GB1560935A - Proofing presses - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO PROOFING PRESSES (71) We, D. TIMMINS & SONS (BRISTOL) LTD., a British Company, of Brook Road, Fishponds, Bristol BS16 3SH, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment:- This invention relates to proofing presses as used for proofing a printing cylinder before the printing operation proper is started. Such proofing presses normally comprise a main impression drum, on which a sheet of paper is secured, and means for mounting the printing cyclinder closely adjacent to the drum usually in contact therewith. Elaborate and accurate control means are necessary to maintain proper registry and the proofing press also includes means for wiping or doctoring the surface of the printing cyclinder after ink has been applied so that the small gravure cells of the printing cyclinder are filled with ink in the usual manner.

A conventional proofing press of this type cannot be used to proof a printing cylinder of the "stereo" type, having a rubber or other elastomeric surface with a raised printing image. Such stereo cylinders are commonly used for printing wallpaper and other patterns having a relatively coarse image, but may also be used for fine art work. It is an object of the invention accordingly to provide an attachment for a proofing press of the type described which will permit the press to be used for stereo cylinders.

Broadly stated the invention consists in a proofing press designed for use with a stereo printing cylinder having a resilient printing surface, the press including a frame, means for supporting an impression cylinder and further means for supporting the stereo printing cylinder approximately at the same horizontal level, means for adjusting one cylinder horizontally in relation to the other to bring them close to contact with each other, and a synchronizing toothed drive between the two cylinders, and including an attachment comprising a support provided with means for attachment to the frame of the press, and carrying an inking cylinder, and means for adjusting the position of the axis of this inking cylinder in relation to the printing cylinder, and an adjustable doctor blade positioned to engage the surface of the inking cylinder to from a trough for holding ink.

According to a preferred feature of the invention the inking cylinder has a gravuretype surface with multiple small indentations.

In a particular preferred construction the support for the the inking cylinder includes a horizontal pivot, and the inking cylinder is movable upwards and downwards and bears down on the surface of the printing cylinder.

The invention may be performed in various ways, and one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic plan view of a proofing press fitted with a stereo cylinder proofing attachment, in accordance with the invention, Figure 2 is a diagrammatic side elevation of the press, Figure 3 is a plan view of the attachment removed from the press, Figure 4 is a front elevation of the attachment, Figure 5 is a cross-section on the line A-A in Figure 4, and Figure 6 is a side elevation of the attachment.

Referring to the drawings the main proofing press comprises a base 10 having bearings 11 at each side to support a main impression drum 12 provided with the usual means for securing a sheet of paper wrapped around its periphery. The bearings 11 are mounted on supports 11A which can be adjusted together in a front-to-rear direction, on guides 11B. At the front of the base 10 is provided a pair of parallel horizontal ways 13 accurately aligned parallel with the axis of the drum 12 and arranged to support a printing cylinder 17 to be proofed. In particular there are a pair of slides 14, 15 mounted on the ways 13 and having bearing assemblies 16 to receive and locate the spindle ends of the cylinder 17.

These bearing assemblies may be designed to open and close hyuraulically, to allow the spindle and cylinder 17 to be removed readily, and the apparatus includes also means for moving the slides 14, 15 lengthwise as required This facilitates a rapid change-over of the printing cylinder, for example for washing purposes.

The press also includes delicate hydraulic control mechanism (not shown) for shifting the bearings 11, 1 lA and the whole drum 12 bodily towards and away from the printing cylinder 17, in order to obtain the required delicate contact for normal gravure cylinder proofing operation. Adjustable stops 50 are provided, one on each side to set up the required final position.

The apparatus as so far described is applicable to proofing normal gravure type cylinders but cannot be used for "stereo" cylinders with raised elastomeric printing images, and the attachment now to be described makes the press adaptable to both types.

The attachment includes a support comprising a pair of side arms 20, each mounted on a sliding base 21 which can be moved from front to rear by means of a lead screw 22 on each side of the base, both screws being interconnected to maintain parallelism. The two arms 20 have pivot horizontal bearings 24 at their upper ends each carrying a cranked arm or bracket 25 and the two arms have further bearings 26 supporting the spindle ends of a gravure-type rubber inking roller 27, i.e.

having a surface with multiple small indentations or impressions. A doctor blade 28 is mounted on further pivots 29 carried by the two arms, and so as to engage a side surface of the inking roller and thereby form an inking trough, means are included for adjusting the position of this doctor blade and particularly its angle in relation to the surface of the inking roller.

The attachment also includes a nylon toothed gear 30 designed to be fitted to the spindle at one end of the stereo cylinder 17, and a large diameter nylon annulus gear 32 designed to be fitted to the end of the impression drum 12. The gears are arranged such that they will mesh before the stereo cylinder 31 makes contact with the surface of the drum 12 and are so designed that the speed of movement of the surface of the stereo cylinder is synchronised with the movement of the paper on the drum.

In use with the stereo cylinder 17 and drum 12 so adjusted that the cylinder 17 clears the surface of the paper on drum 12 by a very small distance of less than .001", ink is introduced by hand into the trough between the inking roller 27 and the doctor blade 28, and the stereo cylinder 17 is rotated a small distance to start the inking of its surface. The main impression drum 12 is then rotated by hand or otherwise and consequently drives the stereo cylinder through the gears 30 32 so that an impression of the image on the cylinder is transferred to the paper and checked or proofed in the normal manner.

Figures 3 to 6 illustrate details of a practi-cal form of the attachment. In this embodiment the attachment comprises a pair of side arms or brackets 25 interconnected by front and rear tie bars 40, 41. The inking roller 27, on a spindle 42 is located by a pair of screw threaded bearing spigots adjustable by knurled screws 43 which permit the whole roller to be removed for washing. The doctor blade 28 is mounted on a holder 44 which is fixed at each end on a pair of studs 45 each pivoted appropriately on the respective bracket 25.

The doctor blade support is counter-balanced by a pair of weights 46 and can be clamped by hand levers 47 and adjusted lengthwise by means of knurled adjusting members 48. The inking roller can move upwards and downwards and bears downwards on the cylinder to be proofed.

To obtain the required close positioning between the impression drum 12 and the stereo cylinder 17 a pair of manual screwthreaded adjusting stops 50 are provided one on each side of the machine and the hydraulic mechanism for shifting the drum 12 is arranged to halt automatically when the drum support bearings meet these abutments. With appropriate adjustment it can be arranged that the drum always halts just clear of, or in very light contact with, the cylinder 17, so as to avoid exerting excessive pressure on the cylinder which would deform the elastomeric surface.

WHAT WE CLAIM IS: 1. A proofing press designed for use with a stereo printing cylinder having a resilient printing surface, the press including a frame, means for supporting an impression cylinder and further means for supporting the stereo printing cylinder approximately at the same horizontal level, means for adjusting one cylinder horizontally in relation to the other to bring them close to contact with each other, and a synchronizing toothed drive between the two cylinders, and including an attachment comprising a support provided with means for attachment to the frame of the press and carrying an inking cylinder, and means for adjusting the position of the axis of this inking cylinder in relation to the printing cylinder, and an adjustable doctor blade positioned to engage the surface of the inking cylinder to form a trough for holding ink.

2. A proofing press according to claim 1, in which the inking cylinder has a gravuretype surface with multiple small indentations.

3. A proofing press according to claim 1 or claim 2, in which the support for the inking cylinder includes a horizontal pivot, and the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. locate the spindle ends of the cylinder 17. These bearing assemblies may be designed to open and close hyuraulically, to allow the spindle and cylinder 17 to be removed readily, and the apparatus includes also means for moving the slides 14, 15 lengthwise as required This facilitates a rapid change-over of the printing cylinder, for example for washing purposes. The press also includes delicate hydraulic control mechanism (not shown) for shifting the bearings 11, 1 lA and the whole drum 12 bodily towards and away from the printing cylinder 17, in order to obtain the required delicate contact for normal gravure cylinder proofing operation. Adjustable stops 50 are provided, one on each side to set up the required final position. The apparatus as so far described is applicable to proofing normal gravure type cylinders but cannot be used for "stereo" cylinders with raised elastomeric printing images, and the attachment now to be described makes the press adaptable to both types. The attachment includes a support comprising a pair of side arms 20, each mounted on a sliding base 21 which can be moved from front to rear by means of a lead screw 22 on each side of the base, both screws being interconnected to maintain parallelism. The two arms 20 have pivot horizontal bearings 24 at their upper ends each carrying a cranked arm or bracket 25 and the two arms have further bearings 26 supporting the spindle ends of a gravure-type rubber inking roller 27, i.e. having a surface with multiple small indentations or impressions. A doctor blade 28 is mounted on further pivots 29 carried by the two arms, and so as to engage a side surface of the inking roller and thereby form an inking trough, means are included for adjusting the position of this doctor blade and particularly its angle in relation to the surface of the inking roller. The attachment also includes a nylon toothed gear 30 designed to be fitted to the spindle at one end of the stereo cylinder 17, and a large diameter nylon annulus gear 32 designed to be fitted to the end of the impression drum 12. The gears are arranged such that they will mesh before the stereo cylinder 31 makes contact with the surface of the drum 12 and are so designed that the speed of movement of the surface of the stereo cylinder is synchronised with the movement of the paper on the drum. In use with the stereo cylinder 17 and drum 12 so adjusted that the cylinder 17 clears the surface of the paper on drum 12 by a very small distance of less than .001", ink is introduced by hand into the trough between the inking roller 27 and the doctor blade 28, and the stereo cylinder 17 is rotated a small distance to start the inking of its surface. The main impression drum 12 is then rotated by hand or otherwise and consequently drives the stereo cylinder through the gears 30 32 so that an impression of the image on the cylinder is transferred to the paper and checked or proofed in the normal manner. Figures 3 to 6 illustrate details of a practi-cal form of the attachment. In this embodiment the attachment comprises a pair of side arms or brackets 25 interconnected by front and rear tie bars 40, 41. The inking roller 27, on a spindle 42 is located by a pair of screw threaded bearing spigots adjustable by knurled screws 43 which permit the whole roller to be removed for washing. The doctor blade 28 is mounted on a holder 44 which is fixed at each end on a pair of studs 45 each pivoted appropriately on the respective bracket 25. The doctor blade support is counter-balanced by a pair of weights 46 and can be clamped by hand levers 47 and adjusted lengthwise by means of knurled adjusting members 48. The inking roller can move upwards and downwards and bears downwards on the cylinder to be proofed. To obtain the required close positioning between the impression drum 12 and the stereo cylinder 17 a pair of manual screwthreaded adjusting stops 50 are provided one on each side of the machine and the hydraulic mechanism for shifting the drum 12 is arranged to halt automatically when the drum support bearings meet these abutments. With appropriate adjustment it can be arranged that the drum always halts just clear of, or in very light contact with, the cylinder 17, so as to avoid exerting excessive pressure on the cylinder which would deform the elastomeric surface. WHAT WE CLAIM IS:

1. A proofing press designed for use with a stereo printing cylinder having a resilient printing surface, the press including a frame, means for supporting an impression cylinder and further means for supporting the stereo printing cylinder approximately at the same horizontal level, means for adjusting one cylinder horizontally in relation to the other to bring them close to contact with each other, and a synchronizing toothed drive between the two cylinders, and including an attachment comprising a support provided with means for attachment to the frame of the press and carrying an inking cylinder, and means for adjusting the position of the axis of this inking cylinder in relation to the printing cylinder, and an adjustable doctor blade positioned to engage the surface of the inking cylinder to form a trough for holding ink.

2. A proofing press according to claim 1, in which the inking cylinder has a gravuretype surface with multiple small indentations.

3. A proofing press according to claim 1 or claim 2, in which the support for the inking cylinder includes a horizontal pivot, and the

ininkg cylinder is movable upwards and downwards and bears down on the surface of the printing cylinder.

4. A proofing press including an attachment substantially as described with reference to the accompanying drawings.