Method for controlling a casting method, control system for a casting method, device and computer program

Abstract

The present invention relates to a method for controlling the temperature of a casting method, in particular of a die casting method, comprising: determining at least one output variable indicative of at least one temperature of a casting mould, wherein the at least one output variable is detected by means of at least one thermal imaging camera during an open state of the casting mould, controlling at least one input variable indicative of at least one input value of the casting method depending on the output variables such that a temperature difference of at least one temperature of the casting mould to a predefined temperature profile is minimised, wherein the at least one output variable is estimated by means of a state estimator during a closed state of the mould based at least on the output variable detected during the open state of the casting mould. The invention also relates to a control system for a casting method, in particular for a die casting method, to a device and a computer program.

Description

[0001] Method for controlling a casting process, control system for a casting process, device and computer program

[0002] The invention relates to a method for controlling, in particular for temperature control, a casting process, in particular a permanent mold casting process. The present invention also relates to a control system for a casting process, in particular for a permanent mold casting process, comprising at least one control means for controlling at least one input variable indicative of at least one input variable of the casting process, in particular as a function of at least one output variable indicative of at least one temperature of the casting process, in particular of a temperature of a casting mold, more preferably of a temperature trajectory of the casting process or of the casting mold, such that a temperature difference, in particular a predicted temperature difference, between the temperature of the casting process and a preset temperature profile is minimized. The present invention further relates to a device and a computer program.

[0003] State-of-the-art methods for temperature control in casting processes are already known. Essentially, a distinction is made between two conventional control options: feedforward control and simple feedback control.

[0004] In feedforward control, at least one input variable, which is indicative of at least one input parameter of the casting process, is preset by a process engineer before each casting cycle. However, with regard to feedforward control, it has been shown in practice that this control can lead to significant temperature fluctuations between individual casting cycles, which can lead to defects and / or casting errors in the production of individual castings.

[0005] In simple feedback control, for example, the flow rate of a coolant is controlled as a function of at least one measuring device arranged in the casting mold, in particular a thermocouple. If, for example, the temperature measured by the at least one thermocouple exceeds a preset temperature limit, a coolant flow is activated. The coolant flow is activated until the temperature measured by the at least one thermocouple falls below a further preset temperature limit. A control strategy described in this way can also be referred to as bang-bang control and is possible in many commercial permanent mold casting plants. Although information from the respective casting process, in particular the temperature measured by a thermocouple, is used, the response time of such a control is slow because it can only react to temperature fluctuations that have already occurred.It has been shown that with such a control, significant temperature peaks can occur, especially shortly after the mold is filled with the mold filling or the melt.

[0006] Furthermore, the use of thermocouples within the mold has proven to be disadvantageous in terms of maintenance. Furthermore, it is very time-consuming to constantly check whether the measured values ​​​​provided by the thermocouples are correct, which can further limit the functionality of the feedback control.

[0007] Based on this, the present invention is based on the object of specifying a method for temperature control of a casting process, in particular a permanent mold casting process, which enables reliable temperature control of a casting process while avoiding high maintenance costs. A control system for a casting process, a device, and a computer program comprising program instructions are also to be specified, which enable reliable temperature control of a casting process while avoiding high maintenance costs.

[0008] The above-mentioned object is achieved according to a first aspect of the invention in an above-mentioned method in that the method comprises the following steps:

[0009] Determining at least one output variable indicative of at least one temperature of a casting mold, wherein the at least one output variable is detected during an open state of the casting mold by means of at least one thermal imaging camera, wherein the at least one output variable is determined during a closed state of the casting mold by means of a state estimator based at least on the temperature detected during the open state of the casting mold

[0010] output variable is estimated, and

[0011] Control of at least one input variable indicative of at least one input variable of the casting process as a function of the output variables such that a temperature difference of at least one temperature of the casting mold to a preset temperature profile is minimized.

[0012] In this respect, a method can be provided that enables temperature control of a casting process in a structurally advantageous manner. By recording at least one output variable using at least one thermal imaging camera, the complex installation of multiple thermocouples within the casting mold is no longer necessary.

[0013] Using at least one thermal imaging camera, it is advantageously possible to specify or determine, in particular, output variables indicative of the temperature at multiple positions of the mold, in particular multiple positions within the mold, at the same time. This can significantly reduce maintenance effort, since one thermal imaging camera can replace a large number of thermocouples and their functionality can also be verified much more easily.

[0014] Furthermore, extensive tests and simulations have surprisingly shown that the discontinuous measurement of the at least one output variable, namely only when the mold is open, leads to sufficient temperature control of the casting process based on the preset temperature profile. In particular, by estimating the at least one output variable while the mold is closed, in which case, in particular, no information from the at least one thermal imaging camera is available, sufficient temperature control with regard to the preset temperature profile can be ensured.

[0015] The at least one output variable detected by the at least one thermal imaging camera is, in particular, at least one measured value from the thermal imaging camera. With regard to increased measurement accuracy, it is preferred that the at least one thermal imaging camera determines a plurality of output variables indicative of the temperature at various locations on the mold, and that the control of the at least one input variable and / or the estimation of the at least one output variable in the closed state of the mold is carried out based on the plurality of output variables.

[0016] The at least one thermal imaging camera in question is, in particular, a detection device that enables the temperature of specific objects or areas of specific objects to be detected over a specific distance. In particular, the at least one thermal imaging camera is designed to receive infrared radiation. For example, the wavelength of the received infrared radiation can be in a wavelength range of approximately 3.5 pm to 15 pm.

[0017] Preferably, at least one input variable is controlled indicatively for at least one input variable of the casting process. In particular, the at least one input variable is indicative of a flow rate of a coolant, wherein the coolant flows, for example, through channels arranged in the casting mold and thereby cools the casting mold. This enables reliable adjustment of the temperature of the casting mold. For example, the at least one input variable can also be indicative of at least one heating rate of a heating element or heat source arranged in the casting mold. This enables rapid adjustment of the temperature of the casting mold to a preset temperature profile.

[0018] For example, the at least one input variable is indicative of at least one input variable if it allows a conclusion to be drawn about the input variable. In particular, the at least one input variable can be measured values ​​and / or data indicative of the at least one input variable. For example, the input variable can be the input variable itself or measured values ​​and / or data that represent the input variable or from which the input variable can be derived. For example, the at least one input variable can be a temperature of a coolant in Kelvin, wherein in such a case the at least one input variable can also be the temperature of the coolant in Kelvin or other measured values ​​and / or data that represent the temperature of the coolant or from which the temperature of the coolant can be derived.The above preferably also applies with regard to the at least one output variable indicative of at least one temperature of the casting mold. In this respect, the at least one input variable refers in particular to the physical condition, for example the temperature of the coolant in Kelvin, whereas the at least one input variable or the at least one output variable can also refer to measured values ​​and / or data which allow conclusions to be drawn about the at least one input variable or the at least one temperature of the casting mold and / or which represent the at least one input variable or the at least one temperature of the casting mold. The typically set input variables are, for example, indicative of the flow rates of a coolant and / or the cooling times during a casting cycle.

[0019] Furthermore, it has proven particularly advantageous in practice if one, in particular a further, input variable is controlled by means of the control system, wherein the further input variable is preferably indicative of at least one heating rate of a heating element or heat source arranged in the mold. This enables rapid adjustment of the temperature of the mold to a preset temperature profile.

[0020] By means of a state estimator, the at least one output variable can be estimated when no measured output variable is available from the at least one thermal imaging camera, namely in particular when the casting mold is closed.

[0021] A state estimator is a component in control systems that estimates the internal state of a dynamic system, such as the casting process. For example, the state estimator determines the at least one output variable during a closed state of the casting mold based on the at least one recorded output variable during the open state of the casting mold from the past, as well as based on the at least one controlled input variable. The state estimator can use mathematical models and algorithms to calculate the best possible estimate of the at least one output variable during a closed state of the casting mold from the available data for the past output variables and the past or present input variables.A further preferred embodiment is characterized in that the control of the at least one input variable is based on a model-based control algorithm, and that the model-based control algorithm is preferably designed as a state controller and / or as a model-predictive controller.

[0022] For example, the model-based control algorithm can be based on a dynamic model of a temperature balance within the casting mold, wherein the dynamic model requires in particular an estimate and / or a value of the at least one output variable for controlling the at least one input variable.

[0023] A state controller can, for example, be a control system used to control the state of the casting process using at least one input variable. For example, the state controller functions by estimating the current state of the system using at least one output variable. Subsequently, the estimated state can be compared with a predetermined state, and the at least one input variable can be adjusted such that the estimated state is changed toward the predetermined state.

[0024] For example, a state controller typically uses feedback, where the error between the current state and the specified target state is multiplied by a constant and used as a control signal. This constant, usually configured as a matrix, especially a feedback matrix, is often referred to as the controller gain and determines the strength of the control.

[0025] A model predictive controller is based in particular on a so-called MPC model. In model predictive control, the aim in this case is in particular to achieve a preset temperature profile, which is a target temperature profile. The preset temperature profile can, for example, also simply be a desired constant temperature. The aim of the control is to keep the measured and / or predicted temperature of the casting process, in particular the temperature of the casting mold, as close as possible to the desired temperature profile during or between casting cycles. To this end, for example at discrete time intervals, not only the current state of the process can be monitored, for example by recording and / or estimating at least one output variable, but also the state of the process for a specific future time interval can be estimated and / or controlled.The model predictive control is therefore based on an optimization problem, namely to optimize the output variable with respect to the preset temperature profile by controlling at least one input variable.

[0026] For example, the optimization problem may involve a cost function, the cost function of which is to be minimized. The mold filling as a measured disturbance and the at least one input variable can be considered. Preferably, at least two input variables are considered, which are preferably indicative of the flow rate of a coolant and the heating rate of a heat source.

[0027] An exemplary cost function that can be optimized using model predictive control can be based on the following formula:

[0028] The first sum term penalizes For example, the temperature difference between the output variable indicative of a predicted temperature or indicative of a predicted temperature trajectory and a preset temperature profile. |yfc+i|fc| I can, for example, correspond to the predicted temperature or the predicted temperature trajectory. For example, |yfc+i|fc| I is calculated using the transfer function G(s) described below and the input variables ü k+i \ k Furthermore, it is preferred that the term r k+i corresponds to the preset temperature profile.

[0029] The second sum term For example, it penalizes changes in the input variables. This can particularly affect changes in the flow rate of a coolant or the heating rate of a heat source. &ü k+i \ kcan, for example, indicate the change of at least one input variable between time k+1 and the previous time.

[0030] The third sum term For example, it directly penalizes the input variables. This ensures, in particular, that the absolute amount of coolant flow or the absolute heating rate of a heat source is minimized.

[0031] The degrees of freedom of the model predictive control or optimization problem are determined by the variables UPH, UCH, and the weighting matrices Q, R, and S. For example, the variable HPH specifies how many time intervals in the future the calculation should be performed. A time interval can, for example, range between 0.5 s and 10 s.

[0032] For example, the variable ncH specifies for how many time intervals in the future at least one input variable can be changed.

[0033] Preferably, the variables UPH and ncH can be adapted to the underlying optimization problem. For example, it is preferred that the variable UPH at least specifies the duration of a casting cycle, which can last between 1 and 10 minutes, for example.

[0034] The weighting matrices Q, R, and S specifically indicate the weighting of the individual sum terms in the overall evaluation. For example, the weighting matrices Q, R, and S can be identity matrices with the constants q, r, and s on the diagonal. Such a configuration has proven advantageous when using model predictive control to reduce complexity while achieving satisfactory results.

[0035] A further preferred embodiment is characterized in that the state estimator further estimates the at least one output variable during a closed state of the casting mold as a function of the at least one input variable. This enables an estimation of the at least one output variable during the closed state, since further known and / or measured variables that influence the casting process, in particular the temperature of the casting mold in an open state of the casting mold and which influence the at least one input variable, are used as the basis for the state estimation.

[0036] A further preferred embodiment is characterized in that the state estimator comprises a Kalman filter and / or is designed in particular as a Kalman filter, and in that the state of the at least one output variable is calculated or estimated while the casting mold is closed using the Kalman filter, in particular at defined time intervals. This allows the state of the casting process to be reliably calculated or estimated. In particular, the state of the casting process is calculated based on a detection of the at least one input variable in the past and / or present and of the at least one output variable in an open state of the casting mold in the past. Using the current state of the casting process, the various future temperature trajectories can be calculated within the framework of the model predictive control, on the basis of which the at least one input variable can be controlled.

[0037] For example, other state estimators can also be used that employ known stochastic state estimation methods. In particular, the state estimator can be designed as an SMC filter, especially a particle filter. The idea behind an SMC filter is to estimate a current, but unknown, probability density in a state space and to use this to derive statements about the most probable state. A sufficient state estimator for the state of at least one output variable in a closed state of the mold can also be achieved using the aforementioned state estimator.

[0038] A further preferred embodiment is characterized in that the model-based control algorithm is based on a data set, wherein the data set in particular comprises measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold, and in that a correlation determined based on the data set between the at least one input variable and the at least one output variable is used by means of the control algorithm to control the at least one input variable. The data set preferably comprises a plurality of input variables, in particular at least two different input variables.Alternatively and / or additionally, the control algorithm can also be based on a heuristic model. Optionally, the model-based control algorithm can also be used to determine correlations and / or interactions between the input variables. By calculating the correlation and / or interactions between the input variables and / or the correlation with the output variable, the effect of a change in one variable on another variable can be reliably calculated.

[0039] For example, the aforementioned control algorithm can include a grey-box model. Alternatively, the control algorithm can be purely data-based or based on principles known from the state of the art, which are subsequently parameterized using data.

[0040] A grey-box model can be represented, for example, by the following formula:

[0041] Yout is preferably the output variable, which is indicative of at least one temperature of the casting process. Uin preferably refers to the various input variables, whereby a total of n different input variables can be present. For example, the various input variables can be in the Laplace domain. The function Gi(s) is preferably a transfer function, which can be represented in particular by the following formula for the individual input variables: Ki is preferably a gain factor of the respective input variable, whereby Ti can in particular be a time constant.

[0042] It has been shown that the illustrated grey-box model can provide an advantageous model for calculating the correlation between the at least one input variable and the at least one output variable.

[0043] A further preferred embodiment is characterized in that the data set comprises historical data, in particular data from previously carried out casting tests and / or data from series production, wherein the data set is preferably expanded by data acquired during the execution of the casting process, in particular by measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold, and / or that the control algorithm is parameterized by means of estimated values, wherein the control algorithm is preferably validated and / or expanded during the execution of the casting process by recorded data, in particular by measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold.This makes it possible to use a data set which allows the correlation between the at least one input variable, the at least one output variable and, for example, disturbance variables to be taken into account.

[0044] A further preferred embodiment is characterized in that the control algorithm considers the at least one input variable and the one output variable, as well as their correlation to one another. This allows the control algorithm to reliably calculate various possible temperature trajectories and to control the at least one input variable in such a way that a, in particular predicted, temperature difference between the temperature of the casting process and a preset temperature profile is minimized. Furthermore, it is preferred that, in the case of multiple input variables, the model-predictive control also considers the correlation between the multiple input variables.

[0045] A further preferred embodiment is characterized in that the control algorithm and / or the state estimator includes an opening state of the casting mold, a filling of the casting mold, and / or a measurement inaccuracy of the at least one thermal imaging camera as a further input and / or disturbance variable, and in that the control algorithm and / or the state estimator takes into account the correlation of the further input and / or the disturbance variable to the at least one input variable and / or the at least one output variable. This enables reliable control of the at least one input variable and / or the at least one input variable, since the opening state of the casting mold, the behavior of the casting mold filling, or deviations in the casting mold filling as a measured disturbance variable, and / or a measurement inaccuracy of the at least one thermal imaging camera can also be included in the control.The mold filling as a disturbance variable can in particular be the time of the mold filling, the composition of the mold filling, the amount of the mold filling and / or the temperature of the mold filling.

[0046] A further preferred embodiment is characterized in that the at least one input variable is a flow rate of a coolant, a temperature of a coolant, a duration of a casting cycle, a quantity of a casting mold fill, a composition of a casting mold fill, a temperature of a casting mold fill, a time of a casting mold fill, a temperature of a heat source, and / or a heating rate of a heat source. As a result, an input variable indicative of one of the aforementioned input variables can be controlled such that a temperature difference between the temperature of the casting process and a preset temperature profile is minimized. It is preferred that an input variable is indicative of an input variable. Preferably, several of the aforementioned input variables can also occur multiple times, for example, if several cooling circuits for coolants are present during the casting process.

[0047] Particularly preferably, the at least one input variable is indicative of the flow rate of a coolant. This allows the flow rate of a coolant to be controlled based on the model predictive control in such a way that the aforementioned temperature difference is minimized.

[0048] Preferably, at least two input variables are controlled, indicative of two input variables of the casting process. In practice, it has proven preferable in terms of control accuracy if two input variables are used, with one input variable preferably indicative of the coolant flow rate and one input variable preferably indicative of the heating rate of a heat source. This enables adjustment of both the coolant flow rate and the heating rate of the heat source based on model-predictive control.

[0049] A further possible embodiment is characterized in that at least one further output variable indicative of at least one further temperature of the casting process is detected by means of a thermocouple, in particular by means of a thermocouple arranged at least partially within the casting mold, and in that the at least one input variable is controlled as a function of the at least one output variable and the at least one further output variable. This allows the at least one further output variable to be used for control, in particular for control during a closed state of the casting mold, thereby further improving the accuracy of the control.

[0050] Furthermore, it is possible for the state estimator to estimate the at least one output variable, particularly during a closed state of the casting mold, as a function of the at least one further output variable. This can further improve the accuracy of the state estimator.

[0051] Furthermore, the state estimator can also estimate the at least one output variable during an open state of the casting mold depending on the at least one further output variable. This is because the parallel use of at least one thermal imaging camera and at least one thermocouple allows the advantages of both measuring devices to be combined. For example, the use of a thermal imaging camera can usually provide a more precise temperature reading, whereas a thermocouple is usually more robust and reliable. Furthermore, it may not be possible to measure the temperature at the desired location. Therefore, the result of the state estimator can be further improved by combining the two measuring devices.

[0052] According to a second aspect of the present invention, the above-mentioned object is achieved in a control system for a casting process in that the control system further comprises at least one thermal imaging camera for detecting the at least one output variable during an open state of the casting mold, and in that the at least one control means estimates the at least one output variable during a closed state of the casting mold by means of at least one state estimator based at least on the output variable detected during the open state of the casting mold.

[0053] A control system can, for example, be a device for evaluating data, controlling other devices, and / or outputting signals. The control system can, for example, be part of a casting device, a casting apparatus, and / or a casting system.

[0054] The control system may comprise hardware and / or software components. The control system may, for example, comprise at least one memory with program instructions of a computer program and at least one processor configured to execute program instructions from the at least one memory. Accordingly, control devices comprising at least one processor and at least one memory with program instructions are also to be understood as being disclosed, wherein the at least one memory and the program instructions are configured, together with the at least one processor, to control the at least one input variable. The at least one input variable is controlled, for example, via a control connection.

[0055] According to a preferred embodiment, the control system regulates, as at least one input variable, a flow rate of a coolant, a temperature of a coolant, a duration of a casting cycle, a quantity of a mold fill, a composition of a mold fill, a temperature of a mold fill, a time of a mold fill, a temperature of a heat source, and / or a heating rate of a heat source. The control system can also regulate at least two or more of the aforementioned input variables.

[0056] Preferably, the control system is designed to carry out a method described above.

[0057] According to a third aspect of the present invention, the aforementioned object is achieved by a device comprising at least one processor and at least one memory containing program code, in that the memory and the program code are configured to cause the at least one processor to cause a device to execute and / or control at least the aforementioned method. In this case, either all steps of the method can be controlled, or all steps of the method can be executed, or one or more steps can be controlled and one or more steps executed.

[0058] In an exemplary embodiment, the device according to the third exemplary aspect of the present invention comprises at least one control system according to the second aspect of the present invention and a casting system suitable for carrying out a method according to the first aspect of the present invention.

[0059] The aforementioned object is also achieved according to a fourth aspect of the present invention by a computer program in that the computer program comprises program instructions that cause a processor to execute and / or control the aforementioned method when the computer program is running on the processor. In this specification, a processor is understood to mean, among other things, control units, microprocessors, microcontrol units such as microcontrollers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), or field-programmable gate arrays (FPGAs). In this case, either all steps of the method can be controlled, or all steps of the method can be executed, or one or more steps can be controlled and one or more steps executed.The computer program can, for example, be distributable over a network such as the Internet, a telephone or mobile network and / or a local area network. The computer program can be at least partly software and / or firmware of a processor. It can equally be implemented at least partly as hardware. The computer program can, for example, be stored on a computer-readable storage medium, e.g. a magnetic, electrical, electromagnetic, optical and / or other type of storage medium. The storage medium can, for example, be part of the processor, for example a (non-volatile or volatile) program memory of the processor or a part thereof. The storage medium is, for example, tangible, and / or non-transitory.

[0060] The above-described embodiments and exemplary configurations of all aspects of the present invention, which initially stand alone in principle, should also be understood to be disclosed in all combinations with one another. Further advantageous exemplary embodiments of the aspects of the invention can be found in the following detailed description of some exemplary embodiments of the present invention, in particular in conjunction with the figure. The figure attached to the application is, however, intended only for the purpose of clarification and not to determine the scope of protection of the invention. The attached drawing merely reflects the general concept of the present invention by way of example. In particular, features contained in the figure should in no way be understood as a necessary component of the present invention.

[0061] In the following, the invention is explained using exemplary embodiments with reference to the drawing. The drawing shows

[0062] Fig. 1 exemplary temperature curves based on different temperature control systems and different detections of at least one output variable.

[0063] Fig. 1 shows different temperature profiles based on different temperature control systems and different detections of at least one output variable as well as a preset temperature profile 2.

[0064] In addition to the preset temperature profile 2, two temperature profiles 4 and 6 are specified, which are based on a model-predictive controller, wherein the temperature profile 4 is based on a continuous measurement of at least one thermocouple arranged in the mold for measuring the output variable indicative of at least one temperature of the casting mold, and wherein the temperature profile 6 is based on a discontinuous measurement in an open state of the casting mold using a thermal imaging camera for measuring the output variable indicative of at least one temperature of the casting mold. With regard to the temperature profile 6, the at least one output variable indicative of at least one temperature of the casting mold is estimated in a closed state of the casting mold using a state estimator, since in such a case no information from the at least one thermal imaging camera indicative of at least one temperature of the casting mold is available.

[0065] The gray areas 8 of the graph correspond in particular to the periods in which the casting mold is in an open state and therefore an output variable indicative of a temperature of the casting mold can be detected by means of the at least one thermal imaging camera.

[0066] In contrast, the white-shaded areas 10 are those areas in which the casting mold is closed and therefore no output variables indicative of a temperature of the casting mold are provided by the at least one thermal imaging camera and the at least one output variable is therefore calculated by a state estimator in this period.

[0067] In addition, two further temperature profiles 12 and 14 based on a simple PI control are shown. Temperature profile 12 is based on a continuous measurement of at least one thermocouple arranged in the mold to measure the output variable, and temperature profile 14 is based on a discontinuous measurement of at least one output variable indicative of at least one temperature of the mold in an open state of the mold using at least one thermal imaging camera. The PI controller is active in temperature profile 14 only when the mold is open, while a preset flow profile is used when the mold is closed.

[0068] The root of the mean square error - which is a parameter commonly used to evaluate the respective control system - for the preset temperature profile 2 is 12.3°C for temperature profile 4, 14.3°C for temperature profile 6, 14.7°C for temperature profile 12 and 18.9°C for temperature profile 14 in the period shown.

[0069] Although it is evident that the use of information from at least one thermal imaging camera leads to a certain deterioration in the control performance, the control performance is still satisfactory even when using at least one thermal imaging camera and is preferable in that the use of at least one thermal camera avoids the costly installation and maintenance of several thermocouples.

[0070] It is also evident that the model-predictive controller leads to significantly more accurate control than a simple PI controller, since the model-predictive controller can estimate at least one output variable indicative of the mold temperature using a state estimator, even when the mold is closed. The correspondingly estimated output variable can then be used to control at least one input variable and thus the mold temperature. In such a case, a simple PI controller can only switch to pure forward control.

[0071] As an input variable indicative of an input variable, an input variable indicative of a flow rate of a coolant can be controlled in the controls shown in Fig. 1.

[0072] The exemplary embodiments of the present invention described in this specification are to be understood as disclosed in all combinations with one another. In particular, the description of a feature encompassed by an embodiment – ​​unless explicitly stated otherwise – should not be understood in this case to mean that the feature is essential or essential to the function of the exemplary embodiment. Terms used in the claims such as "comprise," "have," "include," "contain," and the like do not exclude further elements or steps. The wording "at least partially" includes both the case "partially" and the case "completely." The wording "and / or" is to be understood to mean that both the alternative and the combination are intended to be disclosed, thus "A and / or B" means "( ] or (B) or ( and BJ".A plurality of units, persons, or the like, in the context of this specification, means multiple units, persons, or the like. The use of the indefinite article does not exclude a plurality. A single device or means may perform the functions of multiple units or devices recited in the claims. Reference numerals indicated in the claims are not to be construed as limitations on the means and steps employed.

Claims

Patent claims 1. Method for temperature control of a casting process, in particular of a Gravity casting process, comprising: Determining at least one output variable indicative of at least one temperature of a casting mold, wherein the at least one output variable is detected during an open state of the casting mold by means of at least one thermal imaging camera, wherein the at least one output variable is estimated during a closed state of the casting mold by means of a state estimator based at least on the output variable detected during the open state of the casting mold, and Control of at least one input variable indicative of at least one input variable of the casting process as a function of the output variables such that a temperature difference of at least one temperature of the casting mold to a preset temperature profile is minimized.

2. Method according to claim 1, characterized in that the control of the at least one input variable is based on a model-based control algorithm, and that the model-based control algorithm is preferably designed as a state controller and / or as a model-predictive controller.

3. Method according to claim 1 or 2, characterized in that that the state estimator further estimates the at least one output variable during a closed state of the mold as a function of the at least one input variable.

4. Method according to one of claims 1 to 3, characterized in that the state estimator comprises a Kalman filter and / or is designed in particular as a Kalman filter, and in that the state of the at least one output variable is calculated during a closed state of the casting mold by means of the Kalman filter, in particular in defined time intervals.

5. Method according to one of claims 1 to 4, characterized in that the model-based control algorithm is based on a data set, wherein the data set comprises in particular measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold, and in that by means of the control algorithm a correlation determined on the basis of the data set between the at least one input variable and the at least one output variable is used to control the at least one input variable.

6. Method according to claim 5, characterized in that the data set comprises historical data, in particular data from previously carried out casting tests and / or data from a series production, wherein the data set is preferably extended by data acquired during the execution of the casting process, in particular by measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold, and / or that the control algorithm is parameterized by means of estimated values, wherein the control algorithm is preferably validated and / or expanded during the execution of the casting process by recorded data, in particular by measured values ​​of the at least one thermal imaging camera for the at least one output variable during an open state of the casting mold.

7. Method according to one of claims 1 to 6, characterized in that the control algorithm takes into account the at least one input variable and the one output variable as well as their correlation to one another.

8. The method according to claim 7, characterized in that the control algorithm, in particular the state estimator, further includes an opening state of the casting mold, a filling of the casting mold and / or a measurement inaccuracy of the at least one thermal imaging camera as a further input and / or disturbance variable, and in that the control algorithm takes into account the correlation of the further input and / or the disturbance variable to the at least one input variable and / or the at least one output variable.

9. Method according to one of claims 1 to 8, characterized in that the at least one input variable is a flow rate of a coolant, a temperature of a coolant, a duration of a casting cycle, an amount of a casting mold filling, a composition of a casting mold filling, a temperature of a casting mold filling, a time of a casting mold filling, a temperature of a heating source and / or a heating rate of a heating source.

10. Method according to one of claims 1 to 9, characterized in that that at least one further output variable indicative of at least one further temperature of the casting process is detected by means of a thermocouple, in particular by means of a thermocouple arranged at least partially within the casting mold, and that the at least one input variable is controlled as a function of the at least one output variable and the at least one further output variable.

11. Control system for a casting process, in particular for a permanent mold casting process, comprising: at least one control means for regulating at least one input variable indicative of at least one input variable of the casting process as a function of at least one output variable indicative of at least one temperature of the casting process, in particular of a temperature of a casting mold, such that a temperature difference between the temperature of the casting process and a preset temperature profile is minimized, characterized in that the control system further comprises at least one thermal imaging camera for detecting the at least one output variable during an open state of the casting mold, and in that the at least one control means estimates the at least one output variable during a closed state of the casting mold by means of a state estimator based at least on the output variable detected during the open state of the casting mold.

12. Control system according to claim 11, characterized in that the control system has as at least one input variable a flow rate of a coolant, a temperature of a coolant, a duration of a casting cycle, an amount of a casting mold filling, a composition of a Controls a mold filling, a mold filling temperature, a mold filling time, a heat source temperature, and / or a heat source heating rate.

13. Control system according to claim 11 or 12, characterized in that the control system is designed to carry out a method according to one of claims 1 to 10.

14. A device comprising at least one processor and at least one memory containing program code, wherein the memory and the program code are configured to cause a device with the at least one processor to execute and / or control at least the method according to one of claims 1 to 10.

15. A computer program comprising program instructions that cause a processor to execute and / or control the method according to one of claims 1 to 10 when the computer program is running on the processor.

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