FR2653866A1 - METHOD FOR MANAGING THE OPERATING CONDITIONS OF AN ULTRA VIOLET DRYER - Google Patents

Abstract

Process for the management of the operating conditions of an ultra-violet dryer, characterized in that it consists in providing a permanent control by PLC of all the components inducing an immediate reactive response and a corresponding reactive command, namely: - electrical controls from each transmitter to the transmission concerning voltage, current and energy flow, - information checks to each ventilation group concerning safety thermals, circuit breakers, monostats or pressure switches, safety thermostats, - checks safety devices for closing the dryer and the electrical cabinet, - checks on the conveyor regarding its various operating phases, namely start-up, acceleration, stabilized speed, deceleration, stop; - controls for external variations such as: coating stop, paper cut, emergency stop, power cut.

Description

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  The present invention relates to a method for the management

  operating conditions of an ultraviolet dryer.

  Until now, the management of the operating conditions of an ultraviolet dryer is done essentially manually. It is actually a passive control because the dryer in operation is provided with devices providing information that is interpreted by the user to manually perform the functions.

necessary corrections.

  So there is no visual translation of the operation or

  possibility of automated intervention on the dryer.

  The object of the invention is to remedy these drawbacks of

devices of the prior art.

  According to the invention, this result is obtained with a method for the management of the operating conditions of an ultraviolet dryer, characterized in that it consists in providing a permanent control of all the organs inducing an immediate reactive response and a corresponding reactive control, namely: - electrical controls of each emitter at the emission concerning the voltage, the intensity and the energy flow (possibly); - information checks at each ventilation group concerning safety thermals, circuit breakers, monostats or pressure switches, safety thermostats, - safety checks at the closures of the dryer and electrical cabinet; controls at the level of the conveyor with regard to its different operating phases, namely start-up, acceleration, stabilized speed, deceleration, stopping; - controls for external variations such as: coating stoppage,

  paper cut, emergency stop, power cut.

  The general method which is the subject of the invention will be explained below. In advance, to ensure good polymerization, the dryer will be linked to the acceleration of the conveyor, as the conveyor will also be linked to the progress of powering the dryer. There will be an obligation of interdependence of the two systems controlled and managed by a PLC. In the following we mean by "PLC" any management device such as: - a PLC - a microcomputer or computerized system - a servo regulator For this purpose, the user provides the U.V. installation with a

  analog signal related to the speed of the machine.

  For the powering up of the transmitters, one, at each speed step, one, two, three, x transmitters or

group of transmitters.

  During its start-up phase, each lamp is powered at full power. Once a lamp has reached its operating speed, it falls back into reduced power and waits for others

  have passed the same transitional regime.

  At the end of the transient regime of all transmitters, the conveyor is completely unbridled. As the speed related to the polymerization phase progresses, each emitter one after the other passes to

  full power according to the progressive values of this speed.

  If, for any reason, the xth emitter has not yet reached its operating speed, the conveyor remains clamped by the automaton at the speed corresponding to the needs of heat dissipation and it is only once the regime transient finished and characterized by the latter transmitter, that the conveyor can again resume its acceleration with the subsequent ignition at full power

the latest issuers.

  For the deceleration of the conveyor, the operation is as follows. The speed is reduced, and at each value thereof, the transmitters successively pass from full power to reduced power. We can therefore be in an intermediate speed regime involving part of the transmitters at full power while the rest is at reduced power. The consumption of the UV dryer is

  therefore proportional to the speed engaged.

  The increase in power in connection with the acceleration of the conveyor and in the same way the reduction of power in connection with the deceleration of the conveyor, can be carried out stepwise or

continuous way.

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  However, when all the transmitters are at reduced power, the system is at the critical threshold of use. The controller will then take into account a threshold tolerance which will be a compromise between the desired crosslinking compared to a gradual increase in the temperature of the paper. Beyond the user-defined acceptable paper temperature limit, all transmitters will be switched off: - either in a UV cascade shutdown process depending on the deceleration, - or a total and immediate shutdown of all transmitters or by

group of transmitters.

  The reduced power state of all transmitters indicates the upper limit of the speed while the maximum temperature is bearable

  paper gives the low limit of speed.

  This speed differential is the transient

  crosslinking at deceleration.

  Beyond this critical threshold, set by the user, all the emitters go off together or separately and simultaneously the coating

paper is deleted.

  To restart the system, it will take a few minutes, period during which the emitters will return to their required room temperature before any reboot. This period is related to the temperature drop of the transmitter and controlled by the controller which, from a low temperature limit of the transmitter the

  slower, automatically initiates the restart of the installation.

  Each cassette has its own ventilation system, the

  air flow being related to each particular phase of UV operation.

  Air ventilation is necessary for the evacuation of ozone and the cooling of the cassette components: reflectors, shields, radiated perimeter, electromechanical locking tabs.

  the transmitter, carriers, and frame itself, machine environment.

  The value of the air flow is determined according to each

  operating mode of the lamp.

  During the power supply period of the lamp (preheating regime), voltage and electrical intensities are related to the internal pressure of the lamp which is itself related to the temperature

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of the bulb.

  To allow the voltage and the intensity to reach their nominal operating value quickly, the ventilation will be reduced to the most thermal flow possible corresponding to the absorption capacity of the most fragile component during a time

minimum preheating.

  An electrical measurement of the voltage or of the intensity, a measurement of energy flow, or a timer precalibration of an arbitrary value of a preheating time make it possible to switch from

  preheat to the next mode, ie the rated speed.

  This is the state in which the transmitters are at their nominal power ratings (the voltages and currents are at the values prescribed by the transmitter manufacturer) and in which the ventilation gives an air flow sufficient to maintain the temperature of the transmitters. components of the cassette to values

  less than their deterioration value.

  There is also a half power regime which reduces the parasitic thermal energy released by the UV emitters by about half of the initial value. So considering that the equation of thermal exchanges is made up of the factors that compose it to the power one, in fact the value of the flow of air through the

  "transmitter-reflector" torque decreases by half.

  As for the regime of stopping ventilation, it is the following.

  Whether the shutdown of the installation is consecutive to the rated speed or the half-power regime, the frequency converter is shunted or goes to its maximum value, thus making it possible to obtain an air flow rate much higher than the nominal flow rate. which causes: - the almost immediate temperature drop of the components of the cassette and the transmitters - the reduction of the time necessary for the process of restarting the installation The installation of an air cushion at the right of the radiating face allows to repel energetically any light product (example: sheet, band, canvas, etc ...) which, for various reasons, would tend to

  to get closer, even to touch the hot elements of the radiating part.

  After a certain time given by automaton or timer or other means,

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  and that defines the experience of cooling all the components not only of the cassette but also of the installation, the ventilation

  stop. A new complete cycle can then be undertaken.

  For filters, air is drawn from a clean environment (one per cassette). However, to compensate for the increase in the pressure drop of the fan due to the gradual fouling of the filter, a pressure switch continuously measures the vacuum in the air column between the filter and the fan. The variation of the signal is sent back to the regulation system of the electrical cabinet (as for example regulator, or PLC or microcomputer) which acts on the variable speed drives of the fans

blowing and extraction.

  When the signal from the pressure switch reaches 10 volts, 20 mA or any other analogue signal, for example: - an alarm signals the fact - the display or the screen indicates "dirty filter At this moment, the user has one, two or three days to clean its filter.At the end of this period, the ultraviolet installation stops itself.This period of one, two or three days will be set in fixed value on site at startup in depending on the clogging speed of the filter, which is directly related to the cleanliness of the air in the workshop After this time, the controller stops the installation Each transmitter is linked to a time counter or time management in the PLC of its own, as soon as one of the meters reaches the limit of the lifetime of the transmitter, then, at this moment the process of signaling and automatic shutdown of the installation

  proceeds from the same principle as that defined for the filters above.

  The PLC counts the time of use of each transmitter, and integrates in time value each restart of the transmitter. At the limit of its service life, the signaling process commits itself, and the installation then operates for a determined duration, after

  from which it stops automatically and compulsorily.

  Each transmitter is separately controlled for voltage and temperature. The signals are sent back to the PLC which manages the piloting process of all the transmitters as well as the speed variation of the

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  conveyor according to the behavior of the transmitter (s). This permanent management of the electrical characteristics of each transmitter within the tolerances indicated by the manufacturer, combined with the monitoring of the service life, guarantees the good crosslinking of the varnish. If one of the transmitters did not find its operating regime after five minutes, the process of reporting and automatic shutdown of the installation proceed in the same way as the one defined for

filters above.

  Regardless of the power management of the transmitters, the process provides a variety of parameters management: - Aeraulic management to fans - Variable parameters such as transmitter life and filter fouling - Closed loop management - Conveyor speed associated with Emitter commitment rate The controller takes into account the various parameters that are the following: -control of the supply voltage, network inducing a measurement correction voltage intensity to the transmitters - control of the opening closing of the dryer - control closing cabinet medium voltage - flow control at each transmitter temperature control by transmitter - control of the limit temperature of the dryer components - control of the information of the dryer environment (start / stop coating, strip breaking, etc.) .) - control of rejected length -7 -

Claims (8)

  1. A method for managing the operating conditions of an ultraviolet dryer, characterized in that it consists in providing a permanent control by PLC of all organs inducing an immediate reactive response and a corresponding reactive control, namely: electrical checks of each transmitter on transmission concerning voltage, current and energy flow, - information checks at each ventilation group concerning safety thermals, circuit breakers, monostats or pressure switches, safety thermostats, safety checks at the closures of the dryer and the electrical cabinet, - controls at the conveyor level with regard to its various operating phases, namely startup, acceleration, stabilized speed, deceleration, stopping; - controls for external variations such as: coating stoppage,   paper cut, emergency stop, power cut.   2. Method according to claim 1, characterized in that for the power of the transmitters, is engaged successively at each speed step, one, two, three, x transmitters or group of transmitters, that during its startup phase, each lamp is powered at full power, once a lamp has reached its operating mode, the latter falling back into reduced power and waiting for the others to have exceeded the same transient regime, as at the end of the transient regime of all the emitters the conveyor is completely unbridled, as the speed linked to the polymerization phase progresses, each emitter one after the other switches to full power according to the progressive values of this speed.   3. Method according to claim 2, characterized in that if for any reason the x th emitter has not yet reached its operating speed, the conveyor remains clamped by the automaton at the speed corresponding to the dissipation requirements. thermal and that once the transient regime is completed and characterized by the latter emitter, - 8 - 2653866   the conveyor can resume its acceleration again with ignition successively at full power.   4. Method according to any one of claims 1 to 3,   characterized in that for the deceleration of the conveyor the speed is reduced, that at each value thereof, the transmitters pass   successively the full power in reduced power.   5. Method according to any one of claims i to 4,   characterized in that the ramp up in connection with the acceleration of the conveyor and in the same way the power reduction in connection with the deceleration of the conveyor, are realized by bearing or continuously.   6. Process according to any one of claims 1 to 5,   characterized in that each cassette has its ventilation system, the rate of the air flow being connected to each particular phase of the UV operation, the value of the air flow is determined according to each operating regime of the lamp, that during the power-up period of the lamp (preheating regime), voltage and electrical currents are related to the internal pressure of the lamp.   lamp which is itself related to the temperature of the bulb.   7. Method according to any one of claims 1 to 6,   characterized in that for shutting down the ventilation, whether the shutdown of the installation is consecutive to the nominal speed or to the half-power mode, the frequency converter is shunted or goes to its maximum value, thus making it possible to obtain a debit much higher than the nominal flow, which causes: - the almost immediate temperature drop of the cassette components and transmitters, - the reduction of the time required for the installation restart process.   8. Process according to any one of claims 1 to 7,   characterized in that each transmitter is linked to a specific time management means in the PLC, each transmitter being controlled separately in voltage and temperature.