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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
  • B41P2235/00—Cleaning
  • B41P2235/10—Cleaning characterised by the methods or devices
  • B41P2235/26—Spraying devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
  • B41P2235/00—Cleaning
  • B41P2235/30—Recovering used solvents or residues
  • B41P2235/31—Recovering used solvents or residues by filtering

Definitions

• This invention relates generally to screen printing and specifically to apparatuses and methods for cleaning printing ink and other materials from printing screens and frames used in screen
• the imaged screen mesh is normally made of silk, plastic or metal and is held in place by a screen frame made of wood, plastic or
• the ink contains pigment or dye in an appropriate vehicle.
• Patent No. 3,580,261 discloses a printing screen cleaner which
• a screen is passed on a
• the cleaner has other drawbacks which prevent the efficient and effective cleaning of a printing screen. Specifically, it utilizes only two opposing lines of spray nozzles within the enclosure and, therefore, each area of the screen is sprayed only once as the screen passes
• the screen is generally not adequately cleaned when the cleaning cycle has been completed
• the work involves handling the screen by insertion into the machine, removal and manual brush
• the screen washing apparatus of U. S. Patent No. 3,656,493 utilizes an enclosure and a single spray nozzle which is directed over the screen by a control mechanism to spray a predetermined pattern. Specifically, the nozzle sweeps horizontally in one direction across the screen to an end position
• the nozzle is then ratcheted down a few rows of the screen whereupon it sweeps in the opposite direction to an opposite end position and is ratcheted down to begin the process again.
• the cleaning process has to be monitored to ensure that the single sweep was sufficient to remove the printing ink and the screen must be manually sprayed if the single sweep was not sufficient.
• the gun is controlled with manual pre-sets which must be adapted to spray a particular screen size, and insertion of a different size screen into the
• washing apparatus requires additional programming of the spray pattern of the device, thus further reducing the efficiency and cost effectiveness of the apparatus. Additionally, the operator is exposed to solvent fumes whenever it is necessary to manually
• No. 4,420,004 utilizes a single row of adjacent nozzles which moves horizontally with respect to a screen to spray the screen and remove the printing ink as well as the stencil or print pattern.
• the single row of spray nozzles requires a continuous back and forth sweeping motion of the nozzle row which must be repeated until
• Such apparatuses also utilize numerous adjustable or movable parts
• existing apparatuses include elements or sections which must be constantly adjusted to wash screens of different sizes. While the apparatuses will wash short screens and
• the different integrated systems of the cleaning apparatuses include coupling and connecting points and associated seals which are often subject to wear and failure.
• the leakage may present potential points of leakage. In addition to the mess and waste associated with such leakage, the leakage may also present potential points of leakage. In addition to the mess and waste associated with such leakage, the leakage may also present potential points of leakage. In addition to the mess and waste associated with such leakage, the leakage may also present potential points of leakage. In addition to the mess and waste associated with such leakage, the leakage may also present potential points of leakage. In addition to the mess and waste associated with such leakage, the leakage may also present potential points of leakage.
• This invention solves the problems associated with
• nozzles yields repeated and increased screen coverage with sprayed cleaning liquid to provide improved cleaning and removal of undesired printing inks and other contaminants from the screen and surrounding frame in a single cleaning cycle.
• apparatus of the present invention utilizes two opposing pluralities
• a reservoir is positioned beneath the pluralities of
• the supply reservoir which holds the recycled cleaning solvent is also connected to a decantation drum
• the cleaning apparatus which receives used solvent from the reservoir and holds the solvent for settling of the suspended contaminants and subsequent decanting of the cleaning solvent for re-use.
• the cleaning apparatus is enclosed in a housing to prevent the cleaning solvent and solvent fumes from entering the atmosphere or area adjacent
• a vapor recovery system is coupled to the housing to remove vaporized cleaning solvent.
• oscillating mechanism moves the screen in an oscillating motion having a period of motion in the range of about 3 to about 20 inches, and preferably around 10 inches.
• the mechanism operates to move the screen in a complete cycle of the oscillating motion (i.e., forward and then backward) approximately 20 times per minute.
• the continuous oscillation of the screen in combination with the opposing grids of spray nozzles provides repeated
• each area of the screen is continually being sprayed resulting in a faster more efficient cleaning cycle which does not have to be continually repeated as required with other known screen cleaning
• the embodiment of the present invention thus provides rapid cleaning of ink and other printing materials from a printing screen and surrounding frame with the attainment of very clean screens and screen frames.
• the screen is oscillated
• the opposing grids of spray nozzles of the embodiment are operable to deliver sprayed cleaning solvent to a screen at a rate, for example, of
• the guide brackets are mounted to the pluralities of spray nozzles to provide guidance to the screen as it is oscillated.
• the opposing guide brackets define a narrow path therebetween and also between the spray nozzles for passage of the screen.
• the guide brackets maintain the screens generally perpendicular to the spray patterns or streams from the nozzles for effective cleaning.
• the brackets are mounted at an angle to the spray nozzles so as not to interfere with the spray from the nozzles.
• brackets are essentially fixed, an assembly of various moving parts is not necessary, thus reducing manufacturing costs and the labor costs associated with adapting the apparatus for
• the fixed brackets are also more durable, requiring very little or no maintenance or repair.
• a reservoir is positioned proximate the spray nozzles and is integrated with the cleaning chamber to hold the cleaning liquid which is sprayed on the screen.
• the reservoir also holds
• the integral sloping wall directs the used liquid into the reservoir and eliminates the need to
• a vertically-oriented pump is coupled between the reservoir and the nozzles and pumps the cleaning solvent to the nozzles to thereby constantly cycle and recycle the solvent.
• a portion of the pump is mounted inside of the reservoir such that the cleaning liquid is pumped directly from the reservoir to the spray
• the internal pump of the invention reduces the number of exposed fluid lines, valves and seals which, in turn, prevents leaks
• the internal pump prevents any leaks which may occur
• the pump is preferably a higher capacity pump
• the supply reservoir which holds the
• recycled cleaning solvent may also be connected to a decantation
• apparatus is enclosed in a housing to prevent the cleaning solvent and solvent fumes from entering the atmosphere or area adjacent
• a vapor recovery system is coupled to the housing to remove vaporized cleaning solvent and to control odor associated with the cleaning procedure.
• the oscillating mechanism moves the screen in an
• oscillating motion having a period of motion in the range of about 3 to about 20 inches, and preferably around 8-10 inches.
• each area of the screen is continually being
• the screen is sprayed
• One embodiment of the invention further comprises a wipe down booth positioned proximate an open end of the enclosed housing. A screen is manually transferred to the wipe down booth after it is cleaned and excess cleaning liquid is removed, such as by a cloth
• the wipe down booth is configured to capture the excess cleaning liquid from the screen.
• reservoir tank to contain and recapture the cleaning liquid
• a vertical pump contained within the integral reservoir to further
• FIG. 1 is a side view, in partial cross-section, of an
• Fig. 2 is an end view of the embodiment of the present invention shown in Fig. 1 taken along lines 2-2 of Fig. 1 .
• Fig. 3 is a side view in partial cross section of another embodiment of an oscillator screen cleaning apparatus in accordance with the principles of the present invention.
• Fig. 4 is a cross-sectional view of the embodiment
• Fig. 3 is a perspective view of a wipe down booth of the embodiment shown in Fig. 3.
• Fig. 6 is a cross-sectional view along lines 6-6 of Fig.
• 1 2 is preferably formed of fourteen gauge stainless steel and is supported above a floor surface by legs 17.
• nozzles 1 8 are connected, via a supply line 20, to a reservoir 22
• the cleaning solvent 24 is pumped from
• Oscillating mechanism 25 comprises a push-pull device 26, which is connected to a movable track 28
• push-pull device 26 includes an actuatabie plunger 29
• the plunger 29 of push-pull device 26 is coupled to track 28, and when the push-pull device 26 is actuated, the plunger slides the track 28 and screen 16 lengthwise back and forth inside housing 12 in an oscillating motion. The oscillating movement
• oscillating mechanism 26 ensures that the plurality of spray nozzles 18 repeatedly cover all areas of the screen 16 with sprayed cleaning solvent 24.
• the plurality of nozzles 18 are arranged in two separate grid patterns one on each side of the cleaning chamber 14 to spray
• the floor 32 of housing 12 is sloped to form a funnel-shaped surface so that used sprayed
• cleaning solution or solvent which drips from the sprayed screen 16, falls against floor 32 and is drained into reservoir 22 through a drain opening 33.
• the collected solvent may then be pumped again back through line 20 and nozzles 18 to be resprayed against screen 16. In this way, the cleaning solvent 24 is re-used
• the high capacity spray capability of the present invention ensures effective cleaning of screen 16 with the re-used spray as will be discussed in greater detail below.
• a drip pan 37 extends outwardly from the front end 39 of housing 12 beneath access opening 34 to catch cleaning solvent which drips from the
• Track 28 moves within a larger channel 38 and specifically slides lengthwise in channel 38.
• Channel 38 is
• a low friction material such as ultra high molecular density polyethylene (UHMDPE) is inserted between track 28 and channel
• the guide channel 40 ensures that the screen 16 is held generally vertically between the opposing grids of spray nozzles 18 for more effective cleaning of the screen.
• channel 40 also preferably includes a layer 45 of the low friction UHMDPE to ensure smooth movement of screen edge 39 along the guide channel 40.
• the oscillating mechanism 25 moves track 28 within channel 38 and oscillates screen 16 back and forth in front of the opposing grids of spray nozzles 18.
• the oscillating mechanism 25 includes a push-pull device 26 such as a
• pneumatically operated solenoid pneumatically operated solenoid.
• Other mechanically oscillating devices might also be utilized in place of push-pull device 26.
• the device 26 is shown on the outside of the body 47, but also may be
• the plunger 29 is coupled through a coupling fixture 48 to an arm 49 which is fixed at one end to track 28. Arm
• liquid seal 50 which guides arm 49 to ensure a smooth, straight and generally longitudinal movement of arm 49 and track 28 inside the cleaning chamber 14.
• the liquid seal 50 protects from loss of cleaning liquid through hole
• plunger 29 moves back and forth thereby pulling and pushing track
• push-pull device 26 of the present invention and arm 49 should be dimensioned to provide a range or period of motion of from about 3" to about 20" and preferably around 10". That is, it has been determined that movement of screen 16 in a
• an oscillator frequency of approximately 20 cycles per minute for the oscillating mechanism 25 of the present invention is a sufficient oscillating motion to provide an efficient
• mechanism 26 involves moving the track 28 the full range or period
• the oscillator screen cleaning mechanism of the present invention will now be described in greater detail with respect to its operation and the delivery of the sprayed cleaning solution or solvent 24 to the screen 16. Specifically, a cleaning
• liquid or cleaning solvent 24 is placed in reservoir 22 which may be made of stainless steel and preferably has a capacity of, for
• Pump 23 is preferably a high capacity pump, to deliver,
• valves 55, 56 When valves 55, 56 are open, the pump 23 pumps
• Filter unit 59 removes foreign
• a suitable filter for such a purpose is the 50 micron bag filter which removes different materials such as tape, mesh, adhesive, dry ink
• Filter unit 59 allows the solvent 24 to be continually re-used to spray screen 16. As mentioned above, the
• a valve 60 is connected in the supply line 20 and may be closed to prevent liquid
• the supply line 20 branches at a point along its length, such as point 61 , to direct cleaning solvent to the spray
• the solvent is directed into supply branches 64, 66 located proximate the top of the cleaning chamber 14.
• the branches 64, 66 feed into pluralities of vertically extending
• finger lines 68, 70 which are coupled to their respective supply branches 64, 66 and extend generally vertically
• branch 64 feeds the
• Each vertical finger line contains a plurality of spray nozzles 18 arranged in a generally straight vertical line thereon.
• the nozzles 18 are vertically spaced apart along the lengths of each finger line.
• each plurality 68, 70 are horizontally spaced apart one from the other and extend generally parallel with each other from their respective supply branches.
• the finger lines of each plurality 68, 70 are also
• each plurality of finger lines 68, 70 defines a spraying plane of nozzles 18 as illustrated in Fig. 2.
• the spraying planes of nozzles 18 are
• the flat spray pattern 75 is vertically oriented so that the horizontal oscillating motion provided by oscillating mechanism 25
• nozzles 18 of each finger line are spaced along the finger line 74 to provide pattern overlap of the spray patterns.
• nozzles 76, 77 are spaced such that their spray patterns overlap at area 80.
• the overlapping spray patterns ensure complete coverage of screen 16 with the sprayed solvent.
• a nozzle suitable for use within the present invention yields a spray pattern approximately
• invention is capable of delivering a high quantity of sprayed cleaning solvent to screen 16 during a cleaning cycle. Specifically,
• the spraying system of the present invention including high capacity pump 23 and the opposing grids of spray nozzles 18, is operable to deliver sprayed cleaning solvent to the screen 16 at a rate in the range of about 60 to about 21 5 gallons per minute.
• the present invention yields a very efficient cleaning cycle.
• the cleaning solvent 24 is
• solvent is again pumped through line 20 and filter unit 59 to be
• reservoir 24 may need to be recycled. To do so, the used solvent
• a decantation tank may be transferred to a decantation tank either manually or through
• decantation tank 82 is coupled to reservoir 22 through line 84 and pump 86.
• the used cleaning solvent is pumped into the decantation tank 82 wherein the ink and other contaminant particles which are suspended in the solvent are allowed to settle.
• the decanted solvent may then be removed from tank 82 and transferred back into reservoir 22 for
• the spraying system of the oscillator screen cleaning apparatus 10 of the present invention is configured to be quickly
• draining branch 90, 92 extend
• the draining branches 90, 92 beneath the cleaning chamber 14 converge at point 94 and are connected through a dump valve 96 into reservoir 22.
• the dump valve 96 is actuated, either manually or pneumatically, the entire system
• Housing 12 completely encloses the finger lines 68, 70 and spray nozzles 18 to ensure that all of the cleaning solvent
• the housing 12 has a flue 98 formed in the top thereof which is coupled to a vapor recovery system 100
• the vapor recovery system ensures that vaporized solvent from cleaning chamber 14 does not escape into the atmosphere to be breathed in by workers, thereby further creating a more healthy work environment.
• cover 104 on the top wall 41 of housing 12 allows access to the cleaning chamber 14 from above.
• Figs. 3, 4, 5 and 6 illustrate another embodiment of an oscillator screen cleaning apparatus.
• Skid 1 17 provides easy mobility of the cleaning apparatus 1 10.
• plurality of spray nozzles 1 18 are connected via a supply line 120 to a reservoir 122 containing an amount of cleaning solvent or
• cleaning liquid 124 Suitable cleaning compositions are disclosed and discussed hereinabove.
• the cleaning liquid 124 is pumped
• Pump 123 includes an intake
• the oscillating mechanism 128 is coupled to the chamber 1 14 for moving screen 1 16 back and forth within the chamber in front of the spray nozzles 1 18 to more effectively and efficiently clean the screen (see Fig. 6).
• the oscillating mechanism 128 comprises a push-pull device 130 , such as a pneumatically
• the push-pull device 130 is mounted to a support structure 133 which extends
• Push-pull device 1 30 includes an actuatable plunger 1 34 which is coupled to a tang
• plunger 1 34 moves back and forth and
• An appropriate slot 1 37 is formed in the
• opening 137 is dimensioned to allow an
• the plurality of nozzles 1 18 are
• the cleaning liquid 124 is pumped by pump 123
• the filter is preferably a 50 micron
• bag filter which removes different materials such as tape, mesh,
• the reservoir 122 includes an integrally formed sloping wall 140 which is positioned below cleaning chamber 1 14 to capture the sprayed cleaning liquid which drips from the screen and subsequently direct the captured liquid into reservoir 122. As illustrated in Fig. 3, the
• housing 1 12 integrally forms both the reservoir 124, the cleaning
• the cleaning liquid is contained so that it may be reused and the prevention of cleaning liquid loss amounts to a cost savings for the operator of the invention.
• reservoir tank 122 with the cleaning chamber 1 14 eliminates the need for a separate reservoir tank which must then be coupled to
• the integral reservoir 122 and chamber 1 14 of the present invention eliminates leakage and waste associated with the various valves and seals.
• a drip pan 150 extends outwardly from the housing beneath the access opening 146 to catch cleaning liquid which drips from the screen 1 16 when it is removed from the cleaning chamber 1 14 after it has
• the drip pan 150 provides coupling to a wipe down booth 152 which further captures excess
• the screen is positioned on movable track 132 to be oscillated back and forth by the oscillating mechanism 128 (see
• the movable track 132 moves or oscillates within a larger channel 154 and specifically slides
• Various strips of low friction material 156 such as Teflon ® are positioned between the channel 154 and movable track 132 at the sides and beneath the track 132 to insure movement and oscillation of the track.
• mechanism preferably moves the screen at approximately 20 cycles per minute to provide efficient and effective screen cleaning.
• a cycle comprising full movement of the screen in one direction and then back, i.e., 10" forward and then 10" back.
• the oscillating mechanism 128, pump motor 127 and a dump valve 169 for draining the system are preferably coupled to
• the controls are preferably be positioned above or adjacent to reservoir 122 as illustrated in phantom in Fig. 3 by an electrical control cabinet 158 and air control cabinet 160.
• the solvent 124 is pumped by pump 123 through the supply line 120.
• Pump 123 is preferably a high capacity pump to deliver, about 60-215 gallons per minute depending upon the requirements for the screens being cleaned.
• the supply line branches at point 162 to provide fluid to various riser lines or finger lines 164 which support the nozzles 1 18 to form opposing spray nozzle grids.
• the pumped fluid is directed up the riser lines 164 and through the nozzles 1 18 to spray both sides of the screen 1 16 as illustrated in Fig. 4 by the spray patterns 166.
• the spray patterns 166 are preferably vertically oriented and overlap vertically one with the other to provide complete coverage of screen 166.
• the nozzles 1 18 are
• spraying planes are defined by the nozzle grids and the spray planes coincide generally in the center of the cleaning chamber 1 14 where the screen passes (See Fig. 4).
• the entire screen area is constantly sprayed with cleaning liquid 124 to effectively and efficiently clean the screen.
• the screen is preferably guided between the nozzle grids generally parallel to the grids and
• the oscillator screen cleaning apparatus 1 10 readily accepts screens which have
• adjustably fixed guide brackets 170 are mounted to
• each bracket 170 is preferably U-shaped and extends vertically with the riser lines 164 at an angle thereto (See Fig. 3).
• guide bracket 170a extends at an angle between riser line 164a and riser line 164b.
• the brackets are angled between the riser lines 164 so as to not interfere with the spray from spray nozzles 1 18.
• the guide brackets 170 engage the sides of the screen 166 to guide it and maintain it in an upright position.
• pairs of guide brackets 170 are mounted between the
• the fixed guide brackets 170 extend between each riser line 164 and thus maintain
• the adjustably fixed guide brackets 170 eliminate the need for constantly adjusting a guide mechanism to customize the cleaning apparatus 1 10 for screens of different heights and/or widths
• the guide brackets 170 of the invention reduce the cost of manufacturing the apparatus because they eliminate specially fabricated adjustable parts which are subject to wear and subsequent replacement. Furthermore, labor costs are reduced because an operator is not required to adjust the
• oscillating screen cleaning apparatus 1 10 utilizing guide brackets 170 is more durable and eliminates maintenance normally required with an adjustable screen guiding assembly.
• the ends of the U-shaped guide brackets 170 are preferably threaded and are held to the riser
• brackets 170 may be adjusted inwardly or outwardly as necessary with respect to the spray nozzle grids for handling screens with
• each nozzle 1 18 forms a generally V-shaped flat spray pattern 166 which is vertically
• the nozzles 1 18 are spaced along each riser line 164 to preferably provide pattern overlap of the spray patterns
• a suitable spray nozzle 1 18 would produce a spray pattern of approximately 10 inches wide.
• the cleaning solvent 124 is continually filtered and re-used within the oscillator screen cleaning apparatus 1 10.
• the present invention utilizes a wipe down booth 1 52 to
• booth 1 52 The top 1 79 of booth 1 52 is open as is the side 1 80 closest
• front 1 82 of booth 1 52 includes a short wall 1 84, preferably 3
• the screen 1 16 can then be wiped off and dried, such as with a cloth.
• the side wall 177, back wall 176 and short front wall 184 ensure that the excess liquid is contained and
• apparatus 1 10 is configured to be quickly drained, such as for
• a dump valve 1 69 is coupled in the supply line 120 between filter

Landscapes

• Inking, Control Or Cleaning Of Printing Machines (AREA)
• Nozzles For Electric Vacuum Cleaners (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Combined Means For Separation Of Solids (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Edible Seaweed (AREA)
• Paper (AREA)
• Toys (AREA)
• Screen Printers (AREA)

Applications Claiming Priority (5)

Publications (2)

Family

ID=27010720

Family Applications (1)

Country Status (9)

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Family Cites Families (6)

• 1996
  • 1996-02-06 AT AT96906264T patent/ATE172670T1/de not_active IP Right Cessation
  • 1996-02-06 ES ES96906264T patent/ES2125101T3/es not_active Expired - Lifetime
  • 1996-02-06 WO PCT/US1996/001393 patent/WO1996024492A1/en active IP Right Grant
  • 1996-02-06 AU AU49705/96A patent/AU4970596A/en not_active Abandoned
  • 1996-02-06 BR BR9607829A patent/BR9607829A/pt not_active IP Right Cessation
  • 1996-02-06 DK DK96906264T patent/DK0808248T3/da active
  • 1996-02-06 DE DE69600876T patent/DE69600876T2/de not_active Expired - Fee Related
  • 1996-02-06 EP EP96906264A patent/EP0808248B1/de not_active Expired - Lifetime
  • 1996-02-06 CA CA002211415A patent/CA2211415C/en not_active Expired - Fee Related

Non-Patent Citations (1)

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