DE3320637A1 - Device for recording the conveyance of liquid in the inking and damping unit of printing machines - Google Patents

Abstract

The invention relates to a method and a device for the visual recording of the special features which characterise the production of layers of liquid by the process of liquid separation. These features, i.e. the liquid lamellae, threads and droplets, only occur when the separating operation is proceeding and are influenced during this process by different parameters, such as the layer thicknesses, the mixing ratio, the viscosity, etc. The recording, according to the invention, of the light scattered over these features therefore provides a measure which directly characterises the operation of liquid separation and can be used for the locally restricted monitoring or control of said process. In this case, it allows, in particular, the parameters which influence these features to be measured, i.e. the layer thicknesses or the mixing ratio, etc. Layers of liquid are produced by the process of liquid separation, in particular in printing machines and varnishing and gluing machines. The invention can be applied advantageously on machines of this type. It can be used specifically in offset printing machines for checking the quantity ratio of the printing ink to the damping medium.

Description

The invention relates to a method and a device for non-contact, real-time metrological detection the splitting of liquid layers in roller gaps Characteristic properties of printing machines or sizes.

The invention allows in particular the measurement of liquid quantities and liquid quantity ratios per unit area at the exit of a nip of two with the relevant liquid or the relevant liquid mixture partially or completely covered rollers, which roll on each other and thereby the existing ones in the roller gap Split the liquid layer at its exit. This splitting of liquid layers occurs in particular in Printing machines and lacquer and glue application machines on and thereby enables the advantageous application of the invention.

Purpose:

The splitting of liquid layers is used in technology in the j generally for the purpose of creating thinner layers of liquid of defined thickness, area or limitation and substance Composition. In most cases, the film formation process will be carried out in such a way that at least two rollers generally covered with sub-freezing liquids Roll on each other and the resulting liquid layer in the nip is split at its exit. As

^ O special features of the splitting of liquids considered here occurring liquid lamellae, threads and droplets by the inventive method or the inventive Device recorded locally in real time and stored in the corresponding

talking machines are used for control and regulation units will.

State of the art:

In addition to that from the Forschungsgesellschaft Druckmaschinen e.V. already applied for patent with the file number P 3205 941.8 no methods or devices are known in which as characteristic features of the creation of liquid layers liquid lamellae, threads and droplets of liquid occurring by means of two rollers rolling on top of each other can be detected. With the device or the method for which the patent with the file number P 3205 941.8 has been applied for, the resulting at the gap exit due to vibrations of the liquid lamellae and liquid threads and emitted sound waves are measured and processed.

In all other known measuring devices, for 'non-contact Real-time detection of the splitting of liquid layers, the layer thicknesses at a greater distance from the gap exit measured. In general terms, energy in the form of electromagnetic waves is transmitted through the liquid layer. th sent and at suitable wavelengths that of the liquid layers absorbed portion of the emitted energy detected by means of a detector.

State of the art criticism:

The previously used for the control of liquid splitting -set measuring devices, which the thickness of the liquid layers grasp at a greater distance from the gap exit, have in general the disadvantage that their values are independent of whether

the stratification process is in progress or whether it is interrupted is. They are therefore only suitable to a limited extent for the metrological control of these processes. There was an interruption or disturbance of the liquid splitting, however, without temporal Delay in the omission or in changes to the liquid lamellae and shows threads of liquid at the gap exit the method according to the invention does not have this disadvantage - it allows therefore the detection of such disturbances without a time delay directly at the place of their occurrence and is therefore essential Real-time control of liquid splitting suitable.

The offset printing process, for example, can be used to illustrate this difference between these layer thickness measuring devices and the method according to the invention. In this case, an apparently sufficient dampening solution thickness on a surface element of the printing plate not intended for ink acceptance does not guarantee that this surface element will not accept ink as a result of stronger evaporation of the dampening solution and / or excessive pressure in the roller gaps between the inking rollers and the printing plate; In the opposite case, an apparently correct dampening solution layer on a surface element of the printing plate intended for ink acceptance does not guarantee that there will not be insufficient pressure in the roller gaps between the inking rollers and the printing plate and the resulting incomplete displacement of the dampening solution results in incomplete ink acceptance; so so-called 'watermarks ¹ are created.

Because such malfunctions are essential for the functioning of the offset printing process fundamental splitting of the dampening solution film on the surface elements not intended for ink acceptance or the splitting of the printing ink / dampening solution emulsion the surface elements provided for the color recording the geometric Extension and 'the material composition of the

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Liquid lamellae, threads and droplets have a strong influence on them, and they are detected by the method according to the invention directly at the point of their formation and thus without a time delay.
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Compared to the acoustic detection of the, liquid lamellae Sound waves emitted and threads emitted by the inventive optical detection of the geometric extent and material composition of the same has the advantage that the liquid splitting by focusing the optical radiation in the longitudinal direction, the gap can be detected locally narrowly limited. As there are no microphones with one for this purpose required directional characteristic is with the acoustic Measure the liquid splitting over the entire length of the gap detected integrally.

Task:
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The invention is based on the object of a quantitative and characterizing the splitting of liquid layers to offer locally detecting measuring methods in real time, which do not influence the layer formation process, and for control purposes or control of such processes can be used.

Solution: * ■

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The object is achieved in that by means of an optical radiation source used for the splitting of liquids As characteristic features emerging and disintegrating liquid lamellae and threads are irradiated and the -them scattered portion of the incident radiation with an op-

table radiation receiver is received and processed electronically and brought to the display. The spectral, spatial and temporal distribution of the irradiation intensity as well as the detection angle and the distance between the optical receiver and the irradiated cleavage point are kept constant during the measurement, which means that the received, scattered radiation intensity depends on the geometric extent or shape and depends on the material composition of the liquid lamellae, threads and droplets. The spectral distribution of the irradiated intensity and the spectral distribution of the received intensity, screened out by means of filters, for example, can be matched to the optical properties (refractive and absorption indices) of the material components of a liquid mixture to be split in such a way that the received radiation intensity only depends on the geometric expansion or shape of the liquid lamellae, threads and droplets depends.

In the case of a homogeneous liquid, the geometric expansion or shape of the liquid lamellae, threads and droplets depends on the thickness of this liquid layer present in the gap between two rollers rolling on each other. The method according to the invention can therefore be calibrated in these cases, which occur in high pressure machines and lacquer and glue application machines, in addition to the metrological control of the liquid splitting so that the liquid layer thickness is displayed directly.

The geometric expansion or shape of the liquid lamellae, threads and droplets depends on the consistency of the liquid given by the interactions of the molecules with the same thickness of the liquid layer in the gap between two rollers rolling on each other and is therefore elasticity for liquids of different viscosity and interfacial tension different. The method according to the invention can therefore also be used for

Measurement of these fluid properties can be used. In the offset printing process in particular, the Device due to the high consistency difference between the printing ink and the dampening solution in the gap exits between the inking rollers and the printing plate Metrological control of the proper inking of the printing plate can be used.

Takes the place of a homogeneous liquid in the gap two rollers rolling on top of each other produce a heterogeneous mixture of liquids of different consistencies the geometric expansion or shape of the liquid lamellae, threads and droplets of the structure or distribution of the rivers fluid components in the nip. It can be used alone Cleavage from the liquid component with the smallest Consistency (viscosity), whereby the lamellae, threads and droplets characteristic of this component appear An example of this is the splitting of the dampening solution at the spa] output between an inking roller and a surface element of the printing plate, which by the dampening solution before the Color acceptance was protected. In the other cases the division of the stratum will be carried out in such a way that it is in statistical terms Mean progresses along the maximum of the concentration of the 'component which has the lowest consistency. Lies this component in one consisting of two liquid components Mixture in uniformly distributed form, the process according to the invention can on the basis of the effects caused by it Shortening of the liquid slats and threads for measurement purposes Detection of the mixing ratio can be used. So who especially in offset printing machines the color - dampening solution - "emulsion lamellae and threads with increasing dampening solution content disintegrate earlier and consequently, on average, a reduction or Experienced shortening, their optical detection according to the invention for the control or regulation of the printing ink / dampening solution quantity ratio can be used.

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To disturbances caused by fluctuations in the ambient light Could be caused to suppress, the optical radiation source can be controlled so that it a Emits a sequence of light pulses (alternating light) and the same controlled optical radiation receiver the scattered parts of the radiated light pulses detected synchronously. The GE-. scattered light can / i also by means of optical filters, prisms, Grating etc. can be analyzed spectrally.

The use of light-emitting diodes or diode lasers results in an extensive miniaturization of the invention Device and thus its use in tightly limited space is possible. The measurement location is thus in the color and printing units of printing machines freely selectable.

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The equipment of the device according to the invention with a Device for freely selectable specification of the irradiation angle and the detection angle and the distance from the source and the receiver from the illuminated cleavage point enables the device according to the invention to be optimally adapted.

The spatial distribution of the liquid lamellae, - Threads and droplets at the gap exit scattered radiation intensity can through the use of a location-sensitive Radiation receiver in the device according to the invention can be detected by measurement.

The fact that the reflectance or absorption spectra of the printing inks and the dampening solution, which in the offset printing process are used, within certain wavelength ranges lying in the infrared spectrum are not essential can distinguish through the use of appropriate infrared radiation sources or infrared radiation receiver in the device according to the invention can be advantageously used.

Scattered by the lamellae, threads and droplets of liquid

-lite radiation then only depends on the geometric Expansion or shape of the same.

The principle on which the invention is based is generally for the non-contact, real-time measurement of Fluid properties, such as viscosity, mixing ratio, the layer thicknesses etc. applicable by bringing a volume of liquid into a force field, this force field splits the volume of liquid into Partial volumes and the resulting and disintegrating liquid lamellae, threads and droplets Scattered light emitted by an optical radiation source and the scattered light component with a radiation receiver is received and electronically evaluated.

Achievable benefits:

The advantages that can be achieved with the invention are in particular that the characteristic features of the production of Liquid layers through the process of liquid splitting and the fluid properties influencing them, e.g. the viscosity, the layer thicknesses, the mixing ratio, etc.

also characterize the light scattered at these features. The real-time measurement according to the invention of this Features, i.e. on the liquid lamellae, threads and -droplets of scattered light therefore provides a direct cleavage process characteristic measure that can be used to control and regulate these processes. Another benefit of the The invention is that by focusing the light, the irradiated and detected part of the gap exit is kept small and thus a locally limited metrological control of the liquid splitting is possible.

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GQPY

With the device according to the invention, disturbances of the
• Liquid splitting processes, for example when coloring

of offset printing plates can occur directly at their location

Originating and thus detected without contact without a time delay. In addition, the invention can be calibrated in such a way that that it is di-.rect, for example when used in high-pressure machines Ink layer thicknesses and when used in offset printing machines directly the printing ink / dampening solution ratio for display

brings.
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Since the device according to the invention can be largely miniaturized, it can be used in all known printing machines and lacquer and glue application machines with a largely free choice of measuring points for control and regulation purposes.
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Exemplary embodiments are explained below with reference to the drawings.
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Fig. 1 shows a section of an offset printing machine with

Inking and dampening system, which is the core of the process represents every offset printing machine,

Fig. 2 shows a measuring arrangement.
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Description:

In Fig. 1 a section of an offset printing machine is shown, which represents the process-related core of each offset printing machine. In detail, Pos. 1 shows here the
Printing forme cylinder with the clamped offset plate, item 2
the dampening system with a rolling on the offset plate

Fountain solution applicator roller and pos. 3 the inking unit with the

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the offset plate rolling inking rollers (4 and 5). The radially hatched part of the offset plate marks the non-printing surface elements and the cross hatched part Part of the printing surface elements of the printing plate. Fig. 1 also shows a detail of the cleavage processes required for proper inking of the offset plate, i.e.

- the splitting of the dampening solution film between the offset plate and the dampening solution form roller,

- The splitting of the printing ink / dampening solution emulsion between an element provided for the ink acceptance Offset plate and the inking roller 4,

- The splitting of the dampening solution between one is not provided for the ink acceptance element of the printing plate and the inking roller 5 and

- Between the splitting of the printing ink / dampening solution emulsions the inking rollers.

The device B according to the invention is in the nip exit between the plate cylinder 1 and the inking roller 4 drawn.

in Fig. 2 an embodiment of the invention is shown, which is described below.

Here pos. 20 shows a gap exit that of two on top of each other Rollers rolling at the peripheral speed ν (18 and 19.) is formed, the outer surfaces of which with a liquid mixture are covered, which is split at this gap exit. In the cutting plane A-A, pos. the optical radiation source with which a certain area of the gap exit-it is illuminated under the beam angle α will. Pos. 27 shows the optical radiation receiver,

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with which is the proportion scattered under the detection angle α

the incident radiation is recorded and electronically processed will.

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Claims (10)

Research Society for Printing Machines e.V. Lyoner Strasse 18, 6000 Frankfurt am Main Device for detecting the liquid transport in the inking and dampening systems of printing machines a. ) \ Device for contactless metrological ^ - ^ version of the liquid transport through roller gaps of inking and dampening units in printing machines, characterized in that that with an optical radiation source at the output of the nip of the roll resulting and disintegrating liquid lamellae, threads and - irradiated droplets with a certain irradiation intensity at a certain irradiation angle and that with an optical radiation receiver under a certain detection angle of the Liquids, threads and droplets of liquid scattered around Part of the intensity is received and electronically processed. 2.) Device according to claim 1, characterized in that that the optical radiation source is a sequence of light pulses emits and the optical radiation receiver detects their scattered components synchronously. 3.) Device n # ch claim 1, characterized in that that the scattered light by means of optical filters, prisms, grids, etc. is spectrally analyzed. 4.) Device according to claim 1, characterized in that that this includes a device with which the angle of incidence and the detection angle and the distance the source and the receiver of the illuminated gap can be adjusted as desired. 5.) Device according to claim 1, characterized in that that the radiation source infrared radiation in a wavelength range emits, in which the refraction and absorption indices of the liquids to be split are do not differ significantly. 6.) Device according to claim 1, characterized in that that the radiation receiver only in infrared radiation proves a wavelength range in which the refractive and absorption indices of the liquids to be split do not differ significantly. 7.) Device according to claim 1, characterized in that da3 as a radiation source one or more light-emitting Diodes or diode lasers are used. 8.) Device according to claim 1, characterized in that that for the simultaneous detection of the under different Angle scattered parts of the irradiated intensity a location-sensitive radiation receiver is used will. 9.) Device according to claim 1, characterized in that that the light shines on the liquid slats, threads and -Droplets are scattered in the gap exit between an inking roller and the printing plate. 10.) Method for non-contact, real-time metrological acquisition of fluid properties, characterized, a) that a volume of liquid is brought into a force field will, b) that this force field splits this volume of liquid causes in partial volumes, c) that to the resulting in this Faltprözess and disintegrated liquid slats, threads and droplets emitted by an optical radiation source Light is scattered, d) that the scattered light with an optical radiation receiver Will be received, e) that the received light is evaluated by measurement technology