TW202140169A - Hydraulic casting unit - Google Patents

Abstract

Disclosed is a casting unit having a casting cylinder embodied as a differential cylinder and a hydraulic pressure intensifier.

Description

Hydraulic casting unit

The present invention relates to a hydraulic casting unit according to the preceding technical solution 1 of the present invention.

For example, in the publication DE 10 2017 220 836 A1 from the applicant, the basic structure of this type of casting unit used in a molding machine such as an injection molding machine, a die-casting machine, or a thixomoulding machine is disclosed. Therefore, the casting unit has a double-acting casting cylinder, the piston of the double-acting casting cylinder delimits the proximal base cavity of the piston base, and the proximal end surface of the piston rod of the double-acting casting cylinder delimits the annular cavity. In known solutions, during the pre-filling and mold filling phases, for example, the basic chamber is connected to the low-pressure storage by a 2-position 2-way (2/2-way) seat valve configured as an active logic system A device in which the annular chamber of the casting cylinder is connected to the basic chamber by a control valve, so that the pressurized medium displaced in the self-decreasing annular chamber in the pre-filling stage is supplied by the control valve in the differential or regeneration circuit To the incremental base chamber. In the mold filling stage, the pressurized medium connection with the tank for injection can be activated by the control valve close to the tank, and the control valve between the piston chamber and the annular chamber can be closed. Then in the pressure holding stage, the basic chamber is connected to the high-pressure reservoir by another control valve, wherein the connection with the pressurized medium of the low-pressure reservoir is blocked by the active logic system. In this pressure holding stage, the pressurized medium connection between the annular chamber and the storage tank is kept open by the previously mentioned proximal control valve of the storage tank, so that the melt in the chamber is compressed under high pressure and compensates for any Potential material shrinkage.

The basic structure of the active logic system used in this casting unit is known from the publication DE 10 2005 035 170 B4.

The casting unit disclosed in the publication DE 10 2017 221 500 A1 is not provided with any differential or regeneration circuit. In the pre-filling and mold filling stages, the basic chamber of the active logic system is impacted by the pressure of the low-pressure chamber, and the outflow proximal control valve is actuated, so that the piston of the casting cylinder expands at a predetermined speed. In the transition from the pre-filling stage to the mold filling stage, the outflow proximal valve is further actuated, so that the piston is accelerated and deployed at a relatively high speed. The pressurized medium displaced from the decreasing annular chamber flows to the outflow reservoir through the outflow proximal control valve, and when the outflow reservoir reaches a predetermined pressure, it then flows toward the reservoir through the check valve or aperture. Therefore, the maximum volume flow rate of the storage tank and the turbulence associated with it are reduced. After the pre-filling phase ends, the pressure intensifier (multiplier cylinder) is accelerated to start the pressure holding phase, and the increased pressure accumulates in the basic chamber herein. Here, the acceleration of the pressure intensifier is achieved because the annular chamber of the pressure intensifier is connected to the low-pressure reservoir or tank by the control valve.

In contrast, the present invention is based on the purpose of realizing a casting unit with a differential circuit and a pressure intensifier, which can realize an optimized casting procedure with lower complexity in terms of equipment.

This objective is achieved by a casting unit with the features of patented technical solution 1.

The advantageous improvement scheme of the present invention is the subject matter of the subordinate technical scheme.

The hydraulic casting unit according to the present invention is preferably conceived to be used in an injection molding machine, a die-casting machine or a thixoforming machine, and has a casting cylinder, which is constructed as a differential cylinder, and the piston of the differential cylinder delimits The proximal basic cavity of the base and the proximal annular cavity of the piston rod. In addition, a low-pressure source is provided, which can be connected to the basic chamber especially by means of a shut-off valve device. In addition, a hydraulic intensifier is provided. The hydraulic intensifier is used as a booster unit in the pressure-holding stage, and is conceived to promote the expansion movement of the casting cylinder, especially to increase the pressure in the base chamber. The casting unit also has a control valve device, which is conceived to connect the annular chamber to the base cavity of the casting cylinder in the form of a regeneration circuit through the first pressurized medium flow path during the pre-filling stage. Chamber; especially in the mold filling stage ("injection"), through the second pressurized medium flow path, it is conceived to be used to connect the annular chamber to the pressurized medium tank, especially the storage tank; and especially in The pressure intensifier is used to activate the pressure intensifier in the pressure holding phase, and it is conceived to actuate the third pressurized medium flow path, which leads to the pressure chamber of the pressure intensifier. According to the present invention, the valve device is isolated into three-directional proportional valves, and the three-directional proportional valves can be activated in a mutually decoupled manner. The first directional proportional valve is disposed in the first pressurized medium flow path, the second directional valve is disposed in the second pressurized medium flow path, and the third directional valve is disposed in the third pressurized medium flow path.

Due to this isolation structure mode, the regeneration movement, injection and pressure accumulation can be controlled in an open or closed loop independently of each other, so that the casting process can be controlled in an optimized open loop or closed loop with the lowest complexity in terms of equipment .

According to the present invention, the three-directional proportional valve, which is simple in terms of equipment and can be activated in a mutually independent manner, is provided for implementing the basic functions of the casting unit, that is, the regeneration pre-filling stage, the mold filling stage, and the holding pressure stage. The regeneration movement of the casting cylinder permits the use of a smaller reservoir as a low pressure source. Due to the lower pressure difference, less air pockets and therefore less wear are generated during the regeneration function. Since a smaller first-directional proportional valve with better resolution is used during the pre-filling period, the movement of the casting cylinder can occur more accurately.

In an improved solution, the main piston of the pressure intensifier delimits the pressure chamber of the pressure intensifier by its effective larger end face in the increasing direction, and by its effective smaller end face delimiting pressure in the opposite direction The back pressure chamber of the intensifier, especially the annular chamber of the pressure intensification chamber.

In an improved solution, the back pressure chamber of the pressure intensifier can be fluidly connected to the pressurized medium tank through the third pressurized medium flow path, thereby implementing open-loop control of the drainage in the pressure holding stage and thereby enabling the pressure to be activated Enhancer.

In a variant of this objective, the pressure intensifier pressure chamber in an improved solution can be fluidly connected to the pressurized medium source through the third pressurized medium flow path, so that the pressure intensifier in the pressure-holding stage depends on the inflow Control and be able to start in this way.

The directional proportional valve is preferably constructed to have a closed position. In the closed position, the respective pressurized medium flow path is blocked or actuated to the closed position.

In an improved solution, it is possible to provide or be able to configure a discharge path from the basic chamber of the casting cylinder to the pressurized medium tank through the first and second directional proportional valves. This leakage path can be actuated or configured in particular by the two mentioned directional proportional valves according to the detected pressure or time pressure gradient in the basic chamber.

In an improved solution, at least one of the directional proportional valves, at least the first and second directional proportional valves, preferably all three directional proportional valves, is constructed to form a two-way proportional valve, especially a 2-position valve. 2-port flow control valve. The respective directional proportional valve or 2-position 2-port flow control valve is preferably a pilot control type, especially an electro-hydraulic pilot control type.

In an improved solution, in terms of at least one attribute, at least two of the directional proportional valves, preferably all directional proportional valves, are designed to have the same structure, or especially the same. Using the directional proportional valve of the same structure, or using the same directional proportional valve under boundary conditions, represents a particularly efficient solution in terms of construction, procurement, production, maintenance and operation, and especially cost.

The term "same structure" in this text can refer to one or more of the properties of a directional proportional valve, such as, for example, type, connector, number of connectors, diameter of connectors, connection diagram, start type, valve body, Itinerary, switching time and the like.

The term "same configuration" may alternatively or additionally refer to ratings. In this context, it is advantageous to prove that the first-directional proportional valve has a rating smaller than that of the second and third-directional proportional valves, because the volume flow of the pressurized medium in the first pressurized medium flow path and the third The pressurized medium flow path is relatively small.

In an improved solution, the pressure control in the basic chamber is implemented by means of the relief flow path and the first and second directional proportional valves. In this way, pressure peaks or pressure overshoots in the basic chamber can be advantageously controlled and/or eliminated.

The accumulation of pressure in the pressure-holding phase essentially occurs by the pressure intensifier with the third-directional proportional valve in the control position, especially by means of open-loop or closed-loop control from the pressure intensifier annular chamber discharge and the second The open position of the directional proportional valve controls the pressurized medium connection between the annular chamber of the casting cylinder and the storage tank.

In an improved solution, the pressure chamber of the pressure intensifier for accelerating the latter can be connected to a low-pressure source, especially a hydraulic reservoir, by a shut-off valve or the like. Here, the second pressurized medium flow path from the annular chamber of the pressure intensifier toward the pressurized medium tank/toward the storage tank is actuated by a third-directional proportional valve.

In a variant of the present invention, the shut-off valve device is constructed as a 2-position 2-port active logic system with a pilot valve. The active logic system makes it possible to shut off or open the pressurized medium connection between the low pressure reservoir and the base chamber of the casting cylinder, and will be activated when the pressure builds up during the pressure holding phase, so as to close in an extremely fast and reliable manner, This makes it possible to terminate the mold filling stage in an extremely fast and precise manner.

In an alternative solution, instead of a shut-off valve device with an active logic system, a shut-off valve is constructed downstream of the low-pressure source, wherein the check valve is placed between the shut-off valve and the base chamber of the casting cylinder . The shut-off valve blocks and opens the connection with the casting cylinder. When the pressure accumulates in phase III or the pressure holding phase, respectively, the check valve closes the connection.

The closed-loop or open-loop control of the above-mentioned procedure can alternatively take place by means of a valve, which can be adjusted by means of a servo motor.

In order to retract the casting cylinder and/or the pressure intensifier, and/or to pre-charge the casting cylinder and/or the pressure intensifier, in an improved solution, the casting unit has a hydraulic pump, which is constructed as a variable row The metering pump can be constructed as a constant displacement pump with a servo motor and a servo inverter, or as a variable displacement pump with a three-phase AC motor and frequency converter, or as a variable displacement pump with a three-phase AC motor Pump.

In this paper, pre-filling the annular chamber of the casting cylinder has the effect of avoiding the initial shock during the initial pre-filling stage.

Therefore, in a preferred improvement, the casting unit has a device for pre-filling the piston side and the ring side of the casting cylinder and/or the pressure intensifier.

Preferably, the device for pre-charging is configured by a hydraulic pump and assigned shut-off and pre-charging valves.

In an improved solution, the shut-off and pre-fill valve is designed so that the pressure connector of the hydraulic pump can be connected to the annular chamber of the pressure intensifier and/or the annular chamber of the casting cylinder and/or through the shut-off and pre-fill valve. Or the basic chamber of the casting cylinder. The annular chamber of the casting cylinder used to pre-fill or retract the annular chamber is supplied with pressurized medium especially when the third-directional proportional valve is closed.

In an improved solution, at least the shut-off and pre-fill valve with a blocking position is designed as a 4-position 3-way switching valve. In addition, the 4-position 3-way switching valve has a first switching position. In the first switching position, the annular chamber of the pressure intensifier and the annular chamber of the casting cylinder are connected to the pressure connector of the hydraulic pump, and in the first switching position Among them, the first pressurized medium flow path, preferably through an unlockable check valve, can be connected or connected to the pressurized medium tank.

In an improved solution, the shut-off and pre-charge valve has a second switching position in which the base chamber of the casting cylinder is connected to the pressure connector of the hydraulic pump, and in the second switching position, The pre-charge pipeline is connected to the pressurized medium tank, and the pressure intensifier annular chamber in the first switching position and the annular chamber of the casting cylinder can be connected to the pressure connector of the hydraulic pump by the pre-charge pipeline.

Fig. 1 illustrates the important mechanical components of the hydraulic casting unit 1 of the die casting machine according to the present invention.

Correspondingly, the casting unit 1 has a casting cylinder 10 which is constructed to constitute a differential cylinder, and the piston 11 of the casting cylinder is correspondingly constructed to have a piston rod 12. The piston 11 and the casing 13 of the casting cylinder jointly delimit the proximal base chamber 14 and the annular chamber 15 through which the piston rod 12 passes. The casting piston 16 inserted into the injection chamber 18 of the casting sleeve 17 is fastened to the end portion of the piston rod 12 protruding from the housing 13. The filling opening 19 for the liquid or viscous molding compound (referred to as the melt hereinafter) is positioned in the casting sleeve 17 and the workpiece to be molded is composed of the liquid or viscous molding compound. The casting sleeve 17 is attached to the casting mold 20, which usually consists of a movable mold half and a fixed mold half. The two mold halves delimit a mold cavity 21, also called a cavity, which is constructed to correspond to the geometric shape of the workpiece to be molded. The injection chamber 18 leads to the mold cavity 21 through the casting pipe 22.

This type of casting unit 1 is used to introduce the melt into the casting mold 20, where high speed and subsequent high pressure are required due to the rapid solidification procedure to completely fill the casting mold 20 and to compress and compensate for the shrinkage of the material during solidification.

In the exemplary embodiment according to the present invention illustrated in FIG. 2, the casting cylinder 10 is assigned as the pressure intensifier 21 of the amplifying unit, which is also referred to as a multiplier cylinder, which is constructed as a differential cylinder, for example. The main piston 26 delimits the pressure intensifier pressure chamber 28 by the bottom surface, and the piston rod 30 passes through the pressure intensifier back pressure chamber in the form of an annular chamber 32. The construction of this type of pressure intensifier 24 is known so that further explanation can be omitted.

The supply of pressurized medium to the illustrated casting unit 1 occurs by a hydraulic pump 34, which is constructed as a constant displacement pump in the illustrated exemplary embodiment and is driven by a speed control motor 38, such as Build a servo motor with a servo inverter, or build a three-phase AC motor with a frequency converter. The pressure connector of the hydraulic pump 34 is connected to the shut-off and pre-fill valve 42 which is constructed to constitute a 4-position 3-way valve through a pump pipeline. In the illustrated initial position or its center position centered on the spring, the shut-off and pre-charge valve 42 blocks the pressurized medium connection between the hydraulic pump 34 and the base chamber 14. By means of two solenoids and hydraulic pilot control, the shut-off and pre-charge valve 42 can be switched to two channel positions a, b, in which the shut-off and pre-charge valve 42 and the hydraulic pump 34 The function of the device for pre-charging the casting cylinder 10 and the pressure intensifier 24 is realized, which will be further described below.

The annular chamber 15 of the casting cylinder 10 can be connected to the basic chamber 14 through a first pressurized medium flow path 23 and a first directional proportional valve 27 arranged therein. In the illustrated exemplary embodiment, the following first directional proportional valve 27 is constructed to constitute an electro-hydraulic pilot-controlled 2-position 2-port proportional valve, which has a spring pre-charged initial position or blocking position, and is obtained from the applicant’s file It is called 2WRCE-4X and is built as a flow control valve. By actuating the electro-hydraulic pilot control, the opening profile of the valve 27 is activated according to the actuation signal, and the annular chamber 15 for regenerative movement is connected to the basic chamber 14

In addition, the annular chamber 15 of the casting cylinder 10 can be connected to the storage tank T by the second pressurized medium flow path 44 in which the second directional proportional valve 46 is disposed. The second directional proportional valve 46 has the same structure as the first directional proportional valve 27 in the valve type direction, but has a higher rating than the latter because of the volume flow of the pressurized medium by the second directional proportional valve 46 It is larger than the volume flow in the regeneration movement performed by the first directional proportional valve 27. The second directional proportional valve 47 is also constructed as an electro-hydraulic pilot control 2/2 flow control valve. In its initial position, the valve blocks the connection with the pressurized medium of the tank T, and by actuating the electro-hydraulic pilot signal according to the actuation signal. The hydraulic pilot is controlled to actuate the opening section towards the tank T.

The second pressurized medium flow path 44 can be fluidly connected to the pre-charge line 50 by a check valve 48 open to the second pressurized medium flow path 44. The pre-charge line 50 is blocked at the initial position of the spring pre-charge of the check valve 48.

The pump line 40 between the third directional proportional valve 29 and the pressure intensifier annular chamber 32 leads to the third pressurized medium flow path 25. A check valve 70 that opens toward the pressure intensifier annular chamber 32 is disposed in the pump line 40 between the branch of the pre-charge line 50 from the pump line 40 and the mouth. In the condition that there is sufficient pressure in the pump pipe 40 and the pre-charge pipe 50, the two check valves 48 and 70 are opened, so that the annular chambers 15 and 32 of the casting cylinder 10 and the pressure intensifier 24 are supplied. In this way, the casting cylinder 10 and the pressure intensifier 25 can be retracted, and the back pressure required for pre-filling the casting cylinder 10 and the pressure intensifier 24 can be accumulated in the respective annular chambers 15, 32 . For this purpose, the shut-off and pre-charge valve 42 has a first switching position a, in which the pressure connector P of the hydraulic pump 34 is connected to the pump line 40 and the pre-charge line 50, and In this first switching position, the first pressurized medium flow path 23 with a storage tank can be connected or connected to the pressurized medium tank T by means of an unlockable check valve 72.

The pressure at the output end of the hydraulic pump 34 can be delimited by a pressure relief valve that opens toward the tank T in a manner known per se.

According to the present invention, the pressure intensifier 24 and the casting cylinder 10 are assigned a valve device which is isolated into three flow control valves 27, 46 and 29, which can be activated in an independent manner and their In each situation, a continuously adjustable electro-hydraulic pilot control valve with two connectors is constructed.

The pilot-controlled 2-position 2-port seat valve constitutes an active logic system 41. The pilot control is performed by the pilot valve 52, which is built to form a 3-position 2-port valve. The input connector A of the active logic system 41 is connected to the low-pressure reservoir 56 through the low-pressure reservoir line 54. Regarding the connectors A and B, the active logic system 41 can also be assembled in the reverse order. The output connector B of the active logic system 41 is connected to the basic chamber 14 of the casting cylinder 10.

From the publications DE 10 2017 220 836 A1 and DE 10 2005 035 170 B4 cited at the beginning of the specification, the potential structure of the active logic system 41 is known, so that only the structural elements relevant to the understanding of the present invention will be explained here, and in other ways Refer to this prior art. Therefore, the active logic system 41 has a stepped main piston 60, which is precharged against the valve seat 58 together with the pressure acting on the surface A5 from the low pressure reservoir ND by the switching pilot valve 52, and blocks the active The pressurized medium between the connectors A and B of the logic system 41 and therefore between the low-pressure reservoir line 54 and the pressure line 59 is connected. The pressure line 59 leads into the base chamber 14 of the casting cylinder 10. The main piston 60 has an inner hole from the face A5 toward the face A3, thereby ensuring pressure balance between the face A5 acting in a closed manner and the face A3 acting in an open manner. The active logic system 41 can be opened and closed in a targeted manner through the control plane A4. Here, the surface A4 may be selected so as to be greater than the difference A5-A3, or the control pressure of the reservoir ND may be set to be correspondingly higher in order to reliably open the active logic system 41.

The sump pipeline 62 is connected to the sump connector of the pilot valve 52, and the input connector of the pilot valve 52 is connected to the control reservoir or the low pressure reservoir ND through the pipeline 64. By energizing the solenoid of the pilot valve 52, the pilot valve can be adjusted to the switching position against the force of the spring. In the switching position, the annular control chamber of the active logic system 41 delimited by plane A4 is connected to the low pressure The reservoir ND allows the main piston 60 to lift from the valve seat 58 due to the pressure acting on the annular end surface A4, and activate the fluid connection between the connectors A and B.

The active logic system 41 is embedded so that the flow can flow through the active logic system 41 with minimal pressure loss, and when the pilot valve 52 is actuated accordingly, it is closed in a highly reproducible manner with minimal switching time. In order to optimize the subsequent closing behavior, the stroke of the active logic system 41 can also be limited. Due to this specific configuration of the active logic system 41, even at large ratings, only a small amount of control fluid flow is required to open and close the active logic system 41 in a fast and reproducible manner.

In addition, by actively opening and closing the active logic system 41 by means of the pilot valve 52 and reliably keeping the active logic system 41 closed by means of the reservoir pressure, operation reliability is enhanced. Here, it is possible to freely select the shutdown condition by actively shutting down the active logic system 41. This closing can take place, for example, based on pressure, force of load, movement path, movement speed, and the like.

As illustrated in Figure 2, the low-pressure reservoir 56 can be connected to the pressure intensifier pressure through a 2-position 2-port seat valve (hereinafter referred to as the reservoir shut-off valve 66, which is piloted and controlled by the pilot control valve 68) Chamber 28. For this reason, the pressurized medium itself is controlled to be emitted from the low-pressure reservoir 56. The chamber after the reservoir shut-off valve 66, in the pre-filled initial position of the pilot control valve 68, acts in a closed manner in this article, and is impacted by the pressure of the low-pressure reservoir 56 and in the switching position by the pressure from the storage tank. , Whereby the reservoir shut-off valve 66 connects the low pressure reservoir 56 to the pressure intensifier pressure chamber 28. Therefore, in this switching position, the pressure intensifier 24 is inflated in the promotion direction.

The functional mode of the casting unit 1 illustrated in FIG. 2 during the first described stage I to stage III will be explained below.

In order to prevent the generation of pressure waves in the direction of the casting cylinder 10 during the initial movement of the casting cylinder 10 during the pre-filling phase, the pressure waves cause initial vibrations, and the active logic system 41 (also known as the reservoir shut-off valve) is opened. Previously, the casting cylinder 10 was pre-filled before the initial pre-filling stage I. The above situation occurs because under the condition of the retracted casting cylinder 10 and the pressure intensifier 24, the annular chamber 15 of the casting cylinder 10 and the pressure intensifier annular chamber 32 of the pressure intensifier 24 can be assisted by the hydraulic pump 34 and the pressure intensifier. The shut-off pre-charge valve 42 activated to its first switching position is pre-charged to the maximum pumping pressure by opening the check valves 48 and 70. Under the condition of this method, the first directional proportional valve 27, the second directional proportional valve 46, and the third directional proportional valve 29 are closed so as to prevent a short circuit toward the storage tank. The shut-off and pre-fill valve 42 preferably has a non-return function.

In a subsequent step, the melt according to FIG. 1 is filled into the injection chamber 18 of the casting sleeve 17 through the filling opening 19, and the pre-filling stage I is started. To this end, the hydraulic pump 34 is activated by the ramp function, and the basic chamber 14 of the casting cylinder 10 is inflated to the value of the reservoir pressure of the low-pressure reservoir 56 by shutting off and the second switching position b of the pre-filling valve 42 . Therefore, the casting cylinder 10 slowly expands without any resistance to the initial shock of the pre-filling in the annular chamber 15 until the fluid contained in the annular chamber 15 is compressed and there is a balance of forces on the piston 11. In this context, it is important that due to this control action, the pressure in the base chamber 14 of the casting cylinder 10 is equal to the pressure in the low-pressure reservoir 56 in a vibration-free manner. Thereafter, the low-pressure reservoir 56 can then be connected to the base chamber 14 by the active logic system 41 (reservoir shut-off valve), and the low-pressure reservoir 56 can be connected to the pressure intensifier pressure by the reservoir shut-off valve 66 Chamber 28.

If the pump 34 can generate a sufficiently high pressure, this method is unnecessary. Under the condition of the annular chamber 15 which is correspondingly highly prefilled, the low-pressure reservoir 56 can also be switched to the piston chamber 14 by the active logic system 41.

Depending on customer requirements, a common piston reservoir can be used for casting cylinders and pressure intensifiers, or else a dedicated piston reservoir can also be used in each situation.

Thereafter, the first directional proportional valve 27 is actuated by the pilot control, so that the pressurized medium displaced from the annular chamber 15 is directly supplied to the basic chamber 14 in the manner of a regeneration circuit. This enables the casting cylinder 10 to start and move smoothly (no vibration, and in a regenerative and controlled manner). Therefore, the melt is accelerated and displaced in the direction of the mold cavity 21 according to FIG. 1. The above situation occurs until the melt reaches the mold feed orifice and the pre-filling stage I is completed.

Due to the regenerative movement of the casting cylinder 10 in the pre-filling stage I, less pressurized medium is removed from the low-pressure reservoir 56 so that the low-pressure reservoir 56 can be smaller than in the conventional solution without regenerative movement的量。 The volume. Since the pressure loss caused by the differential circuit is small, and because the first-direction proportional valve 27 is less than one or two rated values, the resolution of the casting cylinder speed can be improved, allowing a lower speed and improved reproducibility Move the casting cylinder 10.

Another advantage of the regenerative movement is that because the pressure loss on the first-direction proportional valve 27 is lower, and because the pressurized medium from the annular chamber 15 will not resist the outflow of the tank pressure (0 Pa) but resist the low-pressure reservoir 56 Due to the fact that there is less pressure in the valve 46, on the piston 11, and on the housing 13 of the casting cylinder 10 and the associated control block, there are fewer air pockets, and therefore less wear.

According to the present invention, by actuating the first directional proportional valve 27 and the second directional proportional valve 46 (which are arranged in series with the former), the pressure in the basic chamber 14 can be actively affected in the sense of pressure reduction or pressure release. For example, it is easy to eliminate the pressure overshoot in the basic chamber 14 on this path.

According to the present invention, the pressure in the base chamber 14 can be influenced by the third-directional proportional valve 29, which can be activated completely independently of the first-directional proportional valve 27 and the second-directional proportional valve 46. Due to the independent pressurized medium flow paths 23, 44, 25 and valves 27, 46, 29, more precise and dynamic control of the pressure in the base chamber 14 is produced.

Once the melt reaches the mold feed orifice, the actual mold filling procedure (phase II) is initiated. When the filling (injection) of the mold occurs with a low mold filling force, the regeneration movement continues to occur. Therefore, at the time point when the melt reaches the mold feed orifice, for example, by a jump function, the first directional proportional valve 27 is adjusted to the position where the pressurized medium between the annular chamber 14 and the basic chamber 15 is connected, so that The melt is injected into the mold 20 at a high injection rate (up to 10 m/s). Here, the operation continues in the regeneration mode, in other words, the pressurized medium displaced from the annular chamber 15 is supplied to the incremental base chamber 14.

This type of regeneration method has the following advantages. Compared with the conventional solution, less pressurized medium must be removed from the low pressure reservoir 56.

Under the condition that injection occurs under a higher mold filling force, when the melt reaches the mold feed orifice, the first directional proportional valve 27 is moved to its closed position by, for example, a jumping function, so that the annular chamber 15 The pressurized medium connection with the base chamber 14 is interrupted. In parallel with this, the outflowing second directional proportional valve 46 leads to a predetermined opening section of the tank T by, for example, a jumping function. The above situation causes the melt to be injected into the mold cavity 21 at a high injection rate, wherein, contrary to the method under the condition of low mold filling force, the operation does not take place in a regenerative manner, and therefore the maximum force of the casting cylinder 10 can be utilized.

In principle, a hybrid form can also be considered, in which the first directional proportional valve 27 is adjusted to its blocked position according to the force of the load only during phase II.

Phase II can also be fully operated in regeneration mode. However, the premise is that the required force of the load in Phase II can also be achieved in the regenerative mode. In this situation, the second directional proportional valve 46 can be replaced by a quick switching valve for releasing the annular chamber 15 in stage III.

Once the mold cavity 21 has been completely filled, the transition to stage III occurs. To this end, at the end of the mold filling phase II, the third-direction proportional valve 29 is actuated in the opening direction of the connection between the pressure intensifier annular chamber 32 and the tank T by the pilot control. The second directional proportional valve 46 is opened at the same time. The pressure release setting in the annular chamber 32 of the pressure intensifier accelerates the main piston 26 and therefore accumulates high pressure in the base chamber 14 so that the piston 11 is subjected to high pressure impact and the melt is finally compressed. Once the desired holding pressure is reached, the second directional proportional valve 29 is reset in the closing direction by the pressure regulator. In a situation where the closing of the second directional proportional valve 29 cannot occur quickly enough, the directional proportional valves 27 and 46 can be actuated toward the sump T by activating the mentioned release path to eliminate the problem in the basic chamber 14 Pressure overshoot.

Since the first 2-port proportional valve 27 has a dual function for controlling the regeneration and pressure in the basic chamber 14, the 2-port proportional valve 27 replaces the 3-port proportional valve (50% connection between A and T; A and The 50% connection between P) can be used together with the rated value, which is less than at least one of the rated values of the 3-port proportional valve (100% A and T). The smaller rating results in improved dynamics.

Compared with the conventional solution, the described casting unit has the advantage that the pressurized medium removed from the annular chamber 15 by the regenerative movement of the casting cylinder 10 can be directly supplied to the foundation of the casting cylinder 10 through the first directional proportional valve 27 Chamber 14. A further specificity is the active shutdown of the active logic system 41 at the end of phase II.

The active logic system can also be replaced by a shut-off valve and an external check valve.

Disclosed is a casting unit whose casting cylinder in the pre-filling stage can be moved in a regenerative manner by a first flow control valve. In addition, this first flow control valve has the following function: controlling the pressure in the base chamber of the casting cylinder. The casting cylinder in the mold filling stage can be moved regeneratively or non-regeneratively, so as to be controlled by the second flow control valve. In addition, the amplifying unit configured as a pressure intensifier is turned on by the third flow control valve during the pressure maintaining stage. The pressure in the basic chamber can also be controlled by the third flow control valve. All the mentioned flow control valves can be activated in a mutually decoupled manner. Combined, these flow control valves make it possible to control the pressure in the basic chamber in an extremely precise and dynamic manner, and represent a better solution than a solution with a 3-way flow control valve.

none

Hereinafter, the preferred exemplary embodiment of the present invention will be explained in more detail with the help of schematic drawings, in which: [Fig. 1] A schematic diagram showing a casting unit; and [Fig. 2] A simplified hydraulic circuit diagram showing an exemplary embodiment of a casting unit.

Claims (12)

A hydraulic casting unit of a molding machine, the molding machine is in particular an injection molding machine, a die-casting machine or a touch-forming machine, the hydraulic casting unit has a casting cylinder (10), the casting cylinder is constructed as a differential cylinder and It has a piston (11) by which a proximal base chamber (14) and a proximal annular chamber (15) of the piston rod are delimited; and a low-pressure source (56) for the low-pressure source One of the casting cylinders (10) can be connected to the basic chamber (14) for its unfolding movement; and has a hydraulic intensifier (24) that is conceived to increase the basic chamber (14) at a low pressure stage ); and has a control valve device by which the annular chamber (15) can be fluidly connected to the basic chamber (14) via a first pressurized medium flow path (23) ), and can be fluidly connected to a pressurized medium tank (T) through a second pressurized medium flow path (44), and through the control valve device, leads to a pressure chamber of the pressure intensifier (24) A third pressurized medium flow path (25) of the chamber (32) can be activated or configured to activate the pressure intensifier (24), characterized in that the valve device is isolated into a three-directional proportional valve ( 27, 46, 29), the three directional proportional valves can be activated in a mutually decoupling manner, wherein a first directional proportional valve (27) is arranged in the first pressurized medium flow path (23), and a second A directional proportional valve (46) is disposed in the second pressurized medium flow path (44), and a third-directional proportional valve (29) is disposed in the third pressurized medium flow path (25). Such as the casting unit of claim 1, wherein a main piston (26) of the pressure intensifier (24) delimits a pressure intensifier pressure chamber (28) by its larger end surface effective in the increasing direction, and A pressure intensifier back pressure chamber (32), especially a pressure intensifier annular chamber, is delimited by its smaller end face effective in the opposite direction, wherein the pressure intensifier back pressure chamber (32) is The third pressurized medium flow path (25) can be fluidly connected to a pressurized medium tank (T). For example, the casting unit of claim 1 or 2, which has a drainage path, which can be configured from the foundation according to the pressure or time pressure gradient detected in one of the foundation chambers (14). The chamber (14) faces the pressurized medium tank (T) through the first direction proportional valve (27) and the second direction proportional valve (46). Such as the casting unit of any one of claims 1 to 3, wherein at least one of the directional proportional valves (27, 29, 46) is constructed to form a better electro-hydraulic pilot control 2-position 2-port flow control valve. Such as the casting unit of any one of the preceding claims, wherein at least the second directional proportional valve (46) and the third directional proportional valve (29), or the first to third directional proportional valves (27, 29, 29) At least two of 46), preferably all directional proportional valves (27, 29, 46), have the same structure. The casting unit of any one of the preceding claims, wherein the pressure intensifier pressure chamber (28) can be connected to a low pressure source or the low pressure source (56) through a reservoir shut-off valve (66). The casting unit of any one of the foregoing claims, wherein the shut-off valve device is constructed with a pilot valve (52) and a 2-position 2-way active logic system (41). Such as the casting unit of any one of the preceding claims, which has a hydraulic pump (34) constructed as a variable displacement pump, or constructed as a constant displacement pump with a servo motor and a servo inverter The metering pump can be constructed as a variable displacement pump with a three-phase AC motor and a frequency converter, or as a variable displacement pump with a three-phase AC motor. The casting unit according to any one of the foregoing claims has a device (34, 42) for pre-charging the casting cylinder (10) and/or the pressure intensifier (24). For example, the casting unit of claim 8 or claim 8 and claim 9 has a shut-off and pre-charge valve (42), which is conceived to be used for the pressure of the hydraulic pump (34) The connector is connected to the pressure intensifier annular chamber (32) and/or to the annular chamber (15) of the casting cylinder (10) and/or to the base chamber (14) of the casting cylinder (10) . Such as the casting unit of claim 10, wherein the shut-off and pre-fill valve (42) is designed as a 4-position 3-way switching valve, which has a first switching position (a), in which the The pressure intensifier annular chamber (32) and the annular chamber (15) of the casting cylinder (10) are connected to the pressure connector (P) of the hydraulic pump (34), and in the first switching position, the The first pressurized medium flow path (23) can preferably be connected or connected to the pressurized medium tank (T) by an unlockable check valve (72). Such as the casting unit of claim 11, wherein the shut-off and pre-fill valve (42) has a second switching position (b), in which the basic chamber (14) is connected to the hydraulic pump ( 34) the pressure connector (P), and in the second switching position, a pre-charge pipeline (50) is connected to the pressurized medium tank (T), and the pre-charge pipeline can be in the The pressure intensifier annular chamber (32) and the annular chamber (15) of the casting cylinder (10) in the first switching position (a) are connected to the pressure connector (P) of the hydraulic pump (34) .

Images