• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A method for determining a sealing point in a casting process, wherein casting material is filled in a fluid phase at least once under pressure in a mold cavity (4), wherein at least one course of a characteristic of the pressure of the casting material size is measured from the at least one curve a rate is determined by changes and from the rate of changes the seal point is determined.
    公开号:AT514836A1
    申请号:T756/2013
    申请日:2013-09-30
    公开日:2015-04-15
    发明作者:Georg Dipl Ing Dr Pillwein；Josef Dipl Ing Giessauf；Matthias Dipl Ing Simma
    申请人:Engel Austria Gmbh；
    IPC主号:
    专利说明:

    The present invention relates to a method for determining a sealing point in a casting process with the features of the preamble of claim 1 and a shaping machine.
    Such casting processes include, for example, injection molding processes or die casting processes.
    Under a forming machine is any machine to understand, which is suitable to fill casting material in a fluid phase under pressure in a mold cavity. In particular, these are injection molding machines, die casting machines, transfer molding and the like.
    During the injection of casting material, a screw or a piston is moved in the direction of the mold cavity. This movement can be specified as a velocity profile over path or time, as a pressure profile over a path or time, or as a path profile over time. In practice, it is common to use a combination of these in succession. The implementation of initially a speed-controlled injection phase with a subsequent pressure-controlled phase (holding pressure phase) has become particularly established. In the post-pressure phase, the shrinkage associated with the cooling of the material in the mold is to be compensated in part. In general, one will try to maintain the emphasis as long as possible. The transfer of pressure into the cavity is possible until the material in the thinnest cross-section - in most cases the gate of the component - solidifies so far that no material flow is possible. A reprinting period up to this point, also called the sealing point, is therefore to be striven for. Too short holding times, ie early pressure reduction before sealing the sprue or bleed lead to a flow of material from the cavity. High shrinkage, sink marks, and poor reproducibility are the result. On the other hand, too long hold-up times can increase the overall cycle time, or result in increased machine power consumption.
    From the literature, a method for Siegelpunktsbestimmung is known. In this case, the cycle time is changed by a certain amount from cycle to cycle, and determines the shot weight for each shot of this series of experiments. Now in a diagram, the shot weight on the holding time is carried on.
    The graph shows that after a certain holding time - the victory point *, the weight no longer increases with increasing holding time (see Figure 3a).
    The disadvantage of this method is that many different parts must be weighed and sometimes very long series of tests must be performed.
    The object of the invention is therefore to provide a simplified method for determining the sealing point. Furthermore, a shaping machine for carrying out such a method is to be provided.
    This object is achieved by a method having the features of claim 1 and a shaping machine having the features of claim 18.
    This is done by measuring at least one course of a variable characteristic for the pressure of the casting material, from which at least one course a rate of changes is determined and from the rate of change the sealing point is determined.
    By a method according to the invention, a determination of the sealing point can be carried out without weighing the molded parts.
    In order to detect the course of the variable characteristic of the pressure of the casting material, it is practicable to carry out a multiplicity of measurements at different times during the casting cycle. Theoretically, however, the necessary information about the pressure of the casting material can already be obtained with two measuring points as a course.
    For the sake of clarity, reference will now be made to the pressure curve and to the pressure change. In the case that a characteristic variable is measured instead of the pressure, analogous statements apply. By way of example, variables which are characteristic for the pressure can be those which are in a known functional relationship to the pressure.
    Further advantageous embodiments of the invention are defined in the dependent claims.
    Particularly preferred is a method in which at least one pressure profile of the casting material is measured, from which at least one pressure profile a rate of pressure changes is determined and from the rate of pressure changes the sealing point is determined
    If the at least one pressure profile is measured on the injection side, it is preferably provided to use an injection pressure sensor and / or a worm travel sensor for this purpose.
    If the at least one pressure curve is measured on the closing side, it can be provided by measuring at least one of the group of closing force, in-mold pressure, ejector force, bar elongation, tool respiration, deformation of a tool, force and / or pressure on a tool and / or a closing unit measure up.
    In a particularly preferred embodiment, it can be provided that the casting material is acted upon by a variable pressure from a side facing away from the mold cavity side of a gate, by means of an actuator, wherein the at least one pressure profile in the mold cavity is measured. In this case, an injection unit, in particular a plasticizing screw, can be used as the actuator.
    In a further preferred embodiment of the invention, it can be provided that the casting material in the mold cavity is acted upon by means of an actuator with a variable pressure, wherein the at least one pressure profile is measured from one of the mold cavity side facing away from a gate ago. In this case, for example, a closing drive and / or an ejector drive and / or a Kemzug and / or an embossing die can be used as an actuator.
    By additionally modulating a variable pressure on the existing reprint, the influence of the complete freezing of the material in the sprue on the pressure profile signal can be increased. It is of secondary importance whether the variable pressure is applied on the inlet side and measured on the cavity side, or whether the variable pressure is applied on the cavity side and measured on the inlet side. It is crucial for these embodiments that the casting material in the runner is subjected to pressure fluctuations.
    In order to achieve a particularly good propagation of the variable pressure by the casting material and a consequent good detectability of the signal, it can be provided that the casting material with a variable pressure in the form of an oscillating pressure profile, in particular a periodic (for example, sinusoidal, rectangular or triangular) Pressure profile is applied.
    Depending on whether the pressure changes or their rate are recorded over several casting cycles or only a single casting cycle, various criteria for achieving the sealing point can be created. First, the sealing point may be determined as a time at which the rate of pressure change falls below a threshold, or the sealing point may be determined as a time at which the rate of pressure change substantially disappears. This procedure is characterized by a particularly easy determination of the sealing point.
    However, it can also be provided that the sealing point is determined as a point in time at which the rate of the pressure change changes from a first, essentially constant value to a second, essentially constant value. Compared to the previously described procedure is in this embodiment, the
    Determination of the sealing point, although somewhat more difficult. But in principle sufficient for a single cycle for determining the sealing point, without it being necessary to apply an additional variable pressure by an actuator.
    As already mentioned, exactly one casting cycle in which casting material is filled into the mold cavity can be used to determine the sealing point.
    However, it can also be provided that a plurality of casting cycles, in which casting material is filled into the mold cavity, are carried out, wherein the pressure changes, the rate of which is determined, are determined between pressure profiles of different casting cycles, wherein the casting cycles are preferably carried out with different holding pressure times. As a result, the accuracy of the determination of the sealing point can be increased.
    It is particularly preferred that the sealing point is used to determine the holding pressure time. On the one hand, this can be done fully automatically in the system control of a shaping machine. It can also be a Wamhinweis for the operator, if the set reprint is too short or too long, or the calculated setpoint for the reprinting time for the operator are presented as a suggestion. Furthermore, it can be provided to stop machine movements when the determined holding pressure time is reached.
    Further details and advantages of the invention will be apparent from the figures and the associated description of the figures. Showing:
    1a and 1b Schließkraftverläufe and differences in closing force curves for two different holding times,
    2 shows several differences of closing force curves,
    3a and 3b results of a method for determining the sealing point according to the prior art brw. for comparison, a method according to the invention,
    4 shows a reprint profile and the associated tool respiration when carrying out a method according to the invention using a modulated, variable pressure; FIG. 5 shows a variant of the method from FIG. 4 in which two cycles are performed with phase-shifted, variable pressures;
    6a and 6b dosing volume and closing force as a function of time to illustrate a further embodiment of the method according to the invention,
    Fig. 7 shows an injection molding machine according to the invention with electrical
    Closing drive as well
    Fig. 8 shows an injection molding machine according to the invention with hydraulic
    Closing drive.
    To illustrate the emergence of Figure 2 are shown in Figures 1a and 1b for a two Schließkraftverläufe and on the other hand, the difference of the two clamping force curves. The closing force curves differ in that they were operated with different holding times when they were created. How this difference in the closing force curve is reflected, is clear in Figure 1b. Due to the slightly longer holding time, additional casting material is conveyed into the cavity, which increases the pressure in the cavity and consequently the closing force. Of course, a slight time shift between the maxima of the two closing force curves can be seen, which is also a result of the different length of holding pressure times.
    FIG. 2 shows several differential closing force profiles as shown in FIG. 1b. Casting cycles were carried out with holding times between 0.2 and 2.6 seconds, with time intervals of 0.2 seconds each being used. The curves are difference curves between clamping force curves, which are each characterized by 0.2 seconds of different holding pressure time.
    As can be seen, starting from a certain holding time, a uniform difference curve sets in, whereby only the maximum of the difference curves around the
    Difference in reprinting time is shifted. From this it can be concluded that from the time when the uniformity of the difference curves sets in, the sealing point has been reached. This is illustrated more clearly in FIG. 3b, in which in each case the difference between the maxima-which in this case represents the rate of the pressure change-is plotted against the holding pressure time. The criterion used here is that the applied rate of pressure changes falls below a threshold value or substantially disappears. For comparison, FIG. 3 a shows the result of a test series in which the molded part weight is plotted at different hold-up times.
    As can be seen from the comparison of FIGS. 3 a and 3 b, a simpler and more accurate determination of the sealing point can be achieved by a method according to the invention.
    In a further embodiment of the invention, it is provided to superimpose a varying pressure profile on the post-pressure profile by the plasticizing screw. This pressure profile is clearly visible before reaching the sealing point in the closing pressure curve. After reaching the sealing point, this is no longer the case, because the casting material is solidified in the sprue. Also in this way, the victory point can be determined.
    For clarification, this is shown in Figure 4, wherein in the upper graph, the applied by the injection unit Nachdruckprofil and in the lower diagram, the tool force derived from the closing force is plotted against the time.
    The calculation of the tool breathing takes place with prior determination of an effective spring constant which describes the deformation of the closing unit of the forming machine under closing force and injection pressure.
    In FIG. 4, the time at which the oscillation induced by the post-pressure variation has subsided on the tool breathing can be clearly recognized. This time marks the seal point.
    In a further refinement of this method, two shaping cycles can be carried out, wherein the triangular profiles modulated onto the emphasis are in each case phase-shifted by 180 °. This is shown in the uppermost diagram in FIG. The middle diagram shows the associated tool breaths, which are also derived from the closing force.
    Finally, the last diagram in FIG. 5 shows the difference between the tool breaths from the middle diagram in FIG. The mutually phase-shifted, modulated pressure profiles on the one hand cause a gain of the induced signal in the difference of the tool breathing and on the other hand, a background behavior is eliminated by the difference formation (at least partially).
    The waste detectable in the second diagram in FIG. 4 (caused by the shrinkage of the molded part during cooling during the holding pressure phase) of the tool respiration, which is superimposed on the oscillation induced by the variable pressure profile, can be filtered out in this way in the last diagram in FIG.
    In fact, it is also possible to determine the sealing point in terms of, for example, the metering volume plotted against the time or the closing force also plotted against the time for only a single cycle. Corresponding curves are shown in FIGS. 4a and 4b, this being carried out in each case for different melt temperatures. It may therefore also be helpful to change an additional variable which has an influence on the pressure of the casting material in order to facilitate a determination of the sealing point. Although the sealing point in Figures 4a and 4b can be easily recognized by the presence of a small bend. As a criterion for the sealing point, it can thus be used here that the rate of the pressure change changes from a first, essentially constant value.
    FIGS. 7 and 8 each show an injection molding machine 1 according to the invention with a closing unit 2 and an injection unit 3, wherein in the first case an electric closing drive and in the second case a hydraulic closing drive are provided.
    In this exemplary embodiment, the injection unit 3 has a plasticizing screw 5 through which casting material-for example plasticized plastic-can be filled into a mold cavity 4. The thinnest point close to the mold cavity 4, at which first a hardening of the casting material takes place during filling, is called gate 9. To drive the plasticizing screw 5, the injection drive 6 is used.
    In the present embodiment, the casting material is applied by means of the plasticizing screw during the Nachdruckphase with a variable pressure profile. The effect of this variable pressure profile can be measured on the closing side by means of the hydraulic pressure sensor 12 (FIG. 8, hydraulic case), by means of the force sensor 13 (FIG. 7) or by a cavity pressure sensor 10. (See Figures 4 and 5.) In the case of an electric closing drive, the force sensor can be designed as a strain gauge or as a torque sensor in the drive.
    The aforementioned sensor and the injection drive are each connected to the control or regulating device 7.
    It is also possible to use the closing drive (it is irrelevant whether this is carried out electrically or hydraulically) as an actuator for applying a variable pressure. In this case, a pressure sensor 11, an injection pressure sensor 8 or a worm-travel sensor (usually integrated in the injection drive 6) can be used to measure the pressure of the casting material.
    Innsbruck, September 30, 2013
    权利要求:
    Claims (18)
    [1]
    1. A method for determining a sealing point in a casting process, wherein casting material in a fluid phase at least once under pressure in a mold cavity (4) is filled, characterized in that - at least one course of a characteristic of the pressure of the casting material size is measured - from which at least one course a rate of change is determined and - from the rate of change the point of the seal is determined.
    [2]
    2. The method according to claim 1, characterized in that the at least one profile by measuring at least one of the group closing force, internal pressure, Auswerferkraft, Elongation, tool breathing, deformation of a tool, force and / or pressure on a tool and / or a clamping unit is measured
    [3]
    3. The method according to claim 1 or 2, characterized in that the at least one profile by means of an injection pressure sensor (8) and / or a worm travel sensor is measured.
    [4]
    4. The method according to any one of claims 1 to 3, characterized in that the at least one course during a post-pressing phase of a casting cycle is measured.
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that the casting material from one of the Formteilkavität (4) facing away from a gate (9) is acted upon by means of an actuator with a variable pressure, wherein the at least one profile in the mold cavity (4) is measured.
    [6]
    6. The method according to claim 5, characterized in that an injection unit, in particular a plasticizing screw is used as the actuator.
    [7]
    7. The method according to any one of claims 1 to 6, characterized in that the casting material in the mold cavity (4) is acted upon by means of an actuator with a variable pressure, wherein the at least one profile of one of the mold cavity (4) facing away from a gate ( 9) is measured ago.
    [8]
    8. The method according to claim 7, characterized in that a closing drive and / or an ejector drive and / or a core pull and / or an embossing punch are used as the actuator.
    [9]
    9. The method according to any one of claims 5 to 8, characterized in that the casting material is subjected to a variable pressure in the form of an oscillating pressure profile, in particular a periodic pressure profile.
    [10]
    10. The method according to any one of claims 1 to 9, characterized in that the sealing point is determined as a time at which the rate of pressure change falls below a threshold.
    [11]
    11. The method according to claim 10, characterized in that the sealing point is determined as a time at which the rate of pressure change substantially disappears.
    [12]
    12. The method according to any one of claims 1 to 9, characterized in that the sealing point is determined as a time at which changes the rate of pressure change from a first, substantially constant value to a second, substantially constant value.
    [13]
    13. The method according to any one of claims 1 to 12, characterized in that the at least one profile by measuring at least one of the group closing force, internal pressure, Auswerferkraft, beam elongation, tool breathing, deformation of a tool, force and / or pressure on a tool and / or a clamping unit is measured.
    [14]
    14. The method according to any one of claims 1 to 13, characterized in that the at least one profile by means of an injection pressure sensor (8) and / or a worm travel sensor is measured.
    [15]
    15. The method according to any one of claims 1 to 14, characterized in that exactly one casting cycle, is filled in the molding material in the mold cavity (4) is performed.
    [16]
    16. The method according to any one of claims 1 to 14, characterized in that a plurality of casting cycles, in which casting material in the mold cavity (4) is filled, are performed, wherein the pressure changes whose rate is determined between pressure curves of different casting cycles are determined the casting cycles are preferably carried out with different holding pressure times.
    [17]
    17. The method according to any one of claims 1 to 16, characterized in that the sealing point is used to determine the holding pressure.
    [18]
    18. Forming machine with - an injection unit (3) for filling a molding cavity (4) with a casting material, - at least one measuring device (8, 10, 11, 12, 13) for determining at least one course of a characteristic of the pressure of the casting material size, a control or regulating device (7) connected to the measuring device (8, 10, 11, 12, 13), which is designed to determine a rate of changes from the at least one course and to assign the sealing point to the rate of change determine Innsbruck, on September 30, 2013
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4411609A|1980-04-18|1983-10-25|Hitachi, Ltd.|Apparatus for molding plastic|
    DE19536566C1|1995-10-02|1997-02-06|Arburg Gmbh & Co|Process for controlling the cavity pressure on a cyclically operating machine|
    EP0897786A2|1997-08-21|1999-02-24|K.K. Holding AG|Regulation process for an injection moulding machine for plastics|
    US3977255A|1975-08-18|1976-08-31|Control Process, Incorporated|Evaluating pressure profile of material flowing to mold cavity|
    JPH03143613A|1989-10-31|1991-06-19|Japan Steel Works Ltd:The|Identification method and device for solidification time in injection molding|
    JP3806787B2|1997-10-17|2006-08-09|三菱重工プラスチックテクノロジー株式会社|Injection molding method|
    AUPP176898A0|1998-02-12|1998-03-05|Moldflow Pty Ltd|Automated machine technology for thermoplastic injection molding|
    JP4648885B2|2006-09-19|2011-03-09|住友重機械工業株式会社|Injection molding machine and control method of injection molding machine|
    CN101028740B|2007-04-12|2010-05-19|华南理工大学|Injection-machine parameter setting method with automatically-resetting graded injection speed and position|
    DE102007029977B4|2007-06-28|2009-09-24|Sumitomo Demag Plastics Machinery Gmbh|Method for carrying out the closing force reduction in a closing unit of an injection molding machine|DE102015107024B3|2015-05-06|2016-07-21|BT Bayern Treuhand Management & Technologie AG|Determining process parameter values in an injection molding process|
    法律状态:
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    ATA756/2013A|AT514836B1|2013-09-30|2013-09-30|Method for determining a sealing point|ATA756/2013A| AT514836B1|2013-09-30|2013-09-30|Method for determining a sealing point|
    DE102014014172.1A| DE102014014172B4|2013-09-30|2014-09-24|Procedure for determining a seal point|
    CN201410763895.4A| CN104626493B|2013-09-30|2014-09-29|Method for determining seal point|
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