US3592136A

US3592136A - Offset printing apparatus cleaner

Info

Publication number: US3592136A
Application number: US788143A
Authority: US
Inventors: Thomas G Selman
Original assignee: NRG Manufacturing Ltd
Current assignee: NRG Manufacturing Ltd
Priority date: 1968-01-05
Filing date: 1968-12-31
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13
Also published as: FR1604471A; YU769A; DE1900394B2; DE1900394C3; DE1900394A1; AT299267B; GB1191591A; YU33010B; DK122796B

Abstract

The invention relates to a device for cleaning a printing cylinder and comprising a roller for applying ink solvent to the cylinder and a device for wiping excess solvent around the cylinder to be deposited on a solvent absorbent strip attached to the cylinder. The volatile solvent may subsequently evaporate to leave the strip once more absorbent.

Description

D United States Patent 1 1 3,592.1 36

|72| Inventor ThomuG. Selma: [56] References Cited -t UNITED STATES PATENTS 2.363,8l7 11 1944 Taylor 101/425 ux 2,691,344 10/1954 McMullen..... 101/425 e 2,944,484 7/1960 Bruce 101 425 [73] gfi 'k f 3.089.415 5/1963 Grembecki et 111.. 101/425 [32] Mom Jan 3.094.068 6/1963 Gericke .1 101/425 y 3.I44.826 8/1964 Lang etal. 101/425 [33] Great Britain 3 881/68 FOREIGN PATENTS 1,093,803 l0/l958 Germany l0l/425 Primary ExaminerRobert E. Pulfrey Assistant Examiner-C. Coughenour Anomzy-Cushman, Darby and Cushman [54] OFFSET PRINTING APPARATUS CLEANER Claims 3 Damn Figs ABSTRACT: The invention relates to a device for cleaning a [52] US. Cl 101/425, printing cylinder and comprising a roller for applying ink sol Nil/ 423. l0ll4l5.l vent to the cylinder and a device for wiping excess solvent [5H Int. Cl B4lf35/00 around the cylinder to be deposited on a solvent absorbent [50] Field of Feardl l0l/l23 strip attached to the cylinder. The volatile solvent may sub- 125 sequently evaporate to leave the strip once more absorbent.

PATENTEUJULIBIEWI 3.592.136

SHKET 1 OF 2 A ttorneyg PATENIEU M1319?! SHEET 2 OF 2 I nuenlor Ms Gnu-9g silman a, 05mm, 0%, a Mm A llorney:

OFFSET PRINTING APPARATUS CLEANER The present invention relates to an improvement in or relating to printing apparatus, and more particularly to an improved device for cleaning a cylinder surface such as the blanket of offset printing apparatus, after a printing cycle has been completed. For example, in offset printing apparatus if a short run printing cycle has been carried out using a particularly printing plate, and it is then desired to change the plate, the new plate cannot be used until the previous impression on the blanket has been removed so that the fresh impression may be featured clearly on the surface. The blanket may be cleaned by applying a solvent to the surface of the blanket for example with a cloth so that ink is absorbed and transferred to the cloth or other solvent applying means. However, residual cleaning solvent must thus be allowed to evaporate from the surface of the blanket before printing may recommcnce.

According to the present invention we provide printing apparatus including a cylinder, means for selectively applying ink solvent to the cylinder solvent absorbent means attachable to the cylinder, and a solvent wiping means selectively operable to wipe ink solvent circumferentially of the cylinder towards the solvent absorbent means. Preferably the cylinder has a part of its surface adapted to receive a printing blanket, the solvent absorbent means is arranged to extend longitudinally of the cylinder at one end of the blanket receiving part of the surface thereof, and the solvent wiping means is mounted on a support adapted to be held stationary with respect to the axis of the cylinder. Thus the arrangement pro vides that, upon rotation of the blanket cylinder after cleaning, residual solvent or inky solution on the blanket is wiped clear by the wiping means and is moved round to the end of the blanket adjacent said absorbent means, the wiping means when depositing the residual solvent in a position from which it may readily be absorbed by the absorbent means,

The apparatus of this invention may be used with any print ing machine, but is particularly suitable for use with an offset machine having an automatic blanket washup attachment including blanket cleaning means for introducing cleaning solvent to the surface of the blanket. In such a device the ink is readily transferred from the blanket to the solvent introducing cleaning device, residual solution or solvent being deposited adjacent said absorbent means.

Conveniently said absorbent means may comprise an elongate strip of absorbent material extending longitudinally of the cylinder and having a peripheral extent less than that of a recessed portion of the cylinder surface which portion normally receives the end clamps of the blanket. Preferably the absorbent strip may be mounted radially inwardly on a partcylindrical solvent permeable sheet, said sheet forming a continuation of the cylindrical surface of the blanket receiving part of the cylinder. Desirably said permeable sheet may be in the form of an elongate plate having passages extending therethrough in directions radial with respect to the cylinder. conveniently said absorbent strip may comprise a sheet of sponge material. Alternatively the absorbent material may be formed synthetic plastics material. Desirably said wiping means may comprise a blade extending longitudinally of the cylinder and mounted on a frame pivotable between an operative position in which the blade contacts the surface of the cylinder and an inoperative position in which the blade is clear of the surface of the blanket. The blade may be flexible and is preferably formed of rubber. Conveniently the solvent applying means may comprise a roller having an absorbent surface adapted to be placed in contact with the cylinder. The cleaning solvent applying roller may be mounted on the same frame member as the wiping blade. If desired, the frame may be pivoted to and retained in an intermediate position, between said operative and inoperative positions, in which the cleaning solvent applying roller is free from contact with the blanket but the blade is still in contact therewith. Suitably the cleaning solvent applying roller may be positioned above a reservoir of cleaning solvent so that the bottom part of the applying roller is immersed in the cleaning solvent within the reservoir.

Advantageously means may be provided for rotating the cleaning solvent applying roller when in contact with the cylinder, and preferably said applying roller rotating means causes rotation of the applying roller in the same sense as the rotation ofthe cylinder during the cleaning cycle.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, of one embodiment ofthe invention, in the form ofa blanket cylinder cleaning device for use with offset printing apparatus. Reference will be made to the accompanying drawings in which:

FIG. 1 shows a blanket cleaning device of the present invention, when both a cleaning roller and a cleaning blade are in contact with the blanket to be cleaned;

FIG. 2 shows the device of FIG. 1 in an intermediate position in which the blanket cleaning roller is in an operative position but the cleaning blade is still operating on the surface of the blanket cylinder; and,

FIG. 3 is a view, similar to FIG. 2, but showing the blanket cleaning device in its inoperative position where both the cleaning roller and the cleaning blade are clear of the surface of the blanket cylinder.

Referring now to the drawings, and in particular to FIG. 1, there is shown a transverse sectional view ofa cleaning device associated with the blanket cylinder of an offset shaft device. is cylindrical sponge cleaning roller 1 rotates in the an ticlockwise sense in contact with a blanket plate 2 on the surface of a blanket cylinder 3. The cleaning device further includes a flexible wiper blade 4 attached at the free end of a bracket 5 secured to the frame 6 of the cleaning device. The cleaning device further includes a cleaning solvent tank 7 containing cleaning fluid 8 which is entrained by the rotation of the sponge surface 1 on the cleaning cylinder 9 mounted on a shaft 10 journaled within the frame 6 of the cleaning device. The shaft 10 is driven for rotation in the anticlockwise sense by suitable driving linkage which is not shown in the accompanying drawings.

The cleaning blade 4 consists essentially of a single main blade 40 arranged so that, in the operative position of the blade assembly, the blade 40 wipes the cylindrical surface of the blanket 2, and further that a reinforcing strip 4b placed behind the main blade 4a serves to increase the flexural strength of the blade 4a to help resist deformation of the blade 40 caused by frictional contact of its operative edge with the surface of the blanket 2.

The blanket cylinder 3 is driven for rotation in the anticlockwise sense about shaft 11 by a suitable driving mechanism not shown in the drawings. The leading edge of the blanket 2 is clamped at 13 to the cylinder 3 and a similar clamp 14 retains the trailing edge of the blanket fixed with respect to the cylinder 3. As can be seen from FIG. 1, the trailing edge of the blanket 2 passes in tension over a sharp edge 15 of the cylindrical surface of the roller 3 and, due to the tension in the blanket 2 exerted by the blanket trailing end clamp 14, the trailing part of the blanket extends in a straight line along a substantially chordal direction with respect to the cylinder 3 between the sharp edge 15 an the clamp 14. However, a part cylindrical plate 16 is clamped in position so that it forms a continuation of the cylindrical surface of the blanket 2 radially outward with respect to the trailing end clamp 14. The arcuate plate 16, which is mounted just radially outwardly ofa pad of sponge material 25, is perforated by passages 17 extending along directions radial of the cylinder 3. The plate 16 is retained in position by a Z-shaped bracket 18 secured to the clamp-containing well of the cylinder 3 by means of a stud 19 extending radially outwardly from the well and a nut 20 threadedly engageable on the stud so as to clamp one limb of the Z-shaped clamp 18 against the surface of the well.

A set of countersunk bolts 21 extending through and received in suitably arranged recesses within the arcuate plate 16 bears against the bracket 18 but with a flat spacing nut 24 therebetween. Each spacing nut 24 is also threadedly engageable on the associated bolt 21 so that the order of assembly of the plate 16, bracket 18 and bolts 21 will be as follows. Each bolt 2] is first inserted, in a radially inward direction, into the corresponding recess in the plate I6, each flat spacing nut 24 then being threadedly secured on its associated bolt 2l so as to clamp the bolt with respect to the plate 16. At this stage the sponge pad 25 is positioned in contact with the plate I6 so that the spacer nuts associated with the various bolts 21 are received in suitable apertures in the sponge pad 25. After this the plate [6, together with its various bolts 2l, is brought into engagement with the Z-shaped bracket 18 by engagement of the bolts 21 within the various apertures 22 of the Z-shaped bracket [8. Finally each bolt 21 is provided with a washer and a clamping nut 23 which is then tightened and the structure thus made secure.

FIG. 1 shows the cleaning device in its operative position in which the sponge surface 1 of the cleaning cylinder 9 is in con tact with and exerts a scrubbing action against the blanket 2 during rotation of the shafts l and II. Furthermore the scraper blade 4 is shown as contacting the surface of the blanket 2.

In order to withdraw the cleaning device from contact with the blanket the main frame 6 of the cleaning device is pivotally mounted on a shaft 26 secured to the frame of the offset printing apparatus, and pivotable movement of the frame 6 about the shaft 26 in a clockwise direction will withdraw firstly the cleaning cylinder assembly and subsequently the blade from contact with the blanket 2.

FIG. 2 shows an intermediate position in which the frame 6 of the cleaning device has been rotated through a small angle in the clockwise direction so that the surface of the cleaning sponge l is clear of the blanket 2 and the blade 4 is still scraping the surface of the blanket.

In FIG 3 further clockwise rotation of the cleaning device has taken place, and both he cleaning sponge I and the blade 4 are now free from contact with the blanket, and normal printing may take place.

By way of further explanation, one cleaning cycle of the apparatus illustrated will now be described, commencing with the application of cleaning fluid and ending with the preparation of the blanket for further printing.

When it is desired to clean the blanket 2 of an offset printing device the frame 6 of the cleaning device is pivoted in an an ticlockwise direction until the sponge surface 1 ofthe cleaning cylinder 9 and the blade 4 are in contact with the surface of the blanket, as shown in FIG. 1. The pivotal movement ofthe frame 6 about the shaft 26 may be achieved either by a manual control lever moved by the operator of the apparatus, or by suitable automatic programming devices which require merely a single wash control to be actuated. For example, the movement of the frame may be effected by driven rotation of a suitable cam engaging with a cam follower associated with the frame.

The shafts l0 and II are then rotated in the anticlockwise direction so that a scrubbing action takes place between the sponge surface I and the blanket 2, cleaning solvent being lifted from the tank 7 by the sponge 1 and being deposited on the cylindrical surface of the blanket 2 and dissolving ink therefrom, the inky solution being transferred to the sponge I by means of which it is carried in an anticlockwise direction down into the tank 7. The blade 4, positioned just downstream of the point of contact between the sponge and blanket 2, then wipes clean the surface of the blanket 2 by removing the residual cleaning solvent, just deposited on the surface of the blanket by the sponge I, together with any ink absorbed by the solvent. The washup cycle is preferably carried out for three to four revolutions of the blanket cylindcr, since the particularly advantageous arrangement described will clean the blankct 2 thoroughly in only these few rotations of the cylinder 3.

During the washing rotations of the cylinder 3 the cleaning solvent wiped by the blade 4 tends to build up just below the wiping edge of the blade and, as the blanket cylinder rotates, the solvent and dissolved ink is moved relatively to the surface of the cylinder 3 towards the chordal portion of the trailing end of blanket 2, and is then wiped on to the arcuate surface of the perforated plate 16. The solvent and dissolved ink may then pass through the perforations of the plate I6 and are absorbed by the sponge 25.

At this stage, since solvent has been deposited and removed simultaneously, there will be a slight residue ofink and solvent on the surface of the blanket since almost invariably the blade 4 would not be able to cope with clearing the surface of the blanket 2 completely while solvent is still being deposited by the sponge 1. Accordingly the frame 6 of the cleaning device is pivoted in a clockwise direction through a small angle until it reaches the intermediate position, illustrated in FIG. 2, in which the blade 4 is still in contact with the surface of the blanket 2 but the sponge I is now completely free from contact with the blanket. One or two revolutions of the blanket cylinder 3, while the cleaning device is in this intermediate position, will be sufficient to remove the residue of the ink and solvent.

Now the blanket will be completely clean and will be dry since the blade 4 will have wiped all the cleaning fluid and dis solved ink onto the sponge 16 at the trailing end of the blanket. The cleaning device may then be rotated further in the clockwise direction until both the sponge I and the blade 4 are free from contact from the blanket 2 and normal printing may be resumed.

Since the solvent chosen is a volatile material the sponge 25 will tend to dry out during the early part of the next printing cycle so that by the end of the printing cycle, when a further blanket washup cycle is required, the sponge 25 will once again be dry and ready to absorb the ink and cleaning fluid deposited thereon by the blade 4 of the cleaning device.

The plate l6, although described as being a cylindrical plate with perforations in the form of bores 17 extending in the radial direction with respect to cylinder 3, may be perforated by means of slits running in the radial direction and extending longitudinally of the plate, by two sets of intersecting diagonal extending slits forming a grid of slits across the plate, or by being constructed from a suitable porous material such as sintcred metal. Clearly the precise nature of the ink and solvent permeable plate 16 does not affect the scope of the invention, the only requirement being that ink and solvent are capable of passing from the outer cylindrical surface of the plate 16 on to the sponge 25.

We claim:

I. Printing apparatus including frame means, a cylinder carried by said frame means, an ink receiving surface formed on said cylinder and means for cleaning ink from the cylinder, such cleaning means comprising:

a. means supported by said frame means for applying ink solvent to said cylinder,

b. solvent absorbent means attached to said cylinder ink receiving surface; and

c. means supported by said frame means for wiping excess solvent circumferentially of said surface towards said solvent absorbent meansv 2. Printing apparatus according to claim I, and including:

d. part cylindrical demountable blanket means attached to the cylinder and forming said ink receiving surface, said solvent absorbent means being arranged to extend longitudinally of said cylinder along one edge of said blanket means; and

. pivotable support means supported by said frame means and carrying said solvent wiping mean for movement between a solvent wiping position and an inoperative position.

3. Printing apparatus according to claim 2, and including:

f. recessed surface means on said cylinder for receiving the end clamps of said blanket means, and

g. an elongated strip of absorbent material within said recessed surface means, constituting said solvent absor bent means and extending longitudinally of the cylinder and having a peripheral extent less than that of said recessed surface means.

4. Printing apparatus according to claim 3, and including part cylindrical solvent permeable means having the same radius and center of curvature as said blanket means, said absorbent strip being mounted on said solvent permeable means radially inward thereof.

5 Printing apparatus according to claim 4, wherein said sol vent permeable means comprises:

h. an elongate plate, and

j. passage means extending through said plate in directions radial with respect to the cylinder 6. Printing apparatus according to claim 2, wherein said wiping means comprises a wiper blade extending parallel to the axis of said cylinder, and wherein the inoperative position of said pivotable means is a position in which said wiper blade is withdrawn from contact with said cylinder.

7. Printing apparatus according to claim 2, wherein said solvent applying means comprises:

k. a roller;

l. solvent absorbent surface means on said roller;

m. solvent bath means for introducing ink solvent to said ab sorbent surface means; and

n. means for pivotally mounting said roller for movement between a solvent applying position in contact with said cylinder and an inoperative position out of contact with said cylinder.

8. Printing apparatus according to claim 7, wherein said pivotable support means also carries said solvent wiping means.

9. Printing apparatus according to claim 7, and including means for rotating the solvent applying roller when in contact with the cylinder.

10. Printing apparatus according to claim 9, wherein said roller rotating means drives the applying roller for rotation in the same direction of rotation as that of the cylinder in use of the apparatus.

Claims

1. Printing apparatus including frame means, a cylinder carried by said frame means, an ink receiving surface formed on said cylinder and means for cleaning ink from the cylinder, such cleaning means comprising: a. means supported by said frame means for applying ink solvent to said cylinder; b. solvent absorbent means attached to said cylinder ink receiving surface; and c. means supported by said frame means for wiping excess solvent circumferentially of said surface towards said solvent absorbent means.

2. Printing apparatus according to claim 1, and including: d. part cylindrical demountable blanket means attached to the cylinder and forming said ink receiving surface, said solvent absorbent means being arranged to extend longitudinally of said cylinder along one edge of said blanket means; and e. pivotable support means supported by said frame means and carrying said solvent wiping mean for movement between a solvent wiping position and an inoperative position.

3. Printing apparatus according to claim 2, and including: f. recessed surface means on said cylinder for receiving the end clamps of said blanket means, and g. an elongated strip of absorbent material within said recessed surface means, constituting said solvent absorbent means and extending longitudinally of the cylinder and having a peripheral extent less than that of said recessed surface means.

5. Printing apparatus according to claim 4, wherein said solvent permeable means comprises: h. an elongate plate, and j. passage means extending through said plate in directions radial with respect to the cylinder

6. Printing apparatus according to claim 2, wherein said wiping means comprises a wiper blade extending parallel to the axis of said cylinder, and wherein the inoperative position of said pivotable means is a position in which said wiper blade is withdrawn from contact with said cylinder.

7. Printing apparatus according to claim 2, wherein said solvent applying means comprises: k. a roller; l. solvent absorbent surface means on said roller; m. solvent bath means for introducing ink solvent to said absorbent surface means; and n. means for pivotally mounting said roller for movement between a solvent applying position in contact with said cylinder and an inoperative position out of contact with said cylinder.