EP0976475A1 - Filling system for the Production of moulded parts from thixotropic metal billets in die-casting machines - Google Patents

Abstract

Each material entry channel (20, 21, ...) has a circular or elliptic cross section with a substantially constant area over its entire length. Directly adjacent to the material entry cavity (19) there is a bend (25, 26, ...). Between the bend (25, 26, ...) and the respective inlet opening (35, ...) there is a straight tubular section. The center line of the bend has a constant radius and a tangent at one end parallel to the longitudinal axis (1) of the cylindrical cavity (12) of the casting chamber. Its tangent at the other end coincides with the center line of the respective straight tubular section.

Description

The present invention relates to a die casting machine for producing molded parts thixotropic metal bolt, containing a casting system, which has a cylindrical Casting chamber cavity connects with a mold cavity, the pouring system one has a cylindrical casting cavity directly adjacent to the casting chamber cavity and contains at least one gate, and all of the gates laterally from the Guide the lateral surface of the pouring cavity away, and each pouring channel has a concentric one Center line and at its end directed against the mold cavity, an inlet opening for Introducing the thixotropic metal alloy into the mold cavity, and the connection of the pouring system with the casting chamber cavity by means of a concentric one Longitudinal axis of the cylindrical casting chamber cavity vertical through opening happens, and the inlet openings with respect to the through opening are arranged so that the surface normals of the inlet openings do not coincide with the longitudinal axis of the cylindrical casting chamber cavity coincide.

Die casting machines for the production of molded parts from thixotropic metal bolts are on known. For example, EP-A 0 718 059 describes a horizontal die casting machine for Production of molded parts from a thixotropic alloy slurry, using the die casting machine an oxide scraper to avoid oxide inclusions in the alloy structure of the molding contains

The process for the production of molded parts from thixotropic, i.e. partially solid / partially liquid, Metal bolts are called thixoforms. All bolts come as metal bolts from a metal that can be converted into a thixotropic state. In particular can the metal bolts made of aluminum, magnesium or zinc or of alloys of these metals consist.

With thixoforming, the thixotropic properties of partially liquid or partially solid metal alloys exploited. The thixotropic behavior of a metal alloy means that a suitably prepared metal behaves unloaded like a solid, under However, shear stress reduces its viscosity to such an extent that it is similar to a Metal smelt behaves. This involves heating the alloy into the solidification interval between liquidus and solidus temperature required. The temperature should be set that, for example, a structure fraction of 20 to 80% by weight is melted, the However, the rest remains in solid form

With thixoforming, partially solid / partially liquid metal is used in a modified die casting machine processed into molded parts. The die casting machines used for thixoforming differ from die casting machines for die casting metal melts by, for example, a longer equipped casting chamber for receiving the thixotropic metal pin and a larger piston stroke required thereby, and for example a mechanically reinforced design of the thixotropic metal alloy leading parts of the die casting machine due to the higher pressure load on these parts during thixoforming.

Thixoforming is done, for example, with a horizontal die casting machine. At These machines have the casting chamber that receives the thixotropic metal bolt horizontal. In thixoforming, a thixotropic metal bolt is turned horizontally into one horizontal casting chamber of a die casting machine and by pressurization using a casting piston at high speed and under high pressure in a conventional manner casting mold made of steel, in particular hot-work steel, i.e. in the mold cavity is introduced or shot in, the thixotropic metal alloy froze in this. The pressure applied to the thixotropic metal bolt is typically 200 to 1500 bar and in particular between 500 and 1000 bar. The the resulting flow rate of the thixotropic alloy pulp is, for example 0.2 to 3 m / s and in particular 0.3 to 2 m / s.

That which forms during the solidification of the thixotropic metal alloy in the casting mold Cast structure essentially determines the properties of the molded parts. The microstructure is characterized by the phases, such as mixed crystal and eutectic phases, the Cast grain, such as globulites and dendrites, segregations as well as structural defects, such as porosity (Gas pores, micro voids), and impurities such as oxides.

The metal bolts used for the thixoforming of partially solid alloys have a process-related nature fine grain on the - if during the pretreatment of the thixotropic Metal bolts, i.e. during the heating of the metal bolts and their transport into the Die casting machine, no grain coarsening occurs - again in the alloy structure of the Find molded parts. A fine grain generally improves the material properties, increases the homogeneity of the alloy structure and helps to avoid structural defects in the molded part. The thixoforming of partially solid alloys shows in comparison to the die casting of Metal melting also has other significant advantages. This includes significant energy savings as well as shorter production times, because firstly the thixotropic metal bolts in the Compared to the die casting of metal melts prior to thixoforming less high and therefore less long to heat up and secondly in the mold cooled faster, or returned to a solid state, resulting in a reduction contributes to the coarsening of the grain. The energy saving mainly results from that a large part of the heat of fusion as well as the total superheat, i.e. the the Metal alloy additionally supplied heat to achieve a temperature increase about the melting point to ensure the molten state of the metal alloy, and the energy for keeping the melt warm is eliminated. Another advantage is also the better dimensional accuracy due to lower shrinkage and the manufacturing to consider shaped parts close to the final dimensions, which reduces the machining steps and alloy material is saved. In addition, the processing temperature is around 100 ° C lower the change in temperature of the individual components of the Die casting machine smaller, which increases the tool life. The opposite the die casting of molten metal, lower processing temperature for thixoforming also allows the processing of alloys with a low iron content, since no alloying the tools happen by melting. In addition, thixoforming allows one better mold filling with fewer air pockets.

In the die casting machines known from the prior art, a metal bolt is used in a thixotropic state, usually a thixotropic aluminum bolt, into a casting chamber (or more precisely: in a casting chamber cavity located in the casting chamber) and by pressurizing a mostly cylindrical constriction on one End of the casting chamber, the so-called through opening. It will sheared thixotropic material. The sheared, thixotropic material is then, starting from a pouring cavity adjacent to the through opening, into trapezoidal pouring channels deflected and then gets into the mold cavity of a mold. Usually the sprue channels at an approximately right angle to the concentric central axis of the through opening arranged. The arrangement between the casting chamber and the mold cavity is described in the following referred to as the pouring system The pouring system thus serves to initiate the in the Casting chamber located thixotropic alloy pulp in the mold cavity of the mold.

Due to the mechanical stress on the thixotropic alloy pulp during this Transfer from the casting chamber cavity into the mold cavity occurs through shear softening the thixotropic alloy, i.e. the thixotropic alloy is by shear softening more fluid.

a) Gutes Füllverhalten: Das Eingusssystem muss möglichst gleichmässig über seinen gesamten Querschnitt gefüllt werden. Im verwendeten Geschwindigkeitsbereich der thixotropen Legierung darf es zudem zu keinen Gas- oder Oxideinschlüssen kommen.

b) Gutes Strömungsverhalten: Die Strömung muss möglichst laminar sein, damit Verwirbelungen und unerwünschte Entfestigungen des thixotropen Materials vermieden werden.

c) Gutes Scherverhalten: Die Scherentfestigung muss möglichst homogen über den gesamten Querschnitt erfolgen, wobei die Scherentfestigung möglichst gering gehalten werden soll.

d) Geringer Wärmeverlust: Das thixotrope Material sollte auf seinem Weg durch das Eingusssystem möglichst wenig an Wärmeenergie verlieren.

e) Minimales Volumen des Eingusssystems: Das am Schluss des Thixoformprozesses im Eingusssystem verbleibende Material wird für den Füllprozess der Formkavität nicht verwendet. Daher sollte das Eingusssystem ein minimales Volumen aufweisen, um eine optimale Ausbringung von thixotropem Material in die Formkavität zu gewährleisten.

f) Gutes Nachspeisungsverhalten: Während der Erstarrung des Formteils muss das im Eingusssystem befindliche, thixotrope Material zusammenhängend flüssig bleiben, damit einerseits die Druckübertragung vom Giesskolben auf das Formteil aufrechterhalten werden kann und andererseits das durch die erstarrungsbedingte Schrumpfung verürsachte Volumendefizit des Formteils durch Nachspeisung von thixotropem Material kompensiert werden kann.

g) Gute Druckübertragung: Das Eingusssystem sollte einen möglichst geringen Druckabfall zwischen Giesskammerhohlraum und Formkavität bewirken.

The following requirements are placed on a pouring system for thixoforming:

a) Good filling behavior: The pouring system must be filled as evenly as possible over its entire cross-section. In addition, there must be no gas or oxide inclusions in the speed range of the thixotropic alloy.

b) Good flow behavior: The flow must be as laminar as possible so that turbulence and unwanted softening of the thixotropic material are avoided.

c) Good shear behavior: The shear softening must be as homogeneous as possible over the entire cross-section, whereby the shear softening should be kept as low as possible.

d) Low heat loss: The thixotropic material should lose as little heat energy as possible on its way through the pouring system.

e) Minimum volume of the pouring system: The material remaining in the pouring system at the end of the thixoforming process is not used for the filling process of the mold cavity. Therefore, the pouring system should have a minimal volume in order to ensure an optimal application of thixotropic material in the mold cavity.

f) Good make-up behavior: During the solidification of the molded part, the thixotropic material in the casting system must remain coherent so that the pressure transfer from the casting piston to the molded part can be maintained on the one hand and the volume deficit of the molded part caused by the solidification-related shrinkage due to the replenishment of thixotropic material can be compensated.

g) Good pressure transmission: The pouring system should cause the lowest possible pressure drop between the casting chamber cavity and the mold cavity.

The pouring systems known from the prior art only meet these requirements partially. In particular, the known pouring systems have too large a volume, so that the output of thixotropic material per molded part can be significantly improved can. A too large volume of the pouring system used in particular affects the economics of the process.

Another disadvantage of the known pouring systems relates to the speed-dependent Filling behavior. The filling behavior of a pouring system can vary depending on the piston speed and the initial state of the thixotropic bolt are very different. So it can with high piston speeds, for example, to undesirable air pockets in the thixotropic alloy slurry of the casting system come. With very fast mold filling Turbulent flow conditions can occur during thixoforming, resulting in Gas inclusions (air, release agent or lubricant) can result in the molded part, causing a any subsequent heat treatment desired, for example solution annealing, of the molded part is often impossible. Gas inclusions located near the surface of the molded part can be undesirable, for example, in solution annealing, due to the high gas pressure Cause blistering.

Another disadvantage of the known pouring systems concerns the uneven flow behavior. The during thixoforming after filling the pouring system with thixotropic In most cases, material flow is uneven. It was especially recognized that abrupt changes in direction and / or changing cross-sectional relationships lead to local speed changes of the thixotropic material. It was also found that with angular cross sections of the sprue, only a part of the available cross-section is used effectively for the management of the thixotropic material.

In view of the disadvantages of the known pouring systems for Die casting machines for the production of molded parts from thixotropic material has become the Inventor made the task of providing a pouring system, which the above Avoids disadvantages and that for a casting system of a die casting machine for thixoforming set requirements optimally met

According to the invention, this is achieved in that each sprue has a circular one or elliptical cross-section with a substantially constant cross-sectional area over its entire length has and immediately after the pouring cavity a bend contains, the part of the sprue located between the elbow and the inlet opening describes a straight, tubular piece of duct and the elbow is designed in such a way that its center line has a constant bending radius and a tangent to the to center line drawn to the through opening with the same bending radius at the through opening runs parallel to the longitudinal axis of the cylindrical casting chamber cavity and a tangent to the center line at the manifold end directed towards the inlet opening coincides with the center line of the straight, tubular duct piece.

The changes in direction remain due to the inventive design of the pouring system and also the related shear softening of the thixotropic alloy pulp minimal during transport from the through opening to the inlet opening.

Each sprue channel preferably has an amount between the sprue cavity and the inlet opening constant cross-sectional area. This will make the flow rate the thixotropic alloy kept as constant as possible and the shear effect on the minimized thixotropic alloy

More preferably, the sum of the cross-sectional areas corresponds to the individual sprue channels essentially the cross-sectional area of the through opening. The sum of the the cross-sectional areas of the individual pouring channels which are adjacent to the pouring cavity preferably by no more than ± 10% from the cross-sectional area of the through opening.

In a further preferred embodiment of the sprue system, the sprue contains a gate area towards the mold cavity, which is in the corresponding Inlet opening ends. The pouring channels preferably have between the pouring cavity and the respective gate area a tubular channel piece with a circular cross-section and constant radius on Here the channel section between the casting cavity is concerned and gate area on the one hand the manifold and on the other hand that between the manifold and Bleed area of the straight channel section of each sprue. Through this circular cross-section, the ratio of surface to volume is also minimized The circular cross-section allows full use of the available channel cross-section.

The inlet openings preferably have an elliptical cross section. The inlet opening results from the intersection of the gate area of the sprue with that in the Mold cavity produced, diverging molded part. With a flat molded part wall this results in an elliptical inlet opening. This results in curved part geometries usually more complex cut surfaces.

The gate area represents a channel-shaped transition area between the straight Section of the sprue with a circular cross section and the inlet opening. Preferred the gate area has a cross-section along its center line which is gradual from a circular to an increasingly flat elliptical cross-section merges, this transition region in an elliptical one corresponding to the inlet opening Cross section ends. The cross-sectional area is preferred in the gate area in terms of amount kept essentially constant, with changes in amount the cross-sectional area of up to 30% is included; in particular, the Gradually widen the cross-section of the gate area along its center line or narrow.

In a further preferred embodiment, the pouring system according to the invention has a collection pocket for the forehead oxide layer of the thixotropic metal bolt on during the Pretreatment, storage and the heating process of the thixotropic metal bolt forms usually a metal oxide layer. To include such oxidic components in the To avoid alloy structure of the molded part, the oxide surface of the thixotropic Metal pin mostly removed before or in the casting chamber. Usually remains an oxide layer on the face of the thixotropic bolt. The in the inventive Embodiment of the pouring system provided collection pocket thus allows the deposit this end oxide layer in a fluid-mechanical dead zone at that of the through opening distal end of the casting cavity. The catch bag is included. for example, by a cylindrical protuberance of the casting cavity on the through opening distant side formed.

The casting system according to the invention is preferred for horizontal die casting machines used.

The straight duct sections of the sprue ducts are more preferably perpendicular to the longitudinal axis of the casting chamber cavity. The bending radius corresponds to the center line in the Elbow of a sprue containing the distance of the through opening from a straight line the center line of the straight, tubular duct piece of the corresponding sprue.

According to the invention, the bending radius of a center line in the manifold area is determined, for example in that the intersection of the bisector between the longitudinal axis of the casting chamber cavity and the center line of the straight section of the corresponding Gating channel is determined with a plane through the through hole, the Distance of this intersection from the center of the through opening the bending radius Rk results.

The transition between the casting chamber cavity and the casting cavity can be sharp-edged or be rounded. With the sharp-edged design, this transition described through the through opening. However, a rounded transition is preferred. The through opening is described by the point at which the cross section is the smallest, or the cross-section assumes a constant value, i.e. in a casting cavity with a constant cross-section merges. In the rounded embodiment the transition between the cylindrical casting chamber cavity and the Through opening thus becomes a transition area with a continuously tapering Cross section formed. By creating such a transitional area uniform shear effect of the thixotropic alloy pulp. In addition, a sharp-edged transitions and high flow speeds frequently occurring Detachment of the thixotropic alloy flow from the wall of the through opening avoided.

Further advantageous configurations of the pouring system according to the invention result from the dependent claims.

The pouring system according to the invention is suitable in principle for the thixoforming of all Mezal alloys that can be converted into a thixotropic state. Prefers the casting system according to the invention for thixoforming of aluminum, magnesium or Zinc alloys used. The method according to the invention is particularly preferably suitable Casting system for thixoforming of aluminum die casting alloys, especially for AlSi, AlSiMg, AlSiCu, AlMg, AlCuTi and AlCuZnMg alloys.

a) Minimales Volumen des Eingusssystems:
Durch die Verwendung runder Eingusskanäle wird die Gesamtoberfläche so klein wie möglich gehalten. Zudem ist wegen dem optimalen Verhältnis von Oberfläche zu Volumen der Wärmeverlust minimal. Daher wird weniger thixotropes Material benötigt um den Wärmeverlust des thixotropen Legierungsbreis im Eingusssystem zu kompensieren.

b) Gutmütiges Füllverhalten:
Das Füllverhalten des Eingusssystems ist in dem für das Thixoformen üblicherweise angewandten Geschwindigkeitsbereich der Formfüllung, d.h. der Strömungsgeschwindigkeit der thixotropen Legierung, sehr gutmütig, d.h. selbst bei relativ hohen Strömungsgeschwindigkeiten bilden sich keine Lufteinschlüsse.

c) Strömungsverhalten:
Das Strömungsverhalten bei mit thixotroper Legierung bereits gefülltem Eingusskanal ist ausgezeichnet, da die gesamte Querschnittsfläche des Eingusskanales genutzt wird und keine strömungsmechanischen Totzonen vorhanden sind. Zudem ermöglicht der runde Kanalquerschnitt der Eingusskanäle die Ausbildung einer laminaren Strömung für den ganzen bei der Formfüllung auftretenden Strömungsgeschwindigkeitsbereich.

d) Einstellbarkeit der Viskosität:
Infolge der geringen Scherentfestigung der thixotropen Legierung an der Durchgangsöffnung und dem Eingusskanal kann eine hohe Viskosität der thixotropen Legierung bis hin zur Einleitöffnung beibehalten werden. An der Einleitöffnung kann dann die für die Füllung der Formkavität gewünschte Viskosität des thixotropen Legierungsbreis eingestellt werden.

e) Minimaler Druckverlust und gutes Nachspeisungsverhalten:
Der Kolbendruck wird durch die erfindungsgemäss gekrümmten Eingusskanäle sehr gut übertragen, d.h. der Druckverlust in den Eingusskanälen ist minimal und wird infolge des hydrostatischen Druckes vorallem durch die gewählte Höhe der entsprechenden Einleitöffnung bestimmt. Auch das Nachspeisungsverhalten wird infolge des geringen Druckabfalles in den Eingusskanälen im wesentlichen durch die Höhe der Einleitöffnungen bestimmt.

The pouring system essential to the invention has the following advantages over the prior art:

a) Minimum volume of the pouring system:
By using round sprue channels, the total surface is kept as small as possible. In addition, due to the optimal ratio of surface to volume, heat loss is minimal. Therefore less thixotropic material is needed to compensate for the heat loss of the thixotropic alloy pulp in the pouring system.

b) Good-natured filling behavior:
The filling behavior of the pouring system is very good-natured in the mold filling speed range usually used for thixoforming, ie the flow speed of the thixotropic alloy, ie no air pockets are formed even at relatively high flow speeds.

c) Flow behavior:
The flow behavior of the pouring channel already filled with thixotropic alloy is excellent, since the entire cross-sectional area of the pouring channel is used and there are no flow-mechanical dead zones. In addition, the round channel cross section of the sprue channels enables the formation of a laminar flow for the entire flow velocity range that occurs during mold filling.

d) adjustability of viscosity:
As a result of the low shear softening of the thixotropic alloy at the through-opening and the sprue, a high viscosity of the thixotropic alloy up to the inlet opening can be maintained. The viscosity of the thixotropic alloy slurry required for filling the mold cavity can then be set at the inlet opening.

e) Minimal pressure loss and good make-up behavior:
The piston pressure is transmitted very well through the pouring channels curved according to the invention, ie the pressure loss in the pouring channels is minimal and, due to the hydrostatic pressure, is primarily determined by the selected height of the corresponding inlet opening. Due to the low pressure drop in the sprue channels, the make-up behavior is also essentially determined by the height of the inlet openings.

Embodiment

Die casting machine with a horizontal casting chamber, in which the transition from the casting chamber cavity to the casting cavity is sharp-edged and the casting system has two casting channels of the same dimensions, each with a gate area. The cross section of the sprue duct section between the sprue cavity and the gate area is circular and has a diameter of 2 R = 25 mm. The bend radius of the manifolds is 42.5 mm. The through hole diameter is 35 mm. The pouring cavity has a circular cylindrical shape and has a horizontal, concentric longitudinal axis, which also coincides with the concentric longitudinal axis of the casting chamber cavity. The casting cavity has a diameter of 35 mm. The length of the casting cavity is designed such that a collecting pocket for the end oxides of the thixotropic bolts is formed between the two elbows, the cross-sectional dimensions of the collecting pocket corresponding to those of the casting cavity. The straight duct section of each sprue is vertical and is thus perpendicular to the concentric longitudinal axis of the casting chamber cavity, one sprue leading vertically downwards and the other sprue vertically leading upwards. The height of the beginning of the gate area measured from the concentric longitudinal axis of the casting chamber cavity is 102.5 mm. The length of the gate area is 50 mm. The inlet openings lie in a horizontal plane and have an elliptical shape with a major axis length a and a minor axis length b. The shape of the gate area can be in a Cartesian coordinate system, in which the x-axis is placed parallel to the concentric longitudinal axis of the casting chamber cavity, the y-axis is parallel to a vertical and the z-axis also lies in a horizontal plane through the x-axis, such that x (y) = (bR) y / c + R and z (y) (c · R 2nd ) / (b · y - R · y + R · c) applies, where R is the constant radius of the cross-sectionally circular sprue channel piece between the sprue cavity and the gate area, b the length of the minor axis of the inlet opening and c the length or height of the gate area. In this Cartesian coordinate system, the main axis a of the inlet opening is parallel to the z-axis and the secondary axis b is parallel to the x-axis. The inlet openings thus have an ellipse with a minor axis diameter of 2 b = 6 mm and a major axis diameter of 2 a.

Figur 1

zeigt schematisch eine Teilansicht eines vertikal durch die konzentrische Längsachse des Giesskammerhohlraumes verlaufenden Längsschnittes einer erfindungsgemässen Druckgiessmaschine mit zwei Eingusskanälen.

Figur 2

zeigt eine Draufsicht auf die in Figur 1 im Längsschnitt dargestellte Druckgiessmaschine entlang der Linie A-A.

Figur 3

zeigt eine Draufsicht auf die in Figur 1 und 2 dargestellte Druckgiessmaschine entlang der Linie B-B.

Figur 4

zeigt schematisch eine Teilansicht eines vertikal durch die konzentrische Längsachse des Giesskammerhohlraumes verlaufenden Längsschnittes einer weiteren erfindungsgemässen Druckgiessmaschine mit einem einzigen Eingusskanal.

Figur 5

zeigt eine Draufsicht auf die in Figur 4 im Längsschnitt dargestellte Druckgiessmaschine entlang der Linie C-C.

Figur 6

zeigt schematisch eine Teilansicht eines vertikal durch die konzentrische Längsachse des Giesskammerhohlraumes verlaufenden Längsschnittes einer weiteren erfindungsgemässen Druckgiessmaschine mit vier Eingusskanälen.

Figur 7

zeigt eine Draufsicht auf die in Figur 6 im Längsschnitt dargestellte Druckgiessmaschine entlang der Linie D-D.

Figur 8

zeigt verschiedene Ausführungsformen eines Ausschnittes des in Figur 1 dargestellten oberen Eingusskanales, wobei dieser Ausschnitt insbesondere den Anschnittbereich des oberen Eingusskanales betrifft und Figur 8 verschiedene Ausführungsformen dieses Anschnittbereiches in einem vertikal durch die konzentrische Längsachse des Giesskammerhohlraumes verlaufenden Längsschnitt darstellt

Figur 9

zeigt die Draufsicht auf die in Figur 8 im Längsschnitt dargestellten Ausführungsformen des Anschnittbereiches der Figur 1 entlang der Linie A-A.

Further advantages, features and details of the die casting machine according to the invention result from the exemplary embodiments shown in FIGS. 1 to 9 and from the description of the figures.

Figure 1

schematically shows a partial view of a longitudinal section of a die casting machine according to the invention with two sprue ducts running vertically through the concentric longitudinal axis of the casting chamber cavity.

Figure 2

shows a plan view of the die casting machine shown in Figure 1 in longitudinal section along the line AA.

Figure 3

shows a plan view of the die casting machine shown in Figures 1 and 2 along the line BB.

Figure 4

schematically shows a partial view of a longitudinal section running vertically through the concentric longitudinal axis of the casting chamber cavity of a further die casting machine according to the invention with a single sprue.

Figure 5

shows a plan view of the die casting machine shown in Figure 4 in longitudinal section along the line CC.

Figure 6

schematically shows a partial view of a longitudinal section running vertically through the concentric longitudinal axis of the casting chamber cavity of a further die casting machine according to the invention with four sprue channels.

Figure 7

shows a plan view of the die casting machine shown in Figure 6 in longitudinal section along the line DD.

Figure 8

1 shows various embodiments of a section of the upper sprue shown in FIG. 1, this section particularly relates to the gate area of the upper sprue and FIG. 8 shows various embodiments of this gate area in a longitudinal section running vertically through the concentric longitudinal axis of the casting chamber cavity

Figure 9

shows the top view of the embodiments of the gate area of FIG. 1 shown in longitudinal section in FIG. 8 along the line AA.

FIGS. 1 to 9 relate, by way of example, to views of a horizontal die casting machine according to the invention, i.e. a die casting machine with a horizontally arranged casting chamber.

FIG. 1 shows a partial view of a vertically through the concentric longitudinal axis 1 of the casting chamber cavity 12 running longitudinal section of a horizontal die casting machine according to the invention for the production of molded parts from thixotropic metal bolts, wherein in this longitudinal section a part of the horizontal casting chamber 10 and the pouring system 17 can be seen.

The casting chamber 10 contains a cylindrical casting chamber cavity 12 which has a concentric longitudinal axis 1. The pouring system 17 connects the casting chamber cavity 12 to the mold cavity (not shown). The pouring system 17 shown in FIG. 1 has two pouring channels, the pouring channel 20 and the pouring channel 21. The sprue channels 20 and 21 represent tubular structures, the cavities of which each have a concentric center line m ₁ and m ₂ . The pouring channels 20, 21 are connected to the casting chamber cavity 12 by means of a through opening 14 common to both pouring channels. The through opening represents a rotationally symmetrical opening that is perpendicular to the longitudinal axis 1 at the end of the casting chamber 10 on the sprue side.

When the thixotropic metal alloy is pressurized in the casting chamber 10, the thixotropic alloy slurry in the flow direction x through the passage opening 14 of the casting chamber 10 pressed and passes through the sprue 20, 21 into the mold cavity Mold (not shown).

The transition from the casting chamber cavity 12 to the through opening 14 can be sharp or be rounded. The through opening is located at a sharp-edged transition 14 directly at the sprue-side end of the casting chamber 10. The one shown in FIG Die casting machine shows a rounded transition between the casting chamber cavity 12 and passage opening 14. This creates a continuous x in the direction of flow tapered transition area 16.

The pouring system 17 has a directly adjacent to the through opening 14, circular cylindrical casting cavity 19, wherein the cross-sectional area of that shown in Figure 1 Pouring cavity 19 corresponds to the cross-sectional area of the through opening 14 and a concentric longitudinal axis of the casting cavity 19 with the longitudinal axis 1 of the casting chamber cavity 12 coincides The sprue channels 20, 21 lead - seen in the flow direction x - All laterally away from the lateral surface of the casting cavity 19.

The sprue channels 20, 21 have a circular or elliptical cross section, the cross-sectional area of the sprue channels 20, 21 in terms of amount over their entire length, i.e. between the casting cavity 19 and the inlet opening 35 remains constant. The sprue 20, 21 contain a manifold 25, 26 immediately following the casting cavity 19, i.e. a curved, tubular section. The between manifold 25, 26 and inlet opening 35 located part of each sprue 20, 21 describes a straight, tubular Channel piece.

Since the pouring system 17 according to the invention only relates to arrangements in which the surface normals NE _{1 of} the inlet openings 35 do not coincide with the longitudinal axis 1 of the casting chamber cavity 12, each center line m ₁ , m _{2 describes} a curved curve, the curved part of the curve according to the invention being at the beginning of the sprue 20, 21, ie adjoining the casting cavity 19, is located. The curved part of the center line m ₁ , m ₂ has a constant bending radius Rk ₁ . Rk ₂ on. The part of the pouring channel 20 or 21 comprising the curved part of the center line m ₁ or m ₂ is the elbow 25 or 26. The elbow 25, 26 is in each case such that a tangent to the through opening 14 with the same bending radius Rk ₁ . Rk ₂ center line m ₁ , m ₂ runs parallel to the longitudinal axis 1 of the cylindrical casting chamber cavity 12 at the beginning of the manifold located against the through opening 14

The bending radii Rk ₁ , Rk _{2 of} the center lines m ₁ , m ₂ in the bends 25, 26 are selected such that they correspond to the distance d of the through opening 14 from the center line m ₁ , m _{2 of} the straight duct section of the respective sprue 20, 21.

A straight section of the sprue 20 or 21 is connected to the mold cavity-side end 73 or 74 of the elbow 25 or 26, so that the center line m ₁ , m _{2 of} each sprue 20, 21 between the mold cavity-side manifold end 73, 74 and the inlet opening 35, 36 describes a straight line. In FIG. 1, the straight sections of the pouring channels 20, 21 are perpendicular to the concentric longitudinal axis 1 of the casting chamber cavity 12. Accordingly, the center lines m ₁ , m _{2 of} the straight sections of the pouring channels 20, 21 are perpendicular to the longitudinal axis 1.

The bends 25, 26 are further designed such that a tangent to the curved center line m ₁ , m ₂ at the end 73, 74 of the bend directed against the inlet opening 35 with the center line m ₁ , m _{2 of} the straight duct section of the corresponding sprue 20, 21 coincides

The sprue channels 20 and 21 each have a gate region at their end directed against the mold cavity, which ends in the corresponding inlet opening 35, only the gate region 30 of the sprue channel 20 being shown in FIG. The transition from the gate area 30 to the mold cavity takes place through the inlet opening 35, which is perpendicular to the center line m _{1 of} the straight section of the sprue 20. Therefore, the surface normal NE _{1 of} the inlet opening 35 leading through the center of the inlet opening 35 coincides with the center line m _{1 of} the straight duct section of the corresponding sprue 20.

The sprue channels 20, 21 are described between the sprue cavity 19 and the gate area 30, 31 by a tubular channel piece with a circular cross section and constant inner diameter 2 R ₁ , 2 R ₂ . The radii R ₁ , R _{2 are selected} such that the sum of the cross-sectional areas of the two tubular channel pieces with a circular cross-section of the sprue channels 20, 21 corresponds to the cross-sectional area of the through opening 14, ie π • R 1 2nd + π · R 2nd 2nd = π · R D 2nd , where R _D denotes the radius of the circular through opening 14. Accordingly, the pouring channels 20, 21 fictitiously drawn with the same bending radius up to the through opening 14 lie within the through opening 14, so that there is an overlap of the pouring channels 20, 21 with the through opening 14

The length of the casting cavity 19 is designed such that the casting cavity 19 is one between the bends 25, 26 there is a collection pocket 18 for receiving forehead oxides contains the thixotropic metal bolt. Thus, the casting cavity 19 contains on the one hand the conceptually from the mantle surface of the casting cavity 19 to the through opening further developed manifold 25, 26 and on the other hand the collecting bag 18th

The inlet opening 35 shown in FIG. 1 has an elliptical shape, the minor axis the ellipse lies parallel to the x-axis in a horizontal plane parallel to the x-z plane, i.e. the minor axis lies horizontally and in a vertical plane, which is the longitudinal axis 1 of the casting chamber cavity 12 contains. In Figure 1, the inlet opening 35 is thus through the minor axis of length 2 b is shown.

The gate area 30 shown in FIG. 1 relates to a transition area of length c of the pouring channel 20, in which the straight section of the pouring channel 20 with a circular cross section and constant radius R ₁ merges into the elliptical cross-sectional shape of the inlet opening 35. Accordingly, the gate area 30 in FIG. 1, that is to say in a longitudinal section running vertically through the concentric longitudinal axis 1 of the casting chamber cavity 12, has a trapezoidal shape, the trapezoid being of isosceles and having two parallel sides of length 2 R ₁ and 2 b and the parallel sides are arranged at a distance c.

Figure 2 shows a plan view of the die casting machine shown in Figure 1 in longitudinal section along the line AA. In particular, the circular contour of the collecting pocket 18, the sprue channels 20, 21 leading away perpendicularly therefrom and the cut area 30 of the sprue channel 20 can be seen. The gate area 30 describes a continuously widening area of the pouring channel 20, the cross-sectional dimensions of which in this view - starting from the straight channel piece of the pouring channel 20 with a circular cross section - continuously merge into the elliptical cross section of the inlet opening 35. In the view shown in FIG. 2, the inlet opening has a maximum extent of the size 2a, where a denotes the main axis of the ellipse of the inlet opening 35. The widening of the gate region 30 in the direction of the inlet opening 35 shown in FIG. 2 is such that the cross-sectional dimensions of the gate region 30 remain constant along the center line m ₁ .

Figure 3 shows a plan view of the die casting machine shown in Figures 1 and 2 along the line B-B of Figure 2. The ellipse shown in Figure 3 thus describes a plan view onto the inlet opening 35. The inlet opening 35 is located in a direction relative to the longitudinal axis 1 of the casting chamber cavity 12 parallel horizontal plane, i.e. in a too Cartesian x-z axis parallel plane. In a Cartesian coordinate system in which the x direction runs parallel to the longitudinal axis 1 and designates the second horizontal axis as the z-axis 3, the inlet opening 35 shown in FIG. 3 has a minor axis in the x direction of length 2 b and in the z direction a main axis of length 2 a.

Figure 4 shows a partial view of a vertically through the concentric longitudinal axis 1 of the casting chamber cavity 12 running longitudinal section of another according to the invention Die casting machine, in this longitudinal section a part of the horizontal casting chamber 10 with casting chamber cavity 12 and the pouring system 17 can be seen. The pouring system 17 contains a sprue cavity 19 and a single sprue 20. The transition from the casting chamber cavity 12 to the through opening 14 is rounded. The to the Through opening 14 adjacent casting cavity 19 is circular cylindrical, wherein the cross-sectional diameter of the casting cavity 19 is the diameter of the through opening 14 corresponds to and the longitudinal axis of the casting cavity 19 with the longitudinal axis 1 of the casting chamber cavity 12 coincides. From the lateral surface of the casting cavity 19 leads a bend 25 of a single sprue 20 laterally upwards. Subsequently on the manifold 25, the sprue 20 has a straight, vertically leading upward Channel piece, to which a gate area 30 connects. In the shown in Figure 4 In the view, the gate area 30 tapers conically towards the top and ends in FIG Inlet opening 35. The cross-sectional area of the sprue 20 corresponds on its whole Length, i.e. between the casting cavity 19 and the inlet opening 35, essentially the cross-sectional area of the passage opening 14. The length of the casting cavity 19 is such that that a collection pocket 18 for receiving the end oxides of the thixotropic alloy pulp is created. In the embodiment shown here, the length corresponds to the Casting cavity 19 the distance of the passage opening 14 from one to the straight section of the sprue 20 on the side remote from the casting chamber cavity 12, to the longitudinal axis 1 normal tangential plane.

Figure 5 shows a plan view of the die casting machine shown in Figure 4 in longitudinal section along the line C-C. It is circular in addition to the one in this top view see collecting bag 18 of the sprue 20 with its gate area 30. The sprue 20 leads vertically upwards. The gate area 30 relates to this Top view of a continuously expanding area of the sprue 20, the Shape of the gate area 30 is selected such that in cooperation with the in Figure 4 shown the cross-sectional area of the gate area 30 on its entire length remains constant

FIG. 6 schematically shows a partial view of a vertically through the concentric longitudinal axis 1 of the casting chamber cavity 12 extending longitudinal section of another according to the invention Die casting machine. The transition from the casting chamber cavity 12 to the through opening 14 is rounded. Is located after the passage opening 14 a circular-cylindrical molded cavity 19, the cross-sectional diameter of the Corresponds to the diameter of the through opening 14 and its longitudinal axis with the longitudinal axis 1 of the casting chamber cavity 12 coincides from the lateral surface of the casting cavity 19, four elbows 25, 26, 27, 28 go away; in a vertical Plane along the longitudinal axis 1, only two elbows can be seen, namely the manifold 25 of a vertically upward pouring channel 20 and the manifold 26 one vertically downward pouring channel 21. The manifolds 25, 26 just close, channel sections of the sprue channels 20 leading vertically upwards or vertically downwards, 21 with a circular cross-section. The ones that follow the straight duct sections Gate areas 30, 31 show a conical shape in the view shown in FIG tapered cross section. Between the elbows 25, 26 there is a protuberance of the casting cavity 19, the so-called collection pocket 18 included.

Figure 7 shows a plan view of the die casting machine shown in Figure 6 in longitudinal section along the line DD. In this top view four cross-shaped sprue channels 20, 21, 22, 23 can be seen. The concentric center lines (not shown) of these pouring channels 20, 21, 22, 23 form a right angle in this plan view. In the center of this plan view is the collecting pocket 18 shown in a circle. The corresponding gate areas 30, 31, 32, 33 are connected to the straight sections of the pouring channels 20, 21, 22, 23 leading away from the center of the collecting pocket 18. These gate areas 30, 31, 32, 33 describe the transition area between the straight sections of the sprue channels 20, 21, 22, 23 and the corresponding inlet openings 35, 36, 37, 38. The gate areas 30, 31, 32, 33 relate to this plan view continuously widening regions of the pouring channels 20, 21, 22, 23, the shape of the gate regions 30, 31, 32, 33 being selected such that, in cooperation with the view shown in FIG. 4, the cross-sectional area of each gate region 30, 31, 32, 33 remains constant over its entire length All four sprue channels 20, 21, 22, 23 have the same shape and the same dimensions. In addition, the pouring channels 20, 21, 22, 23 are designed such that their cross-sectional area is constant over their entire length, ie from the pouring cavity 19 to the corresponding inlet openings 20, 21, 22, 23. The surface normals NE ₁ , NE ₂ , NE ₃ , NE ₄ on the inlet openings 35, 36, 37, 38 lie parallel to the center lines of the straight sections of the corresponding sprue channels 20, 21, 22, 23. Adjacent surface normals NE ₁ , NE ₂ , NE ₃ , NE _{4 form} a right angle with each other.

FIG. 8 shows various embodiments of a section of the one shown in FIG. 1 upper sprue 20, this cutout in particular the gate area 30 concerns. Accordingly, FIG. 8 shows various embodiments of the gate area 30 in a vertically extending through the concentric longitudinal axis 1 of the casting chamber cavity 12 Longitudinal section. The inlet opening 35 remains for all embodiments of the Gate area 30 unchanged. Essential for the shown embodiments of the Gate area 30 with the gate walls e, f, g is that the gate area 30 as a transition area between the straight duct section of the sprue 20 and the inlet opening 35 over its entire length and for all embodiments of the gate walls e, f, g has the same cross-sectional area everywhere. in longitudinal section according to figure 8, the gate wall f (solid line) has the shape of an isosceles Trapezes and corresponds to the representation of the gate area 30 shown in FIG. 1. The gate wall e has a continuously inwardly curved shape and Gate wall g shows a continuously curved shape.

Figure 9 shows the top view of the embodiments shown in Figure 8 in longitudinal section of the gate area 30 of Figure 1 along the line A-A. The inlet opening remains 35 again unchanged for all embodiments of the gate area 30. To meet the requirement of a constant cross-sectional area along the gate area 30 meet, this requirement for all embodiments of the gate region 30th to apply, the gate walls e, f, g must have one in the top view according to FIG have the larger cross section, the smaller their cross section in the longitudinal section according to Figure 8 is. Accordingly, the gate wall e in FIG. 9 has a trapezoidal shape, while the gate wall f continues to follow the gate wall e is curved inside and the gate wall f compared to the gate wall e in the in Figure 9 top view thus shows a smaller cross-section everywhere. The Gating wall g has a more inward direction than gating wall f Curvature, so that their cross section in the plan view shown in Figure 9 is smaller everywhere compared to the gate wall f.

Claims (14)

Die casting machine for producing molded parts from thixotropic metal bolts, comprising a casting system (17) which connects a cylindrical casting chamber cavity (12) with a mold cavity, the casting system (17) having a cylindrical casting cavity (19) directly adjacent to the casting chamber cavity (12) and contains at least one pouring channel (20, 21, 22, 23), and laterally guide all the pouring channels (20, 21, 22, 23) away from the lateral surface of the pouring cavity (19), and each pouring channel (20, 21, 22, 23) has a concentric center line (m ₁ , m ₂ ) and at its end directed towards the mold cavity has an inlet opening (35, 36, 37, 38) for introducing the thixotropic metal alloy into the mold cavity, and the connection of the pouring system (17) to the casting chamber cavity (12) through a through opening (14) perpendicular to a concentric longitudinal axis (1) of the cylindrical casting chamber cavity (12), and d he inlet openings (35, 36, 37, 38) are arranged with respect to the through opening (14) such that the surface normals (NE ₁ , NE ₂ , NE ₃ , NE ₄ ) of the inlet openings (35, 36, 37, 38) are not included the longitudinal axis (1) of the cylindrical casting chamber cavity (12) coincide,
characterized in that
each sprue (20, 21, 22, 23) has a circular or elliptical cross-section with a substantially constant cross-sectional area over its entire length and immediately after the sprue cavity (19) contains a bend (25, 26, 27, 28), the that part of the sprue (20, 21, 22, 23) between the elbow (25, 26, 27, 28) and the inlet opening (35, 36, 37, 38) describes a straight, tubular piece of channel and the elbow (25, 26, 27 , 28) is designed in such a way that its center line (m ₁ , m ₂ ) has a constant bending radius (Rk ₁ , Rk ₂ ) and a tangent to the same bending radius (Rk ₁ , Rk ₂ ) as far as the passage opening (14) Center line (m ₁ , m ₂ ) at the through opening (14) runs parallel to the longitudinal axis (1) of the cylindrical casting chamber cavity (12) and a tangent to the center line (m ₁ , m ₂ ) against the inlet opening (35, 36, 37 , 38) directed manifold end (73, 74) with the Center line (m ₁ , m ₂ ) of the straight, tubular duct section coincides. Die casting machine according to claim 1, characterized in that the sprue (20, 21, 22, 23) has a gate area (30, 31, 32, 33) at its end directed against the mold cavity, which is in the corresponding inlet opening (35, 36, 37, 38) ends, and the sprue (20, 21, 22, 23) between the sprue cavity (19) and the gate area (30, 31, 32, 33) through a tubular duct piece with a circular cross section and constant diameter (2 R ₁ , 2 R ₂ ) is described. Die casting machine according to claim 1 or 2, characterized in that the inlet opening (35, 36, 37, 38) of a sprue (20, 21, 22, 23) perpendicular to the center line (m ₁ , m ₂ ) of the straight, tubular duct section of the corresponding Sprue (20, 21, 22, 23) is arranged. Die casting machine according to one of claims 1 to 3, characterized in that the center lines (m ₁ , m ₂ ) of the straight, tubular duct pieces of the sprue ducts (20, 21, 22, 23) form a right angle with the longitudinal axis of the casting chamber cavity (12) . Die casting machine according to claim 4, characterized in that the bending radius (Rk ₁ , Rk ₂ ) of the center line (m ₁ , m ₂ ) in the elbow (25, 26, 27, 28) of a sprue (20, 21, 22, 23) Distance (d) of the passage opening (14) from a straight line, containing the center line (m ₁ , m ₂ ) of the straight, tubular duct section of the corresponding sprue (20, 21, 22, 23). Die casting machine according to one of claims 1 to 5, characterized in that the longitudinal axis (1) of the casting chamber cavity (12) is horizontal Die casting machine according to one of claims 1 to 6, characterized in that a transition region between the casting chamber cavity (12) and the through opening (14) (16) with a starting from the casting chamber cavity (12) steadily tapering cross section is arranged Die casting machine according to one of claims 1 to 7, characterized in that the sum of the cross-sectional areas of the individual sprue channels (20, 21, 22, 23) in essentially corresponds to the cross-sectional area of the through opening (14) Die casting machine according to claim 8, characterized in that the sum of the the cross-sectional areas of the individual pouring channels adjacent to the pouring cavity (19) (20, 21, 22, 23) by no more than ± 10% of the cross-sectional area of the Through opening (14) deviates Die casting machine according to one of claims 1 to 9, characterized in that the longitudinal axis of the cylindrical casting cavity (19) parallel to the longitudinal axis (1) of the casting chamber cavity (12) and the cross-sectional area of the casting cavity (19) corresponds essentially to the cross-sectional area of the through opening (12) Die casting machine according to one of claims 1 to 10, characterized in that the length of the casting cavity (19) is chosen such that between the crooked (25, 26) a collection pocket (18) for receiving the end oxides of the thixotropic Metal bolt is formed. Die casting machine according to one of claims 1 to 11, characterized in that the inlet openings (35, 36, 37, 38) have an elliptical cross section. Die casting machine according to one of claims 2 to 12, characterized in that the gate area (30, 31, 32, 33) describes a channel piece, which on the straight, tubular duct section of a sprue (20, 21, 22, 23) adjoining Side has a circular cross section and the cross section of the gate area (30, 31, 32, 33) starting from this circular cross section continuously and steadily into the cross-sectional shape of the inlet opening (35, 36, 37, 38) of the corresponding one Sprue (20, 21, 22, 23) merges. Die casting machine according to claim 13, characterized in that the cross-sectional area of the gate area (30, 31, 32, 33) of a sprue (20, 21, 22, 23) remains substantially constant along its center line (m ₁ , m ₂ ) and nowhere else as varied by ± 30% of the cross-section of the straight, tubular duct piece of the corresponding sprue duct (20, 21, 22, 23) lying against this gate region (30, 31, 32, 33).

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