EP2855051B1 - Delivery device for a metal melt in an injection press - Google Patents

Description

The invention relates to a conveying device for a molten metal in an injection pressure unit, for example, a metal casting machine, with a reservoir for the molten metal and a conveying channel in which the molten metal is fed to a mold cavity, wherein the conveying channel comprises a cylinder bore in which a piston is arranged axially adjustable, and wherein a collecting chamber for the molten metal is provided, from which the molten metal can be introduced into the mold cavity as a result of an axial displacement of the piston by a further line.

In a metal casting machine, a liquid metal, which is usually a metal alloy, is introduced into a mold cavity and cures therein, so that a metal component corresponding to the mold cavity is formed. The introduction of the molten metal can for example be done solely by gravity.

However, it has been shown that this introduction of the molten metal into the mold cavity is relatively slow, in particular in the case of components in which a metal section is formed on a basic body, which is usually made of plastic. The operating speed, i. the number of maximum work cycles per unit time is therefore very limited in the metal casting machine.

From the EP 1 046 445 B1 and WO02 / 085560 A1 a generic conveying device for a molten metal with a piston is known, which is axially adjustable in a cylinder bore. The molten metal can be introduced by means of a rotationally driven screw conveyor, which is arranged perpendicular to the piston, through a lateral inlet bore in a collecting chamber formed in the cylinder bore in front of the piston and then by an axial displacement of the piston in a further conveying line and from this into a mold cavity pressed. This structure is structurally complex and requires a large amount of space.

The invention has for its object to provide a conveying device for a molten metal in a injection pressure unit, for example, a metal casting machine, which has a simple, compact structure and with which the molten metal with high cycle numbers in a mold cavity can be introduced.

This object is achieved by a conveyor device with the features of claim 1. It is also provided that the delivery channel comprises a cylinder bore in which a piston is arranged axially adjustable, and that a collecting chamber is formed for the molten metal, from which the molten metal in Consequence of the axial displacement of the piston can be introduced by a further line in the mold cavity. The collection chamber is preferably formed in the cylinder bore.

According to the invention, it is based on the basic principle to provide a predetermined amount of molten metal in the collection chamber and push out of this by a displacement of the piston and to transport over the continuing line in the mold cavity. The piston then returns to its original position, during the return movement of the piston already new molten metal can flow into the collection chamber. Preferably, the movement of the piston is designed so that the collection chamber is already completely filled with inflowing molten metal, when the piston has reached its upper starting position, so that it can immediately perform its shift, with the molten metal from the collection chamber through the continuing line is pressed into the mold cavity.

The molten metal can be introduced from the reservoir via at least one filling bore into the collecting chamber. While the piston moves back to its initial position, the molten metal flows through the preferably formed in the piston and particularly preferably the piston penetrating filling bore in the piston simultaneously released from the collection chamber. It has been shown that in this way a refilling of the collection chamber can be achieved very quickly and reliably. Preferably, a plurality of filling bores are provided which are connected in parallel and thus ensure rapid filling of the collecting chamber.

The filling or filling holes are constantly during the return movement of the piston to its initial position with on the one hand the reservoir for the molten metal and on the other hand with the collection chamber in connection. This is inventively achieved in that between the outer wall of the piston and the inner wall of the cylinder bore in a predetermined portion of the piston, an annular space is formed and that the annular space via the filling bore or filling holes communicates with the collection chamber. In addition, the annulus from the reservoir is fed with molten metal.

In order to be able to control the inflow of molten metal into the collecting chamber, it is provided according to the invention that the filling bore can be closed at its end opening into the collecting chamber by means of a valve body. If a plurality of parallel filling holes are provided, a common valve body may be provided for this. The valve body can be adjusted between a closed position, in which it prevents the flow of molten metal from the filling bore into the collecting chamber, and an open position, in which it can flow the molten metal from the filling bore or the filling bores into the collecting chamber. For adjusting the valve body, this is connected to an adjustable valve rod, which is preferably provided with a drive, which is controlled by a control device.

In this case, the valve rod is slidably disposed in an axial bore or a longitudinal center bore of the piston, whereby a very compact construction is provided. The valve body and the valve stem can thus both together be moved with the piston within the cylinder bore and adjusted relative to the piston.

The seal between the piston and the cylinder bore is achieved in that the piston sits at least partially in tight fit in the piston.

Preferably, the cross section of the valve body is smaller than the cross section of the cylinder bore, so that the molten metal can freely flow around the valve body within the cylinder bore.

In order to avoid a backflow of molten metal from the secondary line into the collecting chamber, it is provided in a further development of the invention that a check valve is arranged in the secondary line, which may be, for example, a spring-loaded valve body.

Fig. 1

einen Längsschnitt durch eine erfindungsgemäße Fördervorrichtung;

Fig. 2

eine vergrößerte Darstellung des unteren Endes des Kolbens mit dem Ventilkörper in der Schließstellung und

Fig. 3

den Kolben in seiner unteren Position mit dem Ventilkörper in der Offenstellung.

Further details and features of the invention will become apparent from the following description of an embodiment with reference to the drawings. Show it:

Fig. 1

a longitudinal section through a conveyor device according to the invention;

Fig. 2

an enlarged view of the lower end of the piston with the valve body in the closed position and

Fig. 3

the piston in its lower position with the valve body in the open position.

An in FIG. 1 illustrated conveyor 10 has a housing 11 in which a vertical cylinder bore 12 is formed.

To the housing 11, a reservoir 27 is set for a molten metal M, which comprises a container housing 28 in which a container interior 29 is formed, which is filled with the molten metal M. The molten metal M can be supplied to the container interior 29 in liquid form or be produced in it by melting, for example, a metal granulate.

The container interior 29 of the reservoir 27 is connected via at least one obliquely downwardly in the flow direction inclined inlet channel 18 with the cylinder bore 12 in connection. At the inlet of the inlet channel 18, a slag separator 30 effective as a filter is provided in the container interior 29.

In the cylinder bore 12, a piston 13 is slidably inserted under close fit. In an area arranged in the lower half of the axial length of the piston 13, but having an axial distance from the lower end of the piston 13, an annular space 17 is formed on the outer surface of the piston 13. At the lower end of the annular space 17, a plurality of filling bores 16 distributed over the circumference of the piston 13 extend in each case to the lower end face of the piston 13 (see FIG FIG. 2 ). The region of the piston 13 into which the filling bores 16 are formed lies in a sealed manner against the inner wall of the cylinder bore 12.

The piston 13 further comprises a central axial bore 14 in which a valve rod 19 is slidably disposed, which completely penetrates the piston 13 and carries at its lower end downstream of the end face of the piston 13 a plate-like valve body 20. The valve body 20 can by displacing the valve rod 19 relative to the piston 13 between an in FIG. 2 illustrated closed position in which the valve body 20 prevents leakage of molten metal from the filling holes 16, and a in FIG. 3 illustrated open position can be adjusted, in which the molten metal from the filling holes 16 in an underlying, formed in the cylinder bore 12 collecting chamber 15 can flow.

As the Figures 2 and 3 show, the cross section of the valve body 20 is smaller than the cross section of the cylinder bore 12, so that the valve body 20 within the cylinder bore 12 has no sealing function and the molten metal M, the valve body 20 can flow freely.

The cylinder bore 12 and the collection chamber 15 formed in it is connected at the lower end via a further line 21 with a mold cavity F, not shown. The continuing line 21 comprises a lower transverse bore 31, via which the collecting chamber 15 is connected to a vertical riser 22. The riser 22 passes at its upper end in a substantially horizontally extending filling channel 23, from which the molten metal is supplied to the mold cavity, as indicated by the arrow F. In the transition between the riser 22 and the filling channel 23, a check valve 24 is arranged, which has a valve body 25 which of a Spring 26 is tensioned against a direction of flow against a valve seat 32.

In the following, the individual phases of the introduction of the molten metal M in the mold cavity F will be explained.

According to FIG. 1 the piston 13 has reached its upper position, wherein the valve body 20 is in its closed position ( FIG. 2 ) and a leakage of molten metal from the filling holes 16 in the collection chamber 15 is prevented. The collecting chamber 15 is filled with molten metal M. The piston 13 is then moved together with the valve rod 19 down, the valve body 20 remains in its closed position. Since the lower portion of the piston 13 is seated in the cylinder bore 12 in a sealed manner, the metal melt located in the collection chamber 15 is pushed out of the collection chamber 15 and conveyed via the transverse bore 31 and the riser 22 to the check valve 24, which in response to the pressure Force of the spring 26 is open. The molten metal M can thus enter the filling channel 23 and is supplied to the mold cavity (arrow F). When the piston 13 has reached its lower position, the filling operation is completed and the movement of the piston 13 is reversed, that is, the piston 13 is moved upward. In this case, the valve body 20 is first brought into its open position by the valve rod 19 is displaced within the axial bore and the valve body 20 is lifted from the end face of the piston 13 (see FIG. 3 ).

As the Figures 2 and 3 show the annular space 17 in each axial position of the piston 13, ie in the upper Position of the piston 13 according to FIG. 2 and the lower position of the piston 13 according to FIG. 3 as well as in any intermediate position via the inlet channel 18 with the container interior 29 of the reservoir 27 in connection, so that the molten metal M is constantly present at the frontal outlet of the filling holes 16.

Before or with the adjustment of the piston 13 from its lower position, the valve rod 19 is moved with the valve body 20 relative to the piston 13, whereby the valve body 20 comes into its open position. Thus, during the retraction of the piston 13 to its upper position, the molten metal M flows from the reservoir 27 through the inlet channel 18, the annular space 17 and the filling holes 16 into the collecting chamber 15. Due to the method of the piston 13 may be set in the collection chamber 15 optionally a slight negative pressure. A suction or return of the still located in the riser 22 or the filling channel 23 molten metal M is prevented by the check valve 24 closes.

When the piston 13 has reached its upper position and the collecting chamber 15 is filled with the molten metal M, the valve body 20 is moved to its closed position in which it interrupts the connection between the filling holes 16 and the collecting chamber 15. At this moment is again in FIG. 1 reaches the initial position shown, whereupon the piston 13 is moved back down and presses the molten metal M from the collection chamber 15 in the mold cavity (arrow F).

Claims (7)

1. Conveying device for molten metal (M) in an injection die casting unit, having a storage container (27) for the molten metal (M) and a conveying duct in which the molten metal (M) is deliverable to a mold cavity (F), wherein the conveying duct comprises a cylinder bore (12) in which a piston (13) is disposed in an axially adjustable manner, and wherein a collection chamber (15) for the molten metal (M), from which the molten metal (M) is introducible through an onward line (21) into the mold cavity (F) as a result of an axial displacement of the piston (13), is provided, characterized in that an annular space (17) is formed between the outer wall of the piston (13) and the inner wall of the cylinder bore (12), in that the annular space (17) is connected via the at least one filling bore (16) to the collection chamber (15), in that the filling bore (16), on its end which opens into the collection chamber (15), is closable by means of a valve body (20) which is connected to an adjustable valve rod (19), and in that the valve rod (19) is displaceably disposed in an axial bore (14) of the piston (13).
2. Conveying device according to Claim 1, characterized in that the collection chamber (15) is configured in the cylinder bore (12).
3. Conveying device according to Claim 1 or 2, characterized in that the at least one filling bore (16) penetrates the piston (13).
4. Conveying device according to one of Claims 1 to 3, characterized in that the annular space (17) is connected via a plurality of filling bores (16) to the collection chamber (15).
5. Conveying device according to Claim 4, characterized in that a common valve body (20) is provided for all filling bores (16).
6. Conveying device according to one of Claims 1 to 5, characterized in that the cross section of the valve body (20) is smaller than the cross section of the cylinder bore (12).
7. Conveying device according to one of Claims 1 to 6, characterized in that a check valve (24) is disposed in the onward line (21).

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