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
  • B41F35/004—Cleaning arrangements or devices for screen printers or parts thereof for cylindrical screens

Definitions

• the invention relates to a method for cleaning an application device for a flowable substance, the device being provided with supply channels for the substance, and for cleaning a circular stencil which optionally surrounds the application device.
• EP-B 0 277 481 According to AT-B 338 290 and EP-B 0 277 481 it is known to leave the application device in the production position for cleaning and to effect cleaning only by pushing cleaning liquid through the feed channels for the substance. In one case, it was proposed to let the cleaning fluid flow through the openings in the template after the cleaning process. Since this is not practical, EP-B 0 277 481 provides an additional suction device that extends over the entire length of the application device.
• the invention provides that the cleaning liquid is essentially sucked off through the feed channels for the substance after the cleaning process.
• the substance and the cleaning liquid flow through the feed channels for the substance in different directions, which significantly increases the cleaning effect.
• the application of the invention is particularly advantageous if it is provided that at least some of the cleaning liquid is also supplied through the supply channels which serve to supply the substance during the production process.
• Self-cleaning application devices according to the invention are particularly interesting in practice: the flow of the cleaning fluid through the feed channels for the substance in opposite directions dramatically reduces water consumption, while at the same time, in contrast to the previous proposals, the removal of the cleaning liquid after Cleaning process is ensured without additional design effort is required.
• the invention can also be used in application devices of such a type in which cleaning liquid is supplied independently of the distribution system for the application substance.
• cleaning liquid is supplied independently of the distribution system for the application substance.
• an additional line system in the application device also makes sense in the case of application devices designed according to the invention.
• This also has the additional purpose of cleaning the inside of the stencil and any squeegee element particularly intensively.
• the joint cleaning of the round template and application device is the final phase of an overall process consisting of application and cleaning. It is therefore important to consider this overall process or in particular the To make the transition between these two sections optimal.
• the pump supplying the order substance during the production process pulls at least part of the order substance out of the order device in the opposite direction of function, before the cleaning liquid is supplied for the washing process. If this process is supported by the use of suction air, the water consumption is reduced.
• a surprising advantage of the invention is that an application device can be used in the process for stencil cleaning in the context of the method according to the invention, the better it is suitable for its actual production task, namely the evenly broadly distributing supply of substance to an application point.
• an application device in which it is provided that the distribution system of the application device ends in a series of tubular openings, the spacing of which is 5-20 mm, regardless of the length of the application device.
• the tubular ex / Mergers can also be connected to form a muzzle slot.
• FIG. 1 shows schematically a full application cycle including the cleaning phase.
• 2a is a cross section through the application device in the production position
• FIG. 2b the same cross section in the cleaning position.
• FIG. 1 shows the method according to the invention applied to a round stencil screen printing device.
• the invention is in no way limited to textile printing or screen printing, but can be used in connection with any application devices which are moved relative to a web.
• a round template 1 is provided, which is stretched over end rings 2 and moved synchronously with a base 22 for the web to be printed.
• An application device 5 which comprises a distribution device for the substance to be applied and some type of doctor blade, extends through the interior of the circular template 1.
• a doctor blade 4 is provided, which is pressed against the inside of the round template 1 by a magnetic bar 26 (see FIG. 2) arranged below the base 22 and thereby the substance through the openings of the round template 1 into the Web presses.
• substance 18 is removed from a storage container by means of a Pump 14 (preferably a hose pump) is conveyed through hose sections 20 ′ and 20 into application device 5.
• a Pump 14 preferably a hose pump
• this stopper intensifies the cleaning effect of the flowing liquid.
• the hose pump preferred according to the invention is a prerequisite for the use of this measure which embodies the invention or optimizes the overall cleaning process.
• the cleaning body (sponge or the like) passes and thus also cleans the peristaltic pump according to the invention and at the same time separates the substance from the inflowing medium.
• the cleaning of the application device 5 and the round template 1 is shown in FIGS. This takes place in that water 15 from a storage container or from a line connection by means of the pump 14 through the hose sections 20 * and 20 into the
• Application device 5 is pressed. At the same time or alternatively, compressed air can be injected, as indicated by arrow 21. This increases the effectiveness of the cleaning and reduces the water requirement.
• the cleaning liquid can also be used directly, i.e. bypassing the pump 14, into the connection 23 (in FIG. 1 c) of the application device 5, which is easy to imagine.
• the storage container for the substance 18 can be replaced by a container which is filled with another substance 18 '.
• the water injected in the method step according to FIG. 1 d and possibly also introduced into the round template 1 is sucked off in the next method step according to FIG. 1 by means of the pump 14 from the application device 5 and from the optionally available round template. It is possible and expedient to have the method steps according to FIGS. 1d and 1e run several times in succession. In step ld, support by compressed air 21 is possible in each case.
• the cleaning liquid mixed with substance can also be partially discharged via the conveyor belt 22.
• the respective substance permeability of the circular stencil is a factor that also determines the cleaning process.
• the cleaning liquid does not necessarily have to be supplied from a reservoir by means of a pump.
• a suction pump or a suction blower can be used to suck off the cleaning liquid, with a higher suction power than a pump with a reversible conveying direction.
• FIG. 2 shows an application device which fulfills the multiple functions intended according to the invention in a particularly expedient manner.
• the application device according to the invention is designed in such a way that it can be wholly or predominantly cleaned using the substance supply channels and that these channels can also be used, in any way, to the underside of the Applicator cleaning material (mixed with substance) to be discharged through the feed channels for the substance.
• the application device shown in FIG. 2 initially comprises a system for the substance supply, which consists of a tube 11 charged with substance via the pump 14 and a connecting part 23 (FIG. 1 c). This is arranged in a sheet metal housing 8, which contains a width distribution body 9. As described, for example, in the Austrian patent specification 376 612 (Johannes Zimmer), this body 9 divides or halves the substance flow coming from the tube 11 into initially eight division steps which take place within the housing 8.
• a distributor bar 27 is attached to the housing 8 at the bottom, which further divides the substance flow, so that the feed channels 13 for the substance ultimately have a uniform distance between 5 and 20 mm in their mouth region, regardless of how long the order set-up is.
• Fig. 2a the ends of the feed channels 13 (K10) are shown separately, in Fig. 2b a change to the actual mouth is provided with a slot or gap continuing the channels, which facilitate the suction of substance or cleaning liquid can.
• the respective length or application width is decisive for the number of channel division stages in order to achieve the spacing dimension 5-20 mm according to the invention.
• the application device 5 in the example in FIG. 2 is provided with a magnetically compressible roller doctor 4, the possible diameters of which are indicated in the drawing.
• this doctor blade 4 is held on the rear side wall 7 of the application device by a permanent magnet 25 (position II in FIG. 2b).
• a permanent magnet 25 position II in FIG. 2b.
• Magnetic bar 26 so that the doctor blade 4 is pressed against the inside of the stencil 1 and can press the substance supply lying in front of the doctor blade through the openings of the template 1 onto a material web carried by the base 22.
• the invention is not restricted to a specific type of application.
• the application could also be carried out with a doctor blade, in particular a magnetically pressed doctor blade.
• a front side wall 6 forms a cavity 24 which is open at the bottom and in which both the substance to be applied and the cleaning liquid remain enclosed.
• the application device is shown in the production position in FIG. 2a, the arrows indicated indicating the flow of the substance to be applied from the tube 11 into the interior of the cavity 24. It is essential for the invention that the feed channels 13 for the substance open so close to the lower edge of the cavity 24 that through their openings not only remaining application substance but also previously supplied cleaning liquid can be sucked off.
• FIG. 2b shows the application device in a position pivoted preferably for the purpose of cleaning. If the squeegee 4 is in position I, the cleaning liquid is forced together in the area adjoining the feed channels 13, which promotes suction. In the position according to FIG. 2a, however, almost the entire width of the cavity is available for the formation of a substance supply. To support the cleaning process, a change between the attraction of the roller doctor 4 by the magnetic bar 26 (position I) and the attraction by the permanent magnet 25 (position II) can preferably already take place in the position according to FIG. 2a.
• the system described in FIG. 2a can first be used in exactly the same way as for the supply of substance to be applied.
• cleaning liquid is fed into the cavity 24 via lines 16, 17, 17 '.
• lines 16, 17, 17 ' can be connected in any way to a water supply system.
• 2b shows a particularly favorable possibility for this: here the tube 11 is divided in the longitudinal direction by an intermediate wall 12, the cavities on different sides of the intermediate wall 12 on the one hand with the pump 14 or another pump or suction device and on the other hand are provided with a source for the cleaning fluid which ultimately opens into the lines 16, 17, 17 *.
• the lines 17 and 17 ' can be connected to one another in terms of flow technology at one end. 2a and 2b, a row of holes can be arranged in each of the two lines, or a row of holes only in one of the two pipes, two rows of holes in one of the two pipes, etc., as outlet openings.
• the cleaning liquid can be supplied to the application device 5 only via the lines 16, 17, 17 ', only via the supply system for the application substance or via both systems.
• the formation of the mouth of line 16 as Wide slot nozzle makes these particularly suitable for cleaning the front boundary of the cavity 24, whereas the jets emerging through the individual openings of the lines 17, 17 'can clean both the rear boundary of the cavity 24 and the roller doctor blade 4 arranged therein.
• the orifices 16 can be slit or tube-shaped.
• the suction of the cleaning liquid from the cavity 24, insofar as it does not partially escape through the template 1, is carried out by the same system through which the substance intended for application has first been supplied.
• This not only leads to an optimized, in particular water-saving, cleaning of the substance distribution system, but also enables substance 14 to be supplied and the cleaning liquid to be sucked off with one and the same pump. Above all, this eliminates the previously existing requirement of having to equip the application device with additional suction devices.
• the application device 5 shown as an exemplary embodiment in FIG. 2 can be modified in many ways, and some of the details shown are expedient but not indispensable. So it is undoubtedly favorable to control the cleaning process by means of a level sensor which can be rotated and, if necessary, moved longitudinally. This level sensor could also be replaced by a pressure measuring device which is used in the wall of the cavity 24. This is particularly the case when the spatial arrangement of the application device is changed, such as when applied to the underside of a horizontally guided web.
• the procedure itself can be in terms of sequence and The duration of the individual sections can be varied many times, it being possible to have the sequence carried out manually or program-controlled.
• the application device By supplying compressed air, the application device is dried in its interior, but not on its outer surface. If the application device is used after cleaning for a new application process without being removed from the template, dripping water or other cleaning liquid can cause damage 7 by dripping from the back wall of the device. In order to avoid this, the rear wall 7 is provided with a small channel 10, in which the liquid droplets remaining at the top and rear of the device surface after the cleaning process, which run downwards due to gravity, are collected. This measure, which prevents application errors due to liquid residues that could drip onto the stencil, can also be applied to the wall 6.
• the invention has been described on the basis of the circular stencil printing device, but it can also be used in the case of flat stencils or in application processes with direct application of the substance to the web.

Landscapes

• Inking, Control Or Cleaning Of Printing Machines (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (1)

Family

ID=3531860

Family Applications (1)

Country Status (7)

Families Citing this family (1)

Citations (4)

Family Cites Families (2)

• 1994
  • 1994-02-12 BR BR9506778A patent/BR9506778A/pt not_active IP Right Cessation
• 1995
  • 1995-02-13 AT AT95908162T patent/ATE196446T1/de not_active IP Right Cessation
  • 1995-02-13 WO PCT/AT1995/000030 patent/WO1995021745A1/de active IP Right Grant
  • 1995-02-13 ES ES95908162T patent/ES2150555T3/es not_active Expired - Lifetime
  • 1995-02-13 CN CN95192547A patent/CN1081987C/zh not_active Expired - Fee Related
  • 1995-02-13 DE DE59508734T patent/DE59508734D1/de not_active Expired - Fee Related
  • 1995-02-13 EP EP95908162A patent/EP0743904B1/de not_active Expired - Lifetime

Patent Citations (4)

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