WO1994019194A1

WO1994019194A1 - Ink fountain for printing presses

Info

Publication number: WO1994019194A1
Application number: PCT/EP1994/000543
Authority: WO
Inventors: Jean-Lucien Sarda
Original assignee: Sarda Jean Lucien
Priority date: 1993-02-24
Filing date: 1994-02-23
Publication date: 1994-09-01
Also published as: FR2701893B1; FR2701893A1

Abstract

The ink fountain includes a fountain blade (2A) comprising a ramp (12), both blade and ramp being slitted to created mutually independant inking zones. Cylindrical thruster (18) act on the ramp (12) to adjust the thickness of the ink film. A set of cams (25) controlled by levers (33) pivot on shaft (24) to act individually on each of the thrusters (18). Each cam (25) carries two studs (25) and all the cams (25) be brought into rotation simultaneously by the action of pins (29) fixed to the shaft (24) thereby obtaining similar displacement of all the thrusters (18).

Description

INK FOUNTAIN FOR PRINTING PRESSES

The invention herein described concerns the ink fountains acting as a reserve and ink supply to printing presses and relates to an assembly of devices designed to permit these fountains to function in such a way that the flow rate of the ink can be precisely regulated, either by individual controls regulating the flow of ink to mutually independent inking zones or by means of a separate, general control acting upon all the individual controls simultaneously and providing identical adjustment of all the inking zones. This overall adjustment, chosen according to the average inking requirement of the matter to be printed, may be followed up, without affecting the overall ink flow, with a back-up adjustment by zone by operating any one of the zone adjusters individually. The independent adjustment of any one zone has no effect upon the adjustment of other zones. Furthermore, each zone of ink supply is of constant and unvarying thickness, which allows accurate and rapid adjustment of the fountain and vastly improved printing quality in comparison with traditional ink fountains. Since the overall adjustment control for all the inking zones is independent of the controls for individual adjustment zone by zone, it can be optional, depending on the size and type of the presses to be equipped.

These ink fountains are interchangeable with the original fountains of the presses and can replace them either during manufacture or on presses already in existence. At present, the great majority of traditional printing presses are provided with ink fountains consisting of a fountain body 1 Figure 1 supporting a blade 2 made of relatively thin steel foil (of the order of one to one and a half millimetres) which presses against a metal fountain roller 3 on which the reserve of ink 5 sticks and is rolled to form a film between the extremity of the blade 2 and the fountain roller 3. At each end of the fountain body 1 is fixed a plate 4 which retains the reserve of ink 5. Adjusting screws 6 placed along the blade 2 with their centres at regular intervals of about thirty millimetres are carried in holes tapped in the fountain body 1 for this purpose and by exerting variable pressure can modulate the thickness of the ink film by zones. These adjusting screws 6, supported on the projection 7, act directly on the blade 2 or through the intermediary of a thruster 8, usually acting against a return spring 9 with a circlip 10 to compress it. The blade 2 is secured to the fountain body 1 by a set of screws 11. This very simple system of ink supply presents the following disadvantages :

- When the thickness of the ink film is adjusted, the blade 2 constructed of a single piece of steel foil is placed under strain by the action of the adjusting screws 6 and deforms in an incoherent manner at different points, thereby creating ink zones of inaccurate dimensions whose irregular and unstable thickness, due to their uncertain adjustment, causes loss of time and spoils considerable quantities of printed matter. This adjustment is rendered even more of a matter of trial and error by the fact that moving any one adjusting screw 6 interferes with the adjustment of the neighbouring zones.

- The absence of reduction gearing of the controls greatly reduces the adjustment range adding further inaccuracy to what is already a delicate adjustment.

These inadequacies in the accuracy and consistency of the ink supply are extremely prejudicial to optimisation of print quality. Conscious of these deficiencies, the manufacturers of modern presses destined for high quality industrial scale printing have equipped their presses with ink fountains which work according to independent inking zones, producing a film of ink of regular and consistent thickness across the whole width of the inking zone and by inking zone.

These fountains most frequently possess a remote control acting upon each inking zone section, equipped with miniature down-geared motors. These devices are extremely costly and are not compatible with the presses used by the great majority of printers.

The invention described here is intended to remedy the present deficiencies by proposing intermediate technical solutions, compatible in their different forms with all printing presses.

The present invention is principally characterized by the use for its application of :

- simple means of reduction, linear and providing perfect repetition of blade movements and avoiding the use of worm and gear mechanisms, - simple methods of stiffening the active part of the blade by zones so as to obtain good distribution of the pressure exerted to regulate the formation of the ink film,

- simple devices making it possible to control all sections of the blade simultaneously across the whole adjustment range of ink film thickness, while retaining the possibility of adjustment by zones without affecting the adjustment of zones adjusted by the overall control. By way of example, but not constituting a closed list, there follow descriptions of the means employed for the application of the invention with references to the annexed drawings. Figures 2, 3 and 4 show respectively in cross section and in partial longitudinal view the principal mechanisms which enable these fountains to function. Figure 4 shows in detail the control levers of the different components permitting rapid adjustment of the fountain blade either by general movement of all the blade thrusters, combined with the facility to apply fine adjustments to each thruster without affecting the adjustment of the general control.

The fountain blade 2A Figure 2 takes the place of the conventional blade 2 Figure 1 and its lower surface presents the form of a ramp 12 Figure 2 whose angle will be variable depending on the degree of reduction chosen (generally between four and twenty degrees) as a function of the sensitivity of adjustment desired and according to whether this control is obtained by screws, manually operated thrusters or electro-mechanical means. The fountain blade 2A is divided by very fine slits, (diameter of the slits approximately one tenth of a millimetre) spaced at intervals corresponding to the spacing of the screws or thrusters working together with each blade section. The ramp 12 stiffens the active part of each blade section and distributes evenly the pressure exerted by the thruster 10 to ensure the production of an ink film of regular and consistent thickness. In order to prevent any leakage between the blade sections, a plastic film 13 is placed over the blade. According to the destination of the press, this film can be omitted, on condition that the blade sections are jointed by a soft joint made for example from polyurethane elastomer of hardness approximately forty shores. This plastic film is anchored at the rear by means of an eccentric bar 14 equipped with rubber rings bearing against a strip 16. The eccentric bar 14 is moved by a lever 17 Figure 4. The original screw thrusters are replaced with cylindrical thrusters 18 Figure 2. They are guided by threaded bushes 19 which replace the adjusting screws 6 Figure 1 and carry return springs 9 Figure 2 as before. The cylindrical thrusters 18 are equipped at their extremity with adjusting screws 20 with lock-nuts 21 for carrying out the initial adjustment.

The control unit for the screws is composed of two end plates 22 cross-braced by the strip 23 and the fountain blade 2A upon which they are fixed. They are pierced by a shaft 24 on which are disposed the cams 25, one for each thruster, held in position by the spacers 26 Figure 3 and the pins 29. The cams 25, mounted in needle roller bearings 27, are free to rotate on the shaft 24. They are held in place by friction against the adjusting screws 20. They are profiled in such a fashion that one quarter turn entrains the complete opening or closing of the ink film between the fountain blade 2A Figure 2 and the fountain roller 3. They carry on one of their end faces two studs 28 positioned opposite the pin 29 with a degree of liberty equal to the adjustment range (one quarter turn). Rotating the shaft 24 by half a turn in either direction thus causes the movement of all the cams 25, permitting adjustment of the ink flow from minimum to maximum. This rotation is obtained by manual actuation of the lever 30 Figure 4 which is fixed to a gear wheel 31. The gear wheel 31 controls the shaft 24 through a reduction. The pinion 32 causes the shaft 24 to rotate in the same directions as the lever 30. The degree of liberty of the cam 25 Figure 2 between the two studs 28 is used for individual adjustment of each cylindrical thruster 18. For this purpose, the cams 25 Figure 2 are each fitted with a control lever 33. A graduated housing 34 indicates the position of the cams. In different scenarios, the screws 11 of the fountain blade 2A on the fountain body 1 which supports the assembled components enable the fountain to function. Figure 5 shows the same view as Figure 4 including a modification of the fountain blade 2A where the sections of the ramp 12A are not cut into the substance of the blade but are attached by means of two screws 12B to the fountain blade 2A which has been shortened, drilled and tapped for the purpose of receiving the ramps 12A. This modification offers advantages for equipping fountains having fountain blade supports of mediocre geometry or fountain rollers 3 in a defective state, since it permits precise adjustment of sections of the ramp 12A with respect to the fountain roller 3. Figure 6 shows a simplified version in which the shortened blade 2B has no adjustments by cam and no general control lever but, for control of the adjustment of the blade 2B uses the same type of adjusting screws 6, thrusters 8, return springs 9 and circlips 10 as those conventionally employed. The adjusting screws 6 also comprise a graduated circular scale 6A and a pointer 6B to display their position. The simplicity and low cost of the means described above to illustrate the invention, which do not represent an exhaustive list, offer, by the consistent accuracy of the thickness of the ink film that they produce and the rapidity of their adjustment, a solution to inking problems which is open to large scale development. It is a simple matter to motorize the controls of all the individual cams or the general control of the whole set to permit them to be automated in the framework of a remote control system whether or not connected to known systems for analysing the density of the ink film deposited on the print.

Claims

PATENT CLAIMS

1 - An ink fountain for printing presses consisting of a fountain blade (2A or 2B) comprising a ramp (12) in its active part. This blade and ramp have fine slits cut into them to create mutually independent inking zones. These sections of the ramp work in combination with cylindrical thrusters (18) or analogue adjusting screws (6) in order to obtain a linear and repetitive reduction of the displacement movement of the cylindrical thrusters (18) or analogue screws. The angle of slope of this ramp (12), generally somewhere between four and twenty degrees, determines the amplitude of the displacement movement chosen. This ramp (12) also stiffens the extremity of the blade thereby making it possible to obtain good distribution of the pressure exerted by the cylindrical thrusters (18) in the centre of this ramp across the full width of the corresponding inking section. A set of cams (25) controlled by levers (33) pivot on the shaft (24) to act individually on each of the cylindrical thrusters (18). Each of these cams carries two studs (28) and can be brought into rotation simultaneously by the action of the pins (29) fixed to the shaft (24) thereby obtaining similar displacement of all the cylindrical thrusters (18).

2 - An ink fountain for printing presses as specified in Claim 1 , characterized by the fact that the ramps (12) which equip the fountain blades (2A and 2B) may be either machined in the body of the blade or fixed on as an addition.

3 - An ink fountain for printing presses as specified in Claims 1 and 2, characterized by the fact that the ramps (12) can function as desired either in combination or with the aid of the cylindrical thrusters (18) or adjusting screws 6.

4- An ink fountain for printing presses as specified in any one of the above Claims, characterized by the fact that the ink fountain is equipped with an eccentric bar (14) fitted with rubber rings to hold the impermeable film that prevents ink leakage between the blade sections. 5 - An ink fountain for printing presses as specified in any one of the above Claims, characterized by the fact that the simultaneous control of all the cams (25) is optional and does not affect the individual controls of the cylindrical thrusters (18).

6 - An ink fountain for printing presses as specified in any one of the above Claims, characterized by the fact that each cam (25) or the shaft (24) that rotates them can be controlled remotely by electro-mechanical means.

7-An ink fountain for printing presses, characterized by means for regulating the flow of ink either by individual controls regulating the flow of ink to mutually independent inking zones or- by a general control acting upon all individual controls.