WO2023232867A1 - Procédé de commande en boucle ouverte et/ou en boucle fermée d'une soupape à vide sur une cavité d'un outil de coulée - Google Patents

Procédé de commande en boucle ouverte et/ou en boucle fermée d'une soupape à vide sur une cavité d'un outil de coulée Download PDF

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Publication number
WO2023232867A1
WO2023232867A1 PCT/EP2023/064542 EP2023064542W WO2023232867A1 WO 2023232867 A1 WO2023232867 A1 WO 2023232867A1 EP 2023064542 W EP2023064542 W EP 2023064542W WO 2023232867 A1 WO2023232867 A1 WO 2023232867A1
Authority
WO
WIPO (PCT)
Prior art keywords
vacuum valve
valve
hydraulic cylinder
cavity
piston
Prior art date
Application number
PCT/EP2023/064542
Other languages
German (de)
English (en)
Inventor
Franck Marc Alain GIGEZ
Original Assignee
Fondarex Sa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fondarex Sa filed Critical Fondarex Sa
Publication of WO2023232867A1 publication Critical patent/WO2023232867A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/14—Machines with evacuated die cavity
    • B22D17/145—Venting means therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/32—Controlling equipment

Definitions

  • the present invention relates to a method for controlling and/or regulating a vacuum valve on a cavity of a casting tool according to claim 1.
  • the cavity can be connected to a suction line via this vacuum valve in order to evacuate the cavity.
  • the vacuum in the cavity proves to be advantageous for a casting process because it can reduce or avoid the inclusion of air or vapors during the casting process.
  • the vacuum valve should remain open for as long as possible during a casting process.
  • the valve When pouring the liquid metal into the cavity of the mold, the valve must be closed in good time so that no liquid metal is sucked through the (still open) vacuum valve into the suction line for the vacuum.
  • complex measures would be necessary to mechanically remove the solidified metal from the suction line for the vacuum. It may also be necessary to replace parts that have unintentionally come into contact with the liquid metal but are not designed for these temperatures.
  • vapors and gases occur when the liquid metal is poured into the cavity.
  • the vapors result from the heating of the cavity, which changes the vapor pressure in the cavity. Any moisture that may have accumulated on the walls of the cavity evaporates as a result of this heating.
  • materials are applied to the walls that prevent the metal from adhering the cavity should be avoided when cooling. As the cavity heats up when the liquid metal is poured in, these coatings (partially) evaporate, forming vapors. These vapors and gases can lead to unwanted inclusions in the workpiece if these vapors and gases are not extracted.
  • the vacuum valve should be closed as late as possible when filling the liquid metal in order to evacuate the vapors and gases from the cavity.
  • the vacuum valve should close in time so that no liquid metal passes through the vacuum valve.
  • WO 2002 100 573 A1 it is known to drive the valve body (valve tappet) of a vacuum valve on a cavity of a casting tool via a control rod, at the other end of which there is a piston.
  • This piston is part of a cylinder that can be pressurized with gas. It is therefore a pneumatic drive.
  • a closing time of the vacuum valve of less than 1 ms is specified, which results from various constants that are dictated by the design of the arrangement.
  • the vacuum valve should be kept open by the gas pressure against a spring. When the gas pressure is released, the spring force causes the vacuum valve to close.
  • WO 2002 100 573 A1 To change the closing time of a vacuum valve from the open state to To determine the closed state, various parameters are specified in WO 2002 100 573 A1, with which a closing time is to be determined mathematically based on a model of the time behavior of the vacuum valve during a closing process.
  • the present invention is based on the object of optimizing the closing of the vacuum valve of a casting tool during a casting process.
  • This object is achieved by a method for controlling and / or regulating a vacuum valve on a cavity of a casting tool according to claim 1.
  • a piston of a hydraulic cylinder is used as the drive element for the valve tappet of the vacuum valve.
  • the vacuum valve is closed when the valve stem rests on the seat of the valve stem in the vacuum valve.
  • the vacuum valve is (fully or partially) open.
  • the use of the hydraulic cylinder has the advantage that a hydraulic cylinder has better consistency in the movement of the piston of the hydraulic cylinder. Compared to the described pneumatic drive cylinder from the prior art, there are no changes that result, for example, from material fatigue of the spring with increasing age and increasing operating time. Pumping an incompressible hydraulic fluid from a hydraulic cylinder also leads to a more predictable time behavior than the flow behavior of a compressible medium in a pneumatic drive.
  • valve stem of a vacuum valve is integrated into the cavity of the casting tool.
  • This switching rod proves to be advantageous because it allows the hydraulic cylinder to be operated at a certain distance from the casting tool. This can ensure that the changing temperatures of the casting tool have at best a negligible influence on the behavior of the hydraulic cylinder - in particular on the movement of the piston of the hydraulic cylinder. Nevertheless, the switching rod provides a direct coupling of the valve tappet with the piston of the hydraulic cylinder. This also means that the position of the valve tappet is directly linked to the position of the piston of the hydraulic cylinder.
  • the method according to the present invention can also be used for a vacuum valve which is arranged at a smaller distance on the cavity or directly on the side wall of the cavity without using a switching rod.
  • the closing time for the vacuum valve is recorded for the arrangement consisting of the vacuum valve and the hydraulic cylinder for different positions of the piston of the hydraulic cylinder and/or for different positions of the valve lifter of the vacuum valve and for subsequent control or regulation processes saved.
  • the position of the piston of the hydraulic cylinder and/or the valve tappet of the vacuum valve is continuously recorded during a casting process.
  • the time for closing the vacuum valve in correlation with the filling of the liquid metal into the cavity of the casting tool is determined depending on the detected position, taking into account the stored closing time for this position.
  • the Characteristic curve derive a closing time by interpolation if no value pair of the characteristic curve is stored for the currently detected position of the piston of the hydraulic cylinder or the currently detected position of the valve tappet.
  • the interpolation can be done by evaluating the closing times of the characteristic curve
  • This interpolation between these two pairs of values can be, for example, a linear interpolation. It is also possible to take more than two pairs of values into account during interpolation.
  • the closing time here means the time that elapses until the vacuum valve is completely closed when a control signal for completely closing the vacuum valve is output in the respective position.
  • this closing time for the individual positions during calibration in such a way that the closing time is saved when the piston (and thus also the valve tappet) is moved from the rest position to this position in order to close the vacuum valve.
  • this closing time for the individual positions during calibration in such a way that the closing time is saved when the piston (and thus also the valve lifter) is moved from the rest position in the maximum open position of the vacuum valve to the vacuum valve close.
  • the piston and therefore also the valve tappet) then have an initial speed of vo when they are moved beyond the respective position when the vacuum valve is closed.
  • Vacuum valve calibration does not need to be a completed process before the vacuum valve is used.
  • the position of the piston of the hydraulic cylinder and the position of the valve tappet of the vacuum valve are also recorded.
  • the current closing time of the vacuum valve can then be measured based on this currently recorded position.
  • the calibration of the vacuum valve can be updated with this data from the ongoing casting processes. These value pairs can be saved as additional value pairs of the characteristic curve.
  • the characteristic curve can be smoothed using statistical methods.
  • Statistical methods can also be used to give greater weighting to measured value pairs that come from recent casting processes compared to measured value pairs that come from longer-ago casting processes.
  • signs of aging of the vacuum valve are advantageously taken into account in the calibration, which may occur. lead to a change in closing times.
  • error diagnosis is also possible in the sense that the pairs of values from the calibration of the vacuum valve are saved when new and compared with the current pairs of values from the calibration. If a deviation above a threshold value is detected for the closing times at certain positions between the vacuum valve in new condition and the current calibration, an error signal can be generated. Based on this error signal, a request to replace the vacuum valve can, for example, be issued.
  • a control device can output a control signal for closing the vacuum valve, taking the closing time into account, if data from the casting process show that the vacuum valve must be closed after a requested time T requirement that is greater than the stored closing time for the respective position of the piston of the hydraulic cylinder or the respective position of the valve lifter of the vacuum valve, whereby this amount is greater than “0” but is less than a threshold value.
  • the manipulated variables of the casting process can in particular be the time at which the filling of the liquid metal into the cavity begins and/or the filling speed for the liquid metal into the cavity.
  • Predictive monitoring in the sense of controlling or regulating the valve tappet is made possible with regard to the open position, the closed position and also the closing time.
  • This monitoring results from the hydraulic reaction time and the mechanical closing time.
  • the casting process can be expanded beyond the aspect of timely closing of the vacuum valve in a more comprehensive sense optimize.
  • the usual casting process is such that the liquid metal is initially conveyed into the cavity at a low speed. Only after a certain time has elapsed after the start of filling in the liquid metal is the filling speed increased to a maximum speed for filling in the liquid metal.
  • the liquid metal flows into the cavity at maximum speed, this can lead to the flow no longer being laminar, but to turbulence occurring. It can also be observed that the liquid metal (especially if it is aluminum) atomizes as it flows into the cavity. These atomized particles in particular cause problems with regard to the inclusion of vapors or gases in the workpiece, because these atomized particles form aerosols with any vapors or gases that may be present. When the atomized particles come into contact with the “main mass” of the liquid metal again in the further process, the attached vapor or gas particles are also attached, so that inclusions then arise in the workpiece. To avoid this, the following measure makes sense.
  • the vacuum valve is closed during the initial period, the vacuum valve is at least partially opened after this initial period. This allows vapors and gases to be extracted from the cavity. This reduces the effective cross section for the formation of the aerosols described.
  • Whether the vacuum valve is only partially or completely opened essentially depends on which closing time T requirement is required by the casting process and up to which degree of opening of the vacuum valve the stored closing time is shorter than the ordered time T requirement for closing the vacuum valve.
  • the time for closing the vacuum valve is subsequently determined as described above and as explained in connection with Figure 2.
  • Fig. 1 a schematic representation of the procedure for calibrating the hydraulic cylinder and the vacuum valve
  • Fig. 2 a procedure for controlling a casting process.
  • Figure 1 shows a schematic diagram of the procedure for calibrating the hydraulic cylinder and the vacuum valve.
  • a step 1 the current position of the piston of the hydraulic cylinder and/or the current position of the valve tappet of the vacuum valve is recorded.
  • step 2 a control signal is output to close the vacuum valve by the hydraulic cylinder. A time recording is also started.
  • step 3 the time recording started in step 2 is continued.
  • the currently recorded position of the piston continues to be displayed Hydraulic cylinder and / or the valve lifter of the vacuum valve is stored.
  • the control signal for closing the vacuum valve continues to be output.
  • step 3 it is checked whether the valve lifter of the vacuum valve is in the position in which the vacuum valve is completely closed.
  • step 2 in which time recording continues.
  • the currently recorded position of the piston of the hydraulic cylinder and/or the valve tappet of the vacuum valve is also stored.
  • the control signal for closing the vacuum valve continues to be output.
  • step 4 If it is determined in step 4 that the vacuum valve is completely closed. There is a transition to step 5, in which the time recording is stopped. In addition, the time recorded by the time recording for this closing process of the vacuum valve is saved as the closing time of the vacuum valve to the position of the piston of the hydraulic cylinder and/or the valve lifter of the vacuum valve recorded in step 1 for subsequent control or regulation processes of casting processes with this casting tool.
  • step 5 the respective closing time can also be recorded (recorded) from the recorded time for the closing process, starting from the position according to step 1 until the vacuum valve is completely closed, to the time recording value pairs recorded in step 2 and the associated position for each of the positions Total time minus the time recorded for the respective position in step 2).
  • the calibration process of the representation in Figure 1 can be repeated for various positions of the piston of the hydraulic cylinder or positions of the valve lifter of the vacuum valve, so that these positions (sequentially) of the position according to step 1, to which the total time corresponds is recorded.
  • Figure 2 shows a procedure for controlling a casting process.
  • step 201 the position of the piston of the hydraulic cylinder and/or the position of the valve lifter of the vacuum valve is detected.
  • step 201 the closing time is read out from the table generated in accordance with the explanations for FIG. 1, which is stored in step 5 of FIG. 1 for this position recorded in step 201.
  • step 202 the time T requirement is determined by a control or regulating device, within which the vacuum valve must be closed depending on other parameters of the casting process.
  • step 203 the time T request determined in step 202 is compared with the closing time that was read out of the table for the determined position in step 201. If the closing time is less than a threshold value less than the time T requirement determined in step 202, a transition to step 204 occurs, in which the control signal for closing the vacuum valve is output.
  • step 203 If the check in step 203 shows that the closing time is smaller than the time T requirement determined in step 202 by more than this threshold value, a transition to step 201 takes place. If necessary, this transition can also take place in step 202 if the position of the piston of the hydraulic cylinder and/or the position of the valve lifter of the vacuum valve is not to be recorded again.
  • step 203 If the check in step 203 shows that the closing time is greater than the time T request determined in step 202, error treatment can be carried out, which is not shown graphically in detail here.
  • This error treatment consists of the control variables of the casting process - in particular the time and speed of pouring the liquid metal into the cavity Casting tool - can be adjusted so that the closing time is again smaller than the time T requirement, which is determined in step 202.
  • measured values of the current position of the piston of the hydraulic cylinder or the position of the valve stem of the vacuum valve before closing as well as the measured closing time in the ongoing casting process can be used to update the calibration of the vacuum valve.

Abstract

La présente invention concerne un procédé de commande en boucle ouverte et/ou en boucle fermée d'une soupape à vide sur une cavité d'un outil de coulée. Un piston d'un cylindre hydraulique est utilisé comme élément d'entraînement pour le poussoir de soupape de la soupape à vide. Selon la présente invention, pour l'agencement constitué de la soupape à vide et du cylindre hydraulique, le temps de fermeture (2, 3, 4) pour la soupape à vide est détecté (5) pour différentes positions du piston du cylindre hydraulique et/ou pour différentes positions du poussoir de soupape de la soupape à vide (1) et stocké (5) pour des procédures ultérieures de commande en boucle ouverte ou en boucle fermée. Pendant un processus de coulée, la position du piston du cylindre hydraulique et/ou du poussoir de soupape de la soupape à vide (201) est détectée en continu. Le moment précis de la fermeture de la soupape à vide en corrélation avec l'introduction du métal liquide dans la cavité de l'outil de coulée est déterminé (203) en fonction de la position détectée (201), en tenant compte du temps de fermeture stocké (5, 202) pour cette position (201).
PCT/EP2023/064542 2022-06-02 2023-05-31 Procédé de commande en boucle ouverte et/ou en boucle fermée d'une soupape à vide sur une cavité d'un outil de coulée WO2023232867A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102022114043.1A DE102022114043A1 (de) 2022-06-02 2022-06-02 Verfahren zur Steuerung und/oder Regelung eines Vakuumventils an einer Kavität eines Gießwerkzeugs
DE102022114043.1 2022-06-02

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WO2023232867A1 true WO2023232867A1 (fr) 2023-12-07

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PCT/EP2023/064542 WO2023232867A1 (fr) 2022-06-02 2023-05-31 Procédé de commande en boucle ouverte et/ou en boucle fermée d'une soupape à vide sur une cavité d'un outil de coulée

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WO (1) WO2023232867A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5488985A (en) 1993-02-02 1996-02-06 Fondarex, F. Hodler & Cie. S.A. Valve assembly for venting diecasting moulds
WO2002100573A1 (fr) 2001-06-13 2002-12-19 Alcan Technology & Management Ltd. Soupape de depression pour machine a coulee sous pression
JP2007268550A (ja) * 2006-03-30 2007-10-18 Aisin Seiki Co Ltd 真空ダイカスト装置及び真空ダイカスト方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5488985A (en) 1993-02-02 1996-02-06 Fondarex, F. Hodler & Cie. S.A. Valve assembly for venting diecasting moulds
WO2002100573A1 (fr) 2001-06-13 2002-12-19 Alcan Technology & Management Ltd. Soupape de depression pour machine a coulee sous pression
JP2007268550A (ja) * 2006-03-30 2007-10-18 Aisin Seiki Co Ltd 真空ダイカスト装置及び真空ダイカスト方法

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