paper and arranged so that it can be moved at least by the length of the screen template, so that the entire underside of the screen template is cleaned with an is wettable. In practice, wetting in the printing area is sufficient.
• an endless band material can also be provided for receiving the intermediate pressure, or also a print carrier roller.
• continuous cleaning of the continuous web or the print carrier roller can be ensured. Consumables in the form of paper do not then arise.
• FIG. 1 shows the schematic perspective illustration of an intermediate printing device according to the invention and its assignment to the screen template of a screen printing machine, the printing table and doctor blade mechanism of which are not shown,
• Fig. 2 is an enlarged view of the end of the intermediate printing device according to Fig. 1 facing the screen template, but in a position in which the intermediate printing device is about to be moved under the screen template to carry out an intermediate printing and
• Fig. 3 shows the illustration similar to FIG. 1, but during the wetting of the underside of the screen template with a cleaning agent.
• an intermediate printing device 1 is shown, which is assigned to a screen printing machine, not shown.
• the screen stencil 2 which is held in a frame, is shown by the screen printing machine and is arranged in a known manner between an intermediate printing roller which can be moved below it and a doctor unit located above it.
• a toothed rack 3 Also firmly connected to the screen printing machine is a toothed rack 3 arranged laterally and parallel to the longitudinal direction of the screen template 2, which will be discussed later.
• the intermediate printing device 1 is equipped within a support frame 4 with a paper web 5 which can be pulled off a roll and is guided in such a way that it can be guided back to a second roll via an intermediate printing roll 7 and below it.
• the paper web 5 is guided within the support frame 4 so that it can take part in a back and forth movement of the intermediate pressure roller 7 in the direction of the arrows 8.
• a roller 9 which runs transversely to the path of movement of the intermediate pressure roller 7 and, as can be seen from the enlarged illustration in FIG. 2, is immersed in a container 10 which largely surrounds it and which is filled with a liquid cleaning agent. It is a cleaning agent that is able to dissolve the ink used in screen printing.
• the container 10 and the roller 9 guided in it are fastened to a transverse web 11 which is attached to the right end of a double lever 13 which can be pivoted about the axis 12.
• the other lever arm 13a of the double lever is in contact with the tappet 14 of a pneumatic cylinder 15, which makes it possible to pivot the double lever 13 up and down from the position shown in FIG. 1.
• the roller 9 is provided at one end, at which it is supported by journals in one end wall of the container 10, with a pinion 16, which engages with the rack 3 when the cylinder 15 is actuated and when the double lever 13 is pivoted counterclockwise is brought, as is also shown in Fig. 2.
• the intermediate pressure roller 7 protruding from the support frame 4 has on the one hand a bearing and on the other hand two laterally projecting tabs 17 which can be brought into operative connection with the doctoring unit (not shown) or with its drive.
• an impulse is emitted via a corresponding control device, which leads to the intermediate printing roller 7, as shown in FIG. 3, being moved under the screen template of the screen printing machine when the squeegee mechanism returns.
• the double lever 13 was pivoted counterclockwise by the cylinder 15 due to the impulse, so that the cleaning agent roller 9 engages with its pinions 16 in the toothed rack 2 arranged firmly next to the screen template.
• the intermediate pressure roller moves in the direction of arrow 18 (FIG. 3)
• the roller 9 is therefore rotated past the screen template 2 in a counterclockwise direction so that it comes into contact with the underside of the screen template 2.
• the roller 9 therefore wets the same on the underside of the screen stencil 2 with cleaning agent as it is conveyed by the rotation of the roller 9 out of the container 10.
• the cleaning agent is otherwise circulated through the container 10 in a manner not shown, so that the level of the cleaning agent in the container 10 can always be kept constant. Wetting the sieve stencil with the cleaning agent removes paint residues from the sieve stencil, even if the color is already partially dry.
• the roller 9 can be guided along the bottom of the screen template once or several times so that the necessary wetting takes place in any case. For this purpose, the intermediate pressure roller 7 is moved back and forth correspondingly often by the drive of the doctor unit.
• the intermediate printing roller 7 travels along with the paper web 5 completely under the screen template 2, and after the squeegee has been lowered, the remaining ink is printed out on the paper web 5, which is then drawn off and wound up as waste becomes.
• the stencil 2 is also cleaned of dried paint residues.
• the pinion 16 is removed from the rack 3 by pivoting the double lever 13 clockwise, so that the stencil template 2 no longer wets for the cleaning pressure itself and for the corresponding return movement of the intermediate printing roller 7.
• the invention offers a very simple possibility of cleaning a screen template 2 of a screen printing machine, which is done automatically.
• the device is largely maintenance-free and allows screen cleaning without significant production downtime.

Landscapes

• Inking, Control Or Cleaning Of Printing Machines (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Screen Printers (AREA)
• Printing Methods (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=32318904

Family Applications (1)

Country Status (7)

Families Citing this family (6)

Family Cites Families (16)

• 2002
  • 2002-11-27 DE DE10256326A patent/DE10256326A1/de not_active Ceased
• 2003
  • 2003-10-16 AT AT03772227T patent/ATE534516T1/de active
  • 2003-10-16 WO PCT/EP2003/011475 patent/WO2004048098A1/fr not_active Application Discontinuation
  • 2003-10-16 US US10/536,795 patent/US7434510B2/en not_active Expired - Fee Related
  • 2003-10-16 PL PL377001A patent/PL377001A1/pl unknown
  • 2003-10-16 EP EP03772227A patent/EP1565314B1/fr not_active Expired - Lifetime
  • 2003-10-16 AU AU2003280385A patent/AU2003280385A1/en not_active Abandoned

Non-Patent Citations (1)

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