Method and device for monitoring a production plant

Abstract

Method and device for monitoring a production plant (1) containing at least one cyclically operating moulding machine (2) and possibly at least one peripheral device (3), wherein the monitoring is carried out by comparing at least one process variable with at least one reference variable, and a comparison is also possible for values of the at least one process variable in the past.

Description

Method and device for monitoring a production plant

[0001] The present invention relates to a method for monitoring a production plant that includes at least one cyclically operating forming machine and optionally at least one peripheral device, having the features of the preamble of claim 1, a device for monitoring such a production plant, having the features of the preamble of claim 13, a production plant with such a device, a computer program, a computer-readable data carrier, and a data carrier signal. The term "monitoring" encompasses the processes of analysis, in particular error detection and error prevention.

[0002] State-of-the-art methods and devices offer the option of displaying and / or monitoring hundreds of process variables determined from measured values ​​in the form of key figures. Such key figures can be, for example, minima, maxima, mean values ​​or integrals of measurement curves recorded within a cyclical production process (production cycle). Typically, such curves are available as a function of time. Other key figures can also be points in time (from the start of the measurement) at which the curve takes on a certain property, such as the time of the maximum / minimum, the time at which the integral exceeds a certain value, the time at which a defined value is reached, exceeded or undershot, etc.

[0003] Key figures can also be derived from the combination of measurements with different sensors. For example, if the screw position, injection pressure and cavity pressure are measured on a plastic injection molding machine during injection, the connecting parameter "time" or The parameter "sequence of cycles" (also called "shot number") can be used to determine key figures such as the screw position at which the maximum injection pressure is reached, the internal mold pressure at the frontmost screw position, etc.

[0004] For key performance indicators, there is initially no expected value (unlike actual values, which usually have an assigned target value); they often result from multiple factors. An example is the maximum injection pressure in a plastic injection molding machine, which is determined by, among other things, the injection speed, the geometry of the mold cavity, melt viscosity, and mold temperature. This is precisely why these parameters are so interesting, as they can be used to infer unmeasurable or not directly measured influencing factors or their changes.

[0005] Of particular interest is the question of how stable a process state.

[0006] The stability of a process state to a current Time or in a current cycle can be determined, for example, as follows: 1. Setting or determining a reference point in time (or time range) or reference cycle (or cycle range). This determination can be made automatically or by the user. This reference can remain constant or change over time ("floating reference"). 2. Determination of at least one reference value for at least one process variable and / or variables derived therefrom (e.g. key figures), resulting in a reference state for the process state to be assessed 3. Determining or determining the permissible deviations or rates of change of at least one process variable and / or variables derived therefrom 4. Comparison of the current values ​​of at least one process variable and / or variables derived therefrom with the associated at least one reference value and determination of deviations or rates of change. A process variable and / or variable derived therefrom is considered unstable if its deviation or rate of change exceeds a defined permissible deviation or rate of change. 5. Calculate the stability of the process state according to a defined rule. This rule can consider the number of unstable parameters, the degree of instability, or a combination of these. In the simplest case, the process state is considered unstable if at least one process variable and / or a variable derived from it is unstable.

[0007] A stable process state within the meaning of the invention can be achieved, for example, by: Quality of process settings: Setpoints are selected so that • the process is robust against environmental influences • they are actually achieved or can be achieved • they are suitable with regard to the material being processed good condition of elements of the production plant (e.g. the non-return valve, the tool, etc.) good condition of the material to be processed low influence of unmeasured disturbances (e.g. Ambient temperature, drafts, etc.)

[0008] In the current state of the art, it is not possible to compare past values ​​of a process variable with at least one subsequently determined reference value and thus to monitor the production plant.

[0009] It is an object of the invention to enable improved monitoring.

[0010] This object is achieved by a method having the features of claim 1 and a device having the features of claim 13.

[0011] Such a process is carried out by means of at least one computing unit.

[0012] In such a method for monitoring a production plant which has at least one cyclically operating shaping machine and, if applicable,contains at least one peripheral device, the monitoring is carried out by comparing values ​​of at least one process variable with at least one reference value and / or at least one tolerance value, wherein at least one computing unit, which is in data connection with sensors of the production plant, determines a plurality of values ​​of the at least one process variable continuously or discretely in time and stores them in at least one memory, and at least one computing unit (the same at least one computing unit or another at least one computing unit which can access the values ​​of the at least one process variable): offers the user a selection option by which the user can select a subset of values ​​of the at least one process variable from the stored values ​​of the at least one process variable, and / or automatically by at least one computing unit. A subset of values ​​of the at least one process variable is selected; the selected subset of values ​​of the at least one process variable is used to determine the at least one reference value and / or the at least one tolerance value; a comparison of stored values ​​of the at least one process variable with the at least one reference value and / or the at least one tolerance value is carried out, and the result of the comparison is displayed to the user.

[0013] The procedural steps do not have to follow one another immediately.

[0014] The step of comparing stored values ​​of the at least one process variable with the at least one reference value and / or tolerance value can be carried out with respect to all stored values ​​or only with respect to a subset of the stored values, for example for values ​​from a predeterminable point in time or a predeterminable number of a cycle or a subset that contains only those values ​​that relate to a specific mold.

[0015] Such a device for monitoring a production plant , which contains at least one cyclically operating forming machine and optionally at least one peripheral device , comprises : a display device for a user at least one computing unit which is in data connection with sensors of the production plant or can be brought into such connection , wherein the at least one computing unit is configured to continuously or discretely process a plurality of values ​​of at least one process variable of a production facility and in at least one Memory to store, wherein at least one computing unit (the same at least one computing unit or another at least one computing unit which can access the values ​​of the at least one process variable) is configured to carry out a method according to at least one of the disclosed embodiments and is in particular configured to: automatically select a subset of values ​​of the at least one process variable and / or offer the user a selection option by which the user can select a subset of values ​​of the at least one process variable from the stored values ​​of the at least one process variable to use the selected subset of values ​​of the at least one process variable toto determine at least one reference value and / or at least one tolerance value, to carry out a comparison of stored values ​​of the at least one process variable with the at least one reference value and / or the at least one tolerance value and to display the result of the comparison to the user by means of the display device,

[0016] The described tasks can be performed by a single processing unit or by more than one processing unit. One processing unit can be provided for each task, or at least one processing unit can perform at least two tasks.

[0017] The selection of values ​​of the at least one process variable can be made taking into account whether a value has been found to be acceptable by a user or a computing unit, for example because this value corresponds to the production of Good parts can be assigned or based on experience.

[0018] In the invention, the comparison of values ​​of at least one process variable with at least one reference value and / or tolerance value is also possible for values ​​of the at least one process variable lying in the past.

[0019] Monitoring can only be done cycle by cycle or within a cycle.

[0020] Only one value of the process variable or several values ​​of the process variable can be determined per cycle.

[0021] Monitoring can be carried out with regard to only a single process variable or with regard to several process variables, with each process variable being assigned its own reference value and / or tolerance value.

[0022] The state of the art is based on establishing at least one reference value at a specific point in time, which is then compared with the process variable values ​​of the parts newly manufactured in the production facility after the at least one reference value has been established. This procedure is necessary and useful, especially for inline process analysis on a production facility.

[0023] However, if the device is located remotely from the production plant, i.e. if the method is carried out (e.g. as a web application) via a remote data connection, subsequent monitoring is more important than monitoring a shot currently being produced. The invention makes it possible to first determine and store a large number of values ​​of process variables, and then (if necessary) or in the case of a problem) to retrospectively establish at least one reference value and / or tolerance value from the stored values ​​of a process variable and then to determine at which times or in which cycles there were deviations from the at least one reference value and / or tolerance value with regard to (possibly all) stored values ​​of the at least one process variable.

[0024] When monitoring directly on the production plant itself, at least one reference value and / or tolerance value can, for example, be automatically saved in the part data record and loaded when a mold of the forming machine is re-clamped. This option is not readily available for web applications, as such applications generally do not have access to the part data record. For a reference comparison, an interface to the production plant could be created in a web application which transfers the reference values ​​stored therein to the web application when a part data record is loaded, or - alternatively - a separate reference management system could be set up for the web application. However, both solutions increase the complexity of the monitoring.

[0025] If none of these solutions are available, the user has no other choice in the state of the art than to manually redefine at least one reference value after each change of the mold on the production line in the web application or to load it from a memory. This is laborious and carries the risk that, precisely when a comparison with at least one reference value is required, the timely setting of a reference value is forgotten. This would result in a missing evaluation of the shots between the reference shots and the time of reference setting. This problem is also solved by the option of subsequently setting at least one Reference value and / or tolerance value, as provided for in the invention.

[0026] The values ​​of at least one process variable can remain in the memory to which they were written immediately after the measurement, and computing units can access this memory. Alternatively or additionally, they can of course be transferred to another memory, from which they are then accessible to computing units. The same applies to the reference value.

[0027] Advantageous embodiments of the invention are defined in the dependent claims.

[0028] In one embodiment of the method and the device, it is provided that the at least one reference value and / or tolerance value is also used for future values ​​of the at least one process variable as at least one reference value and / or tolerance value.

[0029] In one embodiment of the method and the device, it is provided that the comparison of stored values ​​of the at least one process variable with the at least one reference value and / or tolerance value is carried out for all stored values ​​- optionally without values ​​on the basis of which the at least one reference value and / or tolerance value was determined.

[0030] In one embodiment of the method and the device, it is provided that the comparison of stored values ​​of the at least one process variable with the at least one reference value and / or tolerance value is carried out in such a way that a deviation and / or a rate of change and / or a stability is calculated (the stability can be determined as described in detail in the introduction to the description, however according to of the invention even if the reference state is only determined subsequently).

[0031] In one embodiment of the method and the device, it is provided that a monitoring of several different process variables takes place and the comparison of stored values ​​for the several process variables with at least one reference value and / or tolerance value takes place in such a way that at least two different process variables are combined to form a group and the results of the comparison of a group of different process variables are combined to form a result value for the group and preferably the result values ​​of at least one group are displayed in a row according to cycles or in chronological sequence.

[0032] In one embodiment of the method and the device, it is provided that the user is informed of the times or cycles for which values ​​of the at least one process variable are stored.

[0033] In one embodiment of the method and device, it is provided that the determination of the at least one reference value and / or the monitoring is carried out at a time specified by a user or automatically. Automatic execution of the method for determining the at least one reference value and / or tolerance value can occur, for example, when a stable process has been detected, when a tool change has been detected, etc.

[0034] In one embodiment of the method and the device, it is provided that at least one of the reference values ​​is assigned at least one tolerance value and a comparison of stored values ​​of the at least one process variable with the at least one reference value is only assessed as a deviation if the at least one tolerance value has been reached or exceeded. For example, a tolerance range can be defined by adding an upper tolerance value to the at least one reference value and / or subtracting a lower tolerance value. The upper and lower tolerance values ​​can be the same, but can also be different.

[0035] The at least one tolerance value can be obtained, for example, based on empirical values ​​and / or calculations and / or by using statistical methods, such as determining a tolerance value based on the scatter of the measured values.

[0036] In one embodiment of the method and the device, it is provided that values ​​of the at least one process variable can be selected from cycles that immediately follow one another in time as a subset of values ​​of the at least one process variable. Alternatively, it can be provided that values ​​of the at least one process variable can be selected from cycles that are not immediately follow one another in time as a subset of values ​​of the at least one process variable. One or more values ​​can be selected per cycle.

[0037] Once the subset of values ​​of the at least one process variable has been determined, the at least one reference value and / or tolerance value can be determined in a known manner. It is also known to check the suitability of the at least one reference value and / or tolerance value using test data. According to one embodiment of the method and device, stored values ​​of the at least one process variable are used for at least part of the test data.

[0038] According to one embodiment of the method and the device, it is provided that the values ​​of several process parameters are determined, wherein quality data is stored for at least some of the past times or cycles and for each of the process parameters, an associated reference value and / or tolerance value is automatically determined on the basis of training data and preferably taking quality data into account; for each of the process parameters, it is checked on the basis of test data whether the process parameter is suitable for predicting the quality of molded parts produced with the molding machine and thus determining a set of suitable process parameters; the quality of the reference values ​​and / or tolerance values ​​is assessed and, if necessary, a reference value and / or tolerance value is adjusted; and optionally, these tests are continuously repeated during operation in order to improve the reference values ​​and / or tolerance values.

[0039] Example: Quality control results are available for ten (not necessarily consecutive) cycles from the past. The first five cycles are used to determine a reference value and, if necessary, tolerance limits for the reference value; the remaining five cycles are used for testing. Monitoring is therefore carried out with regard to the remaining five cycles.

[0040] Each production plant has one (preferably only one) cyclically operating forming machine. A cyclically operating forming machine can have several cyclically operating subunits, in particular several cyclically operating plasticizing and / or injection units. In this In this case, the cycle of the production plant is understood as a period of time which results from taking into account all cyclically operating sub-units.

[0041] Optionally, the production plant can also have machines, devices and equipment upstream, downstream or running in parallel to the forming machine, each of which can provide process variables and is preferably equipped with sensors for determining measurement data. Examples of this include, in addition to peripheral devices, devices and systems for supplying the forming machine or the forming tool (cooling and temperature control devices, material conveyors, dosing and mixing systems), for preparing the raw material (dryers, dust extractors), devices for manipulating the molded parts (robots, conveyor belts, separating diverters), quality control systems (optical image processing, scales, measuring devices), systems for further processing or finishing the molded parts or systems for measuring additional process variables from the tool (cavity pressure, temperature, tool breathing or expansion) or the environment.

[0042] The term "production facility" must be distinguished from the term "production site," which comprises a large number of production facilities within a spatially defined area (e.g., a production hall). The invention relates to one production facility, but can, of course, be used for any number of production facilities.

[0043] Examples of cyclically operating forming machines are injection molding machines (especially plastic injection molding machines), transfer presses and injection compression molding machines.

[0044] An example of a peripheral device is a handling device (e.g. robot).

[0045] Examples of process variables are temperatures or pressures in various components of the production plant or - in the case of a plastic injection molding machine - a melt cushion, which is the amount of molten plastic that is located between the tip of the plasticizing screw and the injection nozzle.

[0046] Within the scope of the present disclosure, any reference to a production plant can be understood as a reference only to the shaping machine of the production plant, only to the at least one peripheral device that may be present, or to the entirety of the shaping plant and at least one peripheral device.

[0047] Embodiments of the invention are described with reference to Figures discussed.

[0048] Figure 1 shows schematically a method according to the state of the art.

[0049] Figure 2 shows schematically a method according to the invention.

[0050] Figure 3 shows a user interface for Carrying out the procedure according to Figure 1.

[0051] Figure 4 shows a user interface for Implementation of the method according to the invention

[0052] Figure 5 shows a possible scenario when setting a reference value.

[0053] Figure 6 shows a possible scenario when setting a reference value.

[0054] Figure 7 shows a possible scenario when setting a reference value.

[0055] Figure 8 shows a possible scenario when setting a reference value.

[0056] Figure 9 shows a possible scenario when setting a reference value.

[0057] Figure 10 shows a possible monitoring scenario.

[0058] Figure 11 shows a possible scenario for the Surveillance .

[0059] Figure 12 shows a possible scenario for Surveillance .

[0060] Figure 13 shows the database for Figures 14 to 16

[0061] Figure 14 shows a possible scenario when setting a reference value.

[0062] Figure 15 shows a possible scenario when setting a reference value.

[0063] Figure 16 shows a possible scenario when setting a reference value.

[0064] Figure 17 shows a possible scenario when setting a reference value.

[0065] Figures 18A to 18D each show a possible scenario for setting a reference value.

[0066] Figure 19 shows a diagram of a production plant according to the invention.

[0067] Figure 1 illustrates how a reference value or at least a tolerance value for a process variable is determined in the prior art.

[0068] A reference object is created from the last number of cycles ("shot") considered from the time the reference value was determined. This reference object contains a reference value and, if applicable, at least one tolerance value for each process variable (only one process variable is selected here). From this point on, each new shot is compared with the reference value, and a monitoring result is provided.

[0069] In Figure 2, in one embodiment of the method according to the invention, monitoring is carried out in such a way that not only a predetermined number of cycles immediately before the time of setting the reference value is available for setting the reference value, but also all values ​​of the at least one process variable determined in the past and still available are available. Unlike in the prior art, the setting of the at least one reference value or the at least one tolerance value can be formed from any (consecutive or non-consecutive) subset of cycles. Monitoring is carried out retroactively with the specified reference value and / or tolerance value. for past cycles. The size of the subset can be chosen differently from cycle to cycle.

[0070] Figure 3 shows an operator interface for the prior art method shown in Figure 1. Two hundred cycles are shown from left to right. The upper area shows global information at the highest hierarchy level, while the lower area shows selected specific information on subsystems at lower hierarchy levels. If even just one subsystem in the lower area is shown as unstable, a corresponding display will also appear in the upper area. In addition to process stability, additional information is also shown, such as the value "4T", which means that four setpoints for the temperature were changed, or the value "EZ", which means that run-in cycles with their own setpoints were active. The pause symbol in the upper area symbolizes a production standstill. The frame in the upper area shows the cycles used to define the reference value, including any tolerance values ​​(cf.Figure 1). It can also be seen that there is a gap between the range used to determine the reference value and the range for which an assessment of process stability (here "stable") is possible.

[0071] Figure 4 shows a user interface for the method according to the invention shown in Figure 2. Due to the invention, the gap shown in Figure 3 does not exist here, and an evaluation of the process stability is also possible to the left of the area used to determine the reference value.

[0072] In the following scenarios, it is assumed that quality control results are available for cycles from the past. Those cycles which are The cycles that were found to be in order and whose values ​​were therefore selected for setting a reference value are marked with a circle in the diagrams; those cycles that were found to be out of order are marked with a cross. The first five cycles are used to determine the reference value (here located centrally between an upper and a lower tolerance value), and the second five cycles are used for testing. Monitoring (for test purposes) is therefore carried out for the second five cycles.

[0073] In the scenario shown in Figure 5 , the values ​​of all the first five cycles were found to be OK by the user or by a computing unit and the reference value was set so that all values ​​of the first five cycles were within the upper and lower tolerance values ​​.

[0074] In the scenario shown in Figure 6, all of the first five cycles were found to be faulty by the user or a computing unit and no reference value could be established.

[0075] In the scenario shown in Figure 7, the values ​​of two of the first five cycles were found to be incorrect by the user or by a computing unit, and the reference value was set such that the three values ​​of the first five cycles found to be correct lie within the upper and lower tolerance values. Alternatively, the tolerance values ​​could also be set directly without specifying the reference value; this applies to all embodiments.

[0076] In the scenario shown in Figure 8, three values ​​of the first five cycles were found to be out of order by the user or by a computing unit and the reference value was set so that the two values ​​found to be in order were first five cycles within the upper and lower tolerance value.

[0077] In the scenario shown in Figure 9, it is not possible to specify a reference value. This process variable is therefore not suitable for reject detection using a univariate reference comparison.

[0078] In all scenarios discussed, the selection of the subset of values ​​of the process variable to be used to determine the reference value is carried out either by a user or automatically by at least one computing unit.

[0079] In the scenario shown in Figure 10, the monitoring shows that all values ​​of the five test cycles are OK because they are within the tolerance values ​​around the reference value.

[0080] In the scenario shown in Figure 11, monitoring shows that all but one of the values ​​from the five test cycles are acceptable because they are within the tolerance values ​​surrounding the reference value. Because the value found to be non-compliant is within the tolerance values, it is advisable to adjust the tolerance values ​​so that only the values ​​found to be acceptable are within the tolerance values.

[0081] In the scenario shown in Figure 12, one value of a cycle is also not acceptable and is within the tolerance value. Adjusting the tolerance values ​​is not possible because the value found to be not acceptable is within the range of acceptable values. This process variable is therefore not suitable for reject detection using univariate reference comparison.

[0082] Usually, some time passes between the production of molded parts and the availability of the results of quality measurements, for example because the post-shrinkage of plastic injection-molded parts must be waited for before dimensions can be determined.

[0083] The method according to the invention now makes it possible to retrospectively evaluate molded parts produced before the results were available. The quality of the reference can also be assessed and the reference adjusted if not all quality data were used to create the reference, but rather a portion of the quality data is used as test data.

[0084] The following examples show how quality data can be taken into account when determining reference values.

[0085] Figure 13 shows the values ​​of a process variable for nine cycles. For three of the nine cycles, no quality information is stored ( o ). For four cycles, the quality of the molded parts was assessed as good (+ ), and for a further two as poor (- ). This symbolism is used in relation to Figures 13 to 18D.

[0086] Figure 14 shows an example in which the subset for determining the reference value for at least one process variable is defined such that it contains only good parts. The tolerance values ​​are defined such that the values ​​of the process variable are within the tolerance range. In the simplest case, the minimum and maximum of the values ​​of the process variable of the selected subset define the tolerance range. However, these limits are likely to be too narrow, especially with a small database.

[0087] Analogous to the previous example, only good parts are selected in Figure 15. However, the tolerance values ​​are now determined based on the scatter of the values ​​using known statistical methods. The range between the limits is therefore usually wider than in the previous example.

[0088] The two previous examples have the disadvantage that any bad part information that may have already been stored is not taken into account.

[0089] In the example in Figure 16, the reference value and tolerance values ​​of at least one process variable are defined such that good parts lie within the tolerance range and bad parts lie outside it. This assumes that the values ​​of the process variable for good and bad parts do not overlap or do not overlap greatly, but that a separation as clear as possible is possible. If this is not the case, then the process variable on its own (viewed univariately) does not provide sufficient information about the quality (Fig. 17). Therefore, no tolerance values ​​are defined and this process variable is not used to define a reference value.

[0090] In the example discussed below, the different relevance of a process variable to different quality variables is taken into account. For this purpose, reference values ​​and tolerance values ​​are determined for each individual quality variable, as shown in Figure 16, so that good parts lie within the tolerance range and bad parts lie outside it. If it is not possible to specify tolerance values ​​due to a lack of clearly defined ranges, then, again as shown in Figure 17, no tolerance range is specified. An overall tolerance value for this process variable is then determined from the tolerance values ​​determined for the individual quality variables. In the simplest case, this is the intersection of the tolerance ranges.

[0091] Figures 18A to 18D show the value of a process variable for nine cycles and the quality assessment with respect to three different quality variables. In Figures 18A and 18B, it is possible to determine tolerance values; in Figure 18C, this is not possible because no clear ranges for good and bad parts are identifiable. Therefore, the quality variable assessed in Figure 18C is not used to determine the tolerance values ​​for this process variable (although this quality variable may, of course, be relevant with respect to another process variable).

[0092] Figure 18D shows the tolerance values ​​formed from the intersection of the allowable ranges from Figures 18A and 18B .

[0093] The method described in the previous example can be performed once, or the at least one reference value and / or the at least one tolerance value can be evaluated and / or gradually improved each time additional quality data becomes available. "Additional quality data becomes available" means that quality assessments for additional cycles have been added (additional data points in Figures 18A to 18D) or that additional quality characteristics have been assessed (additional diagrams in Figures 18A to 18D).

[0094] Since manufacturing processes can change gradually over time due to wear, changes in the material or external conditions, it is also possible to give less weight to or ignore the quality information from cycles that have passed in the past when determining the reference value. In this way, a sliding Reference value determination is possible, which takes newer data into account and forgets older data.

[0095] The examples are based on a univariate analysis of the relationships between process and quality data. Of course, the methods described can also be used for multivariate analysis. In multivariate analysis, process variables are transformed into new process variables (for example, by calculating a difference between two process variables) that have clearer relationships to quality data. The previously described methods are applied to these new process variables.

[0096] Figure 19 schematically shows a production plant 1 with a cyclically operating forming machine 2 and a peripheral device 3. The device has a first processing unit 4, a display device 5, a memory 6, and a processing unit 8 connected via a data connection 7. Reference symbols and terminology: 1 production facility 2 forming machines 3 Peripheral device 4 first computing unit 5 Display device 6 storage 7 Data connection 8 second computing unit Key figure determined from process variable, such as Values ​​determined from measurement curves, properties of measurement curves; time at which measured quantities take on certain values, etc. Value of a process variable Value supplied by a sensor or value determined on the basis of the signals supplied by the sensor of a physical quantity of the production plant, one of its components or the processed material Process variable determined from value (s), can be represented in the form of one or more key figures, has a (usually numerical) value for each point in time or cycle Process state reflects the situation of the production plant with regard to at least one parameter, preferably with regard to a plurality of parameters, during the manufacturing process running in forming cycles; the term process state can only refer to the forming machine of the production plant, only to the possibly existing at least one Peripheral device or refer to the entirety of the forming system and at least one peripheral device Reference value Value that is used for comparison with values ​​of a process variable Reference object Combination of a reference value and, if applicable, at least one tolerance value for each desired process variable. Can be present for only one process variable or for several process variables. Reference state Combination of reference values ​​at a specific point in time, which characterizes the state of the production plant or parts thereof at this point in time. Stability in relation to a process is a statement about whether and, if so, to what extent the Process state has changed compared to at least one reference state Setpoint setting value for the production plant

Claims

Patent claims Method for monitoring a production plant (1) by means of at least one computing unit (4, 8), wherein the Production plant (1) contains at least one cyclically operating shaping machine (2) and optionally at least one peripheral device (3), wherein the monitoring is carried out by comparing a plurality of values ​​of at least one process variable with at least one reference value and / or at least one tolerance value, wherein: by at least one computing unit (4, 8) which is connected to Sensors of the production plant (1) are in data connection, a plurality of values ​​of the at least one process variable are determined continuously or discretely and stored in at least one memory (6), characterized in that by at least one computing unit (4, 8): - the user is offered a selection option by which the user can select a subset of values ​​of the at least one process variable from the stored values ​​of the at least one process variable, and / or a subset of values ​​of the at least one process variable is automatically selected by at least one computing unit (4, 8) - the selected subset of values ​​of the at least one process variable is used to determine the at least one reference value and / or the at least one tolerance value - a comparison of stored values ​​of the at least one process variable with the at least one reference value and / or at least one tolerance value is carried out and the result of the comparison is displayed to the user.

2. Method according to the preceding claim, wherein at least one computing unit (4, 8) - preferably in addition to specifying for which times or cycles values ​​of the at least one process variable are stored - visualizes the process state and / or quality data of the production plant (1) for those times or cycles for which values ​​of the at least one process variable are stored.

3. Method according to one of the two preceding claims, wherein at least one first computing unit (4) is arranged on the production plant (1) and at least one second computing unit (8) or a display device (5) that can be addressed by the at least one first computing unit (4) is connected to the at least one first computing unit (4) via a remote data connection (7).

4. Method according to at least one of the preceding claims, wherein the at least one reference value and / or the at least one tolerance value is also used for future values ​​of the at least one process variable as at least one reference value and / or at least one tolerance value.

5. Method according to at least one of the preceding claims, wherein an indication is given to the user as to the times or cycles for which values ​​of the at least one process variable are stored.

6. Method according to at least one of the preceding claims, wherein the determination of the at least one reference value and / or the at least one tolerance value and / or the Monitoring is performed at a time specified by a user or automatically.

7. Method according to at least one of the preceding claims, wherein the comparison of stored values ​​of the at least one process variable with the at least one reference value is carried out in such a way that a deviation and / or a rate of change and / or a stability is / are calculated in each case.

8. Method according to at least one of the preceding claims, wherein a monitoring of several different process variables takes place and the comparison of stored values ​​for the several process variables with at least one reference value and / or at least one tolerance value in each case takes place in such a way that at least two different process variables are combined to form a group and the results of the comparison of a group of different process variables are combined to form a result value for the group and preferably the result values ​​of at least one group are displayed in a row according to cycles or in chronological sequence.

9. Method according to at least one of the preceding claims, wherein at least one of the reference values ​​is assigned at least one tolerance value and a comparison of stored values ​​of the at least one process variable with this reference value is only assessed as a deviation if the at least one tolerance value has been reached or exceeded or undershot.

10. Method according to at least one of the preceding claims, wherein the at least one reference value and / or at least one tolerance value is checked for its suitability by means of test data and stored values ​​of the at least one process variable are used for at least part of the test data.

11. Method according to at least one of the preceding claims, wherein the values ​​of several process parameters are determined, wherein quality data is stored for at least some of the past times or cycles and for each of the process parameters, on the basis of training data and preferably taking quality data into account, an associated reference value and / or at least one tolerance value is automatically determined; for each of the process parameters, on the basis of test data, it is checked whether the process parameter is suitable for predicting the quality of molded parts produced with the molding machine (2) and thus for determining a set of suitable process parameters; the quality of the reference values ​​and / or tolerance values ​​is assessed and, if necessary, a reference value and / or tolerance value is adjusted; and optionally, these tests are continuously repeated during operation in order to improve the reference values ​​and / or tolerance values.

12. Method according to at least one of the preceding claims, wherein the at least one reference value and / or the at least one tolerance value can be adjusted manually by a user and a recalculation takes place after manual adjustment.

13. Device for monitoring a production plant (1), which contains at least one cyclically operating forming machine (2) and optionally at least one peripheral device (3), with: a display device (5) for a user of at least one computing unit (4, 8), which is in data connection with sensors of the production plant (1) or can be brought into such a connection, wherein the at least one computing unit (4, 8) is configured to determine a plurality of values ​​of at least one process variable of a production plant (1) in a time-continuous or time-discrete manner and to store them in at least one memory, characterized in that at least one computing unit (4, 8) arranged on the production plant (1) or at least one computing unit (4, 8) which is connected to the Production plant (1) is in a data connection (7) or can be brought into such a connection, is configured to carry out a method according to at least one of the preceding claims and is in particular configured to: - automatically select a subset of values ​​of the at least one process variable and / or offer the user a selection option by which the user can select a subset of values ​​of the at least one process variable from the stored values ​​of the at least one process variable - to use the selected subset of values ​​of the at least one process variable to determine at least one reference value and / or at least one tolerance value - to carry out a comparison of stored values ​​of the at least one process variable with the at least one reference value and / or the at least one tolerance value and display the result of the comparison to the user by means of the display device (5).

14. Production plant (1) with at least one cyclically operating shaping machine (2) and optionally at least one peripheral device (3), and at least one computing unit (4) which is configured to carry out a method according to at least one of claims 1 to 12.

15. Computer program which, when executed, causes at least one computing unit to carry out a method according to at least one of claims 1 to 12 or to configure the computing unit as a device according to claim 13.

16. A data carrier on which a computer program according to the preceding claim is stored.

17. A data carrier signal which transmits a computer program according to claim 15.

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