EP3256277B1 - Pressure intensifier device, diecasting machine casting unit and operating method - Google Patents

Description

The invention relates to a pressure booster device for pressure increase in a pressure fluid chamber of a piston / cylinder unit according to the preamble of claim 1 and to a casting unit equipped therewith for a die casting machine and to an associated operating method.

Such a pressure booster device is used, for example, to increase the pressure in a pressure fluid space of a casting piston / casting cylinder unit with which a casting unit of a die casting machine is equipped. But it can also be used anywhere for any other purposes where an increase in pressure in a Druckfluidraum a piston / cylinder unit is required for a working piston or piston of the piston / cylinder unit performs a desired work or utility function. In the presently considered construction, the pressure booster device itself is manufactured as a piston / cylinder unit with a pressure booster cylinder and an axially movable in this pressure booster piston. In die casting machines, the pressure booster device primarily serves to provide the increased holding pressure for a casting piston towards the end of a casting process. The intensifier is often called a multiplier.

Conventionally, a check valve is installed in an inlet to the pressure fluid chamber of a casting piston / casting cylinder unit to be controlled in order to prevent backflow of pressure medium from the pressure-increased pressure fluid space, for example back to a pressure fluid reservoir. In one in the patent DE 19 49 360 C3 disclosed multiplier device, the check valve is integrated in the multiplier piston.

Various pressure intensifier devices are known in which the pressure booster cylinder has an outlet region, an inlet region upstream of the outlet region and a piston guide chamber. The pressure booster piston includes a guided in the piston guide chamber piston part and from the piston part in Direction of supply range extending piston rod, which releases a fluid connection of inlet area and outlet area in a maximally moved back release position and blocked in a maximum advancing blocking position with a free end portion with which it extends into the exit area.

The patent EP 2 365 888 B1 discloses such a pressure translator device with integrated check valve. In the outlet region, a valve sleeve axially movable with a limited stroke is arranged in this known pressure booster device, which has a conical valve cone seat on its side facing the multiplier piston, which forms a check valve with a correspondingly conical valve cone-shaped free end face of the multiplier piston rod. For this purpose, the valve sleeve with its valve seat end face connects axially to the inlet region, which is formed as a cylinder portion with respect to a piston rod guide portion and an inlet-side portion of the outlet region and the valve sleeve of larger diameter. The piston rod is guided in the piston rod guide portion of the pressure booster cylinder between the piston guide chamber and the inlet area. About one or more passage bores at the end portion of the multiplier piston rod is a piston chamber of the multiplier with the inlet area in combination. When advancing the multiplier piston abuts against the facing end side of the valve sleeve, whereby the non-return valve formed therefrom is closed. Subsequently, the multiplier piston takes the valve sleeve with the further forward movement.

Check valves are not unproblematic even when used in casting / casting cylinder units of die casting machines. They mean production costs, are prone to failure and susceptible to wear. For spring-actuated valves, spring damage can cause considerable secondary damage.

The patent DE 10 2004 010 438 B3 discloses a hydropneumatic pressure intensifier intended for high pressure applications, comprising at least one hydraulic cylinder portion including a high pressure area and comprising a working piston, and at least one pneumatic cylinder portion including a pressure booster piston. In this pressure booster, the forward movement of the booster piston is started when the feed pressure applied to the working piston reaches a certain one Staudruckwert achieved in which, for example, a pressure intensifier upstream valve switches when a supported by a working piston rod machining tool comes to a tool to be machined to the plant.

A similar differential pressure control of a pressure booster piston is for a pressure-intensified power cylinder unit in the published patent application DE 31 45 401 A1 intended. In this differential pressure control acting on a working piston in the feed direction fluid pressure is fed back via a suction nozzle or a controlled slide to a pressure booster chamber, so that acts on the pressure booster piston, a differential pressure, which moves it forward when the differential pressure exceeds a corresponding minimum value.

The layout DE 20 17 951 discloses a die casting machine with multiplier, in which similarly the advancing movement of the multiplier piston is started when at the end of a casting stroke at the end of the mold filling phase of a respective casting operation, the pressure in the working space of the die / casting cylinder increases due to the now filled mold , An adjustable to a certain pressure hydraulic pilot element then actuates a Zuschaltventil to introduce pressurized fluid in a multiplier piston chamber.

The Utility Model DE 201 00 122 U1 discloses a pressure intensifier used in particular in a punching device with a pressure booster cylinder and an axially movable in this pressure booster piston, the pressure booster piston having a guided in a piston guide chamber of the pressure booster cylinder piston part and extending from the piston part in a pressure cylinder piston rod. In addition, a further piston and another cylinder are present, both of which are formed as a hollow cylinder, wherein the pressure booster cylinder or the pressure booster piston is arranged in the hollow cylindrical recess of the further piston.

The publication WO 2010/070053 A1 discloses an arrangement for a die casting machine with a drive piston received in a working cylinder and with a working cylinder upstream pressure intensifier, wherein on one side of the drive piston, a piston chamber and on the other side of the drive piston an annular space is arranged in the working cylinder. The annular space of the working cylinder is connected by means of a connecting line directly or via a check valve, which is arranged integrated in the pressure booster or bridges this, connectable to the piston chamber of the working cylinder.

The invention is based on the technical problem of providing a pressure booster device of the type mentioned, which can be manufactured with relatively little effort and has a high functional reliability and low tendency to wear. Further objects of the invention are to provide a casting unit equipped with such a pressure booster device for a die-casting machine and an operating method therefor.

The invention solves this problem by providing a pressure booster device with the features of claim 1 and a casting unit with the features of claim 9 and an operating method with the features of claim 10. Advantageous developments of the invention are specified in the dependent claims.

In the pressure booster device according to the invention, the exit region of the pressure booster cylinder has a passage cross-section which is at least as large as a rod cross-section of the free piston rod end section in a section which is passed from the free piston rod end section when moving from its release position to its blocking position. This has the consequence that the pressure booster piston with its piston rod can extend unhindered into the outlet region when it is advanced to provide the desired pressure increase. If necessary, the multiplier piston can advance with its piston rod through the outlet region of the multiplier cylinder and beyond it into the pressure fluid space of the coupled piston / cylinder unit, in order to provide the desired pressure increase by corresponding volume displacement. A check valve can be omitted in this pressure booster device, and by eliminating corresponding movable valve components, the manufacturing cost is reduced. Failures and malfunctions that may occur due to such a check valve in conventional pressure booster devices are eliminated as well, e.g. Spring breaks of spring-actuated mechanical components.

An appreciable return flow of pressurized fluid from the pressure fluid chamber of a coupled piston / cylinder unit or from the outlet region of the pressure booster cylinder back into the inlet region is prevented by the multiplier piston blocking the otherwise released fluid connection of the inlet region and outlet region with its piston rod in the blocking position. Depending on requirements, the blocking of this fluid connection can be realized as a complete shut-off or merely as a predominant shut-off of the maximum passage cross-section of this fluid connection. In the latter case, a residual fluid connection of inlet area and outlet area remains whose flow cross section is significantly smaller than the maximum flow cross section with the piston rod moved back into the release position, eg less than 10% and preferably less than 1% of this maximum flow cross section, in particularly advantageous embodiments in the range of approx 0.01% to approx. 0.1% of the maximum flow area. Such a residual fluid connection may be formed, for example, by one or more corresponding gap regions between the outer periphery of the piston rod and an inner periphery of an opposite cylindrical portion of the exit region. In appropriate applications, it does not lead to a noticeable impairment of the pressure increase function of Pressure translator device, for example, when used in a casting unit of a die casting machine, taking into account the rapid timing of a typical pressure increase phase toward the end of a casting process.

According to one aspect of the invention, in the pressure booster supply line, which opens into a pressure booster piston chamber of the piston guide chamber of the pressure booster cylinder, arranged independently of a pressure in the pressure fluid space of the piston / cylinder unit pressure booster inlet valve, and the outlet region is designed without check valve. By the latter, it is meant that no check valve is coupled to a volume defined by this area, including the subsequent pressure fluid space of the piston / cylinder unit. Thereby, the feed movement of the pressure booster piston can be controlled in an advantageous manner, regardless of the pressure conditions in the piston / cylinder unit, which is associated with the pressure booster device. In particular, the feed movement of the pressure booster piston can be controlled in a respectively desired manner, without being influenced by any pressure fluctuations and delay times of the pressure fluid used in the piston / cylinder unit and the pressure exerted by it. It is also possible with this measure, in contrast to the above-described, conventional differential pressure controls to start the forward movement of the pressure booster piston already comparatively early and in particular even before a building up differential pressure has exceeded a predetermined threshold.

The omission of said check valve means in addition to the above-mentioned advantages also the elimination of a time-delayed behavior related to the pressure rise time for the provided by the pressure booster pressure increase, which can improve the casting process when used in die casting machines.

According to a further aspect of the invention, the outlet region of the pressure booster cylinder is designed as a section which is radially narrowed relative to the inlet region. In this embodiment, the pressure booster piston can block the fluid connection between inlet region and outlet region by moving from the inlet region with the larger cross section into the outlet region with the narrowed, smaller one Cross section moved forward. Conveniently, in this case the cross-section of the free piston rod end portion extending into the exit region is about as large or only slightly less, eg less than 10% and preferably less than 1% less than the portion of the exit region receiving it, in particular eg less than about 0.01% to about 0.1% thereof.

Suitably, a diameter of the respective section of the exit region is greater than a diameter of the free piston rod end section, so that an intermediate annular gap is formed when the piston rod end section advances into the exit region. Depending on the application, this annular gap can remain open or be sealed by means of a suitable ring seal. Alternatively or in addition to this measure, the peripheral edge of the free piston rod end portion receiving outlet region-cylinder portion on the inlet side on an insertion cone. This can facilitate the introduction of the piston rod advancing from the inlet area into the outlet area. If necessary, the piston rod can be correspondingly conically shaped on its free end face.

In a further development of the invention, the pressure booster cylinder is manufactured as a one-piece component. This contributes to minimizing the manufacturing cost. In this case, the one-piece pressure booster cylinder component can be coupled directly to the pressure fluid space of the piston / cylinder unit, in which the pressure increase is needed, such as to a pressure fluid working space of a casting piston / casting cylinder unit of a die casting machine.

In a development of the invention, the pressure booster cylinder has a piston rod guide section between the piston guide chamber and the inlet region. This can support the leadership of the multiplier piston during its axial movement. It may be advantageous in terms of manufacturing technology to design the piston rod guide section with the same diameter as that of the section of the outlet area receiving the advancing piston rod.

In one development of the invention, the outlet region and the inlet region of the pressure booster cylinder have sections of the same cross-section, wherein the inlet region also includes a radial inlet bore, which radially into the latter from the outside Inlet area section of the pressure booster cylinder opens. This allows a particularly simple production of the pressure booster cylinder and a very safe guidance of the multiplier piston in its pressure-increasing forward movement. By advancing the multiplier piston, the radial inlet bore can be shut off and in this way the function for blocking the fluid connection between the inlet region and the outlet region can be provided.

In a further development of the invention, the inlet region includes at least one radial bore and an associated with this, the front side Ausmündende axial bore in the free piston rod end portion. The pressurized fluid is thus supplied in this embodiment through the free end portion of the multiplier piston rod through the pressure fluid space of the piston / cylinder unit to be controlled. In this realization, the fluid connection of inlet area and outlet area can be blocked by blocking the radial piston rod bore through the outlet area. If necessary, the multiplier piston can extend into the exit region with its piston rod even in the maximum retracted release position, which can further improve the guidance of the multiplier piston in the multiplier cylinder.

In a further development of the invention, the inlet region includes at least one axial Längsnutkanal on a peripheral side of the free end portion of the multiplier piston rod. In this case, the pressure fluid to be supplied to the piston / cylinder unit to be controlled flows along the one or more axial piston rod Längsnutkanäle in the pressure fluid working space of the piston / cylinder unit to be controlled. The blocking of the fluid connection of inlet area and outlet area can be effected in this embodiment by means of shutting off the axial longitudinal groove or channels from the remaining, inlet-side inlet area through the outlet area. In this embodiment too, the multiplier piston can still extend into the outlet region with its piston rod in the maximally moved-back release position.

In a development of the invention, an annular seal is arranged on an inner edge of the exit region. This allows a seal and / or additional guidance for the multiplier piston rod.

In one development of the invention, the pressure booster device includes a useful piston position sensor for detecting the position of a piston of the piston / cylinder unit and / or a Multiplikatorkolben position sensor for detecting the position of the pressure booster piston and a controller, the pressure booster inlet valve depending on a Nutzkolben Position signal of the useful piston position sensor and / or depending on a multiplier piston position signal of the multiplier piston position sensor controls and / or controls the pressure booster back pressure valve depending on a Nutzkolben position signal of the Nutzkolben-position sensor and / or of a Multiplikatorkolben position signal of the Multiplikatorkolben position sensor , This makes it possible in particular to control the advancing movement of the multiplier piston as a function of the current position of the piston of the piston / cylinder unit and / or of the current position of the multiplier piston, which in turn can be of particular advantage even when used in a casting unit for a die casting machine , Thus, e.g. the forward movement of the multiplier piston can already be started at a comparatively early stage of the entire working stroke of the casting piston of a casting / casting cylinder unit, which enables extremely short pressure rise times with minimized or no pressure rise delay compared to the conventional arrangements with check valve and / or differential pressure control mentioned above, and thereby also improve the casting quality.

In addition, this measure according to the invention offers the possibility, if desired, of advancing the multiplier piston in its course over its entire stroke from the maximum backward to the maximum advanced position or only along a partial section of this total stroke, independently of the pressure conditions in the various pressure volumes. or to determine control technology freely, eg in the form of a predetermined profile of the time course of the movement path or the movement speed of the multiplier piston or a predetermined profile of the time profile of the pressure in the pressure fluid space of the piston / cylinder unit.

An inventive casting unit for a die casting machine, which is equipped with the pressure booster device according to the invention, allows increased efficiency of the die casting machine and an increased quality of cast therewith Products. The invention also includes a die casting machine having such a casting unit.

The printing machine casting unit according to the invention can be operated in particular by the method according to the invention, in which case the feed movement of the pressure booster piston of the pressure booster device is characteristically started before the end of the mold filling phase. This allows in comparison to conventional operating methods in which the pressure booster piston is started only after the end of Formfüllphase due to the concomitant pressure increase in the casting cylinder, a shortening of the time required for the casting process and also creates the prerequisite for an otherwise optimized flow of the casting process ,

In a further development of the invention, it is provided according to the method to start the advancing movement of the pressure booster piston already at the beginning or during the prefilling phase and thus before the beginning of the mold filling phase. This further helps to achieve the shortest possible pressure rise times and thus to improve the casting quality.

In a further development of the invention, according to the method, the feed movement of the pressure booster piston is controlled or regulated as a function of the useful piston position signal of the useful piston position sensor and / or as a function of the multiplier piston position signal of the multiplier piston position sensor, if the pressure booster device has such a useful piston position sensor or multiplier piston position sensor. Position sensor has. As a result, the advancing movement of the pressure booster piston can advantageously be coupled to the advancing movement of the casting piston, without being dependent on the pressure ratios of a working fluid and / or the melt material to be cast in the casting cylinder.

In a further development of the method according to the invention, the advancing movement of the pressure booster piston in its course over its entire stroke from the maximum backward to the maximum advanced position or only along a portion of this total stroke according to a predetermined nominal profile of the time course of the movement path or the speed of movement Controlled or regulated multiplier piston regardless of the pressure conditions in the various participating pressure chambers or in accordance with a predetermined desired profile of the time course of the pressure in the pressure fluid space of the piston / cylinder unit.

Fig. 1

eine schematische Seitenansicht einer Multiplikatorvorrichtung mit angekoppelter Gießkolben/Gießzylinder-Einheit eines Gießaggregats einer Druckgießmaschine in einer Ausgangsstellung,

Fig. 2

eine Seitenansicht einer beispielhaften baulichen Realisierung der Anordnung von Fig. 1,

Fig. 3

die Ansicht von Fig. 1 in einer ersten Gießphase eines Gießvorgangs der Druckgießmaschine,

Fig. 4

die Ansicht von Fig. 1 in einer zweiten Gießphase vor Multiplikatorstart,

Fig. 5

die Ansicht von Fig. 1 während der zweiten Gießphase nach Multiplikatorstart,

Fig. 6

die Ansicht von Fig. 1 bei Druckerhöhungsstart zu Beginn einer dritten Gießphase,

Fig. 7

die Ansicht von Fig. 1 während einer Nachverdichtung in der dritten Gießphase,

Fig. 8

die Ansicht von Fig. 1 bei Abschluss der dritten Gießphase,

Fig. 9

die Ansicht von Fig. 2 für eine Variante mit Ringspaltabdichtung,

Fig. 10

die Ansicht von Fig. 2 für eine Variante mit querschnittgleichem Zulauf- und Austrittbereich,

Fig. 11

die Ansicht von Fig. 2 für eine Variante mit axialer Zulaufbohrung im freien Endabschnitt der Multiplikator-Kolbenstange,

Fig. 12

die Ansicht von Fig. 2 für eine Variante mit axialen Zulauf-Längsnutkanälen im freien Endabschnitt der Multiplikator-Kolbenstange und

Fig. 13

die Ansicht von Fig. 1 für eine Variante mit gegenüber der angesteuerten Kolben/Zylinder-Einheit gewinkelt angeordneter Multiplikatorvorrichtung.

Advantageous embodiments of the invention are illustrated in the drawings and will be described below. Showing:

Fig. 1

a schematic side view of a multiplier device with coupled casting piston / casting cylinder unit of a casting unit of a die casting machine in a starting position,

Fig. 2

a side view of an exemplary structural realization of the arrangement of Fig. 1 .

Fig. 3

the view of Fig. 1 in a first casting phase of a casting process of the die casting machine,

Fig. 4

the view of Fig. 1 in a second casting phase before multiplier start,

Fig. 5

the view of Fig. 1 during the second casting phase after multiplier start,

Fig. 6

the view of Fig. 1 at pressure increase start at the beginning of a third casting phase,

Fig. 7

the view of Fig. 1 during a post-compaction in the third casting phase,

Fig. 8

the view of Fig. 1 at the conclusion of the third casting phase,

Fig. 9

the view of Fig. 2 for a variant with annular gap seal,

Fig. 10

the view of Fig. 2 for a variant with cross-section equal inflow and outflow area,

Fig. 11

the view of Fig. 2 for a variant with an axial inlet bore in the free end section of the multiplier piston rod,

Fig. 12

the view of Fig. 2 for a variant with axial inlet Längsnutkanälen in the free end portion of the multiplier piston rod and

Fig. 13

the view of Fig. 1 for a variant with respect to the driven piston / cylinder unit angled arranged multiplier device.

In the Fig. 1 schematically illustrated arrangement comprises a pressure booster device 1, also called multiplier or short multiplier, which is coupled to a piston / cylinder unit, here in the form of a casting / casting cylinder unit 2 of a die casting machine. Fig. 2 shows a possible advantageous structural design of this arrangement. As far as not shown here, have a casting piston / casting cylinder unit 2 comprehensive casting unit and equipped therewith die casting machine on a conventional structure.

In the usual way, the casting piston / casting cylinder unit 2 controlled by the multiplier includes a casting cylinder 3 and, as a working or useful piston, a casting piston 4, which is guided with a head part 4a in the casting cylinder 3. The head part 4a is supported in a fluid-tight manner on an inner wall of the casting cylinder 3 via a moving sealing and guiding system 5a and divides it into a casting piston head space 6, which acts as the pressure fluid space of the piston / cylinder unit 2, and a casting piston annulus 7. The casting piston 4 extends with a piston rod part at the end, which is opposite to the head part 4a, from the casting cylinder 3 with sealing by a arranged at an associated end-side passage bore of the casting cylinder 3 sealing and guiding system 5b addition. A drain line 8 with associated drain valve 9 leads from the casting piston annulus 7. The casting piston head space 6 is designed without a check valve, i. there is no check valve connected to this volume.

The multiplier 1 is likewise embodied as a piston / cylinder unit and comprises a pressure booster cylinder 10 and a pressure booster piston 11 guided axially movably in the latter. The multiplier cylinder 10 comprises an exit region 12, an inlet region 13 upstream of the outlet region 12 and a piston guide chamber 14. In addition, it has a piston rod guide section 15 between the piston guide chamber 14 and the inlet region 13. The multiplier piston 11 has at one end a piston part 11a guided in the piston guide chamber 14 and a piston rod 11b extending therefrom out of the piston guide chamber 14 in the direction of the inlet region 13. With its piston part 11a, the multiplier piston 11 is guided via a moving sealing and guiding system 16 in the piston guide chamber 14, while its piston rod 11b is guided in the piston rod guide section 15 by inserting a sealing and guiding system 17 into the piston rod guide section 15. The exit region 12, like the casting piston head space 6, is designed without a check valve. Preferably, in the example shown, the inlet region 13 is designed without check valves.

In the in the Fig. 1 and 2 shown, maximum zurückbewegten starting position, the multiplier piston 11 extends with its piston rod 11b in the piston rod guide portion 15 and ends there in front of the inlet region 13. In alternative embodiments, it may also end in the inlet region 13. With its piston part 11a and the associated sealing and guiding system 16, the multiplier piston 11 divides the piston guide chamber 14 of the multiplier cylinder 10 into a multiplier piston chamber 14a and a multiplier back pressure chamber 14b, which forms a multiplier annular space 14b here. From the multiplier annulus 14b performs a back pressure line 18, also called drain line, with associated multiplier back pressure valve 19, also called multiplier drain valve from. In the multiplier piston chamber 14a opens a multiplier supply line 20 with associated multiplier inlet valve 21. In the inlet region 13 opens a casting piston feed line 22 with associated casting piston inlet valve 23. It should be noted that the terms inlet and outlet present only to distinguish are selected and do not mean that a pressurized fluid could only be supplied or removed via the relevant components. Rather, depending on the application pressure fluid can also be supplied via the drain line and / or discharged via the supply line, for example, to provide a back pressure in the back pressure chamber 14b for moving back the multiplier piston 11. The back pressure does not have to be overpressure, it is sufficient that there is a corresponding differential pressure between the back pressure chamber 14b and the multiplier piston chamber.

In the embodiment of Fig. 1 the outlet region 12 is designed as a section of the multiplier cylinder 10 which is radially narrowed relative to the inlet region 13. This is realized in that both areas are formed by associated axial, cylindrical portions of the multiplier cylinder 10 of different diameters to form a corresponding annular shoulder 24 at the transition of inlet region 13 and outlet region 12. In this case, the smaller diameter or cross section of the outlet region 12 compared to that of the inlet region 13 can be equal to the diameter or cross section of the piston rod guide section 15, which is arranged as a further cylindrical section of the multiplier cylinder 10 on the side of the inlet region 13 opposite the outlet region 12. Likewise, the diameter or cross section of the inlet 13 and the piston rod guide portion 15 radially extended inlet region 13 may be equal to the diameter or cross section of the piston guide chamber 14, which adjoins the piston rod guide portion 15 on the inlet side 13 opposite side. This pairwise diameter equality can have manufacturing advantages.

Fig. 2 shows a structurally advantageous embodiment in which the pressure booster cylinder 10 is made as a one-piece component, which connects with its outlet region 12 directly to the casting piston head space 6 of the casting / casting cylinder unit 2. This one-piece design for the multiplier cylinder 10, which can be attached directly to the casting cylinder 3 of the casting unit with the multiplier piston 11 received in it, has production-technological and functional advantages. In Fig. 2 are the various inlet and outlet lines 8, 19, 20, 22 and associated valves 9, 19, 21, 23 omitted, leading to corresponding sources of pressure fluid or Druckfluidsenken, as known in the art itself. In this case, the term pressurized fluid in the present case means any liquid or gaseous pressure medium which is suitable for the person skilled in the art for use in each particular case of use.

As based on the Fig. 1 and 2 becomes clear, the pressure booster device 1, the multiplier piston 11 as the only movable member. Other moving components, such as a check valve or other movable components to form a backflow preventer, are not necessary. This minimizes the mechanical loads and the susceptibility to wear of the multiplier 1. When the multiplier piston 11 out of his in the Fig. 1 and 2 shown moved home position in the Fig. 1 and 2 to the right, it enters with its piston rod 11b first in the inlet region 13 and then through this into the exit region 12 into it. As soon as it reaches the exit region 12, it constricts the fluid connection from the inlet region 13 to the outlet region 12, whereby a significant reflux of pressurized fluid from the casting piston head space 6 into the inlet region 13 is prevented. For safe, centered entry of the multiplier piston rod 11b into the exit region 12, an insertion aid can be provided. In the embodiment of Fig. 2 This is realized by the fact that the peripheral edge of the exit region 12 formed by the annular shoulder 24 at the transition from the inlet region 13 and the outlet region 12 has a frusto-conical insertion cone 25. Matching this, the multiplier piston rod 11 b is optionally provided with a corresponding frusto-conical insertion cone 26 at its free end face.

The multiplier piston 11 moves to provide the required pressure increase in the casting piston headspace 6 axially forward until it passes with the free end portion of its piston rod 11b in the exit region 12, wherein he depending on the design and needs in a maximum vorbewegten blocking position to the Outlet region 12 into or beyond this out into the casting piston headspace 6 extends. In any case, for this purpose, the outlet region 12 has a sufficiently large passage cross-section for the free piston rod end portion over a portion, which can be passed from the free end portion of the piston rod 11 b during movement of the multiplier piston 11. For this purpose, this passage cross section is at least as large as a rod cross section of the free end portion of the multiplier piston rod 11b. The multiplier piston rod 11b therefore passes unhindered through the relevant section of the exit region 12, without the multiplier piston 11 striking against another component during its forward movement in order to take it along in the forward motion. This also minimizes susceptibility to wear and increases the reliability of the multiplier 1 as compared to conventional integrated or external check valve pressure intensifier devices.

A controller 32 serves to control components of the multiplier device 1 to be controlled in a desired manner. For this purpose, it provides, inter alia, control signals 32a, 32b, 32c, 32d for the aforementioned controllable valves 9, 19, 21 and 23. In particular, in this case, the controller 32 is designed so that it controls the multiplier inlet valve 21 and / or the multiplier discharge valve 19 regardless of the pressure conditions in the casting piston / casting cylinder unit 2.

Optionally, in the example shown, the pressure booster device additionally comprises a useful piston position sensor 33 for detecting the position of the casting piston 4 and / or a multiplier piston position sensor 34 for detecting the position of the pressure booster piston 11. For this position sensors 33, 34, any one skilled in the art can be per se use known sensor types. In this case, the control unit 32, the multiplier inlet valve 21 and / or the multiplier-drain valve 19 in response to a Nutzkolben-position signal 33 a, with which the Nutzkolben position sensor 33 informs about the respective current position of the casting piston 4, and / or a multiplier piston position signal 34a, with which the multiplier piston position sensor 34 informs about the respective current position of the multiplier piston 11, control. In this case, in corresponding embodiments, both or only one of the position sensors are provided, and in corresponding embodiments, both valves 19 and 21 or only one of them are driven in this manner.

With further reference to the Fig. 3 to 8 will be below with the arrangement of Fig. 1 and 2 executable casting described as an exemplary example of the casting unit operating method according to the invention, from which the properties and advantages of this method and the pressure intensifier device according to the invention can be seen in more detail. The associated control measures can be performed by the control unit 32. This may be part of an overall control of the die casting machine concerned or designed as a separate unit specifically for the casting unit.

Before a casting process, the casting piston 4 and the multiplier piston 11 are each in the in the Fig. 1 and 2 shown starting position, which can be defined for example by a respective rear mechanical stop or by an electronic control measure. The casting operation then starts with the fact that, at the beginning of a first casting phase, pressure fluid or hydraulic medium is introduced from the associated pressure fluid source via the casting piston feed line 22 and the opened inlet valve 23 into the inlet region 13 and from there into the outlet region 12 of the multiplier 1 flows from where it enters the Gießkolbenkopfraum 6, as illustrated with a flow arrow S1. At the same time, pressure fluid flows out of the casting piston annulus 7 via the associated drain line 8 when the drain valve 9 is open, as illustrated by a flow arrow S2. As a result, the casting piston 4 moves forward, in Fig. 3 to the right, as illustrated with a movement arrow B1. During this first casting phase, the casting piston 4 typically moves at a relatively slow rate, as is adequate for this so-called prefill phase. The movement of the multiplier piston 11 is thereby controlled or synchronized via the corresponding activation of the associated valves 19 and 21 so that the fluid connection from the inlet region 13 to the outlet region 12 remains unhindered, ie in this first casting phase, no inflow throttling of the fluid connection is effective. For this purpose, the multiplier piston 11 can remain in its maximally moved-back release position or can already be advanced or pre-accelerated at low speed, but only to a degree which does not yet lead to an inflow throttling.

Fig. 4 shows the arrangement at the beginning of a subsequent second casting phase, also referred to as Formfüllphase. During the transition from the first to the second casting phase, the casting piston 4 is typically accelerated to a significantly higher filling speed compared with its velocity during the first casting phase. During this mold filling phase, liquid molten metal is injected at high speed into a casting mold of the die casting machine. The pressure fluid flows are similar to those of the first casting phase, but with partially different pressure fluid flow rates or valve positions, as known in the art. The higher casting piston speed compared to the first casting phase is symbolized by an extended movement arrow B2.

Fig. 5 illustrates the arrangement at a time when the multiplier piston 11 has begun its forward movement. To start the forward movement of the multiplier piston 11, the multiplier piston chamber 14a is supplied with pressurized fluid or hydraulic medium via the associated supply line 20 when the inlet valve 21 is open, as illustrated by a flow arrow S3. The starting time of the multiplier feed movement is control technology using the relevant inlet and / or drain valve technique of the multiplier 1, in particular under appropriate Control of the associated valves 19 and 21 by the control unit 32, suitably predetermined and is depending on the needs and application in the time interval of Formfüllphase, ie the second casting phase, as in Fig. 5 alternatively, only at the end of the mold filling phase or already in the period of the prefilling phase. At the same time, pressurized fluid is discharged from the multiplier annulus 14 via the associated drain line 18 when the drain valve 19 is open, as illustrated by a flow arrow S4.

With increasing forward movement of the multiplier piston 11, the inlet region 13 and in particular the fluid connection of inlet region 13 and outlet region 12 is continuously narrowed by the free end portion of the multiplier piston rod 11b until the multiplier piston rod 11b reaches the outlet region 12 with its free end face and thereby the pressure fluid flow S1 is nearly completely pinched off from the inlet area 13 into the outlet area 12, ie the fluid connection of inlet area and outlet area 12 is blocked. The temporal coordination of the movement of the multiplier piston 11 and the casting piston 4 must be precisely tuned taking into account the other requirements and conditions of the respective casting process and in particular the beginning and end of the mold filling with melt, so that the constriction or constriction of the fluid connection of inlet region 13 and outlet region 12 neither too early nor too late. In this way, a favorable transition from the mold filling phase to a subsequent post-compression phase can be achieved, in which the casting piston 4 is strongly braked by melt compression, as is known.

Fig. 6 illustrates the arrangement at the beginning of a subsequent to the second casting phase third casting phase, the so-called post-pressure phase or Nachverdichtungsphase. For this purpose, the multiplier piston 11 has advanced into the outlet region 12 with the free end section of its piston rod 11 b, thereby blocking or blocking the fluid connection between inlet region 13 and outlet region 12. By this measure according to the invention, the compression of the pressure fluid in the casting piston head space 6 can begin instantaneously or without delay by the multiplier piston 11 with its piston rod 11b by its forward movement volume in the exit region 12 and, if it moves so far forward, even in Gießkolben- Headspace 6 displaced. With this improved functionality is different the inventive multiplier 1 of conventional arrangements with a check valve, which causes an inherent delay.

An annular gap 27 can remain between the outer circumference of the multiplier piston rod 11b and an opposite edge of the exit region 12. The annular gap 27 is kept very narrow, so that the fluid connection between inlet region 13 and casting piston head space 6 is almost completely separated. Depending on the pressure conditions, an extremely low leakage pressure fluid flow, which is not relevant for the pressure casting system in terms of process engineering and control technology, remains depending on the pressure conditions. The annular gap has a free ring cross-section, which is expediently much smaller than 10% and preferably less than 1%, preferably less than 0.01% to 0.1%, of the cross section of the outlet region 12 with the multiplier piston 11 withdrawn.

Fig. 7 illustrates the arrangement in a subsequent course of the third casting phase. In this case, the multiplier piston 11 is moved further forward and emerges through the outlet region 12 into the casting piston head space 6. As a result, the hydraulic pressure in the casting piston head space 6 is increased to a procedurally desired level. Since the melt in the casting mold is hereby also densified, the casting piston 4 still passes through a small residual path in an initial part of the third casting phase Fig. 7 illustrated by a movement arrow B4.

Fig. 8 illustrates the arrangement at the end of the third casting phase. The casting piston 4 has come to a standstill because the melt has been completely compressed with the desired pouring pressure. The melt is already partially solidified at this time in relevant areas of the casting run or the mold, and there is no further forward movement of the casting piston 4 more. The cast product further cools due to heat extraction in the mold.

The hydraulic pressure in the casting piston head space 6 is kept constant by means of pressure control. For this purpose, the multiplier piston 11 is advanced only at extremely low speed, in Fig. 8 illustrated by a shortened movement arrow B5, wherein he displaces just as much pressurized fluid in the casting piston head space 6, as by the Annular gap 27 flows back between multiplier piston rod 11 b and the surrounding outlet region-cylinder edge in the direction of inlet region 13. With this measure, a pressure fluid leakage through this annular gap 27 through the counteracting forward movement of the multiplier piston 11 for the purpose of pressure maintenance is compensated in a simple manner. For this purpose, the corresponding pressure on the multiplier system and / or on the casting cylinder system can be suitably regulated by the control of the associated valves by means of the controller 32 in a manner known per se.

As is clear from the above explanation of a casting process that can be carried out with the multiplier according to the invention, the multiplier according to the invention makes it possible to reduce the pressure rise time for the holding pressure phase in comparison to conventional multiplier devices with a check valve. Towards the end of the mold filling phase, the multiplier constricts the flow of pressurized fluid to the casting piston head space, after which the pressure build-up in the casting piston head space follows virtually without delay. The multiplier according to the invention can be built robust and compact and realized with the multiplier piston as the only movable component.

The multiplier piston, in particular when using the operating method according to the invention, can already be set in motion sufficiently early to already have a relatively high speed at the end of the mold filling phase or at the beginning of the holding pressure phase, and thus to be able to realize a correspondingly rapid increase in pressure. While in conventional multiplier systems with spring-loaded check valve an unavoidable dead time caused by the closing time, which is caused by the accelerated by spring force valve body, this dead time is omitted here due to the omission of such a check valve. The pressure rise time therefore consists in the present case only of the inherently remaining time duration portion due to the finite volume displacement rate for the compression of the pressure fluid in the casting piston headspace.

In corresponding embodiments, the pressure intensifier inlet valve is controlled depending on the useful piston position signal of the useful piston position sensor and / or depending on the multiplier piston position signal of the multiplier piston position sensor, and / or the pressure booster back pressure valve is dependent on the useful piston position signal of the useful piston position sensor and / or from the multiplier piston position signal controlled by the multiplier piston position sensor. In the present case, the term of controlling should, unless otherwise stated, encompass both the possibility of pure control and the possibility of regulation. The feed movement of the pressure booster piston is thus independent of the pressure conditions in the various pressure chambers involved. If necessary, it can be provided to control the advancing movement of the pressure booster piston in its course over its entire stroke from the maximum backward to the maximum advanced position or only along a portion of this Gesamtthubs according to a predetermined nominal profile of the time course of the movement path or the speed of movement of the multiplier piston or to regulate.

Alternatively it can be provided that the control unit by appropriate control of the pressure booster inlet valve and / or the pressure booster back pressure valve, the advancing movement of the pressure booster piston in its time course along its entire stroke from the maximum backward to the maximum advanced position or only along a portion of this Gesamtthubs according to a predetermined nominal profile of the time profile of the pressure in the pressure fluid space of the piston / cylinder unit, ie in the casting piston headspace, controls or regulates. For this purpose, the control unit uses pressure sensor signals of a conventional and therefore not shown in detail pressure sensor, which is associated with the casting / casting cylinder unit of the die casting machine in the usual way.

Such a profile-based control of the advancing movement of the multiplier piston may be based, for example, on a precalculation, which in particular includes a prediction of the desired time at which the multiplier stubs off the pressurized fluid flow to the plunger headspace. The subsequent, multiplier-driven pressure increase is determined by the area-weighted differential speed of multiplier piston and the working piston of the piston / cylinder unit, ie in the case of die casting application of the casting piston or casting cylinder piston. If desired, the speed of the multiplier piston can be adjusted to the speed of the casting / working piston so that the pressure increase assumes a certain value or follows a desired time course. If necessary, the pressure rise can also be temporarily reduced to zero, ie it is pressure constant before, or temporarily set to a negative value, which then corresponds to a reduction in pressure.

The multiplier according to the invention requires only a few components and is comparatively easy to install. The risk of a spring break, as it consists of spring-biased check valves, completely eliminated. While in conventional systems with spring-loaded check valve selbiges swing depending on the design and flow or even begin to beat, this case applicable to the casting process and the service life of the casting aggregate harmful property eliminates thanks to the omitted check valve and the corresponding missing spring-mass system.

A further advantage of the invention when the check valve is omitted is that flow pressure losses are reduced from the pressure fluid source via the inlet valve to the casting piston, in particular during the second casting phase. This allows a smaller design of the casting system and / or a casting with higher casting power.

The advantages and characteristics of the invention apply equally to systems in which the casting piston speed is controlled, as well as to systems with pure control of the casting piston speed. In other words, the multiplier according to the invention can be used independently of the type of Gießzylinderansteuerung in a casting unit. The usability is also possible regardless of whether and in what way so-called differential controls are present on the casting unit, which feedback the outflowing pressure fluid flow in support of inflowing pressurized fluid. The multiplier movement provides an additional pressure fluid flow for the casting cylinder through volume displacement. The compressibility of the melt is generally extremely low, so that the pressure increase acts essentially via the volume displacement of the advancing multiplier piston.

The Fig. 9 to 12 illustrate by way of example some further embodiments of the pressure booster device according to the invention as variants of in Fig. 2 shown type. The embodiment of Fig. 9 is different from the one of Fig. 2 in that for sealing the annular gap area between the inner edge of the outlet region 12 and the advanced multiplier piston rod 11 b, an additional Sealing and / or guide system 28 is provided, preferably as a separate component which is attached to the inner edge of the outlet region 12. In this embodiment, the additional sealing and / or guiding system 28 provides for a corresponding additional sealing of the annular gap 27 or additional guidance of the multiplier piston rod 11b in the outlet region 12. The sealing and / or guiding system 28 can also have a gap-changing function, eg by designing such that, depending on the pressure, for example as a function of the pressure in the casting piston head space 6, it influences the sealing effect, for example reduces the gap, in order to reduce the leakage return flow. The sealing / guiding system 17 in the region of the piston rod guide portion 15 of the multiplier cylinder 10 can also be realized and arranged in this way.

At the in Fig. 10 In the embodiment shown, the inlet region comprises an axial section 13a and a radial inlet bore 13b which opens out from the outside and extends through a housing wall of the pressure booster cylinder 10. The axial inlet section 13a is formed with the same diameter as the outlet region 12 and the piston rod guide section 15 through a common axial central bore in the pressure booster cylinder 10. Thus, in this embodiment, the piston rod guide portion 13, the axial inlet portion 13a and the outlet portion 12 merge into one another without sharp separation. As an alternative to the single radial inlet bore 13b shown, a plurality of radial inlet bores can be distributed on the circumference of the multiplier cylinder 10. Optionally, additional sealing and / or guiding systems can be arranged axially in front of and / or behind the one or more inlet bores 13b in a manner not shown. In this embodiment, the blocking of the fluid connection of inlet region 13a, 13b and outlet region 12 takes place in that the advancing multiplier piston 11 with its piston rod 11b shuts off the junction of the radial inlet bore 13b in the axial inlet section 13a.

At the in Fig. 11 In the embodiment shown, the multiplier piston rod 11b has at its free end section an axial center bore 29 which opens out from the front side and one or more radial inlet bores 30 which extend from the outer circumference to the central bore 29 at a predetermined distance from the front end of the multiplier piston rod 11b. In this embodiment, the multiplier piston can 11 with its piston rod 11 b as shown already in the maximum backward release position with its free piston rod end portion extend into the exit region 12 into it. The pressurized fluid passes from the inlet region 13 via the one or more radial bores 30 to the center bore 29 of the multiplier piston rod 11b and from there into the casting piston head space 6, as illustrated by a flow arrow S5. In order to block the fluid connection of inlet region 13 and outlet region 12, the multiplier piston 11 is advanced until the radial inlet bores 30 have completely passed out of the inlet region 13 into the outlet region 12. The outlet region 12 then blocks with its inner edge the junction of the one or more radial inlet bores 30 and thus blocks the pressure fluid path between the inlet region 13 and the outlet region 12.

In this implementation, the mechanical Einführhilfebereich for the occurrence of the multiplier piston rod 11 b omitted in the exit region 12. The multiplier piston rod 11b is located along the entire movement path of the multiplier piston 11 between its maximum retracted release position and its maximum advancing blocking position in the exit region 12 and can be guided by this.

At the in Fig. 12 In the embodiment shown, the multiplier piston rod 11b has at its free end section one or more longitudinal groove channels 31 which are introduced on the outside of the free end section of the multiplier piston rod 11b from its front end up to a predetermined channel length. As in the embodiment of Fig. 11 can also be in the embodiment of Fig. 12 the piston rod 11b of the multiplier piston 11 always extend into the outlet region 12, also in the Fig. 12 In the release position, the pressurized fluid can flow from the inlet region 13 via the longitudinal groove or channels 31 through the outlet region 12 into the casting piston head space 6, as illustrated by a flow arrow S6. In this case, too, an insertion aid for the entry of the advancing multiplier piston rod 11b into the exit region 12 can be dispensed with. The blocking of the fluid connection of inlet region 13 and outlet region 12 is effected in this example by advancing the multiplier piston rod 11b until the longitudinal groove channels 31 completely out of the inlet region 13 into the outlet region 12 have gotten into it. The multiplier piston rod 11b then in turn shuts off the pressure fluid path between inlet region 13 and outlet region 12, if appropriate leaving the slight annular gap mentioned above.

Incidentally, apply to the embodiments of the Fig. 9 to 12 to the embodiment according to the Fig. 1 to 8 given properties and advantages according to what can be referenced.

In the embodiments of the Fig. 1 to 12 the multiplier 1 is arranged in extension of the piston / cylinder unit 2 driven by it, ie with aligned longitudinal axes of both piston / cylinder units 1, 2. Alternatively, any other geometrical arrangement of the multiplier 1 is relative to the piston / cylinder unit driven thereby. Unit 2 possible, in particular angled arrangements, in which the longitudinal axis of the multiplier piston 11 includes any predetermined angle to the longitudinal axis of the casting piston 4. Fig. 13 shows an embodiment in which a multiplier 1 'is arranged at an angle of 90 ° relative to a driven by him piston / cylinder unit 2', wherein, moreover, the multiplier 1 'to that of Fig. 1 to 12 can correspond and also the driven piston / cylinder unit 2 'of those of Fig. 1 to 12 can correspond. In further alternative embodiments, the multiplier is arranged with the longitudinal axis of the multiplier piston displaced parallel to the longitudinal axis of the casting piston or in opposite directions. In the latter case, the longitudinal axis of the multiplier piston is parallel to the longitudinal axis of the casting piston, but the multiplier piston moves in the opposite direction to the movement of the casting piston.

Claims (13)

1. Pressure intensifier device for increasing pressure in a pressurized fluid chamber of a piston/cylinder unit, preferably of a casting piston/casting cylinder unit of a die casting machine, comprising

   - a pressure intensifier cylinder (10) and a pressure intensifier piston (11), which is guided in an axially movable manner in the cylinder, wherein

   - the pressure intensifier cylinder comprises an outlet region (12), an inlet region (13) upstream of the outlet region, and a piston guiding chamber (14) having a pressure intensifier piston chamber (14a), into which a pressure intensifier inlet line (20) opens, and/or a pressure intensifier backpressure chamber (14b), into which a pressure intensifier backpressure line (18) opens,

   - the pressure intensifier piston comprises a piston part (11a), which is guided in the piston guiding chamber, and a piston rod (11b), which extends from the piston part to the inlet region, in a retracted release position releases a fluid connection between the inlet region and the outlet region and, in an advanced blocking position, blocks this connection with a free end portion, with which it extends into the outlet region, and,

   - over a portion that can be passed through by the free end portion of the piston rod (11b) during movement from the release position into the blocking position, the outlet region (12) comprises a free passage cross section for the free piston rod end portion that is at least equal in size to a rod cross section of the free piston rod end portion,

   - a pressure intensifier inlet valve (21), which is controlled independently of a pressure in the pressurized fluid chamber (6) of the piston/cylinder unit, is arranged in the pressure intensifier inlet line (20), and/or

   - a pressure intensifier backpressure valve (19), which is controlled independently of a pressure in the pressurized fluid chamber (6) of the piston/cylinder unit, is arranged in the pressure intensifier backpressure line (18), and/or

   - the outlet region (12) is designed as a portion of the pressure intensifier cylinder which is narrowed radially relative to the inlet region (13), wherein a diameter of the outlet region is greater than a diameter of the free piston rod end portion in order to form an intermediate open or sealed annular gap (27) between the free piston rod end portion, in the blocking position thereof, and a circumferential rim of the outlet region, and/or wherein a circumferential rim of the cylindrical portion of the outlet region has an insertion cone (25) on the inlet side,

   characterized in that the outlet region (12) is embodied without a check valve.
2. Pressure intensifier device according to claim 1, further characterized in that the pressure intensifier cylinder is manufactured as a one-piece component.
3. Pressure intensifier device according to claim 1 or 2, further characterized in that the pressure intensifier cylinder comprises a piston rod guiding portion (15) between the piston guiding chamber and the inlet region.
4. Pressure intensifier device according to any of claims 1 to 3, further characterized in that the outlet region and the inlet region have portions with a same cross section of the pressure intensifier cylinder, and the inlet region contains a radial inlet bore (13b), which opens radially from the outside into said portion of the pressure intensifier cylinder.
5. Pressure intensifier device according to any of claims 1 to 4, further characterized in that the inlet region comprises at least one radial bore (30) and an axial bore (29) in the free piston rod end portion, where said axial bore is connected to said radial bore and opens at an end face.
6. Pressure intensifier device according to any of claims 1 to 5, further characterized in that the inlet region comprises at least one axial longitudinal groove channel (31) on an outer circumferential side of the free piston rod end portion.
7. Pressure intensifier device according to any of claims 1 to 6, further characterized by a ring seal (28) on an inner rim of the outlet region.
8. Pressure intensifier device according to any of claims 1 to 7, further characterized by

   - an operative piston position sensor (33) for detecting the position of a piston of the piston/cylinder unit and/or a multiplier piston position sensor (34) for detecting the position of the pressure intensifier piston, and

   - a controller (32), which

   - controls the pressure intensifier inlet valve in accordance with an operative piston position signal of the operative piston position sensor and/or in accordance with a multiplier piston position signal of the multiplier piston position sensor, and/or

   - controls the pressure intensifier backpressure valve in accordance with an operative piston position signal of the operative piston position sensor and/or in accordance with a multiplier piston position signal of the multiplier piston position sensor.
9. Casting unit for a die casting machine, comprising

   - a casting piston/casting cylinder unit (2) and

   - a pressure intensifier device (1),

   characterized in that

   - the pressure intensifier device (1) is one according to any one of claims 1 to 8 and is designed to increase pressure in a pressurized fluid chamber (6) of the casting piston/casting cylinder unit.
10. Method for operating a die casting machine casting unit according to claim 9, in which

    - a respective casting process with a casting piston moved forward is carried out successively as a pre-filling phase, a die filling phase and a follow-up pressure phase, and

    - a feed motion of the pressure intensifier piston of the pressure intensifier device is started before the end of the die filling phase.
11. Method according to claim 10, further characterized in that the feed motion of the pressure intensifier piston is started at the beginning of or during the pre-filling phase.
12. Method according to claim 10 or 11, further characterized in that the feed motion of the pressure intensifier piston is controlled in accordance with the operative piston position signal of the operative piston position sensor and/or in accordance with the multiplier piston position signal of the multiplier piston position sensor.
13. Method according to any one of claims 10 to 12, further characterized in that the feed motion of the pressure intensifier piston is subject to open-loop or closed-loop control as regards its progress with respect to time along its complete stroke or only along a subsection thereof in accordance with a predetermined setpoint profile of the progress with respect to time of the movement path or movement speed of the multiplier piston or in accordance with a predetermined setpoint profile of the progress with respect to time of the pressure in the pressurized fluid chamber of the casting piston/casting cylinder unit.

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