Die-casting machine and operating method

Abstract

1. Die-casting machine and operation method. 2.1 The present invention comprises a die-casting machine comprising a casting mold (1), a casting chamber (2), a casting piston (3) arranged in a manner movable in the axial direction in the casting chamber, a molten material inlet channel (4) connected to the casting chamber, a shut-off valve (5) located in the molten material inlet channel, a molten material outlet channel (6) connected to the casting chamber from the casting mold, and a control unit (7) for controlling the casting piston, and a method for operating such a die-casting machine. 2.2 In the case of a die casting machine according to the present invention, according to one aspect of the present invention, a control unit (7) and a shut-off valve (5) for performing each casting process in the mold filling stage are configured to bring the shut-off valve (5) to a closed position and control the casting piston (3) in the casting chamber (2) to advance from the casting start position to the filling end position, which pushes the molten material (14) into the casting mold (1) through the molten material outlet channel (6), and in the subsequent re-filling stage, first the shut-off valve is brought to an open position and the casting piston is returned to the casting start position, and the molten material is supplied to the casting chamber through the molten material inlet channel, and the shut-off valve is controlled to a closed position before the casting piston reaches the casting start position due to the return movement, and the molten material is reabsorbed from the molten material outlet channel by the additional return movement of the casting piston. 2.3 Application Examples: For example, heat-chamber die-casting machine technology.

Description

Technology Field

[0001] The present invention relates to a die-casting machine comprising a casting mold, a casting chamber, a casting piston arranged to be axially movable in the casting chamber, a melt inlet channel leading to the casting chamber, a shut-off valve of the melt inlet channel, a melt outlet channel leading from the casting chamber to the casting mold, and a control unit for controlling the casting piston. The present invention also relates to a method for operating such a die-casting machine, wherein each casting process is performed in a mold-filling phase, and the casting piston of the casting chamber is advanced from the casting start position to the filling end position with the shut-off valve closed, so that the molten material is pressed into the casting mold through the melt outlet channel, and in a subsequent refilling phase, the casting piston is moved back to the casting start position, so that the molten material is supplied back into the casting chamber through the melt inlet channel with the shut-off valve open. Background Technology

[0002] Die casting machines of this type, general type, and similar type, and the associated operating method are generally used to cast specific components, also referred to as cast parts, in each casting process or casting cycle. The die casting machine of the present invention (hereinafter also strictly referred to as the 'machine') and the operating method are particularly suitable for metal die casting, for example, for casting liquid or partially liquid metal melts such as zinc, lead, aluminum, magnesium, titanium, steel, copper, and alloys of these metals. The die casting machine may be a high-temperature chamber die casting machine. In this embodiment, the casting chamber is formed in a casting container immersed in a melt bath prepared by a melt vessel.

[0003] In the mold filling stage of the casting process, to form a casting, the advance of the casting piston receives pressure in the casting chamber and pressurizes the molten material in the casting chamber through the molten material outlet channel into the mold cavity formed by the casting mold. In this regard, the casting mold generally comprises a fixed mold half and a movable mold half, and the space between these mold halves forms a mold cavity, also known as the mold hollow space, or is abbreviated as mold, synonymous with this casting mold. In a typical implementation, the molten material outlet channel includes a riser-tube region of the casting vessel containing the casting chamber on the inlet side and a mouthpiece body attached to the casting vessel on the outlet side; that is, upon leaving the casting chamber, the molten material generally reaches the molten inlet in the region immediately preceding the mold cavity, which has what is known as a gating cone, through the riser-tube region and the mouthpiece body.

[0004] In the refilling phase, the casting piston moves back from the filling end position to the initial position, i.e., the casting start position, and the return movement of the casting piston refills the casting chamber with molten material through the molten material inlet channel. Therefore, the refilling phase is also called the piston return phase.

[0005] In the case of a corresponding machine type particularly suitable for this die-casting machine, the melt outlet channel exits the casting chamber separately from the melt inlet channel; that is, the melt inlet channel and the melt outlet channel form two separate guide channels for the molten material, with a casting chamber inlet opening into the casting chamber and a separate casting chamber outlet opening outside the casting chamber. This configuration facilitates independent control of the melt flow in the melt inlet channel and the melt outlet channel, and the melt flow in the melt inlet channel can be controlled specifically by a shut-off valve located therein.

[0006] Depending on the system configuration, a non-return valve operated purely by molten pressure or an actively operable shut-off valve may be used as the shut-off valve. The latter is currently referred to as a shut-off control valve and is controlled by a control unit. In this general type of die-casting machine and associated operating method, the shut-off control valve is typically kept closed during the entire mold filling phase and open during the entire refilling phase. Compared to a simple non-return valve, an actively controllable or activable shut-off valve provides the option to influence or regulate the molten flow through the molten inlet channel as needed, which is also independent of the molten pressure ratio in the casting chamber and / or the molten inlet channel.

[0007] Depending on the system configuration, the control unit comprises a single control unit in which all control functions of the die-casting machine are integrated, or a plurality of single control units, each controlling and / or adjusting specific machine parts and preferably communicating with one another via communication links. In this case, as is customary, the control unit may be composed at least partially of hardware and / or at least partially of software. In the present case, the control unit controls one or more additional machine parts, particularly the casting piston, more precisely its movement, and, in the case where the shut-off valve is blocked by something such as a shut-off control valve.

[0008] Patent Publication EP 0 576 406 B1 discloses a shut-off control procedure for a system comprising a displacement-type casting piston, known as an alternative to a spool-type casting piston, and a shut-off valve positioned directly at the opening of a molten material inlet channel to a casting chamber. In the case of the spool type, the external dimensions of the casting piston correspond to the internal dimensions of the casting chamber, and the piston is sealed against the walls of the casting chamber. Consequently, in this case, when advancing, the casting piston pushes the molten material of the casting chamber completely forward and applies the pressure necessary to press the molten material into the mold hollow in the process. In the case of the displacement type, since the external dimensions of the casting piston are suitably smaller than the internal dimensions of the casting chamber, when advancing, the casting piston is immersed in the molten material of the casting chamber. The action of pressure on the molten material in this case is caused by the displacement effect of the volume of the casting piston immersed in the molten material.

[0009] Publication DE 32 48 423 A1 discloses a die-casting machine of a similarly general type and a method of operation associated with it, wherein the casting piston has a displacement type forward piston and pressurized gas can be additionally supplied from the molten material inlet channel at a distance upstream of the casting chamber and downstream of the inlet to the casting vessel containing the casting chamber to a shut-off control valve located in the casting vessel containing the casting chamber. During the mold filling stage, the shut-off control valve is kept closed. During the refilling stage, the shut-off control valve is opened and a certain amount of pressurized gas is delivered to the casting chamber. This is to prevent a vacuum from forming in the casting chamber before the shut-off control valve is opened, to prevent the injection of molten material pulled into the casting piston part behind the forward piston, and to bias the gas pressure in the casting chamber to a certain amount higher than atmospheric pressure. After the required amount of molten material is supplied during the refilling stage, the shut-off control valve is closed again.

[0010] In die casting, cycle time—that is, the duration of each casting process as short as possible—is required for economic reasons, and for reasons related to the quality of the casting, the air fraction of the casting is sought to be as low as possible, that is, the minimum porosity of the casting. In particular, to illustrate the latter aspect, Patent Publication EP 1 284 168 B1 describes a method in which, at the start of the mold filling stage and / or prior to the actual mold filling stage, the mold is opened far enough in the pre-filling stage for the molten material to fill the rising channel area and the mouthpiece body area, and subsequently, before the mold is closed, the mold piston advances, and the mold piston advances again to perform the actual mold filling stage. In the said patent publication, the casting piston is of the spool type and functions as a blocking member in that it performs a return motion during the re-filling stage to open the casting chamber inlet and advances during the mold filling stage to block the casting chamber inlet.

[0011] Additional aspects generally considered for this type of die-casting machine, particularly when it is a spool type, are to minimize the wear effect on the walls located opposite the casting piston and the casting chamber caused by the stroke movement of the casting piston in the casting chamber, and to prevent the formation of unwanted molten droplets in the area of ​​the gating cone, which generally forms the inlet-side interface of the mold-side molten channel structure, opening on the outlet side with the gate into the mold hollow for the purpose of joining to the mouthpiece body. The problem to be solved

[0012] Based on the solution of the problem of die-casting machines and related operating methods of the aforementioned type, the present invention provides advantages over the aforementioned prior art, particularly in terms of achieving a relatively short casting cycle time and / or a relatively low air porosity in the casting and / or relatively low wear of the casting piston and casting chamber and / or avoiding the formation of molten droplets in the gating-cone region.

[0013] The present invention solves the above problem by providing a method of operating a die-casting machine having the features of claim 1 or claim 9 and a die-casting machine having the features of claim 10 or claim 11. Advantageous improvements of the present invention are specified in the dependent claims. means of solving the problem

[0014] According to one embodiment of the method of operation according to the present invention of claim 1, in the refilling step of the casting process, a previously opened shut-off valve is closed before the casting piston reaches the casting start position by the return movement, and as a result of the additional return movement of the casting piston, molten material is back-sucked from the molten material outlet channel, that is, partially back-sucked from the molten material outlet channel into the casting chamber. The closing of the shut-off valve can be actively performed by a control unit in the case of a shut-off control valve, or by a preload element that preloads the valve in the closed position, such as a preload spring, in the case of a backflow prevention valve. Consequently, in this method of operation, at the beginning of the refilling step, the shut-off valve is initially opened when the casting piston moves backward, and as a result, the casting chamber is refilled with molten material through the molten material inlet channel, and at the remainder of the refilling step, the shut-off valve is closed, and as a result, molten material can be back-sucked from the molten material outlet channel by the additional backward movement of the casting piston. For opening, if implemented as a shut-off control valve, the shut-off valve is controlled to an open position by an assigned control unit, and if implemented as a backflow prevention valve, the shut-off valve is controlled by the negative pressure of the molten material in the casting chamber.

[0015] The procedure according to the present invention provides the advantage of the necessary refilling of the casting chamber with molten material through the molten material inlet channel and the partial back-drawing of molten material from the molten material outlet channel. In the process, after the filling step, the non-solidified molten material in the molten material outlet channel is not completely back-drafted into the molten material filling level present in the casting chamber or upstream melt bath, but may remain in the molten material outlet channel up to a forward region that can be set and / or predefined by selecting the point at which the shut-off valve is closed and / or the relevant position of the casting piston, and thus there is no need to proceed the subsequent casting process to the filling level from the molten material outlet channel first.

[0016] This procedure according to the present invention offers many advantages due to these characteristics. In this way, the cycle time of a series (consecutive) casting processes can be shortened. Similarly, the movement stroke of the casting piston in the casting chamber can be reduced, and as a result, the associated wear effects can be minimized. Therefore, wear on the wear-affected parts of the casting piston and casting chamber, including conventional piston rings, is also significantly reduced, for example by this procedure according to the present invention, compared to a conventional system where the piston functions as a blocking member for the molten metal inlet channel, because the negative pressure generated during the return movement of the casting piston in the casting chamber can be kept significantly low by appropriately controlling and / or switching the blocking valve as needed. Since the molten metal outlet channel can be maintained primarily filled with molten material between consecutive casting processes, a small amount of air is present in the front part of the molten metal outlet channel at the start of each casting process. This can significantly reduce the porosity of the produced casting, thereby significantly improving the quality of the produced casting.

[0017] The back-drawing of non-solidifying molten material from the molten outlet channel, in a controllable and / or monitorable range—that is, a controllable and / or predefined amount—allows for the formation of undesirable molten material to be very advantageously prevented by back-drawing molten material from within the molten outlet channel to some extent from the exit area of ​​the molten outlet channel, in the gating cone area and / or the mold tool area of ​​the die-casting machine, i.e., from the sprue or the transition or exit of the molten outlet channel or mouthpiece body to the subsequent mouthpiece nozzle or mouthpiece tip. The range of back-drawing can be appropriately set or predefined. That is, it is appropriately selected according to the requirements and conditions of the die-casting machine so that, on the one hand, the formation of molten droplets is reliably prevented, and on the other hand, the molten material still remains relatively far forward, i.e., preferably in the area forward of the molten outlet channel or in an area far forward.

[0018] In an advantageous implementation, the molten material is repulsed at this point even if it is sufficiently far away, on the one hand remaining in a region as far forward as possible from the molten material outlet channel or in a region relatively far forward, i.e., available, and on the other hand, located at a specific distance, for example, about 5 mm to 100 mm from the gating cone or the outlet of the molten material outlet channel, for example, at a relatively low distance behind the molten material outlet channel, particularly at a point located immediately behind this outlet or at a point located at a certain distance from this outlet and at a point where the molten material, which is still relatively liquid, breaks off from the molten material that has already solidified or partially solidified in front of it in the gating cone or mold, for example, at about 10 mm to about 50 mm, preferably about 30 mm to about 40 nm, depending on the requirements, the viscosity of the molten material and / or the system configuration of the machine. In corresponding typical embodiments of the die-casting machine, for this purpose, the reverse suction stroke of the casting piston from the position of the casting piston where the shut-off valve is closed to the casting start position is in the range of 1 millimeter to several millimeters, for example, approximately 2 mm to 20 mm.

[0019] Furthermore, due to reverse suction, the stroke motion of the casting piston during the first stage of the mold filling phase can be utilized in the subsequent casting process to accelerate the casting piston before it begins to pressurize the molten material into the mold, which has the advantage of being usable. This can be advantageous even in cases where there is no sprue or only a relatively small sprue.

[0020] Another advantage of back-suction is its application to the gate of a casting, where the material solidifies before it is still partially liquid in the runner. In this case, the molten material that has not yet solidified in the gating cone can be back-suctioned, so that the molten material does not need to be melted again. Depending on the casting mold and other conditions, this can, for example, result in a molten material ratio of up to about 5% of the amount of molten material introduced into the casting mold.

[0021] In the improvement of the present invention, during the refilling stage, the casting piston is moved backward at a lower speed during the period when the shut-off valve is closed than during the previous period when the shut-off valve is still open. That is, in this case, the casting piston is moved backward at a lower speed during the final reverse suction stage when the shut-off valve is closed than during the initial refilling stage when the shut-off valve is open. This selection of an inconsistent speed profile of the casting piston during the refilling stage has the advantage of allowing the casting piston to reach the casting start position with a moderately slow subsequent reverse suction operation of the molten material, along with rapid initial refilling of the casting chamber.

[0022] In an improvement of the present invention, during the refilling stage of the casting process, the previously opened shut-off valve is closed as soon as the casting piston reaches the valve switchover position by its return motion. In the case of a shut-off control valve, this can be accomplished through an actively controlled valve switchover at this point, and in the case of a backflow prevention valve, it can be accomplished, for example, by stopping the casting piston at the valve switchover position and / or opening the closed casting mold, so that no more melt negative pressure is generated in the casting chamber, and thus the backflow prevention valve is automatically reset to the closed position. This measure causes the shut-off valve to switch from the open position to the closed position upon reaching a specific position, more precisely in this case referred to as the valve switchover position or, alternatively, the valve reversal position, depending on the position of the casting piston. Since the supply of molten material to the casting chamber through the molten material inlet channel is terminated when the shut-off valve is closed, the molten material can be re-sucked into the casting chamber from the molten material outlet channel, and can be re-sucked to a desired extent by the additional return motion of the casting piston to reach the casting start position from the valve switchover position. In the case of a backflow prevention valve, unwanted opening of the shut-off valve during this period can be prevented in that the casting mold is opened before the casting piston moves back from the valve switching position. In an alternative embodiment, activation to reverse the shut-off valve from the open position to the closed position during the refilling phase of the casting process may be triggered in a different way, for example, by a time elapsed that can be predefined for this purpose, for example, after the filling phase has started or after the return movement of the casting piston has started.

[0023] In the advancement of the present invention, the stroke distance between the valve switching position and the casting start position of the casting piston can be variably predefined. This measurement allows for flexible response to various system conditions. The stroke distance between the valve switching position and the casting start position of the casting piston determines the ratio of the final return motion from the valve switching position to the casting start position of the casting piston to the total casting piston stroke, and is given by the distance between the filling end position and the casting start position and, therefore, also by the degree of molten back-suction in the molten outlet channel. This stroke distance is naturally greater than zero and less than the total casting piston stroke, i.e., the stroke distance between the filling end position and the casting start position, and can be set to a corresponding desired value or value corresponding to the requirements of the usage situation, and depending on the conditions of the die casting machine and system situation, for example, approximately 2 mm to 20 mm, more specifically approximately 4 mm to 8 mm, and in corresponding implementations, this value is up to half, up to 1 / 3, up to 1 / 4, or less than these of the total casting piston stroke. As the stroke distance between the valve switching position and the casting start position increases, the degree of back-suction of molten material in the molten material outlet channel increases. Selecting a shorter stroke distance reduces the amount of molten material back-suctioned in the molten material outlet channel. The stroke distance between the valve switching position and the casting start position of the casting piston can be selected differently, for example, for different casting molds that are interchangeably used in a die-casting machine. In an alternative embodiment, where variable adjustment is not required, this stroke distance can be predetermined in a non-changing manner.

[0024] In an advancement of the present invention, during the refilling stage of the casting process, the casting piston is maintained in the valve switching position for a pause period before moving back to the casting start position. The pause period for the return movement of the casting piston can be used to switch the shut-off valve from the open position to the closed position and, if necessary, open the casting mold. Consequently, the shut-off valve can be switched during a period in which there is no molten flow in the molten inlet channel and thus through the shut-off valve, and instead the molten material is fixed in the molten material. The pause period can be appropriately selected, for example, in terms of the temporal duration, for example, the time required for the shut-off valve to switch from the open position to the closed position and / or the time required to open the casting mold, and optionally, the pause period may provide a variablely changeable specification. In an alternative embodiment, the shut-off valve does not interfere with the return movement of the casting piston, that is, after reaching the valve switching position, the casting piston is not completely stopped during the return movement and is switched from the open position to the closed position.

[0025] In an improvement of the present invention, during the refilling stage of the casting process, the casting mold is maintained in a closed state as long as the shut-off valve remains open. This measure ensures that the casting chamber is refilled with molten material through the molten material inlet channel due to the return movement of the casting piston, but no noticeable back-drawing of molten material occurs from the molten material outlet channel as long as the shut-off valve is in the open position. Then, because the casting mold is still closed and generally contains a casting that is already at least partially solidified at this point, a significant amount of air cannot pass through the casting mold into the molten material outlet channel, and thus, during this initial stage of the refilling stage, molten material is not yet back-drafted from the molten material outlet channel into the casting chamber. In an alternative embodiment, the casting mold is already open and / or its opening begins while the shut-off valve remains open.

[0026] In an advancement of the present invention, particularly in the case where a shut-off control valve is used as the shut-off valve, the opening of the casting mold begins after the casting piston reaches the casting start position during the refilling stage of the casting process. This procedure essentially does not cause back-drawing of molten material from the molten material outlet channel until the casting piston reaches the casting start position. As a result of the return movement of the casting piston from the valve switching position, the shut-off control valve closes and returns to the casting start position; thereafter, the casting piston first generates a corresponding negative pressure, and after the opening of the casting mold begins, the molten material is back-drawing from the molten material outlet channel into the casting chamber to that extent due to the associated negative pressure effect.

[0027] In an alternative advancement of the present invention, during the refilling phase of the casting process, the opening of the casting mold begins after the casting piston reaches the valve switching position and before it reaches the casting start position. In this procedure, molten material may be recirculated from the molten material outlet channel or from the molten material outlet channel into the casting chamber while the casting piston is further returning to the casting start position. In a corresponding embodiment, the opening of the casting mold may begin at any desired point during the return movement of the casting piston from the valve switching position to the casting start position, and additionally in a corresponding implementation, it may also begin before the casting piston reaches the valve switching position and the shut-off valve is closed.

[0028] In a further advancement of the present invention, during the refilling stage of the casting process, the casting piston is stopped at the valve switching position and advances from the valve switching position to the casting start position as soon as the casting mold reaches a specific casting piston-triggered mold opening position when the casting mold is opened. In this implementation, the further return movement of the casting piston after stopping at the valve switching position is matched with the opening process of the casting mold in such a way that the casting piston does not advance to the casting start position until the casting mold is opened to a predetermined degree defined by the casting-piston-triggered mold opening position. Consequently, the process of back-drawing the molten material from the molten material outlet channel at the final stage of the refilling stage of the casting process can be further optimized. In an alternative embodiment, the return movement of the casting piston occurs without considering the current opening position of the casting mold, provided there are no application-related requirements therefor.

[0029] In the improvement of the present invention, the casting piston advances from the casting start position reached during the refilling stage of the previous casting process to the prefilling position during the initial prefilling stage of the mold filling stage of the subsequent casting process, at which time the casting mold is not yet completely closed, and thereafter the casting mold is completely closed and the casting piston advances further from this prefilling position to the filling end position. As a result, air that entered the forward region of the molten material outlet channel due to the back-suction of the molten material during the refilling stage of each previous casting cycle can escape through the mold, which is still completely open or at least still partially open at the start of each current casting cycle, and the step of completely closing the mold and actually filling the mold with molten material is executed.

[0030] According to a further embodiment of the present invention, claim 9 relates to which the invention may be provided as an addition or alternative to the first embodiment of claim 1, in a pre-filling step of a start-of-operation casting process prior to the mold filling step, the casting piston of the casting chamber advances from the start-of-operation position to a given pre-filling position with the shut-off valve closed, and then moves back to the start-of-operation position when the shut-off valve is opened. Depending on the requirements and usage conditions, the casting mold may be closed before this pre-filling step or at the start, or alternatively, it may remain open while the casting piston proceeds in this pre-filling step and be closed only before the casting piston returns or when the shut-off valve is opened. In the first case, it ensures that molten material cannot accidentally escape through the mold while it is still open during this pre-filling operation without additional measures. In the latter case, air pressurized in the molten material outlet channel by the pre-filling process may escape more quickly through the mold while it is still open.

[0031] The procedure according to the present invention comprises a specific operation start measurement that can be advantageously applied to a cyclic casting operation of a die casting machine for cyclic casting to produce a plurality of identical castings by a specific casting mold in a successive casting process or casting cycle, for example, after assembling a casting mold or casting tool to a die casting machine or after restarting die casting with a specific assembled casting mold.

[0032] That is, the start-up casting process constitutes the first casting process or casting cycle to produce the desired casting after the machine starts operating. In this start-up, the molten material is not yet located in the forward region of the molten material outlet channel, but rather in the rear region of the molten material outlet channel, up to the molten filling level of the molten material tank in which, for example, the casting chamber or the casting vessel containing the casting chamber is submerged. A specific start-up casting process ensures that the molten material is present in the forward region of the molten material outlet channel even in the first of many casting processes that follow one another after the machine starts operating, in that the casting piston advances from the start-up position along the direction of its end-of-fill position to pressurize the molten material into the casting mold.

[0033] To this end, prior to this mold filling stage, during the pre-filling stage of the start-of-operation casting process, the casting piston advances from the start-of-operation position initially only to the pre-filling position, and the shut-off valve is kept closed so that the molten material in the casting chamber can be compressed into the molten material outlet channel. The pre-filling position of the casting piston is determined by the fact that, upon reaching it, the molten material has filled the molten material outlet channel to a desired, predefined range. The subsequent opening of the shut-off valve and the return movement of the casting piston from the pre-filling position to the start-of-operation position may correspond to the start-of-operation position or the forward position of the casting piston in the casting chamber between the start-of-operation position and the pre-filling position, which refills the casting chamber with molten material through the molten material inlet channel to the maximum amount previously pressurized into the molten material outlet channel from the casting chamber.

[0034] In the case of the first casting process following the start of machine operation, conditions identical or similar in terms of the molten material already available up to the forward region of the molten material outlet channel in this manner exist for the subsequent casting process in the machine's started casting operation. In other words, in that case, the molten material in the molten material outlet channel is already available for this first casting process up to its forward region, for example, from the entire volume of the rise-channel section and from the volume of the mouthpiece body section adjacent to the molten material outlet channel to the forward end region of the mouthpiece body, thus up to a level significantly higher than the tank level of the allocated molten material tank, which is the level at which the molten material is supplied to the casting chamber. In other words, in that case, the molten material in the molten material outlet channel is already available for this first casting process up to its forward region, for example, from the entire volume of the rise-channel section and from the volume of the mouthpiece body section adjacent to the molten material outlet channel to the forward end region of the mouthpiece body, thus up to a level significantly higher than the tank level of the allocated molten material tank, which is the level at which the molten material is supplied to the casting chamber. This has the advantage that, thanks to this single pre-filling, the casting piston stroke required for the subsequent actual mold filling step at the start of operation can already be significantly reduced during the first casting cycle after the start of operation. In an alternative embodiment, instead of this pre-filling means, the first casting process after the start of machine operation is performed with a casting piston stroke that is correspondingly longer than the additional casting process during the operated operation period.

[0035] In the case of the die casting machine according to the present invention, for the purpose of performing each casting process in the mold filling stage, the control unit and the shut-off valve are configured to bring the shut-off valve to a closed position and control the casting piston of the casting chamber to advance from the casting start position to the filling end position in order to push molten material into the casting mold through the molten material outlet channel, and in the subsequent filling stage, to supply molten material into the casting chamber through the molten material inlet channel, the shut-off valve is first brought to an open position and the casting piston is controlled to move back to the casting start position.

[0036] The control unit and the shut-off valve are also configured to control the shut-off valve to a closed position during the refilling stage before the casting piston reaches the casting start position by its return motion, and to control the casting piston to back-suck molten material from the molten material outlet channel by the additional return motion of the casting piston, and / or to control the casting piston during the pre-filling stage of the casting start process before the mold filling stage while the shut-off valve is closed during the casting start process to advance from the casting start position to the pre-filling position in the casting chamber, and then to control the shut-off valve to an open position and return the casting piston to the casting start position.

[0037] Consequently, this die-casting machine is particularly suitable for carrying out the embodiments mentioned in the method of operation according to the present invention. Effects of the invention

[0038] In the improvement of the present invention, the shut-off valve is in the form of a shut-off control valve, and the control unit is configured to control the shut-off control valve. This enables the shut-off valve to be actively controlled through the control unit, thereby allowing it to be set to a desired open or closed position, particularly during the casting process.

[0039] In the development of the present invention, the die-casting machine includes a valve actuator operated by a control unit to actuate a shut-off control valve. The actuator serves as a connecting element between the control unit and the shut-off valve and can be appropriately selected depending on the type of the control unit and the shut-off valve, for example, whether they are electric, magnetic, hydraulic, pneumatic, or mechanical types. Alternatively, the valve actuation function may be directly integrated into the control unit, for example.

[0040] In an improvement of the present invention, the shut-off valve is in the form of a backflow prevention valve preloaded to the closed position. This constitutes an alternative implemented as a shut-off control valve. In this case, the shut-off valve is controlled or operated according to the pressure of the molten material acting thereon, in particular the melting pressure of the casting chamber.

[0041] In an improvement of the present invention, the die-casting machine includes a valve sensor unit for detecting one or more measured variables of a shut-off valve. This provides, for example, feedback to a control unit regarding the current position of the shut-off valve through the valve sensor unit and / or valve diagnostic information regarding whether the shut-off valve is operating without error and / or information regarding what state of use it is in and whether maintenance is required. Brief explanation of the drawing

[0042] Advantageous embodiments of the present invention are illustrated in the drawings. These embodiments and additional embodiments of the present invention are described in more detail below. In the drawings: FIG. 1 shows a schematic cross-sectional view of a part of interest in an embodiment of the present invention of a die-casting machine having a shut-off control valve as a shut-off valve. FIG. 2 illustrates a flowchart for explaining the operation method of the die-casting machine of FIG. 1 from the start of operation. Figure 3 shows the appearance of Figure 1 while operating the machine according to the method of Figure 2 at the start of the mold filling stage of the first casting cycle. Figure 4 shows the appearance of Figure 3 during the mold filling stage. Figure 5 shows the appearance of Figure 3 when the refilling step of the first casting cycle begins after the mold filling step is finished. Figure 6 shows the appearance of Figure 3 during the refilling phase. Figure 7 shows the appearance of Figure 3 after the refilling of the casting chamber with molten metal is completed. Figure 8 shows the appearance of Figure 3 during the molten material back-suction operation following the molten material refilling operation. Figure 9 shows the appearance of Figure 3 toward the end of the first casting cycle. Figure 10 shows the appearance of Figure 3 at the end of the mold filling stage of the second casting cycle. FIG. 11 illustrates a flowchart for explaining the operation method of the die-casting machine of FIG. 1 in a deformation having an initial pre-filling step after the start of operation. Figure 12 shows the appearance of Figure 3 while operating the machine according to the method of Figure 11 at the start of the initial pre-filling stage. Figure 13 shows the appearance of Figure 12 at a later point in the initial pre-filling stage of refilling the casting chamber with molten metal. Figure 14 shows the appearance of Figure 12 at the end of the mold filling step after the initial pre-filling step of the first casting cycle in a variation of the method of Figure 11. FIG. 15 shows a flowchart illustrating the operation method for the die-casting machine of FIG. 1 in a variation having periodic pre-filling before the mold-filling stage of each casting cycle. Figure 16 shows a modified version of Figure 1 of a die-casting machine having a backflow prevention valve as a shut-off valve. Specific details for implementing the invention

[0043] FIGS. 2, 11, and 15 illustrate various advantageous variations of the method of the present invention for operating a die-casting machine in flowcharts. FIGS. 1, 3 to 10 and 12 to 14 and FIG. 16 schematically illustrate parts of interest of a die-casting machine in two embodiments according to the present invention that can be operated by the method according to the present invention. This die-casting machine may be one of the types of hot-chambers for die-casting liquid or partial liquid metal melts, particularly zinc, lead, aluminum, magnesium, titanium, steel, copper, and alloys of these metals. For this purpose, the die casting machine comprises, in particular, a casting mold (1) having a fixed mold half (1a) and a movable mold half (1b), a casting chamber (2), a casting piston (3) arranged to be axially movable in the casting chamber (2), a melt inlet channel (4) leading to the casting chamber (2), a shut-off valve (5) of the melt inlet channel (4), a melt outlet channel (6) leading from the casting chamber (2) to the casting mold (1), and a control unit (7).

[0044] In the examples of FIGS. 1, 3 to 10 and 12 to 14, the shut-off valve (5) is a shut-off control valve (5 S), that is, configured as an activateable shut-off valve that is activated directly by the control unit (7) or optionally by the valve actuator (16) as illustrated. The valve actuator (16) may be any desired actuator of the conventional type as is known to a person of the art to operate such a valve itself. In this regard, depending on the requirements and usage situation, the actuator (16) may be a type of actuator that is particularly electric, hydraulic, pneumatic, or mechanically actuated directly, or a type of actuator that is mechanically actuated through a lever system. In this regard, depending on the requirements and usage conditions, the valve actuator (16) may be a type of actuator that operates in a purely binary manner and switches the shut-off valve (5) only between a first, open position and a second, closed position, or a proportional actuator type that can open the shut-off valve (5) continuously or in multiple stages, that is, a proportional actuator type that can maintain the shut-off valve (5) in one or more partially open positions between a fully open position and a fully closed position. To this end, the valve actuator may include, for example, variablely settable end stops that can be adjusted manually or automatically as needed. In the schematic diagram corresponding to FIG. 1, FIG. 16 illustrates a variation of a die-casting machine, in which the shut-off valve (5) is a non-return valve (5 R It differs from that of Fig. 1 in that it is composed of ).

[0045] In the case of the present embodiment, the control unit (7) is understood to mean all control elements of the die-casting machine for controlling and / or regulating various components of the machine, and for this purpose, the control unit (7) may include, depending on the system configuration, a single control device in which all control functions are integrated, or a plurality of individual control devices, each of which controls and / or regulates specific machine components and preferably has communication links to each other. Similarly, as is customary, the control unit (7) may be composed at least partially of hardware and / or at least partially of software. To illustrate all machine control functions of the control unit (7), activation arrows (7a, 7b, 7c) leading from the control unit (7) to the valve rod (5d) of the casting mold (1), casting piston (3), and shut-off valve (5) are shown purely symbolically and in a representative manner, and the control functions belonging to these machine components are of primary interest in the case of the present embodiment. For simplification, a schematic diagram of the control unit (7) is present only in FIG. 1. In contrast, it is omitted in Figures 3 to 10 and 12 to 14.

[0046] Unless otherwise described below, the control unit (7) and the remaining machine components mentioned have a structure that is ordinary and familiar to a person of ordinary skill, and therefore no further explanation is required here. In the illustrated embodiment, for example as can be seen in FIG. 1, the casting chamber (2) is formed in the casting container (8) of a conventional casting unit in this regard, and the casting container (8) is placed in the melt bath (9) located in the conventional melt container (10) during the casting operation.

[0047] In the illustrated example, the shut-off valve (5) is held in the casting vessel (8) by a valve housing body (5a). The valve housing body (5a) has one or more inlet openings in the form of an inlet (4a) for a melt inlet channel (4) at other locations in the casting vessel (8). That is, the melt material (14) can be introduced from the melt tank (9) into the melt inlet channel (4) through the inlet (4a). The shut-off valve (5) is positioned specifically in the melt inlet channel (4) with a fixed valve seat (5b) and a movable valve closing body (5c). In the illustrated example, the valve closing body (5c) is moved by the valve rod (5d) so as to be axially seated against the valve seat (5b) and, conversely, to be moved away from it, thereby closing and opening the shut-off valve (5), respectively, that is, switching the shut-off valve (5) between an open position VO as illustrated in FIG. 1 and a closed position VS as illustrated in FIG. 3. In this respect, depending on the valve configuration and / or operating conditions, the open position VO may be a fully open position or a partially open position of the valve. In an alternative embodiment not illustrated, the shut-off valve (5) is provided on a cast piston (3) as is known in itself, in which case the molten material inlet channel (4) is connected through the cast piston (3), particularly through it.

[0048] In the machine configurations of FIGS. 1, 3 to 10 and 12 to 14, as previously mentioned, a shut-off valve (5), i.e., a shut-off control valve (5 SThe switch movement of ) is performed by the control unit (7) by, for example, an optional valve actuator (16). In the mechanical configuration of FIG. 16, the shut-off valve (5), i.e., the backflow prevention valve (5 R The switching movement of ) is performed according to the molten material pressure of the casting chamber (2), and the backflow prevention valve (5 R ) is biased to a closed position VS by a conventional type preloading unit (17). When the corresponding melt negative pressure is present in the casting chamber (2), the backflow prevention valve (5 R ) is moved from the closed position VS to the open position VO by this negative pressure opposing the preload force of the preload unit (17). When the melt negative pressure is no longer present, the backflow prevention valve (5 R ) automatically returns to the closed position VS by the action of the preload unit (17). The preload unit (17) can be implemented by a preload spring, such as a compression or tension spring, which is designed and arranged accordingly, for example, and the preload unit (17) of FIG. 16 is illustrated purely as an example and schematically by an example of a tension spring.

[0049] The molten material outlet channel (6) exits from the casting chamber (2) through a riser-channel region and / or a riser-tube portion (6a) formed in the casting vessel (8) in a conventional manner, and then continues to the mold (1) region through a mouthpiece body (6b). For this purpose, likewise in a conventional manner, the mouthpiece body (6b) is coupled to a mouthpiece attachment (11) at the inlet side, through which the riser-tube portion (6a) opens from the casting vessel (8) and leads at the outlet side to a gating cone (12) region of a fixed mold half (1a) in front of the mold cavity (13), which is designed dependently on the cast part formed and produced by the two mold halves (1a, 1b) when the casting mold (1) is closed.

[0050] FIG. 2 illustrates a method of operation according to the present invention in an exemplary variation of the embodiment at the start of operation of the die-casting machine, that is, after operating the machine in a series of corresponding number of casting processes or casting cycles for the purpose of casting a desired number of identical castings. FIGS. 1 and 3 through 10 schematically illustrate machines in different stages of operation during operation according to the exemplary variation of FIG. 2. In this respect, the machines of FIGS. 3 through 10 are illustrated in the embodiment of FIG. 1 only for simplicity. However, the relevant description below applies in the same way to the machine configuration of FIG. 16 unless otherwise noted.

[0051] In the initial operating stage (B1) of FIG. 2, the machine is in a basic state at the start of operation. FIG. 1 illustrates the machine in this operating stage (B1), except that the casting mold (1), which is still open (open state) in the basic state, is already shown in a closed state. Thus, the casting piston (3) is located at the operating starting position (BS). The shut-off valve (5) is still open (open state), and thus the molten material (14) is also present everywhere up to the height of the molten tank level (9a) of the molten tank (9). In particular, the molten material (14) is also located in the molten outlet channel (6) at the same molten level (SH) corresponding to the molten tank level (9a), and the molten material (14) extends, for example, to the central or front region of the rising-channel section (6a) but not yet to the mouthpiece body (6b).

[0052] In the subsequent operation step (B2) of FIG. 2, the first casting cycle is started, and for this purpose, the associated mold-filling phase is performed. To this end, the casting mold (1) is first closed, and the shut-off valve (5) is moved from the open position (VO) to the closed position (VS) and / or maintained in the closed position (VS), which is a shut-off control valve (5) controlled by the control unit (7). S A backflow prevention valve (5) that is automatically controlled by ) or a preload unit (17). RRegardless of whether it is ) FIG. 3 illustrates the machine at this point. Subsequently, the casting piston (3) advances from the operating start position (BS) to the filling end position (FP), that is, moves downward in FIG. 1, 3 to 10 and 12 to 14, respectively, and as a result, the molten material (14) is pressurized and enters the casting mold (1) from the casting chamber (2) through the molten material outlet channel (6). The advancing movement of the casting piston (3) is symbolically indicated by the associated direction of movement arrow GV in the corresponding figure. The molten material flow in the molten material outlet channel (6) is symbolically indicated by the corresponding flow arrow in FIG. 4. FIG. 4 shows the machine at the end of this mold filling stage, which may include a subsequent stage or pressure holding stage known in a known manner, where additional increased subsequent or pressure holding is applied to the molten material (14) in the mold (1).

[0053] In the operation step (B3) of FIG. 2, the mold filling phase is terminated and followed by a refilling phase and / or a piston return phase. To this end, the shut-off valve (5) is switched from the closed position (VS) to the open position (VO), and the casting piston (3) moves backward from the filling termination position (FP), i.e., upward in the relevant drawing. The switching of the shut-off valve (5) is controlled by the shut-off control valve (5 S In the case of ), it is controlled by the control unit (7), and the backflow prevention valve (5 RIn the case of ), the negative pressure of the molten material generated in the casting chamber (2) due to the return movement of the casting piston (3) is controlled. It will be understood that, depending on the type of machine, the forward or return movement of the casting piston (3) may be perpendicular or tilted relative to the vertical direction, rather than in the vertical direction as in the illustrated example. The casting mold (1) is initially kept closed, and after the so-called cooling time, which is the period during which the molten material (4) cools in the mold cavity (13), the molten material (14) solidifies to form the desired casting (15). The return movement of the casting piston (3) draws the molten material (14) from the molten material tank (9) and refills the casting chamber (2) with the molten material (14) through the molten material inlet channel (4). FIGS. 5 and 6 illustrate the machine at the initial and somewhat later points of the refilling stage, respectively. In the refilling step, molten material (14) from the molten material tank (9) refills the casting chamber (2) as shown by the corresponding flow arrow. The return movement of the casting piston (3) is symbolically represented in the corresponding drawing by the associated direction of movement arrow GR.

[0054] In the operation step (B4) of FIG. 2, the refilling of the casting chamber (2) with molten material (14) from the molten material tank (9) through the molten material inlet channel (4) is terminated by switching the shut-off valve (5) from the open position (VO) to the closed position (VS). Shut-off control valve (5) S In the case of ), this is caused by the control unit (7). Backflow prevention valve (5 R In the case of ), this is caused by stopping the return movement of the casting piston (3) so that no more molten negative pressure is generated in the casting chamber (2), and as a result, the backflow prevention valve (5 RThe preload unit (17) automatically returns the casting piston (3) to the closed position (VS). At this point, the casting piston (3) is positioned at the corresponding valve reversal position and / or valve switching position (VU). The casting piston (3) is preferably maintained there for a halt period, the duration of which can be appropriately predefined in such a way that the shut-off valve (5) reaches the closed position (VS) when the halt period has elapsed. Optionally, in this regard, it is possible to select a halt period corresponding to the transition period from the open position (VO) to the closed position (VS) of the shut-off valve (5), or to monitor when the shut-off valve (5) reaches the closed position (VS) and then end the halt period or continue moving the casting piston (3). FIG. 7 illustrates the machine at this point. Meanwhile, the cooling time of the molten material (14) in the casting mold (1) for forming the casting (15) continues.

[0055] After the stop period has elapsed, or after passing the valve switching position (VU) or after the shut-off valve (5) is closed, in the operating step (B5) of FIG. 2, the casting piston (3) is retracted back to the casting start position (GS) for a subsequent second casting process, and as a result, a back-suctioning process of the molten material is initiated. The casting start position (GS) may be the same as the initial operating start position (BS) of the casting piston (3), or may differ to a limited extent. FIG. 8 illustrates a machine in the intermediate position (ZS) of the casting piston (3) during this return movement of the casting piston (3) past or away from the valve switching position (VU).

[0056] In this regard, a shut-off control valve (5) SIn the case of an embodiment having ), it is maintained in a controlled manner in the closed position (VS), and the casting mold (1) is not yet opened, and as a result, additional return movement of the casting piston (3) brings a suction effect to the molten material outlet channel (6) via the casting chamber (2). This creates negative pressure in the gating cone (12) area in such a way that the molten material (14) is already pulled somewhat backward from the mouthpiece body (6b) from the exit in front of the molten material outlet channel (6), for example, specifically as indicated by the reverse suction arrow (14a) in FIG. 8.

[0057] Backflow prevention valve (5 R In the case of an embodiment having ), a shut-off control valve (5 S In an embodiment selected from having ) and in relation to the operation step (B5), other than the above-described procedure shown in 2, at the time prior to the additional return movement of the casting piston (3), the casting mold (1) is opened to at least a predefined range and waits for the cooling time to elapse or end. As a result, the molten material outlet channel (6) is no longer sealed hermetically to the outside atmosphere on the side of the casting mold (1), which results in the molten material negative pressure no longer accumulating in the casting chamber (2) during the additional return movement of the casting piston (3). Therefore, the backflow prevention valve (5 R ) is maintained in the closed position (VS). Instead, the molten material (14), particularly in the front region of the mouthpiece body (6b), is pulled further back from the region of the gating cone (12). That is, limited back suction of the molten material occurs from the furthest front (farthest front) exit side region of the molten material outlet channel (6), preventing the formation of a melt droplet in the region of the gating cone (12).

[0058] The additional return movement of the casting piston (3) from the valve switching position (VU) to the casting start position (GS) is preferably to occur at a piston speed significantly lower than the piston speed at which the casting piston (3) previously moved backward from the filling end position (FP) to the valve switching position (VU).

[0059] The stroke distance between the valve switching position (VU) and the casting start position (GS) of the casting piston (3) determines the degree of back suction of the molten material (14) in the molten material outlet channel (6), and optionally, this stroke distance can be variably predefined or set by the user.

[0060] In the illustrated example, the point at which the shut-off valve (5) is switched to the closed position (VS) to end the refilling of the casting chamber (2) with molten material (14) from the molten material tank (9) is coupled to the casting piston (3) reaching the valve switching position (VU), but in an alternative embodiment, this valve switching may be triggered in a different way, for example, after a certain amount of time has elapsed since the return movement of the casting piston (3) began from the filling end position (FP).

[0061] In the operation step (B6) of FIG. 2, the return movement of the casting piston (3) ends after reaching the casting start position (GS). Meanwhile, the shut-off control valve (5 S Even in the case of a modified embodiment having ), the cooling time for complete solidification of the casting (15) formed in the mold (1) has elapsed, and therefore, in this modified embodiment, in the subsequent operation step (B7) of FIG. 2, the opening of the casting mold (1) can be initiated by the corresponding opening movement of the movable mold half (1b) at this operation time, as shown in FIG. 9 which represents the machine. The opening of the mold (1) is controlled by a shut-off control valve (5 SIn a modified embodiment using ), the previously generated back-suction negative pressure can be immediately released from the area of ​​the gating cone (12), so that as a result, the molten material (14) is drawn further back from the area of ​​the gating cone (12) in the front area of ​​the molten outlet channel (6) in the example specifically illustrated in the front area of ​​the mouthpiece body (6b). Drawing back, that is, the limited re-suction of the molten material (14) to the furthest front of the molten outlet channel (6) from the outlet side, is prevented by the backflow prevention valve (5 R As described in the modified embodiment related to ), the formation of molten droplets in the area of ​​the gating cone (12) is prevented. In both modified embodiments, it is possible to remove the casting (15) formed in each case after the mold (1) is completely opened.

[0062] FIG. 9 illustrates an example of molten material (14) existing from the front region of the molten material outlet channel (6) to the melting-away point (RP) where the re-inhaled molten material is separated from the solidified or partially solidified molten material remaining in the mold (1) and the gating cone (12), or from the exit of the molten material outlet channel or the region of the gating cone (12), maintaining a desired, sufficient distance (AS). This ensures that droplet formation is reliably prevented, and the distance (AS) is exaggerated in FIG. 9 for clarity only and is not shown in actual size. The distance (AS) is approximately 5 mm to 100 mm from the gating cone (12), particularly, for example, approximately 10 mm to approximately 50 mm, preferably approximately 30 mm to approximately 40 nm, and varies depending on the requirements, the viscosity of the molten material and / or the system configuration of the machine, particularly the diameter of the casting piston, rising bore and mouthpiece body. Alternatively, the distance (AS) may also be longer, where the longer the distance (AS), the more air is present in the outlet side area of ​​the molten metal outlet channel (6) before the start of the next casting cycle.

[0063] However, in any case, the molten material outlet channel (6) is filled with molten material (14) at a height higher than the molten material level (9a) of the molten material tank (9), and as a result, in the next casting cycle, as in the first casting cycle after the start of operation as shown in FIG. 3, the molten material (14) in the molten material outlet channel (6) does not need to be advanced (provided) from the molten material level (9a) in advance, and the molten material level (SH) of the molten material outlet channel (6) is at a significantly higher level than the molten material level (9a) at the start of the next casting cycle, and the molten material (14) is preferably already available in the forward area of ​​the molten material outlet channel (6). In this way, the first casting cycle is terminated after the operation step (B7) of FIG. 2.

[0064] To perform the subsequent second casting cycle, the mold (1) is closed at the operating step (B8) of FIG. 2, and the casting piston (3) is moved from the casting start position (GS) to the filling end position (FP) to press the molten material (14) from the casting chamber (2) back into the closed mold (1) through the molten material outlet channel (6). FIG. 10 illustrates the machine at the end of the mold filling step of the second casting cycle, corresponding to the end of the mold filling step of the first casting cycle shown in FIG. 4.

[0065] As illustrated in the comparative manner of FIG. 10, the axial movement stroke of the casting piston (3) from the casting start position (GS) to the filling end position (FP) in the second casting cycle is smaller than the movement for the casting piston (3) to advance from the operating start position (BS) to the filling end position (FP), because in the second casting cycle, the molten material (14) is already at a position significantly higher than the molten tank level (9a) in the molten material outlet channel (6). That is, as schematically illustrated in FIG. 10, the filling end position (FP) in the second casting cycle is located at the end position (FP2) with respect to the position of the casting chamber (2), and this end position (FP2) is further back, that is, further up, than the end position (FP1) considered as the filling end position (FP) of the casting piston (3) in the first casting cycle.

[0066] In other words, the stroke distance HA = FP-GS = FP2-GS between the filling end position (FP) and the casting start position (GS) in the second casting cycle and subsequent casting cycles of the machine's corresponding active operation interval is less than the corresponding stroke distance HA = FP-BS = FP1-BS between the filling end position (FP) and the operation start position (GS) in the first casting cycle, and the difference is determined by the amount of molten material (14) present in the molten outlet channel (6) above the molten tank level (9a) after the first casting cycle and before the second casting cycle. The stroke difference is illustrated in FIG. 10 by the corresponding stroke deviation HD = FP1-FP2 of the filling end position (FP1) after the first casting cycle to the filling end position (FP2) after the second casting cycle. The reduction in this stroke length for the second casting cycle and subsequent additional casting cycles may be up to 30% or up to 50% or more, depending on the type of machine and the casting (15) to be produced.

[0067] The reduction in the stroke length that the casting piston (3) must move during the mold filling stage thereby shortens the cycle time, that is, the duration of each casting cycle for the second and subsequent additional casting cycles, and shortens the operating interval by, for example, up to 5% or 10%. Furthermore, due to the molten material (14) remaining in the molten material outlet channel (6) located above the molten material level (9a) between casting cycles, the air fraction in the outlet side portion of the molten material outlet channel (6) is reduced, and as a result, the air contained in the casting is also reduced, which helps the quality of the casting. In addition, shortening the casting piston stroke can reduce wear on the casting piston and the casting chamber caused by the movement of the casting piston within the casting chamber.

[0068] Subsequently, the mold filling step and subsequent refilling step of the second casting cycle proceed in the same manner as described above for the first casting cycle that can be referenced. This is indicated by the arrow returning from the operation step (B8) to the operation step (B3) in Fig. 2.

[0070] As a shut-off valve (5), a shut-off control valve (5) S In an exemplary embodiment having ), the casting mold (1) is kept closed during the entire refilling step until the casting piston (3) reaches the casting start position (GS) for the next casting cycle. The fact that the mold (1) is opened only at this point leads to the aforementioned instantaneous back-suction effect. In an alternative procedure, the casting mold (1) may be opened earlier, and as a result, the back-suction effect may be configured more uniformly and / or weakened in terms of time. In this regard, in corresponding operational variations, the casting mold (1) is at least for the purpose of refilling the casting chamber (2) with molten material (14) from the melt bath (9) using a shut-off control valve (5 S It remains in a closed state as long as the valve is still open. When the casting piston (3) reaches the valve switching position (VU) and the shut-off control valve (5) closes, the casting mold (1) is opened according to requirements at a point before or after the point of additional return movement of the casting piston (3) from the valve switching position (VU) to the casting start position (GS). As soon as the opening of the mold (1) begins, more air can pass through the outlet of the melt outlet channel (6) into the front area of ​​the melt outlet channel (6), and as a result, the negative pressure effect there can be weakened and / or relieved.

[0071] In another operational variation, the casting piston (3) is maintained in the valve switching position (VU), and after a cooling time has elapsed, the opening of the casting mold (1) begins. As soon as the casting mold (1) opens, it reaches a determined casting piston-triggered mold opening position, which can be predetermined, for example, in a variable or permanent manner. When the movable mold half (1b) moves away from the fixed mold half (1a) by a corresponding predetermined travel length, the casting piston (3) is moved further back from the valve switching position (VU) to the casting start position (GS). In this regard, the casting-piston-triggered mold opening position is selected to allow the entry of air from the melt outlet channel (6) through the gating cone (12) or the mouthpiece nozzle. This can then result in the reverse suction of the molten material (14) from the farthest forward area of ​​the melt outlet channel (6) with a relatively homogeneous change over time without a sudden drop in negative pressure. This example of an operating variation is, for example, a backflow prevention valve (5) as a shut-off valve (5). R The same applies to the mechanical deformation of Fig. 16 having ). Then, as soon as the mold (1) is opened enough for air to flow into the molten metal outlet channel in this way, the molten negative pressure caused by the additional return movement of the casting piston (3) is no longer generated in the casting chamber (2), and the backflow prevention valve (5R) is automatically maintained in the closed position (VS) by the action of the preload unit (17).

[0072] FIG. 11 illustrates a method for operating a die-casting machine according to the present invention in other advantageous variations, which is particularly related to the performance of each first casting cycle after the start of machine operation, and primarily as a shut-off control valve (5) SIt is suitable for machine variation embodiments using ). For this purpose, this operation variation embodiment is resumed from the machine's default state at the start of operation according to the initial operation step (B1) of FIG. 2. In contrast to the operation variation embodiment of FIG. 2, in the operation variation embodiment of FIG. 11, a specific first casting cycle is performed in which the operation start casting process, i.e., the initial pre-filling step, is performed upstream of the mold filling step.

[0073] To this end, in the operation step (B2a) of FIG. 11, this initial pre-filling step is initiated by the casting piston (3) advancing only from the operation start position (BS) to the initial pre-filling position (VP) shown in FIG. 12 after the shut-off control valve (5) is closed and the mold (1) is closed, FIG. 12 illustrates the machine during this operation step (B2a). As a result, the molten material outlet channel (6) is pre-filled with molten material (14) at a height above the molten material level (9a) of the molten material tank (9), preferably to the pre-fill point (VA) in the front area of ​​the mouthpiece body (6b) or the molten material outlet channel (6), and as a result, the pre-fill point (VA) is at a relatively small distance (DS) into the mold (1) from the gating cone (12) or from the exit of the molten material outlet channel (6). This distance (DS) roughly corresponds to the distance (AS) between the reverse suction point (RP) and the exit of the molten material exit channel (6) into the mold (1), and exists, for example, after the re-suction of the molten material (14) from the molten material exit channel (6) described in the operational variation embodiment of FIG. 2 and as shown in FIG. 9.

[0074] Then, in the operation step (B2b) of FIG. 11, a predetermined specific time is maintained until the excess pressure formed as a result of the pre-filling process due to compressed air in the mold cavity (13) is reduced. Then, in the operation step (B2c) of FIG. 11, the shut-off control valve (5) is reversed from the closed position (VS) to the open position (OS), and the casting piston (3) returns from the pre-filling position (VP) to the casting start position (GS). As a result, the molten material is drawn from the molten tank (9) into the casting chamber (2) through the molten inlet channel (4), as described by the flow arrow in FIG. 13, or refills the casting chamber (2), FIG. 13 illustrates the machine at the end of the operation step (B2c) when the casting piston (3) has reached the casting start position (GS) again.

[0075] This molten material refilling process may involve a specific additional back-drawing of the molten material (14) from the molten material outlet channel (6), because a certain amount of air is present even in the closed mold (1) and the mold (1) may not be completely airtight. As a result, the pre-fill point (VA) (where the molten material (14) is pre-filled from the molten material outlet channel (6) to this point) may be displaced somewhat backward by the associated back-flow arrow as shown in FIG. 13, and the pre-fill point (VA) is located further back from the mouthpiece body (6b) compared to FIG. 12. Nevertheless, the molten material (14) remains pre-filled from the molten material outlet channel (6) to the forward region of the molten material outlet channel at a level significantly higher than the molten material tank level (9a) of the molten material tank (9).

[0076] In principle, a backflow prevention valve (5 R A similar pre-filling process is possible for a mechanical modification embodiment in which ) is used as a shut-off valve (5). In this case, the backflow prevention valve (5 R) is kept closed by the molten material pressure in the casting chamber (2), while the casting piston (3) advances from the operation start position (BS) to the pre-fill position (VP). As mentioned above, subsequently, when preparations are made for an appropriate reduction of excess pressure in the operation step (B2b), and then when preparations are made so that the reverse suction of molten material from the molten material outlet channel (6) can be sufficiently hindered or slowed by the activable closure of the molten material outlet channel (6) and / or the sufficiently rapid return movement of the casting piston (3), the return movement of the casting piston (3) from the pre-fill position (VP) to the casting start position (GS) is prevented by the backflow prevention valve (5 R A sufficient amount of negative pressure can be generated in the casting chamber (2) to open the mold, and in this case, molten material can be drawn from the molten material tank (9) into the casting chamber (2) through the molten material inlet channel (4) or refill the casting chamber (2).

[0077] After this initial pre-filling stage is completed, the mold filling stage of the first casting cycle is performed according to the operation stage (B2d) of FIG. 11. To do this, the shut-off control valve (5) returns to the closed position (VS) or the backflow prevention valve (5 R The casting chamber (2) is automatically closed after the negative pressure of the molten material drops, and the casting piston (3) advances from the casting start position (GS) to the filling end position (FP), and as a result, the molten material (14) is pressurized again from the casting chamber (2) to the casting mold (1), specifically the casting cavity (13), through the molten material outlet channel (6).

[0078] Compared to the first casting cycle without pre-filling, as in the operating variation embodiment shown in FIG. 2, the stroke distance HA = FP-BS between the filling end position (FP) and the operating start position (BS) for this mold filling stage of the first casting cycle is shortened due to the initial pre-filling. This stroke shortening for the first casting cycle is achieved similarly to the stroke shortening described above, which is achieved only for the additional casting cycle by the early closing of the shut-off control valve during the refilling stage of the casting cycle preceding the casting cycle, prior to reaching the casting start position (GS) in the operating variation embodiment of FIG. 2 and prior to the additional return movement of the casting piston (3) to the casting start position (GS). FIG. 14 shows the machine in this operating stage (B2d) at the end of the mold filling stage of the first casting cycle, where the stroke deviation HD1 = FP1-FP 1V For a variant embodiment having an initial pre-filling step located after the filling end position (EP1) in the first casting cycle for the operating variant embodiment of FIG. 2 without pre-filling by, the filling end position (FP) is located (FP 1V It is shortened to ). That is, in this operational variation embodiment, as a result of this pre-filling measure, the casting stroke for performing the mold filling operation during the first casting cycle is shortened compared to the operational variation embodiment of FIG. 2 without pre-filling.

[0080] Consequently, in the operational variation embodiment of FIG. 11, the characteristics and advantages mentioned above regarding the shortening of the stroke in the second casting cycle and the additional casting cycle in the operational variation embodiment of FIG. 2 are already achieved in the first casting cycle of the operational variation embodiment of FIG. 11.

[0081] Further progress of the first casting cycle may correspond to the progress of the modified operation embodiment of FIG. 2, separate from the operation step (B3) therein. Alternatively, in the modified operation embodiment of FIG. 11, the first casting cycle may continue according to any desired conventional operation method.

[0082] FIG. 15 illustrates an advantageous variation of the method of operation of FIG. 2 in terms of the performance of the second casting cycle and additional casting cycles. In this variation of the method, each mold filling step of the second casting cycle includes a pre-filling step. In this regard, the operation situation at the end of the operation step (B7) proceeds as described in FIG. 9. In contrast to the operational variation embodiment according to the operational step (B8) of FIG. 2, in the operational variation embodiment of FIG. 15, when the casting piston (3) advances in the operational step (B8a), it does not wait for the mold (1) to be completely closed, but rather the casting piston (3) advances from the casting start position (GS) to the pre-filling position (VP2) for the second casting, at which time the mold (1) is still open. In this embodiment, this pre-filling position (VP2) is also called the cyclic pre-filling position (VP2) to distinguish it from the pre-filling position (VP) in the initial pre-filling step prior to the first casting cycle according to the operational variation embodiment of FIG. 11 and the example shown in FIG. 12.

[0083] This periodic pre-filling enables the molten material (14) previously sucked back from the outlet of the molten outlet channel (6) to advance again in the direction of the outlet of the molten outlet channel (6) according to the operating steps (B5) to (B7) of the operating variation embodiment of FIG. 2, thereby enabling more pre-filling of the molten outlet channel (6) and allowing air to escape unobstructed through the mold (1) that is not yet closed in the front end region of the molten outlet channel (6).

[0084] In the operating step (B8b) of FIG. 15, the casting piston (3) is maintained in this periodic pre-filling position until the mold (1) is completely closed. Thereafter, the remaining process of the mold filling step of the associated second or additional casting cycle is performed according to the operating step (B8c) of FIG. 15, for this purpose, the casting piston (3) proceeds from the periodic pre-filling position to the filling end position (FP) and the filling end position (FP2), respectively, to pressurize the molten material (14) from the casting chamber (2) into the closed mold (1) or its casting cavity (13) through the pre-filled molten material outlet channel (6). At this point, the operating state of the machine corresponds to the operating state of FIG. 10 or the end of the operating step (B8) of FIG. 2. That is, in the operating variant embodiment of FIG. 15, after the mold filling step is finished, the refilling step and additional steps starting from the operating step (B3) of FIG. 2 continue at the end of the operating step (B8c). Periodic pre-filling at the beginning of the mold filling stage of the additional casting cycle and the second casting cycle allows for a further reduction in cycle time and the air fraction of the produced casting by a corresponding amount. In a correspondingly optimized procedure, the operational variations of FIGS. 2, 11, and 15 can be combined to produce the following effect. For each operating interval of the die-casting machine, at the start of operation, all initial pre-filling is first performed by refilling the casting chamber with molten metal according to the variation of FIG. 11, and thereafter the second casting cycle and additional casting cycles are performed according to the variations of FIG. 15. Alternatively, operational variations according to the present invention are possible, such as using only specific initial pre-filling operations and molten metal refilling operations after the start of operation according to FIG. 11, or using only re-sucking according to operating steps (B3) through (B8) of FIG. 2 with or without additional combination with periodic pre-filling according to FIG. 15.

[0085] A die-casting machine according to the present invention is configured to perform the method of operation according to the present invention as illustrated. In particular, in this respect, a control unit (7) is configured to perform a corresponding casting process, and to this end, the control unit (7) controls the casting piston (3) of the casting chamber (2) to advance from the casting start position (GS) to the filling end position (FP) so as to pressurize the molten material (14) into the casting mold (1) through the molten material outlet channel (6) during the mold filling stage, and to this end, in the embodiments of FIGS. 1, 3 to 10 and 12 to 14, a shut-off valve (5 S ) is controlled directly or via a valve actuator (16) to be set to a closed position (VS), and meanwhile, in the case of the machine configuration according to FIG. 16, a backflow prevention valve (5 R ) is automatically maintained in the closed position (VS) under the action of the preload unit (17) and the molten material pressure of the casting chamber. The control unit (7) also controls the casting piston (3) during a subsequent refilling step to move back to the casting start position (GS) to supply molten material (14) to the casting chamber (2) through the molten material inlet channel (4), and to this end, in the machine configuration of FIGS. 1, 3 to 10 and 12 to 14, first a shut-off control valve (5 S ) is controlled to the open position (VO), and in the case of the machine configuration according to FIG. 16, the backflow prevention valve (5R) is in the open position (VO) due to the negative pressure of the casting chamber (2).

[0086] The control unit (7) and the shut-off valve (5) may also be configured to switch the shut-off valve (5) back to the closed position (VS) while it is still in the refilling phase before the casting piston (3) reaches the casting start position (GS) by the return motion, and to control the casting piston (3) back to the return motion to re-suck the molten material (14) from the molten material outlet channel (6). Alternatively, or additionally, the control unit (7) may also be configured to control the casting piston (3) to advance from the operating start position (BS) to the prefilling position (VS) in the casting chamber (2) during the prefilling phase of the operating start casting process, i.e., the first casting cycle, when the shut-off valve (5) is closed, before the mold filling phase, and then control the casting piston (3) to the open position (VO) and return to the casting start position (GS).

[0087] As illustrated in the example, the die-casting machine optionally includes a valve sensor unit (18) for detecting one or more measured variables of the shut-off valve (5). The measured values ​​for each measured variable detected by the valve sensor unit (18) may be provided to a control unit (7) as needed to provide control feedback regarding the current position of the shut-off valve (5). Additionally, or alternatively, the measured values ​​may be used for a diagnostic evaluation to diagnose the current state of the shut-off valve (5), for example, a current state related to a malfunction, and to identify when the shut-off valve (5) requires maintenance.

[0088] Depending on the requirements and usage conditions, the valve sensor unit (18) may include one or more sensors, including optional limit switches that may or may not be linked to the entire machine control system of the die-casting machine or to the control unit (7) which is part of this machine control system, as previously mentioned. The valve sensor unit (18) may be configured to measure the shut-off valve stroke to derive an error diagnosis, for example, to determine whether the valve closing body (5c) is torn and the valve rod (5d) has moved beyond its intended position during the valve closing motion and / or whether the valve closing body (5c) has actually reached the closed position or stopped prematurely. The valve sensor unit (18) may also optionally include a force sensor on the valve rod (5d) to measure the closing force or contact pressure and / or opening force of the valve closing body (5c) for diagnostic monitoring. In the case of an electric or hydraulic and / or pneumatic valve drive, for example, a valve actuator (16), for such monitoring purposes, the valve sensor unit (18) may also include a flow sensor or pressure sensor of a conventional design, regardless of whether there is a link to the control unit (7).

[0089] As is evident from the illustrated exemplary embodiments and the additional exemplary embodiments described above, the present invention provides an advantageous method for operating a die-casting machine, which can achieve a short casting cycle time, a lower air fraction in the casting, a lower tendency for wear of the casting piston and casting chamber due to a reduced casting piston stroke, and / or prevention of molten droplet formation in the gating cone area. The present invention also provides a die-casting machine suitable for carrying out this method of operation, which may be a high-temperature chamber type in particular.

Claims

Claim 1 A method of operating a die casting machine comprising a casting mold (1), a casting chamber (2), a casting piston (3) provided in a manner axially movable in the casting chamber, a molten material inlet channel (4) connected to the casting chamber, a shut-off valve (5) located in the molten material inlet channel, and a molten material outlet channel (6) connected from the casting chamber to the casting mold: in a mold filling step to perform each casting process, with the shut-off valve closed, the piston in the casting chamber advances from a casting start position (GS) to a filling end position (FP) so that molten material (14) is pressurized into the casting mold through the molten material outlet channel; in a subsequent refilling step, the casting piston moves to the casting start position and, with the shut-off valve open, the molten material is supplied to the casting chamber through the molten material inlet channel; and in the refilling step of the casting process, the previously opened shut-off valve (5) is closed before reaching the casting start position (GS) due to the return movement of the casting piston (3), and the molten material (14) in the molten material outlet channel (6) is reversed due to the additional return movement of the casting piston. A method of operating a die-casting machine including suction. Claim 2 A method of operating a die casting machine according to claim 1, wherein in the refilling step, the casting piston moves backward at a lower speed during the period when the shut-off valve is closed than during the period when the shut-off valve is still open; and / or in the refilling step of the casting process, the previously opened shut-off valve is closed as soon as it reaches the valve switching position (VU) due to the return movement of the casting piston. Claim 3 A method of operating a die casting machine, wherein, in claim 2, the stroke distance between the valve switching position and the casting start position of the casting piston may be variably predefined; and / or in the refilling step of the casting process, the casting piston is maintained in the valve switching position for a stopping period before moving back to the casting start position. Claim 4 A method of operating a die casting machine according to claim 1, wherein, during the refilling step of the casting process, the casting mold is maintained in a closed state while at least the shut-off valve is still open. Claim 5 A method of operating a die casting machine according to claim 1, wherein in the refilling step of the casting process, the opening of the casting mold begins after the casting piston reaches the casting start position. Claim 6 A method of operating a die casting machine according to claim 2, wherein, in the refilling step of the casting process, the opening of the casting mold begins after the casting piston reaches the valve switching position and before it reaches the casting start position. Claim 7 A method of operating a die casting machine according to claim 6, wherein in the refilling step of the casting process, when the casting mold is opened, as soon as the casting mold reaches a given casting piston triggered mold opening position, the casting piston stops at a valve switching position and advances from the valve switching position to a casting start position. Claim 8 A method of operating a die casting machine according to claim 1, wherein the casting piston moves from a casting start position reached during the refilling step of each previous casting process to a prefilling position during the initial prefilling step of the mold filling step of a subsequent casting process while the casting mold is not completely closed, and only thereafter the casting mold is completely closed and the casting piston moves to a filling end position. Claim 9 A method of operating a die casting machine according to any one of claims 1 to 8, comprising: a casting mold (1), a casting chamber (2), a casting piston (3) provided in a manner axially movable in the casting chamber, a molten material inlet channel (4) connected to the casting chamber, a shut-off valve (5) located in the molten material inlet channel, and a molten material outlet channel (6) connected from the casting chamber to the casting mold; wherein, in a mold filling step to perform each casting process, the piston in the casting chamber advances from a casting start position (GS) to a filling end position (FP) with the shut-off valve closed, and the molten material (14) is pressurized into the casting mold through the molten material outlet channel; wherein, in a subsequent refilling step, the casting piston moves to the casting start position and the molten material is supplied to the casting chamber through the molten material inlet channel with the shut-off valve open; and wherein, during the operation start casting process, prior to the filling step, in a pre-filling step of the operation start casting process, the casting piston (3) in the casting chamber (2) advances from the operation start position (BS) to a pre- A method of operating a die casting machine, moving to a filling stage (VP), then opening the shut-off valve and returning the casting piston to the casting start position. Claim 10 Casting mold (1); casting chamber (2); casting piston (3) provided in a manner axially movable in the casting chamber; molten material inlet channel (4) connected to the casting chamber; shut-off valve (5) located in the molten material inlet channel; molten material outlet channel (6) connected from the casting chamber to the casting mold; And, as a die-casting machine comprising a control unit (7) for controlling the casting piston, in order to perform each casting process, in the mold filling stage, the control unit (7) and the shut-off valve (5) are configured to control the casting piston (3) of the casting chamber (2) by setting the shut-off valve to a closed position (VS) and moving it from a casting start position (GS) to a filling end position (FP) in order to pressurize the molten material (14) into the casting mold (1) through the molten material outlet channel (6), and in the subsequent refilling stage, the shut-off valve is first set to an open position (VO) and the casting piston is controlled to move it to the casting start position; and the control unit (7) and the shut-off valve (5) are also configured to set the shut-off valve to a closed position (VS) during the refilling stage before the casting piston (3) reaches the casting start position by the return movement, and to control the casting piston so that the molten material outlet is moved by the additional return movement of the casting piston. A die casting machine configured to re-suck molten material (14) from a channel (6); and / or, the control unit (7) and the shut-off valve (5) also control the casting piston (3) in the pre-filling stage of the start-of-operation casting process with the shut-off valve (5) closed before the mold filling stage to move from the start-of-operation position (BS) to the pre-filling position (FP) in the casting chamber, and then control the casting piston to move to the start-of-operation position (GS) by opening the shut-off valve to the open position (VO). Claim 11 In claim 10, the shut-off valve is a shut-off control valve (5 S It is in the form of ), and the control unit is the shut-off control valve (5 S A die-casting machine configured to control ). Claim 12 A die-casting machine according to claim 11, further comprising a valve actuator (16) operated by the control unit to operate the shut-off control valve. Claim 13 In claim 10, the shut-off valve is a backflow prevention valve (5) preloaded in the closed position. R A die-casting machine in the form of ). Claim 14 A die-casting machine, further comprising a valve sensor unit (18) for detecting one or more measured variables of the shut-off valve in any one of claims 10 to 13.

Images