WO1997002145A1

WO1997002145A1 - Squeegee-less printing plate inking

Info

Publication number: WO1997002145A1
Application number: PCT/FR1996/001021
Authority: WO
Inventors: Harry Vivier
Original assignee: Harry Vivier
Priority date: 1995-07-05
Filing date: 1996-07-02
Publication date: 1997-01-23
Also published as: AU6918196A

Abstract

Defects in existing silk screen printing and pad printing processes may be eliminated by means of a pad printing ink duct design avoiding the need to squeegee the printing plate. The ink duct is closed to prevent evaporation of the diluent, and the engraving is filled without using a squeegee so that a cover ink may be used and a high printing rate achieved. Furthermore, the absence of a squeegee simplifies the operation of the printing device as the ink duct is stationary and the pad has a simple reciprocal movement.

Description

DEVICE FOR INKING PRINTING SHEETS WITHOUT SCRAPING

The invention relates to the field of printing relating to the inking of engraved pictures, and the inking of pictures in the form of mesh screens.

The object of the present invention is to obtain an inking of the plates without scraping.

This goal is achieved by eliminating the spreading of the ink on the plate, which causes the removal of the doctor blade, and therefore results in the elimination of the wear of the doctor blade and the plate.

Another aim is to obtain the qualities of screen printing and pad printing without their faults.

The defects of the screen printing are the scraping of the plate and the spreading of the ink in the open air promoting the evaporation of the solvents making the viscosity of the ink unstable.

The defects of pad printing are the scraping of the plate and the need for a more fluid ink to fill the engraving, fluidity resulting in less opacity of the colors, and therefore a less covering marking.

More specifically, the invention is explained using drawings described chronologically.

Figure 1 is a schematic view, in longitudinal section, of an inkwell comprising: - a reservoir block 1 connected to an extension block 2. The cavity 3 _> of block 1, is extended in block 2 by communicating recesses to spread ink in an i + compression cavity. The compression of the en¬ cre results from a depression of the extension 2. This depression can be achieved individually by the slide coulis¬ sant 5, or by the bottom 6 of the cavity - + • In the example , the bottom is in the form of a deformable plate consisting of an elastic membrane 6, made of a material such as rubber, bearing on the honeycomb surface of a support 7 held by a mount 8. In the case of the sinking through the bottom (6,7) ₅ the plate 5 will be locked against the joint 5 ′ _” while the plate 9 of a press will include a boss 10 for pushing said bottom. The hollow engraving of the plate can be carried out by a stencil integral with a metallic fabric 5 stretched over a frame 11 such as a screen printing screen. Otherwise, the plate can be in a uniformly shaped plate of mini dorsal cells closed on the smooth front face to be perforated by an engraving digging up to the crest of the cells, and therefore producing mini-holes at the bottom of the engraving. The rigidity of the plate can be reinforced by support bars 12, each end of which is engaged in a notch 13 of the block 2, or of the frame 11. Removable projections 14 "in the form of threaded bushings, adjust and li¬ put the pressure of a flattening printing pad on the plate under the action of the piston of a press. Stops 15 _" with elastic hold, retract as soon as the stamp covers the engraving of the photograph. These stops can be lameε-reεεort bearing on the plate 9 _" and which, when pushed on the projections 14 _" lose their bearing stiffness by bending under the thrust. In a variant, the stops are formed of a sliding part 15 in a blind hole of the extension 2, and comprising an inclined plane of slight slope resting on a small piece of metal 16 resiliently held by a blade-res¬ fate 17. During the overpressure in the cavity / +, the ink is prevented from returning to the 3 V reservoir ^by a valve 18 with positive control, secured to a control rod 19 tightened by an elastic seal, and comprising a gripping means such as a bulge 20 made of a material such as rubber.

FIG. 2 is a schematic top view of the extension block 2, without the reservoir block 1, and comprising a cutaway to show the bars 12, the membrane 6, and the honeycomb support 7. The ink supplied through the reservoir 3 passes through the recesses 21 and 22 to form a ply in the compression cavity 4 _" when the valve 18 is pulled by the rod 19 engaged in the recess 23. In static, the mini-holes Zl \ do not allow not the passage of ink, this passage being effected during a transient dynamic pressure creating on the ink layer an effective pressure at the end of the flattening sow a printing buffer on the engraving of the plate 5- The overpressure is adjusted by the deformable plate (6,7) which absorbs and restores a displaced volume of ink. In the example, the deformation is carried out by the elastic membrane 6 blistering in the honeycomb support 7.

Figure 3 is an overall schematic view showing a pad printing device comprising the inkwell functioning with the plate 5 in a horizontal position. An object 23 is supported on a rotary support 26 comprising an opening 27, behind which the inkwell is disposed. A support 28, sliding vertically on a frame 29 _" adjusts the height of the pad 30 integral with a mount 31 and a piston 32. The mount projects beyond to act on the projections 12+, and it comprises a gripping means 33 such as two protruding rods for clamping the elastic bulge 20 when the tampon moves. This device allows a simple alternating movement of the tampon, without displacement of the inkwell, and it can comprise a pressure switch triggering the withdrawal of the tampon at the end of the insertion of the extension 2.

Figure 4 is an overall schematic view showing another configuration of the pad printing device comprising the inkwell operating with the plate 5 in the vertical position. A mat 34 transports the object 35 to be printed as applied to the support 36 comprising an opening 27. A cross 37, sliding vertically on a frame 29, adjusts the height of the pad 30 aligned with the plate removable 5 and the opening 27 of the support 36.

Claims

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5-fï £ Sdations:

1 - Device for inking printing plates characterized by an inkwell comprising: - a reservoir (3) whose ink reserve maintains an ink pressure on the back side of a removable plate (5) located in an extension (2) including a compression cavity (4) retaining a sheet of ink, the plate being crossed by mini-holes (24) not allowing, in statics, the passage of the ink, this passage being effected during a transient dynamic pressure creating on the ink sheet an effective overpressure at the end of the flattening of a printing pad (30) on the engraving of said plate, and of means:

- to create dynamic pressure; - to stiffen the plate;

- to prevent the ink from returning to the reservoir during overpressure; - to adjust the overpressure; - to absorb and restore a volume of ink displaced during the overpressure; - for the efficiency of the overpressure; - To limit and adjust the pressure of the stamp on the plate integral with the inkwell which can be in a fixed position, vertically, horizontally, behind an object support (26, 36) including an opening (27).

2 - Device according to claim 1, caracté¬ ized in that the mini-holes (24) are delimited by a stencil forming the engraving.

3 - Device according to claim 1, caracté¬ ized in that the mini-holes (24) pass through the bottom of the etching made on a plate uniformly shaped mini dorsal cells.

4 - Device according to claim 1, caracté¬ ized in that the means creating the dynamic pressure is a pis¬ tone (32.) acting for the elastic depression of the extension (2).

5 - Device according to claim 1, caracté¬ ized in that the plate is stiffened by bars of sou¬ hold (12).

6 - Device according to claim ^• '1, caracté¬ ized in that the means of non-return of the ink in the reser¬ see, is a valve (18) with positive control. 7 - Device according to claim 1, caracté¬ ized in that the means adjusting the overpressure is an elastic means (6) disposed at the rear of the ink sheet and cli¬ ché.

8 - Device according to claims 1 and 7, characterized in that the means absorbing and restoring a displaced ink volume, comprises an elastic membrane (6) bearing on the honeycomb surface of a support (7).

9 - Device according to claim 1, caracté¬ ized in that the means of efficiency of the overpressure comprises stops with elastic resistance (15 to 17) retracted as soon as the tam¬ pon covers the engraving of the plate.

10 - Device according to claim 1, caracté¬ ized in that the means for adjusting the pressure of the pad is achieved by the frame (31) of the pad abutting on projections (14) of the plate.