GB2173739A

GB2173739A - Printing press moisture control

Info

Publication number: GB2173739A
Application number: GB08604638A
Authority: GB
Inventors: Brian Charles Jackson
Original assignee: Jackson B C
Current assignee: Jackson B C
Priority date: 1986-02-25
Filing date: 1986-02-25
Publication date: 1986-10-22
Also published as: GB8604638D0

Abstract

The inking rollers of a printing press, e.g. an offset lithographic press, are treated to a controlled current of air from a manifold 10, apertures 12, Figure 1, directing air towards the rollers, so that the water content is lowered or eliminated. Particularly in multi-colour presses, the dehydrating apparatus need only be brought into operation on those units which are printing heavy or background colour. <IMAGE>

Description

SPECIFICATION Dehydration of printing presses Technical field The invention relates to apparatus for the dehydration of off-set lithographic printing presses for the prevention of ghosting and of the discolouration of the ink.

Background art Patent Specification US 4,524,689 (Lemaster) describes such apparatus comprising an air distribution manifold for placing in proximity to the inking roller system, and preferably near the rollers iast in contact with the plate cylinder. Air is supplied at all times during operation. This can lead to excessive drying, particularly in the production of fine print.

The invention Apparatus according to the invention comprises a manifold for placing in proximity to an inking roller system of a printing press, an aperture in the manifold for directing air onto a printing roller, meansforfeeding airtothe manifold, and means for controlling the amount of air fed to the manifold. The control means preferably comprises electrical circuit for fully opening, decreasing, increasing and fully closing the air feed. Means for attaching the manifold to a frame member of the press should generally be provided.

In a multi-colour printing press, a manifold may be placed in each unit and the air feed may be controlled by a single circuit. The control means may comprise a push button indicating each of the open and other states mentioned above for each manifold.

Thus the apparatus may be brought into operation only on those units which are working or printing heavy or background colour.

Drawings: Figure 1 is an elevation of a manifold in apparatus according to the invention; Figure la shows the mounting on a press of one end of the manifold of Figure 1, Figure 2 is a circuit diagram of means for feeding air to the manifold of Figure 1; Figure 2a is an alternative circuit diagram of means for feeding the air: Figure 3 shows an arrangement of a manifold in proximityto an inking roller system in a press, Figure 3a is an end view of the press in Figure 3, and Figure 4 is a more general view of the press of Figure 3a showing the location of air feed mechanism.

Best Mode The manifold shown in Figure 1 comprises an aluminium tube 10 of 30 mm outside diameter, and a number of iongitudinal slots 12 in the tube 10, each slot being 100 mm long 2 mm wide and separated from the next slot by 10 mm. The tube 10 is blocked at the ends and fed with air through an adjustable connection 14. Figure 1a shows how an end of the bar 10 is bolted by an adjustable bracket 16 to a side member 18 of the press. The press, of which the inking roller system at least is shown in a little detail in Figures 3 and 3a, is well known in itself so only tubes 10, moistening systems 21,22 and ink fountain rollers 61, 62 are referred to here. Figure 4 shows also the location of an air control damper 30,31 for each tube 10, and a common plenum 34 and pump 36 from which they are fed.

Turning now to the circuit diagram of Figure 2 a number of manifolds are schematically indicated as units 1,2,3,4,5, ie butterfly valves for controlling the flow of airto correspondingly numbered press units, in proximity to inking rollers of which the manifolds are placed. The operation of each of the said valves is governed by a control relay indicated as 6CR, 7CR etc. 24 volt power is taken off from a mains transformer at the top of the diagram through a 6A fuse. References to related parts of the circuit are indicated by line numbers on a scale down the left hand side of the diagram. Increase and decrease of air flow is effected by actuating a correspondingly marked switch (line 30, 31) which operates through a contactor and control relay 4CR, 5CR arranged to prevent both increase and decrease being called for at one time.

At line 39, it can be seen how the contactor 4CR and the control relay 6CR increase the flow of air to unit 1. When the valve is fully open a relay 11CR disengages, and gives an indication through a warning light shown immediately below it. The relays 6CR and 11CR increase and decrease the supply of air to unit 1 through an air control or motorized valve (not shown). Similar arrangements for units 2 and 5 are shown at lines 41 to 47. The operation of the contactor 5CR to decrease the flow of air to each of the units 1 to 5 is similarly shown at lines 49 and 58, with warning lights to show when fully closed.

The alternative switch panel circuit in Figure 2a shows at the top of the diagram 30A three phase supply being fed through 1 OA fuses,contacts 1 M, 2M etc. and thermal overload protection circuits O/L1, O/L2 etc to pumps Nos 1,2 etc for manifolds to correspondingly numbered print units (not shown).

Two of the supply lines are also fed to a transformer to the left of the diagram between reference lines 1 and 2 where 110 volts are taken off to the control circuit. An impression contactor is operated automatically by the press when the plates move into contact with the blanket roller. Individual units 1,2 etc can then be switched on as desired. The lines contacted are indicated to the right by the corresponding motor, eg pump motor 1M contacts lines 1, 1, 1,21, and a green light G indicates when the pump is on. Lines 4 to 22 indicate how the other pump motors 2M, 3M etc are similarly operated. Atimer circuit 3TR comprising control relays 1CR, 2CR prevents overload of the system by deferring the connection of later pump motors if all are switched on at one time.

The whole apparatus may be brought into operation by a photoelectric call or a proximity switch, for example, actuated by a movable part of the mechanism or by the presence of paper to be printed.

Claims

1. Apparatus for the dehydration of printing presses which comprises a manifold for placing in proximity to an inking roller system of a printing press, an aperture in the manifold for directing air onto a printing roller, means for feeding air toe manifold, and means for controlling the amount of air fed to the manifold.

2. Apparatus according to claim 1 in which the control means comprises eiectrical circuit for fully opening, decreasing, increasing and fully closing the air feed.

3. Apparatus according to claim 1 or claim 2 comprising a number of manifolds for placing in proximity to roller systems of different press units, and single air feed control means.

4. Apparatusforthe dehydration of printing presses as herein described with reference to Figures 1, 1a and 2 of the drawings.

5. Apparatusforthe dehydration of printing presses as herein described with reference to Figures 1,1 la and 2a of the drawings.