WO2010057231A1

WO2010057231A1 - Setting method for the semi-automatic production of a process-capable basic setting for an injection molding machine

Info

Publication number: WO2010057231A1
Application number: PCT/AT2009/000429
Authority: WO
Inventors: Walter Friesenbichler
Original assignee: Keba Ag
Priority date: 2008-11-21
Filing date: 2009-11-12
Publication date: 2010-05-27
Also published as: AT507593A1; CN102264526B; EP2358514B1; AT507593B1; KR101645378B1; KR20110098920A; EP2358514A1; CN102264526A

Abstract

The invention relates to a setting method for the semi-automatic production of a process-capable basic setting for an injection molding machine (1) for processing molding compounds made of plastic. Using an interactive start-up assistant (15) that is integrated in a control apparatus (14) of the injection molding machine (1) by way of software, wherein said start-up assistant (15) guides an operator of the injection molding machine (1) in steps at least through partial sections of the setting process, values or variables for system-relevant process parameters are determined by which a process-capable basic setting is attained as quickly and reliably as possible. For this purpose, prior to starting a test phase, those conditions are defined on a preliminary basis which significantly influence the flow properties of the molding compound, in particular the injection speed and the compound temperature. In addition, a characteristic for the respective flow behavior is determined at least approximately by the start-up assistant (15), in particular a viscosity of the molding compound that is used under said preliminarily established process conditions. Said characteristic for the flow behavior of the molding compound, and optionally other process characteristics which have been determined or specified, are used to establish a provisional, preliminary setting for the target value and/or for the upper threshold value of the injection pressure for the test phase to be started thereafter.

Description

Setting method for the semi-automatic production of a process-capable basic setting for an injection molding machine

The invention relates to a setting method for the semi-automatic production of a processable basic setting for an injection molding machine for processing molding compositions of plastic, as specified in claim 1.

In the claimed method is a semi-automatic, reproducible and reliable as possible determination and adjustment of the most important operating and process parameters of a plastic injection molding machine, the aim of this adjustment method is when using a new or changed combination of tool, material and injection molding as quickly as possible to find a process-ready initial setting or to achieve the most stable basic setting possible.

As is known per se, the plastic injection molding process represents a direct and fully automatable way of producing a finished part from a raw material, generally requiring little or no post-processing of the molded part obtained and ensuring a high reproduction accuracy. An injection molding process enables cost-effective and rapid production from simple to extremely complex plastic parts in high and highest quantities. This, together with the diverse properties of processable plastics, such as thermoplastics, thermosetting plastics or elastomers, justifies the tremendous importance of the injection molding process in modern production technology, with injection molding processes frequently being regarded as the most highly developed processing processes in plastics processing.

In the conventional injection molding a preferably macromolecular work or plastic, which is supplied by a raw material manufacturer usually as a powder or granules, transferred to a flowable state and pressed into a multi-part mold tool in which this molding material then solidifies and Molded part is removed or ejected after opening the mold tool. Numerous parameters and multi-layered dependencies of the various process variables of material, tool and machine result in a rather complex setting process, which is only of correspondingly high qualified personnel with sufficient reliability, safety and efficiency. The manufacturers of the injection molding machines often offer courses for the operators of the machine operators, in which different procedures for a successful initial setting are taught. The training of these operating personnel represents a not inconsiderable cost and time factor.

Therefore, there has long been a desire and the desire to automate the entire injection molding process including the setup as possible to improve the reproducibility of the quality of manufacture, to simplify the operation and adjustment of the injection molding and as much as possible the necessary expertise in the control to integrate the machine.

The complete adjustment process of an injection molding machine is usually divided into a determination of a process-capable initial setting and a subsequent optimization of the initial setting during the ongoing injection molding process. The inventive method relates to the semi-automatic, guided and reliable as possible determination of a process or functional initial setting. The initial setting thus obtained is then the starting point for the subsequent optimization phase in the current process.

In the past, investigations and work have already been carried out with the aim of at least partially integrating this setting process and the relevant expert knowledge into the machine control. Corresponding work in this field was carried out, for example, at the Institute of Plastics Processing at the University of Leoben in Austria. See, for example, the diploma thesis of Eva-Maria Kern at the Institute for Plastics Processing at Montanuniversität Leoben: "Approach strategy and optimization of an injection molding machine".

Further relevant publications on the topic of the setting of injection molding machines are as follows:

Langecker GR: Approach strategy. Kunstsoffe 7/1995. Carl Hanser Verlag. Gissing K., Knappe W: Delay-dependent switching from injection to holding pressure. Austrian plastics magazine 12/1981.

Sarholz R .: Computational estimation of the injection molding process as a tool for machine setting. Dissertation at the RWTH Aachen, 1980.

The implementation of a control-based approach wizard based on the former work has already shown promising results for a certain number of machine, material, and tool combinations. A special feature of this concept is the very universal approach, which with a minimum of basic information on material, tool and machine is the Auslangen and thus can be used without special adaptation work for a variety of different injection molding machines and applications. Such a start-up assistant, after initially entering a small amount of data about the plastic material used and the configuration of the molding tool and injection molding machine, which data is to be entered by the operator, performs a series of trial manufacturing cycles, the resulting molded parts being easily inspected Quality features are to be evaluated by the operator. The evaluations of the operator are used by the start-up assistant for the planned change of the operating parameters, so that the injection molding process gradually leads to molded parts with sufficiently good quality. The specifications and adjustments made by the start-up assistant are based on recommendations of the material manufacturer, the machine manufacturer as well as on underlying physical relationships and models for sub-processes of the injection molding process. The scope of the data to be provided by the operator, the effort required to assess and evaluate the parts produced on a trial basis as well as the required specialist knowledge about the parameterization of the injection molding process are thus reduced by the technical specifications or support of the startup assistant.

These adjustment methods are performed according to a safe and reproducible scheme for the injection molding machine and the molding tool. This scheme minimizes the risk of damage or misuse. Nevertheless, hitherto cases and combinations of material, tool and machine have been observed for which no satisfactory results could be found with the start-up assistant described above. In particular, case by case initial settings were not sufficiently good Quality has been achieved or sufficiently good results have been achieved only after a disproportionate number of trial cycles and parameter adjustments.

It is therefore an object of the present invention to improve the previously known method to the effect that, in the case of an extended number of combinations of material, tool and machine, with as small a number of test cycles and with greater reliability, as a successful basic or Initial setting for a sufficiently good quality of the molding leads.

This object is achieved by the measures according to claim 1.

An advantage resulting from the procedure according to the invention lies in the fact that a basic setting can already be found after a short period of time, which ensures a higher quality of the molded parts produced with relatively high reliability. As a parameter influencing the semiautomatic initial setting, the large, generally possible value range of the flow behavior, in particular the viscosity, of the workable plastics or molding compositions was identified. Since these are so-called pseudoplastic materials, this viscosity is not merely dependent on the mass or the processing temperature of the materials or molding material, but is the flow behavior or the viscosity of the molding composition, especially of the respective present or chosen Discharge or flow rate, ie dependent on the injection rate of the molding material. In this case, an increased discharge or flow rate of the plastic melt causes increased shear and Entschlaufung the polymer chains of the plastic melt, whereby the flowability of the plastic melt increases, ie decreases their viscosity. This is where the inventive, semi-automatic adjustment method begins. The decisive advantage of the control-technically guided or semi-automatic initial setting according to the method sequence according to the invention thus lies in the fact that a reproducible basic setting of the machine which is relatively independent of the relevant specialist knowledge of the operator and already excellent in terms of production quality and cycle duration is obtained. The adjustment process is still carried out in a particularly functional or process-reliable manner, so that damage to the machine and tool is reliably prevented. In the continuing measures according to claim 2, it is advantageous that a relatively reliable determination of the flow behavior, in particular the viscosity of the plastic melt, which is as free as possible from external influences, is achieved. In particular, at least one injection process is carried out only through the nozzle into the open, ie without an attached mold tool, even before the start of the sample production cycles with the tool attached. From the occurring flow rate, the measured back pressure at the nozzle and from the geometry of the nozzle, a parameter for the viscosity of the material mass is then obtained or calculated. This viscosity parameter is then used to adjust the output values and / or the iteration step sizes for subsequent sample manufacturing cycles.

The measures according to claim 3 and / or 4, a reliable detection of the melt viscosity and the respective flow behavior of the plastic melt can be achieved. In addition, the respectively required sensor systems or detection means for detecting the corresponding parameter values are extremely functionally reliable. Furthermore, in the case of most types of injection molding machines, no separate or no additional measuring means are to be implemented in order to be able to determine the respective present viscosity of the plastic melt at least approximately by calculation.

Also advantageous are the measures according to claim 5, since thereby the highest viscosity or the largest viscosity of the molding composition is used as the starting point for the settings of the dependent thereon process parameters of the injection molding machine. As a result, the highest possible degree of form filling is ensured, so that it is possible to move to a regular production phase relatively quickly.

A relatively short-term successful setting process or a setting procedure with relatively few iteration cycles can also be achieved by the measures according to claim 6. In particular, by taking into account existing material-specific empirical values for the viscosity and their dependence on the respective discharge or flow rate of the plastic melt, good initial values are found for the subsequent sample cycles and a process-ready basic setting is thus produced as quickly as possible or with only a few sample cycles. In the measures according to claim 7, it is advantageous that a suitable limit value for the injection pressure is found without a larger number of iterative tests, in which the mold tool is completely filled during the adjustment phase on the one hand, but is also not oversprayed, so that no or only negligible burrs occur on the molded parts. It also ensures that no overuse or even damage to the mold tool occurs.

By means of the iterative, test-proof procedure according to claim 8, a process-capable setting is determined with high reliability relatively quickly, according to plan and reproducibly, with which qualitatively corresponding molded parts can be produced.

By means of the advantageous measures according to claim 9, on the one hand, checks can be carried out to what extent the respective process parameters have developed or changed in terms of value. From this, the operator can derive corresponding know-how and thus further speed up future setting procedures. In addition, a database can be constructed by means of which the respectively appropriate or hitherto successfully applied settings can be simply assigned to the varying settings or configurations of the machine, in order to subsequently retrieve and reapply them in a simple manner. In addition, situations, conditions and the setting procedures carried out by the setting wizard and set values are documented to identify problem cases and to further optimize the setting wizard.

The measures according to claim 10 ensure that only authorized operators can make changes or adjustments to the settings of the injection molding machine. As a result, impairments of property or quality losses due to improper manipulation of the settings are avoided. In addition, it is ensured that only appropriately authorized or instructed operators can perform the respective operating or Einstellhandlungen. Furthermore, this ensures a corresponding traceability, which results in increased responsibility for various changes in the machine settings. The measures according to claim 11 on the one hand, the probability of errors during the adjustment process can be reduced. In addition, it is thereby made possible to accelerate the setting process on the injection molding machine again.

By means of the measures according to claim 12, the operator retains the full decision-making power with regard to the procedure or scope of support recommended by the start-up assistant. In particular, the operator can decide at any time freely whether support by interaction with the startup assistant is required for the respective adjustment phase or not. For example, assistance can be claimed only for those process phases in which such a process appears necessary. On the other hand, in those setting phases in which no assistance is required, the start assist can be deactivated and, as a result, a faster progress in the setting procedure may be achieved.

By means of the measures according to claim 13, a practicable "exit possibility" is created, by means of which an operator can carry out an orderly abortion of the method when special circumstances occur, for example when detecting a mistake or error in the setting or configuration of the injection molding machine. In particular, a disadvantageous, rigorous shutdown of the start-up assistant by an operator, which can lead to damage in complex injection molding machines and processes, thereby at least largely avoided.

The measures according to claim 14, a so-called endless loop is prevented. In particular, if a satisfactory molding quality is apparently not achievable with the existing configuration, the setting process is terminated with a corresponding hint.

The measures according to claim 15 ensure that already proven or optimal process parameters are maintained and can be used if they continue to be regarded as most suitable. In addition, in the event of an unsuccessful completion of the adjustment procedure assisted by the startup assistant, previously used values or process parameters can be used at any time. Finally, the measures according to claim 16 are advantageous since this makes it possible to reduce the knowledge required by the operator about the material used to a correspondingly identified identifier. Several process parameters which are advantageous or restrictive for the processing of the respective material do not have to be read and entered from data sheets or tables of the manufacturer in a laborious and potentially error-prone manner, but are set automatically on the basis of the material code. The comfort, but also the efficiency with regard to finding a process-capable basic setting are thereby significantly increased. In addition, this also significantly reduces the likelihood of incorrect settings or incorrect operation.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

In each case, in a highly simplified, schematic representation:

Figure 1 shows the structure and the essential components of an injection molding machine.

FIG. 2 shows the plasticizing unit of an injection molding machine; FIG.

3 shows an embodiment of a nozzle of an injection molding machine;

4 shows a diagram comprising the parameters viscosity, injection pressure and average wall thickness of the molded part to be produced.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. The position information selected in the description, such as top, bottom, side, etc. are also related to the directly described and illustrated figure, and these position data are to be transferred analogously to the new position in the event of a change in position. Furthermore, individual features or combinations of features from the shown and described described different exemplary embodiments stand for themselves, inventive or inventive solutions.

All statements on ranges of values in the description of the subject should be understood to include any and all sub-ranges thereof, e.g. the indication 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

In Figs. 1 and 2, the most essential components of a standard injection molding machine 1 for processing plastics are shown greatly simplified. Such an injection molding machine 1 for carrying out a plastic injection molding method has inter alia a machine bed 2, a closing unit 3 for opening and closing a clamped, multi-part mold tool 4 and a plasticizing unit 5, with which the raw material is taken from a storage container 6, is transferred to the flowable state and pressed through a nozzle 7 in the closed mold tool 4.

The mold tool 4 is frequently heatable or coolable by means of a tempering or cooling device in order to enable the crosslinking process in the processing of elastomeric plastics or to effect an optimal or rapid solidification of the molding composition by cooling in the case of thermoplastics.

Among other things, the plasticizing unit 5 comprises a hollow cylinder 8 which can be heated in several zones. A worm shaft 9 which is rotatable and also displaceable in the longitudinal direction transports the plastic granules falling from the storage container 6 into the front section of the plasticizing unit 5. The material becomes to a certain, part by a heater 10, but above all melted by the friction heat occurring during transport, ie plasticized. In particular, the granules are not only conveyed by the worm shaft 9 but also sheared, as a result of which the plastic melts and gradually plasticises or homogenizes. The plasticized material accumulates in the front section, in particular in a nozzle prechamber 11 of the plasticizing unit 5, wherein at the same time the worm shaft 9 recedes towards the rear or opposite the nozzle 7 the plasticizing 5 increasingly distanced. As soon as a sufficient amount of plasticized molding material is present in the nozzle prechamber 11, the plasticizing phase is completed. The nozzle prechamber 11 or the nozzle 12 in this case represents a preferred detection section 12 for the temperature of the plastic melt and / or for the respectively occurring injection pressure of the plastic melt, ie the molding compound.

Then, in the so-called injection phase, the plasticized material is ejected through the nozzle 7 in the front portion of the plasticizing unit 5 and pressed into the mold tool 4 abutting the nozzle 7 until it is completely filled. The injection of the molding material is carried out by an initially speed-controlled, axial forward sliding of the worm shaft 9, wherein a non-return valve 13 at the front end of the worm shaft 9 prevents retraction of the molding material through the worm gear. The worm shaft 9 thus acts in the injection phase as a piston.

At the end of the injection phase, the mold tool 4 is completely filled and it is switched by the speed-controlled, axial forward movement of the worm shaft 9 to a pressure-controlled movement, with only a relatively small way is covered, until the worm shaft 9 finally stops. This phase is referred to as a post-pressure phase, in which the shrinkage associated with the cooling or crosslinking of the molding compound in the mold tool 4 is compensated by further low Nachfördern molding compound or by the solidification under pressure. This post-press phase is particularly important for the quality of the finished molded parts. The holding pressure phase is terminated as soon as the molding compound is solidified at least in the sprue of the mold tool 4. Then the axial pressure is switched off on the worm shaft 9, the nozzle 7 of the plasticizing unit 5 is closed and the forming tool 4 is separated from the nozzle 7 in order to prevent unwanted heat transfer from the nozzle 7 to the forming tool 4 during the remaining cooling phase to avoid.

Subsequently, the cooling or crosslinking phase begins in which the molding in the mold tool 4 at least partially solidifies. After sufficient or complete solidification, the mold tool 4 is opened and the molded part removed or ejected. During the cooling phase, material is usually already melted again in the plasticizing unit 5 for the next production cycle. After closing the mold Tool 4 and the reapplication to the nozzle 7 of the plasticizing 5, the injection molding machine 1 is ready for the injection process of plasticized molding compound for the next molding or the next part series.

It should be noted that the above-described flow of the injection molding process is sometimes greatly simplified and exemplary and is intended only for guidance. Numerous detailed illustrations and variants can be found in the extensive specialist literature.

For the production of a processable sequence, on the one hand, the closing side of the injection molding machine 1 is to be considered, for example, the opening and closing of the mold tool 4, the ejector movement and the mold temperature control. Furthermore, of course, the injection side of the injection molding machine 1, in particular the plasticizing unit 5, has a significant influence on the course of the injection molding process. In this case, for example, the cylinder wall temperature, the movement of the injection unit and the times or parameter parameters during the injection and holding pressure phase are decisive.

Various machine and tool-specific settings such as the opening and closing of the mold, the ejector, the Formsicherungs- pressure and the closing force have no or not appreciable effect on the actual process flow and the quality of the molded parts achieved. Their setting is usually made according to company or manufacturer specific guidelines or these settings are already shown in a control device 14 of the injection molding machine 1 accordingly. An iterative customization of these settings is usually not required.

The focus of the adjustment method according to the invention is therefore in the determination and adjustment of those operating parameters, which significantly determine the process flow and thus the quality of the molded parts obtained. The settings are based on empirical values and guidelines of the raw material manufacturers as well as simple physical relationships for the description of individual sub-processes. However, due to the multiple dependencies of material, mold 4 and injection molding machine 1, the actually suitable setting values can not simply be predetermined, but are usually to be determined in an iterative process. An object of the adjustment method according to the invention Among other things, this involves the determination of these setting values with the least possible number of required iterations and thus the lowest possible number of test production cycles.

For a target-oriented approach strategy, among other things, the influencing variables melt temperature, mold temperature, metering stroke or metering volume, dynamic pressure, injection speed, switching point or switchover criterion to holding pressure, holding pressure, holding pressure time and cooling time must be investigated.

It can be seen from the above explanations that in such an injection molding process there are numerous parameters with complex, mutual influences which represent an increased challenge to the operating personnel for achieving a stable process sequence or for the fastest possible start of a qualitatively satisfactory production process. For the purpose of semi-automatic, guided initial setting of the injection molding machine 1, a start assist 15 is implemented as a program module in its control device 14. This software engineering start-up assistant 15 is implemented in the manner of a so-called wizard, as it is known from many conventional computer-based application programs. In this case, the operator via a user interface, in particular via various input and output means 16 of the control device 14, for example via a screen with touch screen, gradually and systematically passed through the different phases of the initial setting. The control device 14 and / or the start assist 15 can be embodied as an integral part of the injection molding machine 1 and / or as structurally independent, possibly also as a central unit for a plurality of injection molding machines 1.

The approach assistant 15 collects and determines essential data and characteristics about the injection molding tool used, in particular about the molding tool 4, the injection molding material used, in particular the plastic molding compound and possibly the basic operating data or modes of operation of the injection molding machine 1. These data or characteristics are partially entered by the operator and / or automatically determined by test operations.

It is also characteristic of the setting process that usually also a number of trial production cycles are carried out, whereby the produced Parts of the operator in terms of easy-to-determine quality characteristics as objective as possible, but in part to be assessed subjectively. The results of this assessment are entered in each case in the start-up assistants 15 and used by this for further adjustment and improvement of the machine setting, until finally moldings of sufficiently good basic quality can be achieved.

The corresponding setting method can be divided into several phases or sections:

In a first phase, a specification of some essential basic settings concerning the molding tool 4 used and the material used based on material data, as well as a review of important conditions by the operator.

In this phase, for example, the name of the plastic material used and / or its trade name are entered by the operator, whereupon the adjustment ranges of the most important processing parameters or the resulting process limits recommended by the respective manufacturer are automatically imported into the startup assistant 15 from a stored material database become. Among the most important processing parameters include the demolding temperature, the mold temperature, the melt temperature, i. the temperature of the plastic melt, and the plasticizing rate, i. The speed or peripheral speed of the worm shaft 9. The amount of dynamic pressure to achieve sufficient melt homogeneity in plasticizing is also based on recommendations of the material manufacturer and is also dependent on the design of the worm shaft 9. If available, the normally valid for optimal values for the processing parameters preset or otherwise proposed by the startup assistant 15. If manufacturer specifications are missing or if intentionally deviating values are used, these may also be manually changed by the operator. Also, the definition of a new material by the user, as well as their deposit in the database of the start-up assistant 15 is possible in order to be easily retrievable for future uses.

The possible adjustment ranges can also be limited by the start-up assistant 15 as a function of the properties of the respective injection molding machine 1. Such restricting machine properties may be, for example, the maximum injection pressure or the maximum injection speed.

Furthermore, some essential, characteristic data for the mold tool 4 used by the user to specify. Such tool-specific inputs are, for example, the average and the maximum wall thickness of the molded part to be produced and / or the mold tool 4 and optionally further geometric data of the molded part, and certain configurations and embodiments of the mold tool 4, such as whether it is a Execution with a so-called rod gate or with a hot runner acts.

Before starting the semi-automatic adjustment process, the approach assistant 15 checks for the presence of some key constraints and configurations. If an automatic check of individual criteria is technically not possible or not implemented, the operator must check the existence of these conditions and enter the result of this check in an input mask of the start-up assistant 15, for example in the form of a checklist. This ensures that important and possibly safety-relevant criteria are not overlooked or fulfilled. Such criteria are, for example, a correctly mounted mold tool 4, a correctly set mold protection to protect the mold tool 4 from closing when damaged, the

Achieving the correct tool temperature and / or a correctly connected ejector package. Depending on the configuration and material selection mentioned above, other criteria may also have to be checked, such as the achievement of the operating temperature for the hot runner and possibly pre-drying of the plastic granules used, if this should be sensitive to atmospheric moisture.

If the presence of the required conditions has been determined automatically and / or confirmed by the operator, and, in addition, any protective doors and safety devices on the injection molding machine 1 are closed or activated, the next phase of the adjustment process will be after any additional, conscious confirmation by the operator initiated. In the second phase, a series of machine operations or trial manufacturing cycles or part production cycles are carried out and the process variables determined and the identified quality features of the resulting moldings are used to determine suitable setting values or to determine adjustment parameters to be optimized for a process-capable initial setting. It is essential that at least one approximate determination of the viscosity of the plasticized molding composition or a determination of a similar parameter, which characterizes the flow properties of the plastic material, in particular the plastic melt, carried out by means of the control device 14 or with involvement or guidance of the Anfahrassistenten 15.

According to an advantageous embodiment, a so-called empty shot is first carried out by the plasticizing unit 5, i. A discharge of material takes place only through the nozzle 7 of the injection molding machine 1 into the free space instead of into the molding tool 4. The plasticizing speed, i. the volume flow V and the pressure or pressure drop occurring at the nozzle are determined and, via the known geometry of the nozzle 7, the viscosity of the melt is calculated at least approximately. In this melt discharge preferably the same temperature of the melt and the same injection speed control technology specified, which are also provided as output values for the subsequent trial manufacturing cycles with a correspondingly applied mold 4. The determination of the initial value for the injection speed is preferably in dependence on the average wall thickness of the molded part or the ratio of flow length to wall thickness of the molded part, if this is known.

The thereby occurring at the nozzle 7 pressure difference .DELTA.p is determined or the melt pressure ps is measured in the nozzle pre-chamber 11, or starting from one on the

Worm shaft 9 acting force, in particular via the hydraulic pressure, calculated. If necessary, this value is corrected by the external ambient pressure P _A , although the ambient pressure P _{A can} also be neglected. This pressure difference Δp is then used to calculate the viscosity η according to the following formula: k - Ap - e ₀ n =

V

Where the respective formula symbols stand for the following parameters or physical quantities: η .... viscosity (Pa * s or mPas)

Δp ... pressure drop or required pressure (Pa) e ₀ ... 0.815 (constant)

V ... Volume flow (mnvVs) k ... Nozzle conductivity (mm ³ )

The pressure drop at the nozzle 7 can be determined as follows:

Where the respective formula symbols stand for the following parameters or physical quantities:

Ps ... Pressure of the viscous mass in the screw or nozzle prechamber (Pa) P _A ... outer ambient pressure (Pa) The nozzle conductance k, which is further required for calculating the viscosity η, is in relation to the exemplary nozzle geometry with a round cross section corresponding to FIG Representation in FIG. 3 as follows:

π ^■ R ₁ π ^■ R ₂ π • R _λ

The volume flow V can be determined via the plasticizing speed v _s as follows:

4

The respective formula symbols stand for the following parameters or physical variables: v _s ... Plasticizing speed or feed rate of the worm shaft D ... Diameter of the worm shaft

From the determined viscosity η and the mean wall thickness d of the molded part as a further parameter, a suitable initial value will now be obtained from a diagram 17, as exemplified in FIG. 4, in particular from a corresponding data or parameter matrix, ie a table determined for the injection pressure, which is used for the subsequent phase for determining the molding volume. In this table, in which simple practical form usually practicable empirical values are shown, can thereby be determined by interpolation of the respective injection pressure at least approximately. Depending on the type of injection molding machine 1, the injection pressure or the pressure limitation to be set can be indicated as absolute pressure or as a percentage based on the maximum permissible pressure of the injection molding machine 1.

The diagram 17 according to FIG. 4 qualitatively illustrates the content of such a table. In this table, the initial values for the injection pressure and for the pressure limitation, respectively, to be set for different average wall thicknesses d of the molded part are in percent of the maximum permissible or the maximum possible Injection pressure of the injection molding machine 1 as a function of the determined viscosity η registered the plastic melt. These values for the injection pressure are based on empirical worlds or these dependencies are preferably determined experimentally.

The values in the diagram 17 or from the corresponding data-technical table thus flow into the start-up assistant 15 or into the mode of operation of the control device 14 in order to determine a suitable operating point, in particular injection pressure. This diagram 17 is to be regarded as absolutely exemplary and partially distorted.

From now on, a number of machine operations or trial-and-error production cycles are carried out with each mold tool 4 applied to the plasticizing unit 5. In this case, a preliminary determination of the required Dosierweges on the plasticizing unit 5 and a provisional determination of the subsequent switching point from the speed-controlled injection process to the pressure-controlled Nachdruckphase.

At the beginning of this operation, the plasticizing unit 5 or its worm shaft 9 is dosed to approximately 95% of the maximum possible metering path. In this case, plastic granules from the reservoir 6 is plasticized by the heated screw shaft 9 and transported into the section between the screw shaft 9 and nozzle 7, ie in the Düsenvorkammer 1 1, wherein the screw shaft 9 is simultaneously pushed backwards by the material transported to the front. The axial drive, in particular the sliding hydraulic of the worm shaft 9 counteracts the retraction of the worm shaft 9 a certain resistance and thus ensures a certain back pressure in the Düsenvorkammer 1 1. The position of the worm shaft 9 is monitored during the metering by the control device 14. At the Reaching preferably about 95% of the maximum stroke and thus also 95% of the maximum possible dosing volume of the dosing is terminated, ie, the rotational movement of the worm shaft 9 is stopped. The rotational speed of the worm shaft 9 is usually based on information from the material manufacturer.

Subsequently, an exclusively pressure-controlled or pressure-limited injection process in the mold tool 4. The height of the injection pressure used is determined by control technology as a function of the previously determined viscosity η the mass and the minimum wall thickness of the molded part. The exclusive pressure control during the trial injection process ensures that the molding tool 4 is not "over-injected" despite unknown volume, ie that no burrs occur or that the mold tool 4 is not damaged by pressure peaks from the previously determined viscosity η of the plasticized plastic mass also ensures that the mold tool 4 is filled as completely as possible and the recording volume of the mold 4 to be determined is determined as accurately as possible, but without the mold 4 in this Determination of the intake volume to overspray.

Via the control device 14, the end of the forward movement of the worm shaft 9 is detected. This can e.g. via a velocity gradient method. At the end of the forward movement, an at least extensive filling of the mold tool 4 is achieved and the approach assistant 15 determines the preliminary dosing path from the path of the worm shaft 9 that has been traveled in the axial direction. Furthermore, the approach assistant 15 sets the provisional switchover point for the emphasis phase as the starting point for the subsequent trial manufacturing cycles. Further details and variants of this step can be found in the introductory study paper.

After the investigations described above, several trial-and-error production cycles or injection tests follow, the injection process being carried out in a conventional manner with reduced speed, but in contrast to a regular production cycle during the cooling time of the molding compound, no pressurization is applied. In usually several cycles trial parts are manufactured and then tested. If necessary, an attempt is then made by adapting process parameters to Grad of the mold tool 4 and the shape of the finished moldings gradually improve and, where appropriate, to correct the position or the switching criterion for switching to reprint.

If it is possible to fill the mold tool 4 with the selected parameters to at least 95%, and if the set limit pressure is not exceeded, then the next phase is changed, in which the appropriate amount of emphasis is determined via the start-up assistant 15.

If the mold filling was found to be inadequate by the operator, the approach assistant 15 attempts a gradual adaptation of the below-mentioned process parameters within the process limits specified by the injection molding machine 1, the molding tool 4 and the material:

Increasing the injection pressure limit or the injection pressure

Increasing the injection speed Increasing the melt temperature Increasing the mold temperature.

The adaptation of the above parameters takes place in an order or with a priority in which the parameters are listed.

The increment of the changes made is preferably determined by a certain percentage of the margin between the possible and the recommended process limits. In particular, the change in the value of the respective parameter can be a defined, maximum percentage. Accordingly, a change in value with, for example, 20% of the span between the manufacturer-specified limits of minimum and maximum melt temperature can be defined. In the case of multiple adaptation of a parameter in several successive test cycles, however, differently sized step sizes may also be provided. In particular, the step size of the adaptation can also be selected depending on the distance of the parameter value to a predetermined limit value. If, after a certain number of trial-and-error production cycles, a sufficient degree of filling is not achieved or no improvement is achieved, the setting procedure is aborted with an error message from the start-up assistant 15. Further details and variants of this phase can be found in the aforementioned study.

After successful completion of trial manufacturing cycles as described above, at least one complete manufacturing cycle is performed with the previously determined process parameters including pressurization. That is, at the end of the injection process and during the cooling process in which a material shrinkage takes place, the viscous material is further pressed with a certain pressure in the mold tool 4 or nachgefördert until the material in the sprue of the mold tool 4 finally freezes. The height of the initially selected reprint and the technically possible and recommended limits are based on information from the manufacturer of the injection molding machine 1 and / or the material.

The required hold-up time is determined by the time to which the material in the runner is sufficiently solidified and closes with it. This time can be determined approximately from the so-called "cooling time equation":

T ^w

^N holding pressure in s 5 wall thickness in the area of the sprue

Cl 9 e ^f> effective thermal conductivity (of the material) in mm / s

T ^M melt temperature in ⁰ C

T ^w tool temperature in ° C

T ^e maximum demolding temperature

Is the finished molded part after inspection by the operator completely filled or complete in terms of its desired shape and it has no or only marginal burrs or sink marks and no significant delay and also has the surface of the molding of sufficient quality, the approach assistant 15 changes to the next and final phase.

If the quality of the last part produced in each case is found to be insufficient, the reprinting is gradually increased, with subsequent implementation of a further production cycle. If no improvement in the quality is detected or exceeded a certain maximum number of manufacturing cycles, the approach assistant 15 aborts the process with an error message.

In the final phase of the adjustment process, only one adaptation of the mass cushion, i. the amount of material which remains at the end of an injection cycle in the nozzle pre-chamber 11 or in the screw antechamber. For this purpose, the position of the axial end position of the worm shaft 9 after the metering and the position of the switching point or the switching condition are postponed so that at the end of the injection cycle a mass cushion of about 10% of the metering remains in the Düsenvorkammer 11.

To control a production cycle is finally carried out with the final set of manufacturing parameters, stored the parameter set for the subsequent manufacturing process in the control device 14 of the injection molding machine 1 and the start assist 15 terminated properly.

According to an advantageous embodiment, the inputs and operator actions of the operator, the parameters used to carry out the trial production cycles and the process variables determined thereby are stored in a log. Regardless of this, it may be expedient to detect an identity and / or authorization of the operator prior to the start of the setting process and to carry out the setting procedure by means of the start-up assistant 15 only if the authorization has been determined accordingly.

Furthermore, the input of the information by the user concerning plastic material, mold tool 4 and / or injection molding machine 1 may include the electronic detection or read-out of machine-readable data carriers, in particular barcodes or transponders. It is also expedient if the adjustment method at least one point aborted by a command of the operator and the setting or Anfahrassistent 15 can be terminated prematurely.

According to a further embodiment, the start assist 15 can be terminated prematurely by a command of an operator, with the start assist 15 being the one

Sub-processes are still completed or executed, or by start-up assistant 15 those states are still made by which a damage-free shutdown and trouble-free recommissioning of the injection molding machine 1 is ensured.

An effective measure is furthermore to continuously record the number of production cycles carried out in the test phase and to automatically abort the setting process when a predetermined maximum number of trial phases is exceeded without achieving a satisfactory production quality and to output an error message via the startup assistant 15. Furthermore, it is expedient to store existing or previously set process parameters via the start-up assistant 15 and to restore the stored process parameters in the event of premature termination of the setting process.

A practicable measure also lies in the approach assistant 15 accessing a material database when determining suitable setting parameters and process limits and reading out one or more of the following variables as a function of a material designation or data record identification entered by the operator: the minimum and maximum melt temperature; the minimum and maximum tool temperature; the maximum demolding temperature; and the thermal conductivity of the plastic material.

The exemplary embodiments show possible embodiments of the adjustment method or of the start-up assistant 15, wherein it should be noted that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments are possible with each other and this variation possibility due to the teaching to technical action by objective invention in the skill of those working in this technical field expert. So there are also all conceivable variants which can be combined by combinations. individual details of the illustrated and described embodiments are possible, includes the scope of protection.

The object underlying the independent inventive solutions can be found in the description.

REFERENCE NUMBERS

1 injection molding machine

2 machine bed

3 clamping unit

4 mold tool

5 plasticizing unit

6 reservoir

7 nozzle

8 hollow cylinders

9 worm shaft

10 heating

11 nozzle prechamber

12 detection section

13 non-return valve

14 control device

15 Approach assistant

16 input and output devices

17 diagram

Claims

Patent claims

1. Setting method for the semi-automatic production of a process-capable basic setting for an injection molding machine (1) for processing plastic molding compounds, comprising a control technology-supported determination of suitable setting parameters by means of a software in a control device (14) of the injection molding machine (1) integrated interactive start-up assistant (15) in which starting assistance (15) guides an operator of the injection molding machine (step 1) at least through sections of the setting process by exchanging system-relevant instructions and information between the start-up assistant (15) and an operator by means of an operator interface of the control device (14) Setting process includes at least the following phases:

Al.) Input of basic information about the plastic material used, the mold used (4), the injection molding machine used (1) and / or other predetermined or desired machine configurations, process conditions or process limits by an operator;

A2.) Starting a test phase (V) in which several completely or at least partially performed manufacturing cycles are performed with different process parameters and the process variables occurring are determined automatically or by interaction with an operator by fulfilling certain test criteria for the finished molded parts by an operator and the respective result is entered in the start-up assistant (15), and wherein an automated determination of a set of suitable setting parameters and process limits on the basis of Bl.) the basic information entered by an operator,

B2.) Of in the start-up assistant (15) software and / or database-technically illustrated rules and empirical values for selecting suitable setting parameters, as well as on the basis of

B3.) The process parameters determined in the test phase (V) and the determined test results, characterized in that before starting the test phase (V)

Cl.) Those process conditions which have a significant influence on the flow properties of the molding material, in particular the injection rate and the melt temperature, are provisionally

C2.) A parameter for the respective flow behavior, in particular a viscosity of the molding compound used is at least approximately determined by the start-up assistant (15) under these provisionally determined process conditions,

C3.) And this characteristic for the flow behavior of the molding material and optionally further, determined or predetermined process parameters for setting a tentative, provisional set value for the setpoint and / or the upper limit of the injection pressure for the test phase (V) to be subsequently started is used.

2. The method according to claim 1, characterized in that for determining the characteristic for the flow behavior of the molding composition used, a free ejection without an attached mold tool (4) is performed.

3. The method according to claim 2, characterized in that the ejection process at a predetermined discharge or flow rate and / or with a predetermined mass flow through a transition to the mold tool (4) forming nozzle (7) of a plasticizing (5) Injection molding machine (1) and at a predetermined temperature of the molding compound and / or the plasticizing unit (5) takes place and thereby the pressure or pressure drop occurring at the nozzle (7) determined directly or indirectly, in particular on the hydraulics for a screw shaft (9) of the plasticizing unit (5) is measured.

4. The method according to claim 3, characterized in that from the Ausstoßbzw. Flow rate, the determined pressure drop and the respective geometric data of the nozzle (7), the viscosity or an equivalent characteristic for the flow behavior of the plasticized molding material from the Anfahrassistenten (15) is determined at least approximately by calculation.

5. The method according to claim 3, characterized in that the pressure in a nozzle prechamber (11) of the plasticizing unit (5) is determined or measured several times during the ejection of molding material and for determining the flow behavior, in particular the viscosity of the molding composition of the maximum value several individual measurements or several individual calculations is used.

6. The method according to claim 1, characterized in that for the determination of the characteristic for the flow behavior of the molding compound used one of the molding compound used table with empirical values or specifications of the material manufacturer or an approximation formula is used, from which in dependence on at least the ejection or Flow rate and the temperature of the molding composition is determined at least an approximate value for the characteristic of the flow behavior of the molding material.

7. The method according to any one of the preceding claims, characterized in that the characteristic for the flow behavior of the molding material and an average wall thickness of the molded part to be produced are used as input variables for a table or an approximation formula for determining an initial starting value for the upper limit of the injection pressure.

8. The method according to any one of the preceding claims, characterized in that the test phase (V) is subdivided into at least the following phases:

Dl.) At least approximately determination of the volume of the cavity in the mold tool (4) by a pressure-controlled or pressure-limited injection process of molding material and subsequent, provisional determination of the switching point to a holding pressure phase for the molding material and determination of the metering volume based on the in the mold tool ( 4) sprayed molding compound and based on the determined by the operator filling level of the mold tool (4);

D2.) One or more times carrying out trial manufacturing cycles each without emphasis phase, wherein subsequently depending on the respective achieved or determined degree of filling of the mold tool one or more of the parameters comprising injection pressure limitation, injection speed, switching point condition on holding pressure phase, temperature of the molding material and / or the mold tool with the aim of increasing the degree of filling of the mold tool (4) are adapted;

D3.) One or more times carrying out trial manufacturing cycles each using reprinting, whereby subsequently, depending on the respectively achieved or determined quality, in particular the surface quality of the produced molded part, the amount of reprinting with the aim of improving the surface quality is adjusted.

9. The method according to any one of the preceding claims, characterized in that the inputs and operator actions of the operator, the parameters used to carry out the trial manufacturing cycles and thereby determined process variables are stored in a log.

10. The method according to any one of the preceding claims, characterized in that before the start of the setting process, an identity and / or authorization of the operator is detected and the setting method is executable only when appropriately established authorization.

11. The method according to any one of the preceding claims, characterized in that the input of the information by the user regarding plastic material, mold tool (4) and / or injection molding machine (1) the electronic detection or read-out of machine-readable data carriers, in particular of barcodes or Transponders.

12. The method according to any one of the preceding claims, characterized in that the setting process aborted at least one point by a command of the operator and the start assist (15) can be terminated prematurely.

13. The method according to any one of the preceding claims, characterized in that the approach assistant (15) can be terminated prematurely by a command of an operator, wherein the start-up assistants (15) those sub-processes are still completed or executed, or by Anfahrassistenten (15) those states are still produced, by which a damage-free shutdown and easy Wiederinbetrieb- would take the injection molding machine (1) is ensured.

14. The method according to any one of the preceding claims, characterized in that the number of executed in the experimental phase (V) manufacturing cycles continuously recorded and exceeded when exceeding a predetermined maximum number of trial phases (V) without achieving a satisfactory manufacturing quality, the setting process automatically and an error message is issued.

15. The method according to any one of the preceding claims, characterized in that when calling the start-up assistant (15) stored the pre-existing process parameters and the premature termination of the adjustment process, the stored process parameters are restored.

16. The method according to any one of the preceding claims, characterized in that the approach assistant (15) accesses a material database in the determination of suitable adjustment parameters and process limits and reads one or more of the following variables in dependence on a entered by the operator material designation or data record identifier and used for the adjustment process:

- the minimum and maximum melt temperature;

- the minimum and maximum tool temperature;

- the maximum demolding temperature;

- The thermal conductivity of the material.