This application is the U.S. national phase, under 35 U.S.C. 371, of PCT/EP2008/063474, filed Oct. 8, 2008; published as WO 2009/100783 A2 and A3 on Aug. 20, 2009, and claiming priority to DE 10 2008 000 271.2, filed Feb. 11, 2008, and to DE 10 2008 001 309.9, filed Apr. 22, 2008; the disclosures of which are
The present invention is directed to a method and to a device for controlling a printing press. At least one rotating component of at least one printing couple is controlled with respect to a target value for a temperature, which represents the component temperature, by the use of a temperature control device.
A device and a method for controlling the temperature of a component in a printing press are known from DE 44 29 520 A1. The component is temperature controlled by the use of an at least partially circulating fluid. A control element, with which a mixing ratio can be adjusted at an intake point for two fluid streams having different temperatures, is controlled through a temperature measuring site that is located between the intake point for the fluid streams and the component itself.
EP 08 86 577 B1 discloses a device and a method for controlling the temperature of a component. A component temperature is monitored via sensors, and the measured value is provided to a control unit. If the temperature measured at the component deviates from a target value, the control unit will decrease or will increase the temperature of a cooling medium in a cooling unit by a certain amount and wait for a defined period of time. It will then repeat the measurement and the listed steps until the target value is reached again.
EP 03 83 295 A2 discloses a temperature controlling device for printing presses. A temperature of the fluid in an intake line and a surface temperature of the component to be temperature controlled are detected and these temperatures are supplied to a control device. Based upon these temperatures, and, if applicable, also based upon prescribed influencing parameters, such as the paper that is used, the ratio of wetting agent, and target temperatures, for example, a control variable, which is usable for controlling a mixing motor, is determined. This control variable adjusts the ratio between circulating fluid and freshly supplied temperature controlled fluid.
JP 60-161152 A discloses a cooling device of a roller to be temperature controlled. A surface temperature of the roller and a fluid temperature in the inflow path are measured. These values are supplied to a control device for comparison with a target value and for use in controlling a valve.
In WO 2004/054805 A1, a measured temperature, which at least approximately represents the temperature of the component, and especially in the case of a roller, a temperature that represents the surface temperature of the roller, is adjusted to, and/or is maintained at a certain target value through temperature control via a temperature control device. This is carried out using a cascade-type controller structure. Elements of the control or path model are provided in the closed loops.
From WO 03/045695 A1, it is known that for different production speeds, different target temperature values or different maximum values can be prescribed.
DE 10 2005 005 303 A1 relates to a system for controlling the temperature of components of a printing press. It is proposed, among other things, that an intended change in the press speed can be delayed in its execution, such as, for example, by appropriate programming in an evaluation unit, until a certain temperature is reached on the roller.
In DE 10 2004 006 231 B3 a method of transporting dampening agent from a first roller to a forme cylinder is known.
Roller surface temperatures can be controlled only very slowly, in comparison with the ability to control the rotational speed of a press. Therefore, despite various precontrol and derivative action measures, with faster changes taking place in rotational speed, temperatures can lag behind to a greater or lesser extent. In terms of interface technology, temperature control has heretofore been based upon the current rotational press speed, and will therefore attempt to adapt the temperature to it. Ink densities during transient operating phases, such as, for example, during run-up and cool-down phases, therefore may not remain constant enough, or rotational speed may be changed only extremely slowly.
The object of the present invention is to devise a method and a device for controlling a printing press.
The object of the present invention is attained according to the present invention through the provision of a temperature control device for controlling the temperature of at least one rotating component of at least one printing couple. A temperature which represents the component temperature can be controlled, with respect to a target value. At least one drive of an assembly of the printing press can be regulated and/or controlled with respect to a rotational speed that is to be maintained on the basis of a target value for the rotational speed, as prescribed by a control level. A processing or control device is provided. A first rule, for dependence of a temperature on a rotational speed, and a second rule, for dependence of a rotational speed on a temperature, are provided. A target value for rotational speed provided by the control level can first be converted, using the first rule, to a target value for a temperature. Then, using the second rule, this target value can be converted to a modified target value for rotational speed, after passing through a path and/or a control model of the temperature control device.
The benefits to be achieved with the present invention consist particularly in that, even for operating phases that are transient in terms of press speed, a constant ink density can be achieved on the printed product. The present method ensures that the correlation between rotational speed and surface temperature for constant ink density, or for ink viscosity control over an ink curve, is such that, ideally, the surface temperature is adapted to the rotational speed of the press at all times.
In the method in accordance with the present invention, the dynamic response of the rotational speed profile and the dynamic response of the temperature profile are better adjusted to one another. This allows the static ink curve correlation to be adequately realized, even in dynamic cases.
In the solution presented in accordance with the present invention, the change in press rotational speed that is applied is adjusted to the temperature change that can actually be achieved in the process. Specifically, it is based, for example, upon the temperature profile of all relevant temperature control loops that are involved in the process which can be achieved most slowly with respect to rate of change or dynamic response.
Because of essentially high signal quality requirements, with respect to the acceleration curve profiles of controlled electric drives, rather than basing this on a measured temperature profile, it is particularly advantageous to calculate a model profile for a feasible temperature/response profile for the process, with that calculated model profile being smooth in terms of signals, in a control device, such as, for example, in a processor of the temperature control device, and based upon known path model parameters. From this model profile, the required suitable profile of target value for rotational speed, which is smooth in terms of signals, can then be determined. This latter calculation is preferably carried out by determining the inverse relation to the dependence of temperature on rotational speed, which is also called the “ink curve”, of the temperature control loop that is chosen for controlling the rotational speed of the press.
According to the method of the present invention, the profile for rotational speed is no longer provided directly by the control level to the drives or to their drive controls. Instead, first the technologically desired modified profile for the rotational speed target value is determined from this profile. This can be generated, for example, in a separate controller or processing unit or in the controller or processing unit of the temperature control device, and can then be either returned to the control level and from there can be provided to the drives or drive controller, or can be provided directly to the drive controller. It is this modified profile for the rotational speed target value that is then used, at least during transient operating phases, to prescribe the target value for rotational speed of the printing press.
Thus, in the control process of the present invention, for each relevant temperature control loop, a first transformation or ink curve, in which rotational speed is converted to temperature, takes place. Then, this temperature profile is dynamically looped with a model of the closed temperature control path, running times, response times, resulting in the associated physically feasible delayed temperature profile, after which an inverse transformation takes place. An inverse relation of the ink curve, in which temperature is converted back to rotational speed.
In a particularly advantageous embodiment of the present invention, this temperature profile is dynamically looped using the model of the closed temperature control path, running times, response times, which is present, in any case, in terms of parameters.
In another advantageous embodiment of the invention, all of the individual control units, for use in controlling the temperature of the same type of rollers in a printing unit or in a printing tower, are also established as processes in a processing unit, such as, for example, as a computer, in the temperature control assembly. The aforementioned control involving transformation and inverse transformation can also advantageously be incorporated as a process in this processing unit.
The concept of the present invention can be used with particular advantage in conjunction with a multi-loop feedback control. Such a control operates very rapidly and stably, even with longer transport paths for the temperature control medium. The short reaction time enables its use in applications and in processes that have high dynamic ratios and thus also have a steeper slope for the adjusted rotational speed during transient operating phases. Thus, the present temperature control is also highly advantageous in cases in which rapid changes to a target temperature value must be duplicated, and/or in cases in which external conditions, such as, for example, energy input, as a result of friction or external temperature, change very rapidly.
When, at the end of a transient phase, the final rotational speed is reached, the predetermined target value for rotational speed can advantageously be transferred, unaltered, to the drives or drive control, such as, for example, to the section computer.
If more than one temperature control unit or printing unit is present, the minimum can be determined from the existing target/prescribed values and can be used for purposes of modification.
A corrected target value for rotational speed is advantageously determined separately for rollers of eight printing couples, for example. The minimum resulting from these eight values is then processed to obtain the modified target value. This value is transmitted to the control level or to the drive control as a new control target value for rotational speed.
The “temperature curve” n(θ) preferably has a continuous slope, and the maximum temperature for determining the associated rotational speed is limited to a value lower than the maximum.
In a further development, the function at the zero point can have a discontinuity. In this case, the temperature value is raised at the rotational speed 0, so that in a warm environment no condensation is produced.
Preferred embodiments of the present invention are represented in the set of drawings and will be specified in greater detail in what follows.
The drawings show:
A printing press has at least one component, such as a roller 01, and in particular, has an ink guiding roller 01 of a printing couple, which is not specifically shown. This roller 01 can be configured as a roller 01 of an inking unit, for example, and particularly can be embodied as an anilox roller 01, or it can be configured as a cylinder 01 of the printing couple, for example, and particularly as a forme cylinder 01. The printing press further has a control level 31 with a control station, for example, and also with a press controller, through which a press speed “n”, identified here, for example, as the press rotational speed “n”, or the rotational speed “n” for short, is or can be prescribed in one or more drives 32, for example drive motors 32, such as, for example, with controller and motor 34) of the printing press as the target value for rotational speed ntarget. The predetermined value for the press rotational speed “n” is usually provided, as indicated by a dashed line, by the control level 31, such as, for example, by a processor or by a section computer of the control level 31, for example either directly to drive controllers of one or more drives 32, or advantageously to a higher-level drive control 33, which generates an electronic control axis, and particularly generates a virtual control axis. Stated more simply, the drive control 33 generates a continuous rotation of a virtual angular position, in correlation to the prescribed target value for rotational speed ntarget. The higher-level drive control 33 can be a drive control 33 that is assigned to an assembly or to a drive motor 32, which acts or functions a master. It can also represent a supplementary drive control 33, which is not directly assigned to any of the drive motors 32.
The device and the method of operating the printing press, in accordance with the present invention, as will be described below, can be used particularly advantageously together with a printing couple for waterless offset printing, such as, for example, with a printing couple which does not use a dampening agent. In the printing couple, and particularly in such a printing couple for waterless offset printing, the quality of the ink transfer is extremely highly dependent upon the temperature of the ink and/or the temperature of the ink guiding surfaces, such as, for example, the outer surface of rollers 01 or cylinders 01. Furthermore, the quality of ink transfer is also sensitive in relation to a nip speed, or in other words, is sensitive to the press rotational speed “n”.
As has been described in WO 2004/054805 A1, which was mentioned previously, and among other publications, through the use of temperature control with a temperature control device, a measured temperature θb which at least approximately represents the temperature of the component 01, and in the case of a roller 01, a measured temperature and particularly a temperature θb which represents the surface temperature of the roller 01, at least approximately, is to be adjusted and/or is to be maintained at a certain target value θb,target. This is accomplished by measuring the most representative temperature θb possible, on one hand, and by controlling the intake or the removal of energy in the form of heat, on the other. It is already known from WO 03/045695 A1, for example, that for different production speeds, different temperature target values or different maximum values may be prescribed.
The concept represented schematically in
In reference to
The temperature of the component 01 is controlled by the operation of a temperature control device 20, the control element of which is adjusted by a control unit 21. The temperature control device 20 with the corresponding control element and the assigned control unit 21 can also be combined under the term temperature control device 20, 21.
At a measuring point Mi of the component 01, or along a control path 02, such as, for example, along a temperature control path 02, as will be described below, of the temperature control device which controls the temperature of the component 01, a measured value for the temperature θb, which represents the component temperature as accurately as possible, is to be controlled. Depending upon control engineering or technical complexity, the temperature θb, which represents the component temperature, and which is to be controlled, can be measured on the component itself 01, can be measured near the component, or can be measured farther away from the component along the control path 02.
As is shown in greater detail in
Based upon the target value θ″b,target, which is corrected with regard to the control path 02, a corrected target value for rotational speed n′target is then generated using a second rule F2(θ). This second rule, in which n′target=F2(θ), preferably represents the inverse function, or the values reflected by the angle bisectors of the first quadrant, of the first rule F−11(n). If the memory and/or processing unit 37 is assigned only one temperature control unit 20, 21, this corrected target value for rotational speed n′target, optionally after being fed again through a velocity limiter 39, could then be provided to the drive control 33 or the drives 32 as a modified target value for rotational speed n*target, optionally fed through the control level 31. In a variation, in which the memory and/or the processing unit 37 is assigned multiple temperature control devices 20, 21, and particularly is assigned at least a number of temperature control devices that corresponds to the number of printing couples assigned to one and the same web of print substrate such as, for example, eight printing courses, it is advantageous to first determine the minimum of the corrected target values for rotational speed n′target from all off the temperature control devices that are assigned to this memory and/or processing unit 37, shown as step 38 in
In one advantageous embodiment, devices 42 are provided for use in “combining” the, if applicable minimized, corrected target values for rotational speed n′target with the target value for rotational speed ntarget, as originally provided from the control level 31. This allows the responsivity of the memory and/or of the processing unit 37 to be adjusted. Using an adjustable factor “a”, such as 0≦“a”≦1, the part of the originally provided target value for rotational speed ntarget and the part of the, if applicable minimized, corrected target values for rotational speed n′target, which are to be taken into consideration in generating the modified target value for rotational speed n*target can be adjusted. It has proven advantageous for the ratio of the corrected target value for rotational speed n′target to be at least 50%, wherein “a”<0.5, and particularly to be between 60% and 80%, for example, for the value “a” to lie between 0.2 and 0.4.
The procedure for first adjusting the target value for a rotational speed ntarget coming from the control level 31 in a memory and/or processing unit 37 or in corresponding processes in the memory and/or in the processing unit 37 to the set of dynamics, such as, for example, to the response time of the temperature control unit and then correspondingly modifying that target value, can be applied particularly advantageously in operating phases I that are transient in terms of press speed, such as, for example, during the aforementioned run-up phase and/or during a velocity change or during shut down. Although this procedure can also be applied during steady operating phases II, such as, for example, at a constant press speed “n”, for example, at a production speed nP during the steady production phase, the target value for rotational speed ntarget originating from the control level 31 will then advantageously be either “looped” unmodified through the memory and/or processing unit 37, for example, or will be provided directly by the control level 31, without modification, to the drives 32 and/or the drive control 33.
In
In an advantageous embodiment of the present invention, the procedure, which has been described in relation to the press rotational speed “n”, is to be applied to a parallel processing of acceleration values. This is carried out according to the same concept described for the press rotational speed “n”.
In the event of a failure in the control unit 21 and/or the memory and/or processing unit 37 it can be provided that the original target value for rotational speed ntarget will be provided to the drives 32 or to the drive control 33.
In the event of a failure, the target value n*target, which was last transmitted from the memory and/or from the processing unit 37, can also advantageously be accepted as a new initial target value, in order to avoid any target value step changes that might possibly occur.
In principle, the previously described temperature control device 20 can be embodied differently and in such a way that energy, in the form of heat, can be introduced into the component 01 and/or can be removed from the component 01 in a targeted manner. In addition to the advantageous embodiment, which will be described in greater detail below, and involving the introduction of a temperature-controlled fluid, through a corresponding temperature control path 02, other possibilities are also conceivable. For example, these possibilities include the introduction of electrical energy into the component 01 and its conversion there into heat, or, for example, include temperature control, through a fan, the air from which fan is temperature controlled either directly through contact with electrically heated coils or indirectly via a heat exchanger.
What has been described thus far can be applied advantageously on its own. In the discussion which follows, the above-described method will be presented in an application with an advantageous special embodiment of the temperature control device 20 and an advantageous multi-loop control unit 21, all as seen in
In the present example, a temperature control is implemented through the use of a temperature control medium, particularly a fluid, such as water, for example, which is placed in thermal interaction with the component 01 via a temperature control path 02. If the fluid is to flow over the component 01, the fluid can also be a gas or a gas mixture, such as air, for example. For use in temperature control, the fluid is supplied to the component 01 in a first circuit 03, flows through or flows around the component 01, absorbs heat, for cooling the component, or gives off heat, for heating the component, and then flows back, itself correspondingly heated or cooled. In this first circuit 03, a heating or cooling unit can be arranged, which can serve to generate the desired fluid temperature.
In the advantageous embodiment of
The fluid, or a majority of the fluid, is circulated in the secondary circuit 03 along an inflow path 12, through the component 01, along a return flow path 13, and along a path segment 14 between the inflow path 12 and the return flow path 13 by the operation of a drive 11, such as, for example, by the operation of a pump 11, a turbine 11, or in some other way. Based upon the intake, controlled by the valve 07, a corresponding quantity of fluid, after passing through the component 01, flows out through the connection 15 into the primary circuit 04, or a correspondingly reduced quantity of fluid flows through the path segment 14. The portion that flows back through the path segment 14 and the part that has been freshly fed in through the valve 07 to the intake or to the injection point 16, mix together and then form the specifically temperature-controlled fluid for use in temperature control. To improve mixing, in an advantageous embodiment, a mixing path 17, and particularly a mixing chamber 17, is arranged as close as possible downstream of the injection point 16, and particularly is positioned between the injection point 16 and the pump 11.
In the above-described arrangement, but now in which temperature control is carried out, not by the use of a primary circuit 04, but instead by the use of a heating or cooling unit, the intake or injection point 16 corresponds to the point of energy exchange with the relevant heating or cooling unit. The control element 07 now corresponds, for example, to a power control or to the like, which is assigned to the heating or cooling unit. The connection point 10 in the secondary circuit 03 is dispensed with, because all the fluid is now circulated in the circuit 03, and energy is fed in or is removed and/or heat or cold is “fed in” at the intake point 16. In this arrangement, the heating or cooling unit corresponds to the control element 07, for example.
Through the temperature control process, ultimately a determined temperature θb, in this case where b=3, or in other words the temperature θ3 of the component 01, in the case of a roller 01, and particularly the surface temperature θ3 of the roller 01, is to be adjusted to, or is to be maintained at a certain target value θ3,target. This is accomplished by measuring a representative temperature, on one hand, and by controlling the intake of fluid from the primary circuit 04 to the secondary circuit 03 for generating a corresponding combined temperature, on the other hand.
It is thus advantageous for at least two measurement points M1; M2; M3, each with a sensor, S1; S2; S3, respectively, to be provided in the present temperature control device 20 between the injection point 16 and an outlet of the component 01 that is to be temperature controlled. One of the measurement points M1 is located near the injection point 16. At least one of the measurement points M2; M3 is located in the area of the end of the inflow path 12 that is close to the component, and/or in the area of the component 01 itself. The valve 07, the pump 11, the injection point 16 and the connection points 06; 08 are ordinarily spatially close to one another and are arranged, for example, in a temperature control cabinet 18, which is indicated in
In the preferred embodiment of
Temperature control is carried out with the help of a temperature control unit 21 or a control process 21, which will be described in greater detail in what follows. Here, the temperature control unit 21, as seen in
The second control loop has a sensor S2 which is closer to the component, and preferably is shortly upstream of the intake into the component 01, or in a double-loop embodiment, which is not specifically shown, is assigned to the component 01, and a second controller R2. The controller R2 receives, as its input variable, a deviation Δθ2 of the measured value θ2 at the sensor S2 from a corrected target value θ2,target,k (node K2), and generates, at its output, in accordance with its implemented control response and/or control algorithm, a variable dθ1 which correlates with the deviation Δθ2, output variable dθ1, and which is also used to generate the aforementioned corrected target value θ1,target,k for the first controller R1. In other words, based upon the deviation of the measured value θ2 from the corrected target value θ2,target,k, the corrected target value θ1,target,k to be generated for the first controller R1 is influenced by the variable dθ1, dθi, in this case with i=1.
In the embodiment of the controller, which is preferred in connection with the previously described concept for adjusting the press rotational speed “n” to the dynamic response of temperature control, at least one target value θb,target, in this case b=1, 2 or 3, for example, is used in the control process and is modified using at least one element of a path and/or of a control model SRMi, in this case i=1, 2 or 3, of the temperature control device 20, 21, thereby taking into account influences on, and responses of the control path 02, at least to some extent. As stated above, the path and/or the control model SRMi can have one or more of the elements precontrol element for running time, if applicable, with a time constant VLZ and/or a derivative action element VVH and/or a precontrol relating to a control element characteristic by the provision of a velocity limiter VAB and/or a precontrol element relating to heat flow rate VWF.
In the embodiment of the controller shown, the corrected target value θ1,target,k (b=1) of the inner control loop for the first controller R1 is generated at a node K1′, such as, for example, by addition or subtraction, from the variable dθ1 and a theoretical target value θ″1,target, θ″i,target, in this case with i=1, taking into account elements of a path and/or of a control model SRMi.
In principle, a simpler embodiment of the control unit 21 is possible, in which simpler embodiment, only the first two stated control loops form the cascade-type control, or even in the simplest embodiment, only one of the two inner control loops or the outer control loop with its precontrol elements, forms the control unit 21. In this simpler embodiment, in the first case, the corrected target value θ″b,target would be generated, for example, from the SRM of one of the two control loops, and preferably from the outermost control loop, and in the second case, it would be generated from the path model of the sole control loop. In principle, it is the case that, with single-loop control devices 21, one or more elements of the path and/or control model SRMi of this control loop, and with multi-loop control devices 21, one or more elements of the path and/or control model SRMi of one of the loops, but preferably of the outer loop, are used to generate the corrected target value θ″i,target for further processing for adjustment to the dynamic response, or response time of temperature control. In the multi-loop case presented here, a switching device 43 can also be provided, by the use of which switching device 43, and based upon requirements, it can switch from the corrected target value θ″i,target for one of the loops to the corrected target value θ″i,target for a different loop. This can be advantageous, for example, when redundancy, with respect to the sensor system, is to be ensured, or in other words, for example, if the sensor at the measurement point M3 fails or becomes contaminated. In this case, the switching device 43 is preferably embodied as being electronically switchable, so that, using a switching circuit, if the functioning of the relevant sensor Si, with i=1, 2, 3, fails or is faulty, this is detected, and the switching device 43 will be switched. In
In the embodiment which is shown in
The corrected target value θ2,target,k for the second controller R2 is generated at a node K2′, such as, for example, by addition, or subtraction, from the variable dθ2 and from a theoretical target value θ′2,target (or θ″2,target, as discussed below. The theoretical target value θ′2,target is again generated in a precontrol element relating to the heat flow rate V2,WF. Here, the precontrol element V2,WF takes into account, for example, the heat and/or the cold losses on the path segments between the measurement points M2 and M3, by generating a correspondingly increased or decreased theoretical target value θ′2,target which is then processed together with the variable dθ2, to obtain the corrected target value θ2,target,k for the second controller R2.
The above described method of control is therefore based firstly upon the measurement of the temperature directly downstream of the injection point 16 and upon at least one additional measurement taken close to the component 01 that is to be temperature controlled. Secondly, a particularly short reaction time of the control system is achieved. Multiple control loops are interconnected in a cascading fashion. A measured value θ2; θ3, which is located closer to the component 01, is taken into account in the generation of the target value for the inner control loop. Thirdly, a particularly short reaction time is achieved through a precontrol, which introduces empirical values for projected losses along the temperature control path 02. Thus, a target value that is correspondingly increased or decreased by an empirical value is provided to a control loop which is located closer to the control element 07 and based upon projected losses.
In the depiction of
In one embodiment, and in one or in more of the control loops, a path and/or a control model SRMi, which is a precontrol element relating to heat flow rate VWF can be provided. The precontrol element VWF, in this case Vi,WF, with the index i for the target value generation for the ith control loop, takes into account the heat exchange, such as losses and the like, of the fluid over a path segment and is based upon empirical values, such as expert knowledge, calibration measurements and the like. Thus, the precontrol element V1,WF, with the index 1 for the target value generation of the first control loop, takes into account, for example, the heat or cold losses on the path segment between the measurement points M1 and M2 by generating a correspondingly increased or decreased theoretical target value θ′1,target, which is then processed, together with the variable dθ1, to generate the corrected target value θ1,target,k, for the first controller R1. In the precontrol element VWF, a correlation between the input variable, such as the target value θ3,target or θ′2,target or θ′2,target,n, as will be discussed below, and a corrected output variable, such as the modified target value θ′2,target or θ′2,target,n, or θ′1,target,n, also as will be discussed below, is established, and can preferably be modified, as needed, based upon parameters or in some other way. In the outer control loop, or in the control loop having the measured value that lies closest to the component 01, a precontrol element relating to heat flow rate VWF can also be provided. In the present example, however, downstream of the measurement point M3 no further appreciable heat or cold loss occurs. Thus, the path and/or the control model SRMi, which is used to generate the corrected target value θ″b,target to be processed in the memory and/or in the processing unit 37 can, but need not necessarily, have a corresponding precontrol element Vi,WF.
In addition to, or in place of the precontrol element or elements relating to heat flow rate V1,WF; V2,WF, the control unit 21 can have additional or different elements for precontrol.
As is apparent from
Based upon the delay, which corresponds to running time TL2 or T′L3, and the time constants Te2 or T′e3, the path reactions to the activities of the innermost controller R1 are, at first, not apparent at the level of the two outer controllers R2; R3. To prevent or at least to impede an otherwise resulting double reaction of these controllers, which would be an erroneous overreaction that could not be withdrawn, a precontrol element relating to running time and/or time constants VLZ is preferably provided as a path model element for the generation of the target value in one or more of the control loops. By the use of this precontrol element, the projected natural “delay”, resulting from a change in the control element 07, is taken into consideration. Because of the precontrol element relating to running time and/or time constants VLZ, the running time actually required by the fluid, which is determined based upon empirical values or preferably by recording measured values or through computer estimation, is simulated in the control system. The outer controllers R2; R3 then react only to those deviations that are not to be expected, based upon the modeled path properties, and thus are only those deviations that actually require correction. As a result of this symmetry, the outer controllers R2; R3 are made “blind” to the control deviations that are otherwise to be expected, which control deviations are physically unavoidable, and which are already being handled “locally” by the innermost controller R1. The “precontrol element” VLZ thus acts in the manner of a “running time and delay element” VLZ. In the precontrol element VLZ, the described dynamic property of running time and delay is represented and established, but can preferably be modified as needed based upon parameters or in some other way. For this purpose, corresponding parameters T*L2; T*e2; T*L3; T*e3, which are to depict and which represent the current running time TL2 or T′L3 and/or the equivalent time constant Te2 or Te3, for example, can be adjusted in the precontrol element VLZ. The adjustment is to be carried out such that with it, a computer-generated, virtual dynamic target value profile, such as, for example, a target value θ″2,target or θ″3,target, is compared, essentially synchronously, with the corresponding profile of the measured value θ2 or θ3, respectively, for the temperature at the assigned sensor S2 or S3, respectively, at the node K2 or K3, respectively.
For the outer control loop, the virtual, modified target value θ″3,target corresponds with the target value θ″3,target,k, which is to be compared with the measured value, because it is not corrected by an additional control loop. Additionally, in the preferred embodiment, no precontrol element VLZ is provided for the innermost control loop, which has very short paths or running time. In a standardization of the nomenclature, the target value θ′3,target, without further modification, represents the target value θ″3,target.
A precontrol element VLZ of this type, which represents the path model, is advantageously provided at least in the path and/or in the control model SRMi for use in generating the target value of the control loop or control loops which are assigned to the sensor S2 close to the component or which are assigned to the sensors S2; S3 that are located close to the component. In the example, the two outer control loops have a precontrol element VLZ,2; VLZ,3 of this type in their target value generation. Should the path between the valve 07 and the sensor S1 be found to be too long and disruptive, it is also possible to provide a corresponding precontrol element VLZ,1 for target value generation for the inner control loop. Thus, the path and/or the control model SRMi which is used to generate the corrected target value θ″b,target, which is to be processed in the memory and/or processing unit 37, also advantageously has a corresponding precontrol element VLZ,i.
The control dynamics can also be improved, in a further development of the above-described control unit 21, if the conversion of the desired target value profile, at the level of the innermost control loop, is made faster and its following error is decreased by the use of a derivative action element VVH,i in the form of a time constant exchanger, such as, for example, 1st order, typically, a lead/lag filter. This precontrol, in the form of the derivative action element VVH, first effects an amplitude gain or overcompensation in the reaction, in order to accelerate the control process in a respective start-up phase, and then returns to neutrality.
To rule out any stability problems, this measure is preferably carried out only in the target value part that is not influenced by actual values, typically upstream of the respective nodes K1′; K2′, which are an addition or subtraction point, or the like, depending upon the sign. To maintain balance in the outer controllers R2; R3, this dynamic measure must then also be compensated for by the use of corresponding derivative action elements VVH,2 or VVH,3 in the control loops that lie farther toward the outside, and which, if applicable, also act upon one or all of the described precontrols VWF relating to heat flow rate or VLZ relating to running time and/or time constants in the generation of the target value of the subsequent control loop.
In the precontrol element VVH,I, the profile property of the described gain, relative to the input signal is represented and is established, but can be modified in terms, of level and profile, as needed, preferably based upon parameters or in some other way. According to the physical sequence, the derivative action element VVH,i is preferably arranged upstream of the precontrol element VLZ, if it is present, and downstream of the precontrol element VWF, if it is present, in relation to the signal path. The precontrol element VVH can also be used, in one of the embodiments according to
If a precontrol element VVH,i is provided for accelerating the control process, the path and/or the control model SRMi which is used to generate the corrected target value θ″b,target that is to be processed in the memory and/or processing unit 37 should also have a corresponding precontrol element VVH,i.
The control dynamics can be improved in a further development in accordance with the present invention if, in addition to the precontrols or in addition to one of the described precontrols VWF relating to heat flow rate, running time and/or time constants VLZ, and/or the derivative action element VVH, a precontrol relating to rotational speed VDZ is also carried out, for example. Based upon a press rotational speed “n”, more or less frictional heat is produced in a printing couple. If the mass flow of the fluid is to be maintained essentially constant, increased frictional heat can be produced only by decreasing the temperature of the fluid, and vice versa. The above-described control unit 21 would doubtless react, over time, to the change in frictional heat resulting from a decrease or an increase in the fluid temperature, but would react only if the temperature at the sensor S3 displays the undesirable temperature.
To further increase the dynamic response of the control unit 21, particularly under changing operating conditions, such as would occur in a run-up phase, a rotational speed change, and the like, the precontrol element relating to rotational speed VDZ is provided, which, in principle, can be superimposed over all subordinate target value determinations, such as, the generation of the target values θ″1,target, θ″2,target, θ″3,target, giving them the character of correcting variables. However, such superimposition of the outer control loop makes no sense if the measured value of the sensor S3 represents the technologically last valid actual value, such as, for example, the temperature of the effective area, for instance, the roller surface itself. Thus, in the preferred embodiment, the precontrol element VDZ acts only on the generation of target values θ″1,target and θ″2,target, specifically so that a correction value dθn is superimposed over the theoretical target value θ′2,target which is generated by the precontrol element V2,WF which is upstream of the second control loop. The resulting target value θ′2,target,n is used directly, or by corresponding precontrol elements VVH,i and/or VLZ,i, to generate the target value of the second control loop (R2) and at the same time, by the precontrol element VWF,i and, if applicable, the precontrol element VVH,i, to generate the target value of the first control loop (R1). In the precontrol element VDZ, a correlation between the press rotational speed “n” and a suitable correction is established, which can preferably be modified, as needed, based upon parameters or in some other way. The modified target value for rotational speed n*target, which is generated by the memory and/or processing unit 37, is preferably supplied to the precontrol element VDZ. The precontrol element VDZ can be applied independently of the presence of the precontrol elements VLZ; VVH, as will be discussed below, or VAB, as also discussed below, or in addition to one or more of these.
However, if the sensor S3 measures not the outer surface, but a temperature that lies farther toward the interior of the component, which is not the last valid temperature in terms of the process, it can also make sense to allow the precontrol element VDZ to also act on the outer control loop (R3). The same applies to an outer control loop which obtains the measured value not directly from the component 01, but from a sensor S4; S5, which is arranged downstream of the passage through component 01, see
If the control loop, whose path and/or whose control model SRMi is used to generate the corrected target value θ″b,target to be processed in the memory and/or processing unit 37, is positioned upstream of a corresponding precontrol element VDZ, in
In
The functional profile and the gain of the precontrol element VNU for this return flow temperature precontrol are established, and can preferably be modified, based upon parameters.
The controllers R1; R2; R3 from the preferred embodiments according to
In an advantageous embodiment, however, at least controllers R2 and R3 are embodied as so-called “running time-based controllers” or “Smith controllers.” The running time-based controllers R2 and R3, and particularly the running time-based PI controllers R2 and R3, are represented, and are assigned parameters in
In the running time-based PI controller R2; R3, the running time or the delay time of the control path and its time constant, are represented and are established, but can preferably be modified, as needed, based upon parameters or in some other way. For this purpose, corresponding parameters T**L2, T**e2; T**L3, T**e3, which are intended, for example, to represent the actual running time TL2 or T′L3 and/or the time constant Te2 or Te3, can be adjusted in the running time-based PI controllers R2 and R3. The values of the parameters T**L2; T**e2; T**L3; T**e3 and the values of the parameters T*L2; T*e2; T*L3; T*e3 from the precontrol elements VLZ,i, and relating to running time and time constants, should essentially coincide with one another in the proper adjustment and rendering of the control path, since these describe the corresponding control path both in the controller R2; R3 and in the precontrol element VLZ. Thus, if both running time-based PI controllers R2 and R3 and precontrol elements VLZ,i are used in the control unit 21, the same sets of parameters, determined at one time, can be used for both.
The first section 12.1 of the inflow path, generally at 12, extends from the injection point 16 up to the first measurement point M1 with the first sensor S1. It has a first path length X1 and a first average running time TL1. The second section 12.2 extends from the first measurement point M1 up to a measurement point M2, which is situated close to the component, and with the sensor S2. It has a second path length X2 and a second average running time TL2. The third section 12.3, with a third path length X3 and with a third average running time TL3 for the fluid, is connected to the second measurement point M2 and extends up to the target location 22, which, in this case, is the first contact of the fluid in the area of the extended outer surface. A total running time T for the fluid from the injection point 16 up to the target location thus results from the sum of TL1+TL2+TL3.
The first measurement point M1 is chosen to be close to the intake point, and thus is a short distance from the intake point 16, which, in this case, is the injection point 16. Thus, the measurement point M1, which is close to the intake point, or the sensor S1, which is close to the control, is understood as a location in the area of the inflow path 12, which, in relation to the running time of the fluid TL, lies less than one-tenth, and particularly is situated less than one-twentieth, of the distance from the intake point 16 to the point of first contact with the target point 22, which in this case, is the first contact of the fluid in the area of the extended outer surface, such that TL1<0.1 T, and particularly such that TL1<0.05 T. To achieve a high control dynamic response, the measurement point M1, with respect to the running time of the fluid TL1, lies spaced a maximum of 2 seconds, and particularly is spaced a maximum of 1 second, from the injection point 16. As was already described in relation to
Ordinarily, component 01 and temperature control cabinet 18 are not arranged directly adjoining one another in the printing press, so that a line 26, such as, for example, pipework 26 or a hose 26, extends from the temperature control cabinet 18 to an intake 27 into the component 01, for example to a lead-in 27, and particularly to a rotating lead-in 27, and is of a corresponding length. The lead-in into the roller 01 or into the cylinder 01 is illustrated only schematically in
The third measurement point M3, if provided, is also arranged at least close to the component, but particularly is located close to the target point. In other words, it is located in the immediate vicinity of the target point 22 of the fluid, or it detects directly the surface which is to be temperature controlled, which in this case, is the outer surface of the roller 01. In an advantageous embodiment, the measurement point M3 does not detect the fluid temperature, as is the case, for example, with measurement points M1 and M2. Instead, it detects the area of the component which is itself to be temperature controlled. The immediate vicinity of the target location 22 is understood here to mean that the sensor S3 is located between the fluid circulating in the component 01 and the outer surface, or that it detects the temperature θ3 on the outer surface of the component 01 in a contactless manner.
In another embodiment of the temperature control device, the measurement point M3 can be dispensed with. Conclusions regarding the temperature θ3 can be drawn from empirical values through the measured values from the measurement point M2, for example, and based upon a stored correlation, an offset, or a functional correlation. For a desired temperature θ3, for example, and taking into account the press or production parameters, including press rotational speed, surrounding temperature and/or fluid throughput, a blade friction coefficient, and heat flow resistance, a desired temperature θ2 is then regulated as the target value. In this case, this must be taken into account in determining the rules F1(n) and/or F2(θ), since the temperature θ2 represents not the actual surface temperature of the component 01, but ultimately an equivalent temperature. The described rules must then be determined or established under these preconditions. However, the rules F1(n) and/or F2(θ) are ultimately to be adjusted to the local conditions of the measurement value source, based upon the conditions, at every location where the actual value which is to be controlled does not relate to the roller surface or the ink on the roller itself, and instead lies a distance from this, either upstream or downstream, in the control loop. This adjustment can also be advantageous for the aforementioned averaged equivalent measured value
In a further embodiment of the present invention, the measurement point M3 is again dispensed with. However, conclusions regarding the temperature θ3 are drawn from empirical values using the measured values from measurement point M2 and measurement point M4, for example, again based upon, for example, a stored correlation, an offset, a functional correlation and/or by determining the average of the two measured values. For a desired temperature θ3, for example, either a desired temperature θ2 is again regulated as the target value, taking into account the press or production parameters, including press rotational speed, surrounding temperature and/or fluid through rate, or the temperature θ3, which is determined indirectly based upon the two measured values, is regulated. In
In the advantageous embodiment of the temperature control device, that device has a mixing path 17, and particularly has a specially configured mixing chamber 17, in the section 12.1 between the intake point 16 and the first measurement point M1. As was mentioned above, the measurement point M1 is to be arranged close to the intake point, so that the fastest possible reaction times can be realized in the relevant control loop with the measurement point M1 and the control element 07. On the other hand, however, close downstream of the intake point, ordinarily a homogeneous mixture between infed and returning fluid, or in the heated/cooled fluid, is not yet achieved, so that errors in the measured values make control more difficult and, under certain circumstances, substantially delay the achievement of the ultimately desired temperature θ3 at the component 01.
While preferred embodiments of a method and device for controlling a printing press, in accordance with the present invention, have been set forth fully and completely herein above, it will be apparent to one of skill in the art that various changes, for example, in the specific structure of the printing press, in the structure of the at least one rotating component and the like could be made without departing from the true spirit and scope of the present invention which is to be limited only by the appended claims.
Number | Date | Country | Kind |
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10 2008 000 271 | Feb 2008 | DE | national |
10 2008 001 309 | Apr 2008 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2008/063474 | 10/8/2008 | WO | 00 | 7/28/2010 |
Publishing Document | Publishing Date | Country | Kind |
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WO2009/100783 | 8/20/2009 | WO | A |
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Number | Date | Country | |
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20100319559 A1 | Dec 2010 | US |