WO2007036968A1

WO2007036968A1 - Device for collecting molten metal from a crucible and feeding it to a pressure die-casting machine

Info

Publication number: WO2007036968A1
Application number: PCT/IT2006/000248
Authority: WO
Inventors: Gianfranco Maraccani; Federico Albertini
Original assignee: Gauss Automazione S.P.A.
Priority date: 2005-09-28
Filing date: 2006-04-13
Publication date: 2007-04-05
Also published as: EP1928619A1; US20080230574A1; ITBS20050112A1

Abstract

The subject of the invention is a device for collecting, transferring and pouring molten metal into a pouring channel of a die-casting machine or the like starting from a crucible under controlled atmosphere, covered by a hood. The device comprises a support standard (17) positioned externally on one side of the crucible, a slide (18), which can move vertically along said standard and a control group (22) supported by the slide and made to turn a crankshaft (24), which extends part ways into the crucible through a wall in said hood and which holds a ladle (25)at one of its free ends a ladle (25) which is subjected to transitory-rotary movements to dip into and collect molten metal from the crucible and carry and pour the collected metal into the pouring channel of the die-casting machine in reaction to the vertical movements of said slide and rotation of the crankshaft.

Description

"DEVICE FOR COLLECTING MOLTEN METAL FROM A CRUCIBLE AND FEEDING IT TO A PRESSURE DIE-CASTING MACHINE"

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Field of the Invention This invention concerns the equipment for the metallurgical systems field and refers in particular to a mechanical system for collecting molten metal under controlled atmospheric conditions, such as aluminium alloy or the like, from a furnace, crucible or other tank (hereinafter for simplicity and brevity called a crucible) and transferring and pouring it into a means for feeding a die- casting, pressure die-casting or other casting system. State of the Art

In the metallurgical field in question, there already exit various types of devices designed to automate the collecting operations of a molten metal from a crucible and transfer and pouring of the metal in preset doses in collecting tanks, such as the containers of a pressure die-casting or die-casting machines.

These devices comprise means of control for holding a casting ladle or hand ladle and which can be moved so as to dip the ladle into the metal bath, turn it so that the ladle collects a certain amount of molten metal and then move it as far as the container to be fed and then turned to pour in the molten metal. Furthermore however, these known devices have been made to operate in a crucible in an environment atmosphere, a condition that favours however the formation of oxides on the molten metal damaging the end result of the items to be made. The growth in the request for high quality finished products therefore requires the use of operating systems that can function in a closed atmosphere, where the atmosphere in the environment of the sprue basins containing molten metal is kept under control by feeding in inert gas such as nitrogen or carbon dioxide so as to reduce if not avoid the formation of oxides on the metal in the liquid state.

The devices for collecting, transferring and pouring of the molten metal known up to the present, because of their structure, do not however meet this condition, due also to the fact that they operate above the open or semi-open topped crucible and are sometimes subjected to mechanical transmissions inside the crucible. Object and Summary of the Invention The object of this invention is however to propose and realise a device for handling a ladle which is simple and economic to make compared with the well known technical devices and that, except for the ladle, remains completely outside the crucible containing the molten metal to be collected, transferred and poured, without therefore compromising the closed environment under controlled atmosphere which is formed above the crucible.

Such an object is achieved with a device for collecting, transferring and pouring molten metal starting from a crucible under controlled atmosphere, comprising fundamentally a support standard placed on one side of a crucible surmounted by a hood, a movable chute positioned vertically along the support standard and, on board said chute, a control group with a crankshaft which extends partially into the crucible through a wall in said hood and which holds a ladle at its free end which is subjected to translator-rotary movements to dip into and collect molten metal from the crucible and carry and pour the collected metal into a pouring channel of a pressure die-casting machine or the like in reaction to the vertical movements of said chute and rotation of the crankshaft. The advantages which can be attained with this invention can be identified at least in:

- a handling system of the ladle which remains substantially external to the crucible without contacts with or exposure to the hotter parts and completely uninfluential on the controlled atmosphere in the crucible; a drop in the pollution of the environment a saving in energy and economy due to the lack of heat dispersion from the crucible; - maximum reliability of the system together with straightforwardness of construction and installation;

- lack of mechanical transmissions or other controls inside the crucible which can be negatively influenced by the molten metal and its very high temperature; - a secure and easy access to the system for maintenance operations in that it can be easily moved horizontally away from the crucible;

- a safety factor for the operators who can always remain and operate at a distance from the molten metal.

Also worthy of note is: - the precision in the dosage of molten metal using the ladle;

- the reduced wear of the ladle because it always remains at a certain temperature, without any thermal stress and is not exposed to knocks or contact with solid parts when moved; - the better quality of the molten metal alloy in that it is not subject to surface oxidation in the crucible;

- the lower need for cleaning the crucible and maintenance of its refractory lining due to reduced thermal excursion and also due to lack of internal oxidation; - the possibility both of heating the pouring channel and also to keep it in a closed but accessible environment, to avoid thermal dispersion and the risk of oxides forming even at this level.

And, not the least important advantage, the invention system allows the use of ladles with a low load level, reducing in this way the risks for the operator in the phases of each addition of new molten metal. Brief Description of the Drawings

The invention will however be described more in detail with reference to the enclosed indicative and not limiting drawings, in which:

Fig. 1 shows a view from above of the device of the invention associated with a pressure die-casting machine;

Fig. 2 shows a view from the front of the group in Fig. 1 , with the ladle represented by dotted lines in various positions during its movements;

Figs. 3 and 4 show views in perspective from two different angles only of the invention device; Fig. 5 shows the device seen from the rear;

Fig. 6 shows the device seen from one side; and

Fig. 7 shows the device seen from the opposite side and in association with a crucible containing molten metal; Figs. 8 and 9 show, respectively, the device applied to a crucible positioned in two different heights. Detailed Description of the Invention

In said drawings, in particular in Figs.1 and 2, a machine for die-casting or pressure die-casting 10 is schematically shown, which is provided with a pouring channel 11 made to receive molten metal collected from a crucible 12 by means of the device of the invention generically identified by 13.

The crucible 12 is associated and is in communication with a foyer 14 into which, through a loading inlet 15, the molten metal coming from a smelter is loaded. The molten metal moves on, as is known, from the foyer to the crucible by way of the communicating ducts principle, through an intermediate opening. The foyer and crucible are surmounted and closed by a hood 16 inside which is formed and maintained a controlled atmosphere by the introduction of an inert gas, to prevent the molten metal oxidising. The pouring channel 11 extends from above the crucible to the die-casting machine 10 passing through a wall of the overhanging hood 16.

As shown, the device 13 of the invention is placed on one side of the crucible, externally to it, with the function of collecting molten metal from the crucible 12 and pouring it into the pouring channel 11.

The device 13 comprises a support standard 17 along which is a vertically guided and movable slide 18.

The support standard 17 can be fixed on a static supporting plane, but as a preference, on a platform base 19 which can move at least horizontally on a supporting plane so as to approach and distance the device towards and from the crucible according to necessity. Furthermore, the smelter/crucible can be positioned at different heights, at the same level or lower, in respect to the pouring channel 11 as shown in Figs. 8 and 9, respectively. The device 13 may therefore have some vertical support standards 17 of different guide heights of the slide 18, depending on needs. The slide 18 can be moved along the support standard 17 by means of a toothed wheel-indexing rack 20 type transmission driven by an electric or hydraulic geared motor 21 mounted on board said slide. As an alternative for its vertical movements, the slide 18 can be connected to at least one hydraulic or pneumatic linear actuator, not shown. In order to follow the vertical movements, on the slide 18 there is mounted an electric or hydraulic geared motor 22 with an output shaft 23 to which is fixed a crankshaft 24 holding at one of its free ends a ladle 25 made of a refractory material, ceramic, in metal or some other type.

More precisely, the crankshaft 24 has a first arm 26 connected to the output shaft 23 and which extends externally and in parallel to an adjacent side wall 16' of the hood 16 above the crucible, a horizontal section 27 that extends from said first arm 26 inside the hood 16, through an opening 16" provided in its adjacent side wall 16', a second arm 28 that extends from said horizontal section 27 in the same direction and parallel to the first arm 26, and a final arm 29 that is, on one part fixed at right angles to the free end of said second arm, and from the opposite part is fixed rigidly to the ladle 25.

In practice, device 13 remains external to the crucible from the moment that, inside the hood 16 above the crucible 13 there is only one part of the horizontal section 27 of the crankshaft 24 and the second arm 28 with the final arm 29 holding the ladle 25.

On a level with the opening 16" in the wall 16' of the hood 16 - Fig. 2-, is fixed a protection 30, to shield and prevent heat dispersion which has a slot in it surrounded by insulating material 23' through which the output shaft 23 of the geared motor 22 passes and forms a chamber which the first arm of the crankshaft 24 moves in.

The vertical descent and raising movements of the slide along the standard external to the crucible and rotation of the crankshaft with the ladle inside the crucible surmounted by the hood can be controlled cyclically and in sequence at a distance using programmable electronic controls. In this way, with a combination of these transitory-rotary movements it is possible to move the ladle from the top downwards to dip it into the molten metal in the crucible and tilt it downwards in one direction to collect a dose of molten metal depending on the capacity of the ladle, place the ladle in a horizontal position and raise it to the level of the pouring channel and, finally tilt the ladle in the opposite direction upwards, to pour the molten metal in the pouring channel as shown Fig. 1.

Claims

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CLAIMS 1. Device for collecting, transferring and pouring molten metal in a pouring channel or container of a pressure die-casting machine or the like, starting from a crucible under controlled atmosphere, characterised in that it comprises a support standard (17) placed on one side of a crucible covered by a hood, a slide (18) movable vertically along said support standard and, on board said slide, a control group (22) following the vertical movements of the slide and made to turn a crankshaft (24), which extends part ways into the crucible through a wall in said hood and which holds a ladle (25) at one of its free ends which is subjected to transitory-rotary movements to dip into and collect molten metal from the crucible and carry and pour the collected metal into the pouring channel of the die-casting machine in reaction to the vertical movements of said slide and rotation of the crankshaft.

2. Device according to claim 1 , in which said crankshaft (24) has a first arm (26) fixed to an output shaft (23) of a geared motor (22) and which extends to the exterior and parallel to an adjacent side wall (16') of the hood (16) above the crucible, a horizontal section (27) which extends from said first arm (26) inside the hood (16) through an opening (16") provided in its adjacent side wall (16'), a second arm (28) which extends from said horizontal section (27) in the same direction and parallel to the first arm (26), and a final arm (29) from a fixed part at right angles to a free end of said second arm (28) and from the opposite part is fixed rigidly to the ladle (25).

3. Device according to claims 1 and 2, in which only one part of the horizontal section and the second arm with the final arm of the crankshaft holding the ladle are inside the hood above the crucible.

4. Device according to the previous claims, in which the opening (16") in the part of the hood (16) crossed by the horizontal section of the crankshaft is covered by a heat insulation protection and forming a crossways slot for the passage of the outlet shaft of the geared motor and an interior chamber in which the first arm (26) of the crankshaft moves and is protected during rotation.

5. Device according to any of the previous claims, in which said support standard id fixed on a supporting plane.

6. Device according to claim 5, in which said supporting plane is at least horizontally movable towards and away from the crucible.

7. Device according to any of the previous claims, in which slide (18) can move vertically along the standard (17) by means of a mechanical transmission driven by either an electric or hydraulic geared motor.

8. Device according to any of the claims from 1 to 6, in which slide (18) can move vertically along the standard (17) by means of either a hydraulic or pneumatic actuator.

9. Device according to any of the previous claims which rises from a platform which can be adjusted in height also supporting the smelter or crucible it is associated with.