EP2425913A1

EP2425913A1 - Improved device for filing molten metal into pressing chambers in die-casting machines

Info

Publication number: EP2425913A1
Application number: EP11006894A
Authority: EP
Inventors: Claudio Marconi; Claudio Busi
Original assignee: Marconi Srl Forni e Macchine Industriali; Maicopresse SpA
Current assignee: Marconi Srl Forni e Macchine Industriali; Maicopresse SpA
Priority date: 2010-09-06
Filing date: 2011-08-24
Publication date: 2012-03-07
Also published as: ITMI20101606A1

Abstract

An improved device (10) for filling molten metal into pressing chambers in die-casting machines, especially of the type that uses non-ferrous alloys such as aluminium and alloys thereof, stabilised relative to a die-casting machine (12) and to a mould (14) formed by two dies or half moulds (16, 18), a container cylinder (20) provided with a chamber (22) for feeding with liquid metal (24) collected from a smelting tank (23), an injecting piston (26) sliding axially within the same container cylinder, means for feeding and controlling the liquid metal inside said chamber.

Description

The present invention relates to an improved device for filling molten metal into pressing chambers in die-casting machines.
More in particular, the present invention relates to a filling device for pressing chambers in die-casting machines, especially of the type that uses non-ferrous alloys such as aluminium and alloys thereof.
As is known, die-casting is a process wherein the molten metal is introduced in a metal mould or die at high speed and solidified under pressure; such process may be of the so-called type in "hot chamber" or in "cold chamber" according to the construction type of the machine.
Die-casting machines are provided with a container cylinder/feeder wherein the molten metal is introduced, injected in a die or mould by means of a hydraulic piston or injector piston so as to obtain the desired shape for the part to be produced.
Traditionally, the filling of the container cylinder/feeder is carried out through a container or cup containing the molten metal and moved by mechanical means such as articulated robot arms or by means of a raceway with dispensing furnace, or other known systems; the container or cup, for example, contains a predetermined amount of molten metal collected from a smelting tank and transferred to the container cylinder.
However, the traditional techniques exhibit some important drawbacks related to the fact that the operation for transporting the molten metal, typically but not exclusively aluminium and alloys thereof, to the container/feeder by means of the container or cup or raceway with dispensing furnace or other known systems, causes a partial oxidation of the molten metal with consequent influences on the moulding process and on the quality of the finished product in output from the mould or die.
A further drawback is related to the fact that since the traditional filling processes use mechanical systems such as robot arms, raceways etc., they tend to be quite expensive in terms of maintenance, control and programming of the filling cycle.
A further drawback is related to the fact that the use of a container or cup, as well as the use of a raceway with dispensing furnace, require periodical check and maintenance works with possible and consequent production downtimes.
The object of the present invention is to obviate the drawbacks discussed hereinabove.
More in particular, the object of the present invention is to provide an improved device for filling molten metal in pressing chambers in die-casting machines suitable for allowing an easy filling of the container/feeder with the molten metal.
A further object of the present invention is to provide a device for filling the molten metal such as to prevent and/or eliminate the drawback related to the oxidation of the liquid metal, in particular aluminium, contained in the container or cup or in the raceway with dispensing furnace and which occurs during the path from the smelting bath to the die-casting machine.
A further object of the present invention is to provide a filling device suitable for preventing the use of a container or cup and of the devices for moving the liquid metal, raceways with dispensing furnace, etc., thus reducing the related costs.
A further object of the present invention is to provide the users with an improved device for filling molten metal into pressing chambers in die-casting machines suitable for ensuring a high level of resistance and reliability over time and moreover, such as to be easily and inexpensively constructed.
These and other objects are achieved by the in improved device for filling molten metal into pressing chambers in die-casting machines of the present invention, stabilised relative to a die-casting machine and to a mould formed by two dies or half moulds and comprising a container cylinder provided with a chamber for feeding with liquid metal collected from a smelting tank, an injecting piston sliding axially within the same container cylinder, means for feeding and controlling the liquid metal inside said chamber.
The construction and functional features of the improved device for filling molten metal in pressing chambers in die-casting machines of the present invention shall be better understood from the following description, wherein reference is made to the annexed drawing showing a preferred and non-limiting embodiment thereof, wherein:

figure 1 schematically shows a longitudinal section of the improved device for filling molten metal into pressing chambers in die-casting machines of the present invention.

With reference to said figure, the improved device for filling molten metal into pressing chambers in die-casting machines of the present invention, globally indicated with reference numeral 10 in said figure, is stabilised relative to a die-casting machine 12 (only shown schematically and partially) and to a mould 14 defined by two dies or half moulds 16 and 18, whereof one is movable so as to allow the opening of the same mould for removing the finished product.
The device of the invention comprises a container cylinder 20 provided with a chamber 22 wherein the molten metal 24 coming from a tank 23 of a smelting furnace is introduced.
An injector piston 26 engages with the container cylinder 20 and is axially sliding in chamber 22 of the same container cylinder in order to push the liquid metal 24 in the direction of mould 14 through a casting channel 28.
At the end of the container cylinder 20, facing the direction opposite that whereto the injector piston 26 engages, there is arranged a valve or cap 30 having the function of opening and closing the container cylinder 20 and consequently, the casting channel 28 as described hereinafter.
The liquid metal 24 present in chamber 22 arrives from tank 23 through a conduit 32 mechanically coupled with container 20 and enters said chamber through a hole 25 made on the side surface of the container cylinder 20.
At the end of the container cylinder 20 that seats the injector piston 26 and on the opposite side relative to that of connection with conduit 32 there is fixed a union 34 provided with a pipe 36 for the connection to a vacuum generation system.
A sensor 38 is applied on the same container cylinder 20, preferably a laser or ultrasound sensor or other known type such as a mechanical sensor, suitable for performing the function described hereinafter. The filling device of the invention, described in detail hereinabove with reference to component features thereof, is described hereinafter with reference to the operating modes thereof.
The container cylinder 20, through union 34 and pipe 36 connecting to the vacuum generation system, is set to vacuum causing the suction of the liquid metal 24 from tank 23 within chamber 22 of the same container through conduit 32 and hole 25.
Said chamber 22 of container 20 is closed at the two ends through the injector piston 26 and the valve or cap 30.
Sensor 38 controls the filling level of chamber 22 of the container cylinder 20 and when the level of liquid metal 24 has reached the desired amount for filling mould 14, the injector piston 26 starts advancing in axial direction, compressing and pushing the liquid metal and then, once the injector piston 26 has closed hole 25, the vacuum generation system is closed; when said thrust action overcomes the opposing force exerted by the valve or cap 30, it moves allowing the liquid metal 24 to flow through the casting channel 22 and to fill mould 14.
In an alternative embodiment, the valve or cap 30 is controlled and moved with mechanical means, such as for example a piston or a mechanical linkage or the like; such movement is regulated by means of a timer or other known type of sensor.
As can be noticed from the above, the advantages achieved by the device of the invention are clear.
The improved device for filling molten metal into pressing chambers in die-casting machines of the present invention advantageously allows carrying out the filling process of the die-casting mould without the need of feeding the container with liquid metal in an indirect manner through a container or cup, a raceway with dispensing furnace or other traditional systems; in this way, the drawback related to the oxidation of the liquid metal during the path from the smelting furnace to the die-casting machine is prevented.
A further advantage is the fact that the filling device of the invention does not require the use of a container or cup for feeding the molten metal, the devices for moving the container or a raceway with dispensing furnace, with consequent reduction of the related costs.
A further advantage is given by the fact that the filling device of the invention is easily applied also on die-casting devices not originally designed for such specific type of filling.
Even if the invention has been described hereinbefore with particular reference to an embodiment thereof made by way of a non-limiting example only, several changes and variations will appear clearly to a man skilled in the art in the light of the above description. The present invention therefore includes all the changes and versions that fall within the spirit and scope of the following claims.

Claims

An improved device (10) for filling molten metal into pressing chambers in die-casting machines, especially of the type that uses non-ferrous alloys such as aluminium and alloys thereof, stabilised relative to a die-casting machine (12) and to a mould (14) formed by two dies or half moulds (16, 18), a container cylinder (20) provided with a chamber (22) for feeding with liquid metal (24) collected from a smelting tank (23), an injecting piston (26) sliding axially within the same container cylinder, the device characterised in that it comprises means for feeding and controlling the liquid metal inside said chamber.
The device according to claim 1, characterised in that the means for feeding the liquid metal (24) to the chamber (22) of the container cylinder (20) are defined by a conduit (32) coupled with the container cylinder (20) and with the smelting tank (23).
The device according to the previous claims, characterised in that it comprises a system for generating a vacuum within the chamber (22) of the container cylinder (20) connected to said container by means of a union (34) and a pipe (36).
The device according to claim 1, characterised in that the means for controlling the level or amount of liquid metal within the chamber (22) of the container cylinder (20) are defined by a level sensor (38).
The device according to claim 4, characterised in that the sensor (38) is of the laser type.
The device according to claim 4, characterised in that the sensor (38) is of the ultrasound type.
The device according to claim 4, characterised in that the sensor (38) is of the mechanical type.
The device according to one or more of the previous claims, characterised in that it comprises a valve or plug (30) opposite the injecting piston (26) and such as to close the end of the container cylinder in communication with a casting channel (28) suitable for making the liquid metal flow into the mould (14), said valve or plug actuated by the pressure exerted by the thrust of the injecting piston (26).
The device according to claim 8, characterised in that the valve (30) is controlled in the movement by mechanical means of the piston type or linkages.