Ink supply apparatus for intaglio printing press

Abstract

This ink supply apparatus includes a train of ink transfer rollers. One of the rollers comprises a hard core and an outer stratum of multiple layers of cheesecloth wound on the core. This cheesecloth roller runs between two steel surfaced rollers and compressively engages them. It produces a smooth coating of ink on the downstream one of the two hard surfaced rollers. The roller nearest the plate cylinder is adapted for use with an intaglio press, which commonly has at least one plate on the cylinder with at least one recess between circumferentially spaced plate ends. The circumference of the inking roller which engages the plate is made slightly greater than the sum of the circumferential lengths of the plate and the recess, for the purpose of providing a coating of ink on the plate that is slightly heavier along the leading margin of the plate than at other parts of the plate.

Description

CROSS-REFERENCES

U.S. patent application Ser. No. 372,087, filed June 21, 1973, by the present inventors, shows an intaglio press having a paper wiping system, with which the present invention may be used.

U.S. patent application Ser. No. 410,987, filed Oct. 30, 1973, by the present inventors, shows an ink fountain position control mechanism which may be used on a press which also embodies the present invention.

BRIEF SUMMARY OF THE INVENTION

This invention is directed to a solution of the problem of providing an intaglio printing press which will produce a uniform image density from all parts of the printing plate. Certain features are useful with presses generally, and others are useful particularly with intaglio presses of the type using flexible plates clamped at their ends in recesses in the plate cylinder.

One of the features comprises a train of ink supply rollers including an intermediate roller having a hard core covered with a rubber layer and an outer stratum of multiple layers of cloth, preferably cheesecloth. Such a roller produces a very smooth and uniform layer of ink on the transfer roller with which it runs in contact. Furthermore, the cheesecloth stratum on the roller is easily replaced when worn, and its working surface can be renewed by simply peeling off one or more layers of cloth.

A further feature of the invention relates to a method of making such a roller, including the steps of cutting away bands of the outer stratum when it is desired to transfer ink to one or more circumferential bands on the plate rather than covering the entire plate with an ink.

Another feature of the apparatus is concerned with the relationship between the circumference of the inking roller which runs in contact with the plate and the sum of the circumferential length of the plate and the circumferential length of the recess between the ends of the plate. The inking roller circumference must be slightly greater than the sum of the circumferential lengths of one plate and one recess to provide for wear compensation, and also to ensure a heavier layer of ink on the leading margin of the plate than at other parts thereof.

In a press having an intermittently fed paper wiping system, such as that shown in our copending application Ser. No. 372,087, mentioned above, the leading margin of the printing plate encounters fresh wiping material when it meets the wiping web, while the other parts of the plate are wiped by areas of the wiping web which have previously been used and already have some ink absorbed therein. The recessed image areas in the leading margin of the plate therefore, have more ink removed from them than the recessed image areas in the other parts of the plate. In order to provide a uniform image density in all parts of the image printed by the plate, it is desirable to compensate for this uneven wiping action by initially providing a thicker layer of ink on the leading margin of the plate, so that after the wiping operation, the image density is uniform over the entire plate area.

During the transfer of ink from the inking roller to the plate cylinder, a portion of the layer of ink on those parts of the roller which contact the plate is transferred from the roller to the plate. Those parts of the roller which come opposite the recess between the plate ends do not contact the plate and hence do not transfer any of their ink. Hence, those parts of the roller tend to acquire a second layer of ink on the next revolution of the inking roller, which, if the roller circumference is selected as described above, results in an extra heavy deposit of ink on an axial band extending along the leading margin of the plate. This axial band of ink is distributed to some extent circumferentially of the plate by the action of a hard surfaced roller preceding the inking roller in the inking train, which is effective to spread the heavy layer of ink peripherally of the inking roller. As mentioned above, such a heavy band is desirable in order to secure a uniform image density in the printed sheets.

It has been found that cheesecloth is especially effective in distributing a smooth layer of ink on a roller of an inking train. Furthermore, it is relatively inexpensive and easily replaced when worn. It is also easy to cut away parts of the cheesecloth stratum in order to spread the ink on circumferential bands only of the plate.

The winding of an outer stratum of multiple layers of cloth on an inking roller of a printing press is suggested by Ives, U.S. Pat. No. 276,591 (1883). Ives does not suggest the use of cheesecloth, nor does he use his cloth covered roller as an intermediate roller delivering ink to a hard-surfaced transfer roller, but instead runs it against the printing plate.

DRAWINGS

FIG. 1 is a perspective, somewhat diagrammatic view of an inking train for an intaglio press embodying the invention.

FIG. 2 is a plan view of a cheesecloth roller employed in the inking train of FIG. 1.

FIG. 3 is a sectional view taken on the line 3--3 of FIG. 2.

FIG. 4 is a diagrammatic sectional view through the plate cylinder of an intaglio press carrying a single plate.

FIG. 5 is a diagrammatic sectional view similar to FIG. 4 but showing an intaglio press cylinder carrying two plates.

FIG. 6 is a fragmentary, somewhat diagrammatic view illustrating part of the inking train for a two plate press, and illustrating the desired dimensional relationship between the circumference of the inking cylinder and the plate cylinder.

DETAILED DESCRIPTION

FIG. 1 shows an intaglio press having a plate cylinder 1 carrying two plates 2 and 3. Each end of each plate is held within a recess 1a by means of suitable clamping mechanism (not shown) which may be the same as that illustrated in the pending application of Ivaldo Gazzola et al., Ser. No. 298,376, filed Oct. 17, 1972, now U.S. Pat. No. 3,828,672, issued Aug. 13, 1974.

Running in contact with the periphery of the plate cylinder 1 is an inking roller 4 having a peripheral layer 4a of yieldable material, e.g., synthetic rubber. Ink is supplied to the inking roller 4 from an ink reservoir 5 which may be the same as that shown in our copending application, Ser. No. 410,987, filed Oct. 30, 1973. The ink reservoir 5 includes a hard surfaced ink supply roller 6 which cooperates with a roller 7 having an outer stratum 7a of multiple layers of cloth, e.g., cheesecloth or equivalent material wound on a layer 7b of rubber which covers a hard core 7c, usually of steel. The roller 7 runs in compressive contact with roller 6 and another hard surfaced roller 8 which in turn compressively engages the circumference of the roller 4. The compressive engagement is indicated in a drawing by a slight flattening of the outer layer 4a of roller 4 at the points where it engages the roller 8 and the plate cylinder 1.

The details of construction of the cheesecloth roller 7 are illustrated in FIGS. 2 and 3. As best seen in FIG. 3, the roller 7 comprises a hard core 7c covered by a layer 7b of compressible material. A strip 13 of cloth, preferably cheesecloth, is applied to the layer 7b by fastening one end of the strip with a suitable weak adhesive and then winding the strip around the core 7b a multiplicity of times, to form an outer stratum 7a of cheesecloth. When in use, the cheesecloth quickly becomes thoroughly impregnated with ink and constitutes an extremely flexible reservoir of ink. It is effective to take up surplus ink from any parts of the contacting rollers 6 and 8 which have such a surplus and it also is effective to deposit ink on any parts of those rollers where the ink supply is deficient. The result is that the ink is spread smoothly across the entire surface of the roller 8, or those portions thereof which contact the cheesecloth stratum 7a.

As shown in FIG. 2, the cheesecloth stratum 7a may be cut into bands after it is applied to the roller 7 by means of a sharp knife or razor blade, simply by turning the roller while holding the blade in contact with the cheesecloth. The portions of the cheesecloth between the bands which it is desired to retain are easily removed by tearing away, leaving the stratum 7a separated into sections according to the positions of the bands of the plates 2 and 3 which are to be inked.

It has been usual, in prior art presses, to secure the inking of the plates in bands by cutting away bands of material from the surface layer of the inking rollers. Where the cloth rollers are cut away, it is not necessary to cut away the inking rollers.

The roller 7 is held in compressive engagement with the rollers 6 and 8. The roller 7 is fixed on shaft 31 journaled in blocks 32, which are supported for vertical movement and are biased downwardly to maintain the compressive engagement by springs 33. The biasing force of springs 33 is adjustable by screws 34.

The rollers 6 and 8 are driven through a suitable gear train, such as that shown diagrammatically in FIG. 6, so that they move at the same peripheral speeds as the plate cylinder 1. The inking roller 4 is driven only by its contacts with cylinder 1 and roller 8.

FIG. 4

FIG. 4 shows a plate cylinder 14 carrying a single plate 15 whose ends are received in a recess 14a.

FIG. 5

FIG. 5 illustrates diagrammatically the structure of the plate cylinder 1 and the plates 2 and 3, showing that there are two recesses 1a, each of which receives two plate ends.

FIG. 6

This figure shows diagrammatically the plate cylinder 1 and the plates 2 and 3 mounted thereon and cooperating with the inking cylinder 4 having an outer layer 4a of resilient material. In order to spread the ink smoothly from the inking roller 4 to the plates 2 and 3, with a somewhat thicker layer of ink at the leading margins of those plates, the circumferential length of the periphery of layer 4a should be slightly greater than the sum of the circumferential length of one of the plates 2 and 3 and the circumferential length of one of the gaps 1a. The term "circumferential length of a plate", as used in this specification, means that dimension indicated at 21 in FIG. 6, i.e., the circumferential dimension of the part of the plate which engages the inking roller 4. The term "circumferential dimension of a recess", as used in this specification, means the circumferential dimension between the points near the ends of the plates 2 and 3 where those plates are no longer contacted by the roller 4. This dimension is illustrated at 22 in FIG. 6.

There is shown diagrammatically in FIG. 6 a wiping apparatus 23, which may be of the paper web type as shown in our copending application Ser. No. 372,087, filed June 21, 1973. The wiping apparatus 23 includes a pad 24 and a paper web 25 which is driven over the pad and between the pad and the printing plates 2 and 3. The web 25 is advanced intermittently, each time that a gap 1a passes the pad 24. It may be seen that the fresh part of the wiping paper web 25 is engaged by the leading margins of the plates 2 and 3.

An area on the inking roller 4 which comes opposite a gap 1a retains the ink previously applied by contact with roller 8, and has a second layer deposited on it at its next contact with the roller 8. The roller 8 spreads this double layer somewhat backwardly (i.e., clockwise in FIG. 6) along the surface of the inking roller 4.

If the circumferential dimension of the roller 4 is made slightly greater than the sum of the circumferential dimensions of one plate and one recess on the plate 1, then each area of roller 4 carrying a double layer is advanced during each revolution so that it encounters and transfers its double layer of ink to the leading margin of one of the plates 2 and 3.

The function of the wiping web is to remove all ink from the smooth, non-image areas of the plate. Since the web wipes the entire plate, it also removes some of the ink from the recessed image areas of the plate. The fresh web material encounters the leading margin of the plate and is more effective in removing ink from that margin, so that the image areas in that margin have less ink remaining in them after passing the wiping web than the image areas in the other parts of the plate. Hence, the image printed by the image areas in that margin are lighter, i.e., less dense, than the images printed by the other parts of the plate. The double layer of ink deposited on the leading margin by the roller 4 compensates for the uneven removal of ink by the fresh web and results in a uniform image density in all parts of the plate.

The optimum circumference for the inking roller 4 is always slightly greater than the circumferential length of one plate plus the circumferential length of one gap. The "slightly greater" distance is not critical, and may include a small amount to allow for wear of the yieldable outer layer 4a. It may be large enough to permit turning down a worn roller to present a new smooth surface to replace a worn one.

This relationship of the inking roller circumference to the plate and gap dimensions holds true regardless of the number of plates on the plate cylinder. For example, if two plates are used, as in the particular modification shown, the circumference of the inking cylinder 4 will be slightly greater than one-half that of the plate cylinder. If only a single plate is used, as in FIG. 4, the circumference of the inking cylinder 4 will be slightly greater than that of the plate cylinder. If four plates are used, the circumference of the inking cylinder 4 would be slightly greater than one-fourth that of the plate cylinder. In each example, a small amount for wear compensation may be added to the circumference of the inking cylinder 4.

Claims

We claim:

1. Ink supply apparatus for a printing press, including:

a. an inking roller for transferring ink to a printing surface on the press;

b. an ink supply roller for receiving ink from an ink reservoir;

c. means for transferring ink from the supply roller to the inking roller;

d. at least one intermediate roller in said transferring means, said one intermediate roller comprising:

1. a core;

2. a layer of compressible material covering the core; and

3. an outer stratum of multiple layers of cloth wound on the layer of compressible material, the axial length of the cloth stratum being less than the axial length of the core.

2. Ink supply apparatus for a printing press, including:

a. an inking roller for transferring ink to a printing surface on the press;

b. an ink supply roller for receiving ink from an ink reservoir;

c. means for transferring ink from the supply roller to the inking roller;

d. at least one intermediate roller in said transferring means, said one intermediate roller comprising:

1. a core;

2. a layer of compressible material covering the core; and

3. an outer stratum of multiple layers of cloth wound on the layer of compressible material, said cloth stratum comprising a plurality of axially separated sections, each having an axial length less than the axial length of the core.

3. An intaglio press, including:

a. a plate cylinder carrying at least one plate and having at least one recess between circumferentially spaced plate ends;

b. ink supply apparatus, including:

1. an inking roller having a compressible peripheral layer;

2. means supporting the inking roller for rotation in compressive engagement with the plate;

3. said inking roller having a circumference slightly greater than the sum of the circumferential lengths of the plate and the recess, so that the inking roller is effective to apply a heavier layer of ink to the leading margin of the plate than to other parts thereof;

c. plate wiping apparatus, including:

1. a pressure pad;

2. means for advancing a web of fresh wiping material between the pressure pad and the plate when a recess between plate ends is passing the pad, so that fresh wiping material is first engaged by the leading margin of the plate; said fresh wiping material being effective to remove more ink from the image areas of the leading margin than from the image areas of other parts of the plate;

d. said heavier layer of ink compensating for the excessive removal of ink from the image areas of said margin to secure uniform image density.

4. An intaglio press including:

a. a plate cylinder carrying a plurality of plates of equal circumferential extent, with their circumferential ends separated by recesses of equal circumferential extent in the cylinder surface;

b. ink supply apparatus, including:

1. an inking roller having a compressible peripheral layer;

2. means supporting the roller for rotation in compressive engagement with the plate;

3. said roller having a circumference slightly greater than the sum of the circumferential lengths of one plate and one recess, so that the inking roller is effective to apply a heavier layer of ink to the leading margin than to other parts of the plate;

c. plate wiping apparatus, including:

1. a pressure pad;

2. means for advancing a web of fresh wiping material between the pressure pad and the plate when a recess between plate ends is passing the pad, so that fresh wiping material is first engaged by the leading margin of the plate; said fresh wiping material being effective to remove more ink from the image areas of the leading margin than from the image areas of other parts of the plate;

d. said heavier layer of ink compensating for the excessive removal of ink from the image areas of said margin to secure uniform image density.

5. An intaglio press including:

a. a plate cylinder carrying at least one plate and having at least one recess between circumferentially spaced plate ends;

b. ink supply apparatus including:

1. an inking roller having a compressible peripheral layer;

2. means supporting the inking roller for rotation in compressive engagement with the plate;

3. said inking roller having a circumference slightly greater than the sum of the circumferential lengths of the plate and the recess, so that the inking roller is effective to apply a heavier layer of ink to the leading margin than to other parts of the plate;

4. an ink transfer roller comprising a core, a layer of compressible material covering the core, and an outer stratum of multiple layers of cloth wound on the layer of compressible material;

5. an inking train including the inking roller, the ink transfer roller, and an intervening hard surfaced roller; and

6. means supporting the hard surfaced roller in compressive engagement with the inking roller and the ink transfer roller;

c. plate wiping apparatus, including:

1. a pressure pad;

2. means for advancing a web of fresh wiping material between the pressure pad and the plate when a recess between plate ends is passing the pad, so that fresh wiping material is first engaged by the leading margin of the plate; said fresh wiping material being effective to remove more ink from the image areas of the leading margin than from the image areas of other parts of the plate;

d. said heavier layer of ink compensating for the excessive removal of ink from the image areas of said margin to secure uniform image density.