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WO2008001075A2 - A wiper blade and wiper blade assembly for a screen printing machine and a method of fabricating the same - Google Patents

A wiper blade and wiper blade assembly for a screen printing machine and a method of fabricating the same Download PDF

Info

Publication number
WO2008001075A2
WO2008001075A2 PCT/GB2007/002388 GB2007002388W WO2008001075A2 WO 2008001075 A2 WO2008001075 A2 WO 2008001075A2 GB 2007002388 W GB2007002388 W GB 2007002388W WO 2008001075 A2 WO2008001075 A2 WO 2008001075A2
Authority
WO
WIPO (PCT)
Prior art keywords
wiper blade
contact
body member
recess
contact surface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2007/002388
Other languages
French (fr)
Other versions
WO2008001075A3 (en
Inventor
Neil Short
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ASM Assembly Systems Switzerland GmbH
Original Assignee
DEK International GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DEK International GmbH filed Critical DEK International GmbH
Publication of WO2008001075A2 publication Critical patent/WO2008001075A2/en
Publication of WO2008001075A3 publication Critical patent/WO2008001075A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F15/00—Screen printers
    • B41F15/14—Details
    • B41F15/44—Squeegees or doctors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F9/00—Rotary intaglio printing presses
    • B41F9/06—Details
    • B41F9/08—Wiping mechanisms
    • B41F9/10—Doctors, scrapers, or like devices
    • B41F9/1072—Blade construction

Definitions

  • the present invention relates to a wiper blade and wiper blade assembly for a screen printing head, and a method of fabricating the same, in particular for the application of a layer of encapsulant material to a semiconductor wafer.
  • a protective coating is commonly applied to the surface of the semiconductor wafer prior to cutting to form the semiconductor dies. It is important that this protective coating has a uniform thickness and a very smooth surface finish in order to provide good protection.
  • This squeegee 1 comprises an elongate body member 5, generally in the form of a rectangular bar, which includes a recess 6, here of V-section, in the lower edge thereof, and an elongate contact member 7, here a square-sectioned member of a synthetic material, typically a semi-hard polyurethane, which is bonded in the recess 6 in the body member 5, such as to present a pointed contact surface 9 which has sufficient flexibility as to conform to unevenness in the object being printed.
  • squeegees For the printing of encapsulant materials, squeegees have been developed which include a stiffening member at the lower edge thereof.
  • a stiffening member At the lower edge thereof.
  • One such squeegee is disclosed in US-A-6730170.
  • stiffened squeegees represent an improvement as compared to the traditional squeegee
  • a particular problem associated with such squeegees is a lack of flatness along the length thereof, which can be caused by small imperfections which can arise as a result of ridges being ground into the contact surface of the squeegee, and flexing of the squeegee when being moved across the surface of the printing screen.
  • the present invention provides a rigid wiper blade for a screen printing machine, comprising an elongate body member which includes a recess in a surface thereof, and an elongate contact member, having a screen contact surface, which is mounted in the recess by an adhesive.
  • the contact surface is an arcuate surface.
  • the contact surface is a part-circular surface.
  • the contact member includes a recess which is rearward of the contact surface in a direction of printing.
  • the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
  • the inclined surface comprises a planar surface.
  • planar surface is inclined such as to enclose an acute angle with a printing screen.
  • contact member has an arcuate forward surface which extends forwardly of the contact surface.
  • the forward surface is a part-circular surface.
  • the contact member comprises a cylindrical rod.
  • the cylindrical rod has a diameter of about 6 mm.
  • the cylindrical rod has a diameter of less than about 6 mm.
  • the cylindrical rod has a diameter of greater than about 6 mm.
  • the contact member is formed of stainless steel.
  • the contact surface is ground and burnished.
  • the contact surface has an average surface roughness of less than about 0.2 ⁇ m.
  • the contact surface has a flatness of less than about 10 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 5 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 1 ⁇ m over the length thereof.
  • the recess in the body member has an arcuate surface. In one embodiment the recess in the body member has a part-circular surface.
  • the wiper blade further comprises a deformable element which is disposed between the contact member and a surface of the recess in the body member.
  • the recess in the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
  • the deformable element comprises a resilient element.
  • the resilient element comprises a foam rubber element.
  • the resilient element comprises a high-density foam rubber element.
  • the adhesive provides a rigid connection between the contact member and the body member.
  • the adhesive comprises an epoxy resin.
  • the present invention provides a wiper blade for a screen printing machine, comprising an elongate body member, and an elongate contact member, having a screen contact surface, which is mounted to the body member by an adhesive.
  • the contact surface is an arcuate surface.
  • the contact surface is a part-circular surface.
  • the contact member includes a recess which is rearward of the contact surface in a direction of printing.
  • the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
  • the inclined surface comprises a planar surface.
  • planar surface is inclined such as to enclose an acute angle with a printing screen.
  • the contact member has an arcuate forward surface which extends forwardly of the contact surface.
  • the forward surface is a part-circular surface.
  • the contact member comprises a cylindrical rod.
  • the cylindrical rod has a diameter of about 6 mm.
  • the cylindrical rod has a diameter of less than about 6 mm.
  • the cylindrical rod has a diameter of greater than about 6 mm.
  • the contact member is formed of stainless steel.
  • the contact surface is ground and burnished.
  • the contact surface has an average surface roughness of less than about 0.2 ⁇ m. In one embodiment the contact surface has a flatness of less than about 10 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 5 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 1 ⁇ m over the length thereof.
  • the body member includes a recess in a surface thereof, and the contact member is mounted in the recess in the body member.
  • the recess in the body member has an arcuate surface.
  • the recess in the body member has a part-circular surface.
  • the wiper blade further comprises a deformable element which is disposed between the contact member and the body member.
  • the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
  • the deformable element comprises a resilient element.
  • the resilient element comprises a foam rubber element.
  • the resilient element comprises a high-density foam rubber element.
  • the adhesive provides a rigid connection between the contact member and the body member.
  • the adhesive comprises an epoxy resin.
  • the wiper blade is a rigid blade.
  • the present invention provides a wiper blade assembly, including a pair of the above-described wiper blades which are disposed in opposed spaced relation.
  • the wiper blade assembly comprises a frame unit which incorporates the wiper blades and defines a cavity for containing a print medium.
  • the cavity is an enclosed cavity.
  • the present invention provides a method of fabricating a wiper blade for a screen printing machine, comprising the steps of: providing a body member; disposing a deformable element to the body member; disposing an adhesive to the body member; disposing a contact member, having a screen contact surface, to the deformable element; and pressing a levelling member, having a flat levelling surface, against the contact member, such that the deformable element is at least in part deformed and the contact member is rendered flat along the length thereof.
  • the body member includes a recess and the deformable element, adhesive and contact member are disposed in the recess in the body member.
  • the recess in the body member has an arcuate surface. In one embodiment the recess in the body member has a part-circular surface.
  • the contact surface is an arcuate surface.
  • the contact surface is a part-circular surface.
  • the contact member includes a recess which is rearward of the contact surface in a direction of printing.
  • the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
  • the inclined surface comprises a planar surface.
  • planar surface is inclined such as to enclose an acute angle with a printing screen.
  • the contact member has an arcuate forward surface which extends forwardly of the contact surface.
  • the forward surface is a part-circular surface.
  • the contact member comprises a cylindrical rod.
  • the cylindrical rod has a diameter of about 6 mm.
  • the cylindrical rod has a diameter of less than about 6 mm.
  • the cylindrical rod has a diameter of greater than about 6 mm.
  • the contact member is formed of stainless steel.
  • the contact surface is ground and burnished.
  • the contact surface has an average surface roughness of less than about 0.2 ⁇ m.
  • the contact surface has a flatness of less than about 10 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 5 ⁇ m over the length thereof.
  • the contact surface has a flatness of less than about 1 ⁇ m over the length thereof.
  • the deformable element is disposed to the body member such as to define one or more cavities adjacent the deformable element which act to contain the adhesive.
  • the deformable element is disposed to the body member prior to disposing the adhesive to the body member.
  • the deformable element comprises a resilient element.
  • the resilient element comprises a foam rubber element.
  • the resilient element comprises a high-density foam rubber element.
  • the resilient element acts to maintain the contact surface in engagement with the levelling member.
  • the adhesive comprises an epoxy resin.
  • the method further comprises the step of: setting the adhesive, such that the adhesive provides a rigid connection between the contact member and the body member.
  • the wiper blade is a rigid blade.
  • the present invention provides a levelling jig for levelling a contact member of a wiper assembly, the levelling jig comprising: first and second levelling bars which are disposed in opposed relation and each have a flat levelling surface between which a wiper assembly is in use disposed; and a clamping yoke assembly to which the levelling bars are fitted to allow for clamping of the same and the wiper assembly where disposed therebetween, such as to level the contact member of the wiper assembly.
  • the levelling surface of each of the levelling bars comprises a precision-ground surface.
  • the clamping yoke assembly comprises at least two clamping yokes which are disposed at spaced locations along a length of the levelling bars.
  • clamping yokes each comprise a pressure screw, by means of which screws one of the levelling bars is driven against the contact member of the wiper assembly, such as to level the same.
  • Figure 1 illustrates a perspective view of a wiper blade in accordance with a preferred embodiment of the present invention
  • Figure 2 illustrates a vertical sectional view (along section I-I in Figure 1) of the wiper blade of Figure 1;
  • FIGS 3(a) to (d) illustrate fragmentary vertical sectional views (along section I-I in Figure 1) of the fabrication steps in fabricating the wiper blade of Figure 1;
  • Figure 4 illustrates a perspective view of a levelling jig in accordance with a preferred embodiment of the present invention
  • Figure 5 illustrates a side view of the levelling jig of Figure 4, where including a wiper assembly disposed between the levelling bars thereof;
  • Figure 6 illustrates a vertical sectional view (along section II-II in Figure 5) of the levelling jig of Figure 4, where including a wiper assembly disposed between the levelling bars;
  • Figure 7 illustrates a perspective view of a wiper blade assembly in accordance with a preferred embodiment of the present invention
  • Figure 8 illustrates a vertical sectional view (along section III-III in Figure 7) of the wiper blade assembly of Figure 7;
  • Figure 9 illustrates a vertical sectional view (along section I-I in Figure 1) of a wiper blade as one modification of the wiper blade of Figure 1;
  • Figure 10 illustrates a perspective view of a traditional squeegee.
  • the wiper blade 11 comprises a rigid, elongate body member 15, in this embodiment generally in the form of a rectangular bar, which includes a recess 16, in this embodiment of arcuate section, in the lower edge thereof, and a rigid, elongate contact member 17 which has an arcuate contact surface 19, in this embodiment a part-circular surface, and is mounted in the recess 16 in the body member 15 by an adhesive 21, in this embodiment an epoxy resin.
  • the adhesive 21 is of a kind which, when set, is rigid under the pressures as experienced by the wiper blade 11, such as to avoid deflection of the contact member 15 during a printing operation.
  • the wiper blade 11 includes a resilient element 25 which acts as a spacer in spacing the contact member 17 from a surface of the recess 16 in the fabrication of the wiper blade 11.
  • the contact member 17 is formed of a cylindrical rod, here having a diameter of about 6 mm.
  • the contact member 17 is formed of stainless steel.
  • the contact member 17 is ground and roller burnished, which provides the contact surface 19 thereof with an average surface roughness of less than about 0.2 ⁇ m and also work hardens the contact surface 19, such as to provide an increased resistance to wear and corrosion.
  • a resilient element 25 in this embodiment a foam rubber element, preferably a high-density rubber element, is located in the recess 16 in the body member 15.
  • the resilient element 25 comprises an elongate element which extends along a length, here substantially the entire length of the recess 16 in the body member 15.
  • the resilient element 25 could comprise a plurality of elements which are disposed at spaced locations along a length, here substantially the entire length of the recess 16 in the body member 15.
  • the resilient element 25 is adhered in the base of the recess 16 in the body member 15.
  • the resilient element 25 is one or both of sized and shaped such as to define one or more cavities 27 adjacent the resilient element 25 and along the length of the body member 15.
  • the adhesive 21, in this embodiment delivered as a liquid epoxy resin is disposed in the one or more cavities 27 adjacent the resilient element 25 in the recess 16 in the body member 15.
  • the contact member 15 is disposed in the recess 16 in the body member 15.
  • this wiper assembly is levelled in a levelling jig 41, as will be described in more detail hereinbelow, and the adhesive 21 allowed to set, such as to provide a rigid connection between the contact member 17 and the body member 15.
  • Figure 4 illustrates a perspective view of the levelling jig 41.
  • the levelling jig 41 comprises first and second levelling bars 43a, 43b which each have a flat levelling surface 45, in this embodiment a precision-ground surface, which are disposed in opposed vertical relation, and first and second clamping yokes 45a, 45b to which the levelling bars 43a, 43b are fitted to allow for clamping of the same.
  • each of the clamping yokes 45a, 45b comprises a stand 47, a first, clamping screw 49 for clamping the upper levelling bar 43b in position, and a second, pressure screw 51 for applying a pressure, in this embodiment a downward pressure, to the upper levelling bar 43b.
  • the upper levelling bar 43b is first raised to an elevated position and clamped in position by the clamping screws 49 of the clamping yokes 45a, 45b.
  • the wiper assembly is then inserted between the levelling surfaces 45 of the levelling bars 43a, 43b.
  • clamping screws 49 of the clamping yokes 45a, 45b are then released, allowing the upper levelling bar 43b to rest on the contact member 17 of the wiper blade 11.
  • the pressure screws 51 of the clamping yokes 45a, 45b are then wound first to contact the upper clamping bar 43b and then press the upper clamping bar 43b against the contact member 17 of the wiper blade 11, as illustrated in Figures 5 and 6.
  • the contact member 17 of the wiper blade 11 is biased against the resilient element 25 which is disposed in the recess 16 in the body member 15 of the wiper blade 11, thereby resiliently compressing the resilient element 25.
  • the pressure screws 51 are tightened to the point where the contact member 17 of the wiper blade 11 is in perfect, continuous contact with the levelling surface 45 of the upper levelling member 43b, with the resilient element 25 acting to maintain this contact whilst the adhesive 21 is subsequently allowed to set.
  • the establishment of the continuous contact between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b is determined, through visual inspection, of the absence any light passing between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b.
  • a vision system could be utilized to determine the perfect contact between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b.
  • the adhesive 21 is allowed to set, in this embodiment by curing of the epoxy resin, to yield a wiper blade 11 which has a perfectly flat and rigid contact member 17, as illustrated in Figure 3(d).
  • the contact member 17 has a flatness, that is, a deviation in height, of less than about 10 ⁇ m over the length thereof, preferably less than about 5 ⁇ m over the length thereof, and more preferably less than about 1 ⁇ m over the length thereof.
  • FIGS 7 and 8 illustrate a wiper blade assembly in accordance with a preferred embodiment of the present invention.
  • the wiper blade assembly of this embodiment is for use as an enclosed print head, such as of the kind of the PROFLOW (RTM) print head, as available from DEK INTERNATIONAL GMBH (Zurich, Switzerland) and disclosed in WO- A-1998/016387, the content of which is herein incorporated by reference.
  • RTM PROFLOW
  • DEK INTERNATIONAL GMBH DEK INTERNATIONAL GMBH (Zurich, Switzerland) and disclosed in WO- A-1998/016387, the content of which is herein incorporated by reference.
  • the wiper blade assembly comprises a frame unit 61, in this embodiment having an elongate rectangular form, which incorporates a pair of the above- described wiper blades 11, in this embodiment disposed in parallel relation, and defines an enclosed cavity 63 which contains a print medium.
  • the frame unit 61 is adapted to receive a replaceable cassette which contains a supply of print medium, but a supply of print medium could be alternatively maintained, for example, by pumping from a reservoir.
  • the body members 15 of the wiper blades 11 in part define opposite sides of the frame unit 61, here the opposite elongate sides.
  • the body members 15 of the wiper blades 11 are integrally formed with the frame unit 61, here as a single machined component, but could be alternatively formed as separate components.
  • the frame unit 61 includes a pair of cap elements 65 which are disposed to the opposite ends thereof and are configured so as to extend to a height corresponding to the contact surfaces 19 of the contact members 17 of the wiper blades 11, such as to prevent the escape of print medium beyond the ends of the wiper blades 11.
  • cap elements 65 are in the form of skis, here formed of a metal, which are adapted to run on the surface of an underlying printing screen.
  • the wiper blade assembly includes first and second apertured elements 67, 69, here grilles, which are located at upper and lower regions within the cavity 63, such as to provide for homogenization of the print medium.
  • Fabrication is the same as for the wiper blade 11 of the above-described embodiment, except that the levelling members 43a, 43b of the levelling jig 41 have a width which encompasses both of the wiper blades 11 of the wiper blade assembly, such that the levelling jig 41 ensures the flatness and co-planarity of the contact members 17 of the wiper blades 11.
  • the contact member 17 can be configured such as to have a modified, recessed profile rearwardly of the point of contact C of the contact member 17 with a printing screen S relative to the direction of printing P.
  • This configuration provides for an improved print quality for some print media, by preventing adhesion of that print media to a rear section of the contact member 17.
  • the contact member 17 has an arcuate surface 19a, here a part-circular surface, at and forwardly of the contact point C in the direction of printing P, and a recessed surface 19b, here an inclined surface extending rearwardly and upwardly of a trailing edge of the contact surface 19a relative to the direction of printing P.
  • the recessed surface 19b comprises a planar surface which is inclined such as to enclose an acute angle ⁇ with the printing screen S.
  • the recessed surface 19b is machined after the contact member 17 has been ground and roller burnished, and is mounted in the same way as in the above-described embodiment.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ink Jet (AREA)
  • Screen Printers (AREA)
  • Inking, Control Or Cleaning Of Printing Machines (AREA)

Abstract

A wiper blade (11) and wiper blade assembly for a screen printing machine and a method of fabricating the same, the wiper blade (11) comprising an elongate body member (15) which includes a recess (16) in a surface thereof, and an elongate contact member (17), having an arcuate screen contact surface (19), which is mounted in the recess (16) by an adhesive (21).

Description

A WIPER BLADE AND WIPER BLADE ASSEMBLY FOR A SCREEN PRINTING MACHINE AND A METHOD OF FABRICATING THE SAME
The present invention relates to a wiper blade and wiper blade assembly for a screen printing head, and a method of fabricating the same, in particular for the application of a layer of encapsulant material to a semiconductor wafer.
In the manufacture of semiconductor devices, a protective coating is commonly applied to the surface of the semiconductor wafer prior to cutting to form the semiconductor dies. It is important that this protective coating has a uniform thickness and a very smooth surface finish in order to provide good protection.
Currently, such protective coatings are applied using a printing screen with a single large printing aperture which has the same diameter as the diameter of the semiconductor wafer and a squeegee which is driven over the printing screen to fill the printing aperture with encapsulant material.
A traditional squeegee is illustrated in Figure 10. This squeegee 1 comprises an elongate body member 5, generally in the form of a rectangular bar, which includes a recess 6, here of V-section, in the lower edge thereof, and an elongate contact member 7, here a square-sectioned member of a synthetic material, typically a semi-hard polyurethane, which is bonded in the recess 6 in the body member 5, such as to present a pointed contact surface 9 which has sufficient flexibility as to conform to unevenness in the object being printed.
For the printing of encapsulant materials, squeegees have been developed which include a stiffening member at the lower edge thereof. One such squeegee is disclosed in US-A-6730170. Although such stiffened squeegees represent an improvement as compared to the traditional squeegee, a particular problem associated with such squeegees is a lack of flatness along the length thereof, which can be caused by small imperfections which can arise as a result of ridges being ground into the contact surface of the squeegee, and flexing of the squeegee when being moved across the surface of the printing screen.
This lack of flatness in such squeegees provides for an uneven coating, where ridges in the contact surface cause surface defects in the coating which present an unsmooth surface, and flexing causes material to be scooped from a central region of the printing aperture, which undesirably results in the coating being thinner in the central region.
In one aspect the present invention provides a rigid wiper blade for a screen printing machine, comprising an elongate body member which includes a recess in a surface thereof, and an elongate contact member, having a screen contact surface, which is mounted in the recess by an adhesive.
In one embodiment the contact surface is an arcuate surface.
In one embodiment the contact surface is a part-circular surface.
In one embodiment the contact member includes a recess which is rearward of the contact surface in a direction of printing.
In one embodiment the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
In one embodiment the inclined surface comprises a planar surface.
In one embodiment the planar surface is inclined such as to enclose an acute angle with a printing screen. In one embodiment the contact member has an arcuate forward surface which extends forwardly of the contact surface.
In one embodiment the forward surface is a part-circular surface.
In one embodiment the contact member comprises a cylindrical rod.
In one embodiment the cylindrical rod has a diameter of about 6 mm.
In another embodiment the cylindrical rod has a diameter of less than about 6 mm.
In a further embodiment the cylindrical rod has a diameter of greater than about 6 mm.
In one embodiment the contact member is formed of stainless steel.
In one embodiment the contact surface is ground and burnished.
In one embodiment the contact surface has an average surface roughness of less than about 0.2 μm.
In one embodiment the contact surface has a flatness of less than about 10 μm over the length thereof.
Preferably, the contact surface has a flatness of less than about 5 μm over the length thereof.
More preferably, the contact surface has a flatness of less than about 1 μm over the length thereof.
In one embodiment the recess in the body member has an arcuate surface. In one embodiment the recess in the body member has a part-circular surface.
In one embodiment the wiper blade further comprises a deformable element which is disposed between the contact member and a surface of the recess in the body member.
In one embodiment the recess in the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
In one embodiment the deformable element comprises a resilient element.
In one embodiment the resilient element comprises a foam rubber element.
In one embodiment the resilient element comprises a high-density foam rubber element.
In one embodiment the adhesive provides a rigid connection between the contact member and the body member.
In one embodiment the adhesive comprises an epoxy resin.
In another aspect the present invention provides a wiper blade for a screen printing machine, comprising an elongate body member, and an elongate contact member, having a screen contact surface, which is mounted to the body member by an adhesive.
In one embodiment the contact surface is an arcuate surface.
In one embodiment the contact surface is a part-circular surface. In one embodiment the contact member includes a recess which is rearward of the contact surface in a direction of printing.
In one embodiment the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
In one embodiment the inclined surface comprises a planar surface.
In one embodiment the planar surface is inclined such as to enclose an acute angle with a printing screen.
In one embodiment the contact member has an arcuate forward surface which extends forwardly of the contact surface.
In one embodiment the forward surface is a part-circular surface.
In one embodiment the contact member comprises a cylindrical rod.
In one embodiment the cylindrical rod has a diameter of about 6 mm.
In another embodiment the cylindrical rod has a diameter of less than about 6 mm.
In a further embodiment the cylindrical rod has a diameter of greater than about 6 mm.
In one embodiment the contact member is formed of stainless steel.
In one embodiment the contact surface is ground and burnished.
In one embodiment the contact surface has an average surface roughness of less than about 0.2 μm. In one embodiment the contact surface has a flatness of less than about 10 μm over the length thereof.
Preferably, the contact surface has a flatness of less than about 5 μm over the length thereof.
More preferably, the contact surface has a flatness of less than about 1 μm over the length thereof.
In one embodiment the body member includes a recess in a surface thereof, and the contact member is mounted in the recess in the body member.
In one embodiment the recess in the body member has an arcuate surface.
In one embodiment the recess in the body member has a part-circular surface.
In one embodiment the wiper blade further comprises a deformable element which is disposed between the contact member and the body member.
In one embodiment the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
In one embodiment the deformable element comprises a resilient element.
In one embodiment the resilient element comprises a foam rubber element.
In one embodiment the resilient element comprises a high-density foam rubber element. In one embodiment the adhesive provides a rigid connection between the contact member and the body member.
In one embodiment the adhesive comprises an epoxy resin.
In one embodiment the wiper blade is a rigid blade.
In a further aspect the present invention provides a wiper blade assembly, including a pair of the above-described wiper blades which are disposed in opposed spaced relation.
In one embodiment the wiper blade assembly comprises a frame unit which incorporates the wiper blades and defines a cavity for containing a print medium.
In one embodiment the cavity is an enclosed cavity.
In a still further aspect the present invention provides a method of fabricating a wiper blade for a screen printing machine, comprising the steps of: providing a body member; disposing a deformable element to the body member; disposing an adhesive to the body member; disposing a contact member, having a screen contact surface, to the deformable element; and pressing a levelling member, having a flat levelling surface, against the contact member, such that the deformable element is at least in part deformed and the contact member is rendered flat along the length thereof.
In one embodiment the body member includes a recess and the deformable element, adhesive and contact member are disposed in the recess in the body member.
In one embodiment the recess in the body member has an arcuate surface. In one embodiment the recess in the body member has a part-circular surface.
In one embodiment the contact surface is an arcuate surface.
In one embodiment the contact surface is a part-circular surface.
In one embodiment the contact member includes a recess which is rearward of the contact surface in a direction of printing.
In one embodiment the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
In one embodiment the inclined surface comprises a planar surface.
In one embodiment the planar surface is inclined such as to enclose an acute angle with a printing screen.
In one embodiment the contact member has an arcuate forward surface which extends forwardly of the contact surface.
In one embodiment the forward surface is a part-circular surface.
In one embodiment the contact member comprises a cylindrical rod.
In one embodiment the cylindrical rod has a diameter of about 6 mm.
In another embodiment the cylindrical rod has a diameter of less than about 6 mm.
In a further embodiment the cylindrical rod has a diameter of greater than about 6 mm. In one embodiment the contact member is formed of stainless steel.
In one embodiment the contact surface is ground and burnished.
In one embodiment the contact surface has an average surface roughness of less than about 0.2 μm.
In one embodiment the contact surface has a flatness of less than about 10 μm over the length thereof.
Preferably, the contact surface has a flatness of less than about 5 μm over the length thereof.
More preferably, the contact surface has a flatness of less than about 1 μm over the length thereof.
In one embodiment the deformable element is disposed to the body member such as to define one or more cavities adjacent the deformable element which act to contain the adhesive.
In one embodiment the deformable element is disposed to the body member prior to disposing the adhesive to the body member.
In one embodiment the deformable element comprises a resilient element.
In one embodiment the resilient element comprises a foam rubber element.
In one embodiment the resilient element comprises a high-density foam rubber element.
In one embodiment the resilient element acts to maintain the contact surface in engagement with the levelling member. In one embodiment the adhesive comprises an epoxy resin.
In one embodiment the method further comprises the step of: setting the adhesive, such that the adhesive provides a rigid connection between the contact member and the body member.
In one embodiment the wiper blade is a rigid blade.
In a yet further aspect the present invention provides a levelling jig for levelling a contact member of a wiper assembly, the levelling jig comprising: first and second levelling bars which are disposed in opposed relation and each have a flat levelling surface between which a wiper assembly is in use disposed; and a clamping yoke assembly to which the levelling bars are fitted to allow for clamping of the same and the wiper assembly where disposed therebetween, such as to level the contact member of the wiper assembly.
In one embodiment the levelling surface of each of the levelling bars comprises a precision-ground surface.
In one embodiment the clamping yoke assembly comprises at least two clamping yokes which are disposed at spaced locations along a length of the levelling bars.
In one embodiment the clamping yokes each comprise a pressure screw, by means of which screws one of the levelling bars is driven against the contact member of the wiper assembly, such as to level the same.
Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which: Figure 1 illustrates a perspective view of a wiper blade in accordance with a preferred embodiment of the present invention;
Figure 2 illustrates a vertical sectional view (along section I-I in Figure 1) of the wiper blade of Figure 1;
Figures 3(a) to (d) illustrate fragmentary vertical sectional views (along section I-I in Figure 1) of the fabrication steps in fabricating the wiper blade of Figure 1;
Figure 4 illustrates a perspective view of a levelling jig in accordance with a preferred embodiment of the present invention;
Figure 5 illustrates a side view of the levelling jig of Figure 4, where including a wiper assembly disposed between the levelling bars thereof;
Figure 6 illustrates a vertical sectional view (along section II-II in Figure 5) of the levelling jig of Figure 4, where including a wiper assembly disposed between the levelling bars;
Figure 7 illustrates a perspective view of a wiper blade assembly in accordance with a preferred embodiment of the present invention;
Figure 8 illustrates a vertical sectional view (along section III-III in Figure 7) of the wiper blade assembly of Figure 7;
Figure 9 illustrates a vertical sectional view (along section I-I in Figure 1) of a wiper blade as one modification of the wiper blade of Figure 1; and
Figure 10 illustrates a perspective view of a traditional squeegee.
The wiper blade 11 comprises a rigid, elongate body member 15, in this embodiment generally in the form of a rectangular bar, which includes a recess 16, in this embodiment of arcuate section, in the lower edge thereof, and a rigid, elongate contact member 17 which has an arcuate contact surface 19, in this embodiment a part-circular surface, and is mounted in the recess 16 in the body member 15 by an adhesive 21, in this embodiment an epoxy resin.
In this embodiment the adhesive 21 is of a kind which, when set, is rigid under the pressures as experienced by the wiper blade 11, such as to avoid deflection of the contact member 15 during a printing operation.
In this embodiment, as will be described in more detail hereinbelow, the wiper blade 11 includes a resilient element 25 which acts as a spacer in spacing the contact member 17 from a surface of the recess 16 in the fabrication of the wiper blade 11.
In this embodiment the contact member 17 is formed of a cylindrical rod, here having a diameter of about 6 mm.
In this embodiment the contact member 17 is formed of stainless steel.
In this embodiment the contact member 17 is ground and roller burnished, which provides the contact surface 19 thereof with an average surface roughness of less than about 0.2 μm and also work hardens the contact surface 19, such as to provide an increased resistance to wear and corrosion.
The fabrication of the wiper blade 11 will now be described with reference to Figures 3(a) to (d) of the accompanying drawings.
In a first step, as illustrated in Figure 3(a), a resilient element 25, in this embodiment a foam rubber element, preferably a high-density rubber element, is located in the recess 16 in the body member 15. In this embodiment the resilient element 25 comprises an elongate element which extends along a length, here substantially the entire length of the recess 16 in the body member 15.
In an alternative embodiment the resilient element 25 could comprise a plurality of elements which are disposed at spaced locations along a length, here substantially the entire length of the recess 16 in the body member 15.
In one embodiment the resilient element 25 is adhered in the base of the recess 16 in the body member 15.
In this embodiment the resilient element 25 is one or both of sized and shaped such as to define one or more cavities 27 adjacent the resilient element 25 and along the length of the body member 15.
In a second step, as illustrated in Figure 3(b), the adhesive 21, in this embodiment delivered as a liquid epoxy resin, is disposed in the one or more cavities 27 adjacent the resilient element 25 in the recess 16 in the body member 15.
In a third step, as illustrated in Figure 3(c), the contact member 15 is disposed in the recess 16 in the body member 15.
In a fourth step, as illustrated in Figure 3(d), this wiper assembly is levelled in a levelling jig 41, as will be described in more detail hereinbelow, and the adhesive 21 allowed to set, such as to provide a rigid connection between the contact member 17 and the body member 15.
Figure 4 illustrates a perspective view of the levelling jig 41.
The levelling jig 41 comprises first and second levelling bars 43a, 43b which each have a flat levelling surface 45, in this embodiment a precision-ground surface, which are disposed in opposed vertical relation, and first and second clamping yokes 45a, 45b to which the levelling bars 43a, 43b are fitted to allow for clamping of the same.
In this embodiment each of the clamping yokes 45a, 45b comprises a stand 47, a first, clamping screw 49 for clamping the upper levelling bar 43b in position, and a second, pressure screw 51 for applying a pressure, in this embodiment a downward pressure, to the upper levelling bar 43b.
In disposing the wiper assembly in the clamping jig 41, the operation is as follows.
The upper levelling bar 43b is first raised to an elevated position and clamped in position by the clamping screws 49 of the clamping yokes 45a, 45b.
The wiper assembly is then inserted between the levelling surfaces 45 of the levelling bars 43a, 43b.
The clamping screws 49 of the clamping yokes 45a, 45b are then released, allowing the upper levelling bar 43b to rest on the contact member 17 of the wiper blade 11.
The pressure screws 51 of the clamping yokes 45a, 45b are then wound first to contact the upper clamping bar 43b and then press the upper clamping bar 43b against the contact member 17 of the wiper blade 11, as illustrated in Figures 5 and 6.
In tightening the pressure screws 51 of the clamping yokes 45a, 45b, the contact member 17 of the wiper blade 11 is biased against the resilient element 25 which is disposed in the recess 16 in the body member 15 of the wiper blade 11, thereby resiliently compressing the resilient element 25. The pressure screws 51 are tightened to the point where the contact member 17 of the wiper blade 11 is in perfect, continuous contact with the levelling surface 45 of the upper levelling member 43b, with the resilient element 25 acting to maintain this contact whilst the adhesive 21 is subsequently allowed to set.
In this embodiment the establishment of the continuous contact between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b is determined, through visual inspection, of the absence any light passing between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b. In an alternative embodiment a vision system could be utilized to determine the perfect contact between the contact member 17 of the wiper blade 11 and the levelling surface 45 of the upper levelling member 43b.
Following this levelling of the contact member 17 of the wiper blade 11, the adhesive 21 is allowed to set, in this embodiment by curing of the epoxy resin, to yield a wiper blade 11 which has a perfectly flat and rigid contact member 17, as illustrated in Figure 3(d). In one embodiment the contact member 17 has a flatness, that is, a deviation in height, of less than about 10 μm over the length thereof, preferably less than about 5 μm over the length thereof, and more preferably less than about 1 μm over the length thereof.
Figures 7 and 8 illustrate a wiper blade assembly in accordance with a preferred embodiment of the present invention.
The wiper blade assembly of this embodiment is for use as an enclosed print head, such as of the kind of the PROFLOW (RTM) print head, as available from DEK INTERNATIONAL GMBH (Zurich, Switzerland) and disclosed in WO- A-1998/016387, the content of which is herein incorporated by reference.
The wiper blade assembly comprises a frame unit 61, in this embodiment having an elongate rectangular form, which incorporates a pair of the above- described wiper blades 11, in this embodiment disposed in parallel relation, and defines an enclosed cavity 63 which contains a print medium.
In this embodiment the frame unit 61 is adapted to receive a replaceable cassette which contains a supply of print medium, but a supply of print medium could be alternatively maintained, for example, by pumping from a reservoir.
In this embodiment the body members 15 of the wiper blades 11 in part define opposite sides of the frame unit 61, here the opposite elongate sides.
In this embodiment the body members 15 of the wiper blades 11 are integrally formed with the frame unit 61, here as a single machined component, but could be alternatively formed as separate components.
In this embodiment the frame unit 61 includes a pair of cap elements 65 which are disposed to the opposite ends thereof and are configured so as to extend to a height corresponding to the contact surfaces 19 of the contact members 17 of the wiper blades 11, such as to prevent the escape of print medium beyond the ends of the wiper blades 11.
In this embodiment the cap elements 65 are in the form of skis, here formed of a metal, which are adapted to run on the surface of an underlying printing screen.
In this embodiment the wiper blade assembly includes first and second apertured elements 67, 69, here grilles, which are located at upper and lower regions within the cavity 63, such as to provide for homogenization of the print medium.
Fabrication is the same as for the wiper blade 11 of the above-described embodiment, except that the levelling members 43a, 43b of the levelling jig 41 have a width which encompasses both of the wiper blades 11 of the wiper blade assembly, such that the levelling jig 41 ensures the flatness and co-planarity of the contact members 17 of the wiper blades 11.
Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.
In one modification, as illustrated in Figure 9, where the wiper blade 11 is utilized in a uni-directional printing operation, the contact member 17 can be configured such as to have a modified, recessed profile rearwardly of the point of contact C of the contact member 17 with a printing screen S relative to the direction of printing P. The present inventor has identified that this configuration provides for an improved print quality for some print media, by preventing adhesion of that print media to a rear section of the contact member 17.
In this embodiment the contact member 17 has an arcuate surface 19a, here a part-circular surface, at and forwardly of the contact point C in the direction of printing P, and a recessed surface 19b, here an inclined surface extending rearwardly and upwardly of a trailing edge of the contact surface 19a relative to the direction of printing P.
In this embodiment the recessed surface 19b comprises a planar surface which is inclined such as to enclose an acute angle β with the printing screen S.
In this embodiment the recessed surface 19b is machined after the contact member 17 has been ground and roller burnished, and is mounted in the same way as in the above-described embodiment.

Claims

1. A rigid wiper blade for a screen printing machine, comprising an elongate body member which includes a recess in a surface thereof, and an elongate contact member, having a screen contact surface, which is mounted in the recess by an adhesive.
2. The wiper blade of claim 1, wherein the contact surface is an arcuate surface.
3. The wiper blade of claim 2, wherein the contact surface is a part- circular surface.
4. The wiper blade of any of claims 1 to 3, wherein the contact member includes a recess which is rearward of the contact surface in a direction of printing.
5. The wiper blade of claim 4, wherein the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
6. The wiper blade of claim 5, wherein the inclined surface comprises a planar surface.
7. The wiper blade of claim 6, wherein the planar surface is inclined such as to enclose an acute angle with a printing screen.
8. The wiper blade of any of claims 1 to 7, wherein the contact member has an arcuate forward surface which extends forwardly of the contact surface.
9. The wiper blade of claim 8, wherein the forward surface is a part- circular surface.
10. The wiper blade of any of claims 1 to 9, wherein the contact member comprises a cylindrical rod.
11. The wiper blade of claim 10, wherein the cylindrical rod has a diameter of about 6 mm.
12. The wiper blade of claim 10, wherein the cylindrical rod has a diameter of less than about 6 mm.
13. The wiper blade of claim 10, wherein the cylindrical rod has a diameter of greater than about 6 mm.
14. The wiper blade of any of claims 1 to 13, wherein the contact member is formed of stainless steel.
15. The wiper blade of any of claims 1 to 14, wherein the contact surface is ground and burnished.
16. The wiper blade of any of claims 1 to 15, wherein the contact surface has an average surface roughness of less than about 0.2 μm.
17. The wiper blade of any of claims 1 to 16, wherein the contact surface has a flatness of less than about 10 μm over the length thereof.
18. The wiper blade of claim 17, wherein the contact surface has a flatness of less than about 5 μm over the length thereof.
19. The wiper blade of claim 18, wherein the contact surface has a flatness of less than about 1 μm over the length thereof.
20. The wiper blade of any of claims 1 to 19, wherein the recess in the body member has an arcuate surface.
21. The wiper blade of claim 20, wherein the recess in the body member has a part-circular surface.
22. The wiper blade of any of claims 1 to 21, further comprising a deformable element which is disposed between the contact member and a surface of the recess in the body member.
23. The wiper blade of claim 22, wherein the recess in the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
24. The wiper blade of claim 22 or 23, wherein the deformable element comprises a resilient element.
25. The wiper blade of claim 24, wherein the resilient element comprises a foam rubber element.
26. The wiper blade of claim 25, wherein the resilient element comprises a high-density foam rubber element.
27. The wiper blade of any of claims 1 to 26, wherein the adhesive provides a rigid connection between the contact member and the body member.
28. The wiper blade of claim 27, wherein the adhesive comprises an epoxy resin.
29. A wiper blade for a screen printing machine, comprising an elongate body member, and an elongate contact member, having a screen contact surface, which is mounted to the body member by an adhesive.
30. The wiper blade of claim 29, wherein the contact surface is an arcuate surface.
31. The wiper blade of claim 30, wherein the contact surface is a part- circular surface.
32. The wiper blade of any of claims 29 to 31, wherein the contact member includes a recess which is rearward of the contact surface in a direction of printing.
33. The wiper blade of claim 32, wherein the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
34. The wiper blade of claim 33, wherein the inclined surface comprises a planar surface.
35. The wiper blade of claim 34, wherein the planar surface is inclined such as to enclose an acute angle with a printing screen.
36. The wiper blade of any of claims 29 to 35, wherein the contact member has an arcuate forward surface which extends forwardly of the contact surface.
37. The wiper blade of claim 36, wherein the forward surface is a part- circular surface.
38. The wiper blade of any of claims 29 to 37, wherein the contact member comprises a cylindrical rod.
39. The wiper blade of claim 38, wherein the cylindrical rod has a diameter of about 6 mm.
40. The wiper blade of claim 38, wherein the cylindrical rod has a diameter of less than about 6 mm.
41. The wiper blade of claim 38, wherein the cylindrical rod has a diameter of greater than about 6 mm.
42. The wiper blade of any of claims 29 to 41, wherein the contact member is formed of stainless steel.
43. The wiper blade of any of claims 29 to 42, wherein the contact surface is ground and burnished.
44. The wiper blade of any of claims 29 to 43, wherein the contact surface has an average surface roughness of less than about 0.2 μm.
45. The wiper blade of any of claims 29 to 44, wherein the contact surface has a flatness of less than about 10 μm over the length thereof.
46. The wiper blade of claim 45, wherein the contact surface has a flatness of less than about 5 μm over the length thereof.
47. The wiper blade of claim 46, wherein the contact surface has a flatness of less than about 1 μm over the length thereof.
48. The wiper blade of any of claims 29 to 47, wherein the body member includes a recess in a surface thereof, and the contact member is mounted in the recess in the body member.
49. The wiper blade of claim 48, wherein the recess in the body member has an arcuate surface.
50. The wiper blade of claim 49, wherein the recess in the body member has a part-circular surface.
51. The wiper blade of any of claims 29 to 50, further comprising a deformable element which is disposed between the contact member and the body member.
52. The wiper blade of claim 51, wherein the body member and the deformable element are configured such as to define one or more cavities adjacent the deformable element which contain the adhesive.
53. The wiper blade of claim 51 or 52, wherein the deformable element comprises a resilient element.
54. The wiper blade of claim 53, wherein the resilient element comprises a foam rubber element.
55. The wiper blade of claim 54, wherein the resilient element comprises a high-density foam rubber element.
56. The wiper blade of any of claims 29 to 55, wherein the adhesive provides a rigid connection between the contact member and the body member.
57. The wiper blade of claim 56, wherein the adhesive comprises an epoxy resin.
58. The wiper blade of any of claims 29 to 57, wherein the wiper blade is a rigid blade.
59. A wiper blade assembly, including a pair of the wiper blades of any of claims 1 to 58 which are disposed in opposed spaced relation.
60. The wiper blade assembly of claim 59, comprising a frame unit which incorporates the wiper blades and defines a cavity for containing a print medium.
61. The wiper blade assembly of claim 60, wherein the cavity is an enclosed cavity.
62. A method of fabricating a wiper blade for a screen printing machine, comprising the steps of: providing a body member; disposing a deformable element to the body member; disposing an adhesive to the body member; disposing a contact member, having a screen contact surface, to the deformable element; and pressing a levelling member, having a flat levelling surface, against the contact member, such that the deformable element is at least in part deformed and the contact member is rendered flat along the length thereof.
63. The method of claim 62, wherein the body member includes a recess and the deformable element, adhesive and contact member are disposed in the recess in the body member.
64. The method of claim 63, wherein the recess in the body member has an arcuate surface.
65. The method of claim 64, wherein the recess in the body member has a part-circular surface.
66. The method of any of claims 62 to 65, wherein the contact surface is an arcuate surface.
67. The method of claim 66, wherein the contact surface is a part- circular surface.
68. The method of any of claims 62 to 67, wherein the contact member includes a recess which is rearward of the contact surface in a direction of printing.
69. The method of claim 68, wherein the recess in the contact member is defined by an inclined surface which extends rearwardly and upwardly of the contact surface.
70. The method of claim 69, wherein the inclined surface comprises a planar surface.
71. The method of claim 70, wherein the planar surface is inclined such as to enclose an acute angle with a printing screen.
72. The method of any of claims 62 to 71, wherein the contact member has an arcuate forward surface which extends forwardly of the contact surface.
73. The method of claim 72, wherein the forward surface is a part- circular surface.
74. The method of any of claims 62 to 73, wherein the contact member comprises a cylindrical rod.
75. The method of claim 74, wherein the cylindrical rod has a diameter of about 6 mm.
76. The method of claim 74, wherein the cylindrical rod has a diameter of less than about 6 mm.
77. The method of claim 74, wherein the cylindrical rod has a diameter of greater than about 6 mm.
78. The method of any of claims 62 to 77, wherein the contact member is formed of stainless steel.
79. The method of any of claims 62 to 78, wherein the contact surface is ground and burnished.
80. The method of any of claims 62 to 79, wherein the contact surface has an average surface roughness of less than about 0.2 μm.
81. The method of any of claims 62 to 80, wherein the contact surface has a flatness of less than about 10 μm over the length thereof.
82. The method of claim 81, wherein the contact surface has a flatness of less than about 5 μm over the length thereof.
83. The method of claim 82, wherein the contact surface has a flatness of less than about 1 μm over the length thereof.
84. The method of any of claims 62 to 83, wherein the deformable element is disposed to the body member such as to define one or more cavities adjacent the deformable element which act to contain the adhesive.
85. The method of any of claims 62 to 84, wherein the deformable element is disposed to the body member prior to disposing the adhesive to the body member.
86. The method of any of claims 62 to 85, wherein the deformable element comprises a resilient element.
87. The method of claim 86, wherein the resilient element comprises a foam rubber element.
88. The method of claim 87, wherein the resilient element comprises a high-density foam rubber element.
89. The method of any of claims 86 to 88, wherein the resilient element acts to maintain the contact surface in engagement with the levelling member.
90. The method of any of claims 62 to 89, wherein the adhesive comprises an epoxy resin.
91. The method of any of claims 62 to 90, further comprising the step of: setting the adhesive, such that the adhesive provides a rigid connection between the contact member and the body member.
92. The method of any of claims 62 to 91, wherein the wiper blade is a rigid blade.
93. A levelling jig for levelling a contact member of a wiper assembly, the levelling jig comprising: first and second levelling bars which are disposed in opposed relation and each have a flat levelling surface between which a wiper assembly is in use disposed; and a clamping yoke assembly to which the levelling bars are fitted to allow for clamping of the same and the wiper assembly where disposed therebetween, such as to level the contact member of the wiper assembly.
94. The levelling jig of claim 93, wherein the levelling surface of each of the levelling bars comprises a precision-ground surface.
95. The levelling jig of claim 93 or 94, wherein the clamping yoke assembly comprises at least two clamping yokes which are disposed at spaced locations along a length of the levelling bars.
96. The levelling jig of claim 95, wherein the clamping yokes each comprise a pressure screw, by means of which screws one of the levelling bars is driven against the contact member of the wiper assembly, such as to level the same.
PCT/GB2007/002388 2006-06-27 2007-06-27 A wiper blade and wiper blade assembly for a screen printing machine and a method of fabricating the same Ceased WO2008001075A2 (en)

Applications Claiming Priority (2)

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GB0612702.1 2006-06-27
GB0612702A GB2439533B (en) 2006-06-27 2006-06-27 A wiper blade for a screen printing machine and a method of fabricating the same

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WO2008001075A2 true WO2008001075A2 (en) 2008-01-03
WO2008001075A3 WO2008001075A3 (en) 2008-03-06

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DE3207620C2 (en) * 1982-03-03 1985-07-25 Albert-Frankenthal Ag, 6710 Frankenthal Device for applying a strip of glue to a moving material web
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US6237487B1 (en) * 2000-05-08 2001-05-29 James R. Davis Squeegee blade holder
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GB0612702D0 (en) 2006-08-09
GB2439533A (en) 2008-01-02
WO2008001075A3 (en) 2008-03-06

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