The apparatus comprises at least one flowing furnace with which at least one handling unit cooperates, the handling unit being selectively connectable to a respective die. The at least one handling unit is associated with a guide for horizontal translatory motion between a casting position, which lies above the at least one furnace, and a discharge position. The at least one furnace can move vertically in order to couple and uncouple with respect to the corresponding die connected to the at least one handling unit.

The disclosures in Italian Patent Application No. PD97A000264 from which
 this application claims priority are incorporated herein by reference.
 BACKGROUND OF THE INVENTION
 The present invention relates to a low-pressure die-casting apparatus.
 Conventional low-pressure die-casting apparatuses are usually constituted
 by a flowing furnace into which a tube is immersed in order to dispense,
 by feeding pressure into the furnace, the liquid metal into a die which is
 connected in an upward region to the metal draw tube.
 In order to form hollow bodies, such as for example faucets and the like, a
 molding-sand core is arranged inside the die; the core must be destroyed,
 for example by simple shaking, once casting is completed.
 At the furnace there is usually a handling unit which allows to perform the
 various handlings of the die and to load the cores, unload the cast part
 and perform all the operations for the graphitization and cooling of the
 dies.
 The die is loaded so that the molten metal must enter it from below,
 because if the molten metal were to enter from above it would prevent the
 escape of the air and bubbles would therefore form which would reduce the
 quality of the finished product.
 As mentioned above, the furnace has a tube which enters its crucible to
 draw in the vicinity of the bottom and in any case with a head which is
 sufficient to perform a certain number of die filling operations before
 having to open the furnace and introduce further material to be melted.
 In conventional methods, the die is carried by a handling unit exactly
 above the furnace, as occurs for example in the Italian patent application
 no. MI96A001138 in the name of the same applicant, is made to descend
 vertically above it until its lower part, in which there is a hole through
 which the molten material must enter, makes contact with the tube that
 draws from the furnace.
 Casting occurs by pressurizing the furnace by means of compressed air or
 another inert gas, so that the liquid metal rises along the tube, filling
 the entire die.
 This method, however, required a very complicated handling unit.
 Said handling unit, when it moves from the position above the furnace
 toward the discharge region, must in fact open in order to allow the exit
 of the finished product but must also rotate the die halves that
 constitute the die in order to place them in front of the operator.
 In addition to this, the handling unit must be able to overturn the two die
 halves to allow graphitization and washing and cleaning of all the slag.
 Accordingly, the handling unit must have the ability to perform a
 translatory motion and also to move downwards.
 In the system described by the above-mentioned patent application no.
 MI96A001138 there are two furnaces and the handling unit must operate by
 moving to one region and then to the other and is accordingly very
 complicated.
 SUMMARY OF THE INVENTION
 The aim of the present invention is to provide an improved low-pressure
 die-casting apparatus the constructive structure whereof is simplified
 with respect to conventional apparatuses.
 A consequent primary object of the present invention is to provide a
 die-casting apparatus which has a better coupling centering between the
 furnace and the die.
 Another important object of the present invention is to provide an improved
 casting apparatus which allows to work even with very large dies without
 any particular difficulty.
 Another object of the invention is to provide an improved die-casting
 apparatus which ensures practical, durable and effective operation.
 This aim, these objects and others which will become apparent hereinafter
 are achieved by an improved low-pressure die-casting apparatus comprising
 at least one flowing furnace with which at least one handling unit
 cooperates, said at least one handling unit being selectively connectable
 to a respective die, characterized in that said at least one handling unit
 is associated with a guide for horizontal translatory motion between a
 casting position, which lies above said at least one furnace, and a
 discharge position, said at least one furnace being movable vertically in
 order to couple and uncouple with respect to said die connected to said at
 least one handling unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 With reference to the above figures, an improved low-pressure die-casting
 apparatus comprises a flowing furnace 10 of the electric type, or of an
 equivalent type, controlled by a computerized central unit schematically
 designated by the reference numeral 11.
 The apparatus comprises, in this case, a handling unit 12 which can move
 horizontally along guides 13 and is adapted to move a die 14 into the
 casting position.
 The handling unit 12 can be arranged above the furnace 10 for casting into
 d then move horizontally and be arranged at a station for
 loading/unloading said die 14.
 The furnace 10 is supported by a frame 15 provided with means, generally
 designated by the reference numeral 16, for lifting/lowering with respect
 to the ground.
 The means 16 comprise threaded legs 17a, 17b, 17c, 17d which are provided
 with a foot 18; each leg is coupled to a female thread 19 accommodated
 inside a box 20.
 Each one of the female threads 19 is externally provided with teeth and is
 coupled, in this case, to a worm screw 21 which is also accommodated
 inside the box 20.
 The lifting/lowering means 16 comprise a motor drive 22 with an output
 shaft 23 on which a driving pulley 24 is keyed and which engages the worm
 screw 21 of a first leg 17a.
 In particular, said driving pulley 24 (see FIGS. 3-4) is coupled, by means
 of a toothed belt 25 (see FIG. 2) (or another equivalent flexible
 element), to a driven pulley 26 which is arranged at a second leg 17b and
 is in turn keyed to a second shaft 27 which engages the worm screw 21 of
 the second leg 17b.
 The output shaft 23 and the second shaft 27 are each connected, by means of
 a first coupling 28, to a third shaft 29. The third shafts 29 are
 connected, by means of a second coupling 28, to a driven shaft 30 on which
 said worm screw 21 of said third and fourth legs 17c and 17d engages.
 In this case, each one of the third shafts 29 is constituted by a first
 shaft portion and by a second shaft portion 31 which are mutually fixed by
 means of a flanged coupling 32.
 The engagement of each one of the shafts 23, 27 and 30 with the worm screws
 21 of each one of the legs 17a, 17b, 17c and 17d is performed by means of
 holes 33 formed on each one of said boxes 20 and by means of keys 34 which
 ensure the transmission of the torque from the shaft 23, 27 or 30 to the
 worm screw 21, which by meshing with the female thread 19 transmits the
 rotary motion imparted thereto, causing a consequent lifting or lowering
 with respect to the corresponding legs 17a, 17b, 17c or 17d.
 The means 16 in fact ensure the simultaneous lifting or lowering of all the
 female threads 19 to avoid even the slightest imbalance of the furnace 10,
 which contains molten metal to be cast into the dies 14.
 In this manner, in fact, the handling unit 12 acts only as a device for the
 horizontal translatory motion of the dies 14, and once it has reached the
 end of its stroke it is assuredly centered above the furnace 10, so that
 it is sufficient for the central unit 11 to activate the lifting of the
 furnace 10 to produce, by pressurizing the furnace 10, the casting of the
 molten metal into the die 14.
 In addition to this, the frame 15 that supports the furnace 10 is mounted
 on load cells 35 of a per se known type which are also connected to the
 computerized central unit 11.
 The load cells 35 are capable of detecting the load condition of the
 furnace 10, indicating any need to introduce new material to be melted and
 the amount introduced.
 In particular, however, the load cells 35 detect the moment when the
 furnace 10, lifted by the female threads 19 actuated by the motor drive
 22, makes contact with the handling unit 12 that lies above it and is thus
 ready to perform casting.
 Each load cell 35 in fact detects the activation of the motor drive 22,
 which synchronously transmits motion to the female threads 19, lifting the
 furnace 10 while each cell 35 detects the weight of the furnace 10 and the
 weight of the molten metal contained therein.
 Apart from entirely negligible small oscillations, this weight remains
 constant until said furnace 10 makes contact with the handling unit 12.
 At this point the furnace 10 eventually pushes against the die 14 and
 accordingly each load cell 35 detects a load increase peak due to this
 slight thrust.
 In addition, the load cells 35 allow to automatically vary the pressure in
 order to always reach the set threshold in the pressurization process for
 casting the metal into the die, regardless of the variation of the level
 of the metal in the furnace 10.
 The improved apparatus of the invention also allows to work with very large
 dies, since all the translatory motion problems are considerably
 simplified and the handling unit merely provides the simple horizontal
 translatory motion.
 Another advantage is achieved with the present invention in that a
 die-casting apparatus has been provided which has a very simple structure
 and at the same time ensures truly effective operation.
 In practice it has been observed that the present invention fully achieves
 the intended aim and all the objects.
 The invention thus conceived is susceptible of numerous modifications and
 variations, all of which are within the scope of the same inventive
 concept.
 All the details may furthermore be replaced with other technically
 equivalent elements.
 The materials used, so long as they are compatible with the contingent use,
 as well as the dimensions, may be any according to the requirements.