EP0988909A1 - Low pressure bottom casting device for casting metals, especially light metals - Google Patents

Abstract

Apparatus for the low pressure casting of metals has a casting channel (13) between the in-gate (12) and the mold hollow space (9) at an angle to the in-gate. A vent plug (17) is formed as a sand mold body and is pushed into a guide (15) of the mold (5) between an open and closed position, in which it closes the casting channel and the metallostatic pressure of the melt in the mold acts on the plug vertical to the guide. Apparatus for the low pressure casting of metals in divided sand molds (5, 6, 7) comprises an in-gate (12) in one of the two molds (7), to which the casting pipe (4) of a melt container (3) is connected, and is joined to the lowest region of the mold hollow chamber (9), and a vent plug (17) integrated into the mold that can be moved into the closed position with the aid of an external drive (19) after the mold has been filled. A casting channel (13) is provided between the in-gate (12) and the mold hollow space (9) at an angle to the in-gate. A vent plug (17) is formed as a sand mold body and is pushed into a guide (15) of the mold (5) between an open and closed position, in which it closes the casting channel and the metallostatic pressure of the melt in the mold acts on the plug vertical to the guide.

Description

The invention relates to a device for increasing Low pressure casting of metals, especially light metals, in divided sand molds with a sprue in one of the two forms to which the pouring tube of a melt container is connectable and the one with the lowest area of the mold cavity, and with an in the form of integrated stopper, which after the Filling the mold cavity using an external, in the Form engaging drive can be brought into the closed position is.

With the increasing pouring of metals, the melt becomes the melt container or a holding furnace under pressurized to melt over the pouring tube and press the gate into the mold cavity. To the filling of the mold in the pouring tube and in the pouring of the Formed melt column are interrupted to the transport the cast mold and the next one To be able to dock the mold to the pouring tube. Before that, the Melt in the pouring tube to be reset. Furthermore are to take precautions to ensure that the gate is closed during further transport of the mold, at least until the melt is in the sprue is frozen. This is done, for example, by moving it the mold on cooling plates or by using the mold carried cooling plates.

To close the mold after filling are also on Locking slide arranged in the mold and integrated into the mold known (WO 93/11892, WO 95/32826), from an opening position when pouring into a sprue blocking closing position are displaceable. For sand molds - boxless or box-bound- the problem arises that the slider made of a different material sorted out on the preparation of the molding sand Need to become. In many cases, they also adhere to the frozen one Metal in the gate and must be separated Operation can be removed.

In a known version (WO 95/32826, DE magazine "Foundry" 1998, pages 57 to 62) is after the Filling the mold using an external drive from engages the sand mold from the side, molding sand from the Area next to the sprue displaced into the sprue that the Then pour the gate like a plug. This creates considerable abrasion, both in the direction of the pouring tube, as also displaced towards the mold cavity into the melt becomes. The sand particles displaced towards the pouring tube remain in the melt when reset and become transported into the mold cavity during the next casting process, what with considerable loss of quality on the casting is linked, especially if it is made of light metal, e.g. Aluminum alloys exist.

Trying to carry molding sand into the melt to thereby prevent downstream of the sealing plug a particle filter is arranged (DE magazine "Gießerei"), or thereby (WO 95/32826), that the sprue from the pouring tube approach down first is guided and in this sloping area of the gate the drive engages the mold to the molding sand plugs into the sloping section of the sprue to displace. This version contradicts the basic one Demand for the shortest possible pouring distance. The sloping route also contradicts this Principle of rising pouring and can do it in this Area of unwanted turbulence when pouring the Shape coming. Both known versions have the Advantage that the mold does not contain any components that are not of the same type, because the plug from the same molding sand how the mold itself exists and consequently with the molding sand the shape can be worked up. However, it remains in Both cases have the disadvantage that the closure is completely uncontrolled and the quality of the closure of the dimensional stability, which is due to the drive on the Molding sand acting expressiveness and the temporal Force gradient is dependent. In particular, it is not ensures that there is actually an intact closed Grafting forms and the shape is not sideways of the expressed graft breaks out. These are risks especially with large gate cross sections for high ones Casting performance particularly large.

The invention is based on this prior art the task of creating a device while maintaining the pure composition the sand mold a perfect closure in the area the pouring is possible and also with high casting performance and large gate cross sections the quality of the Closure is reproducibly preserved and finally the danger of the introduction of molding sand particles into the melt is minimized.

This object is achieved in that between the gate and the mold cavity connecting these Pouring channel is arranged at an angle to the sprue, and that the sealing plug is formed as a sand molding and in a molded guide between the mold an open position and a closed position in which he Pouring channel closes and the metallostatic pressure of the Melt in the form perpendicular to the guide on the sealing plug works, is movable.

In the embodiment of the invention, the plug is preformed as sand moldings. Furthermore, in the Sand form on the one hand a guide for the sealing plug, on the other hand, a pouring channel is formed at an angle to the sprue, namely in the area of the mold parting plane Shape. The pouring channel is preferably at right angles or at a steep obtuse angle to the flow direction in the gate. With high castings, that is accordingly The pouring channel must also go deep into this form be shaped accordingly deep. The final one The cross section of the pouring channel can then be inserted Core.

The melt is poured into the mold redirected the pouring channel. In the area of the redirection Guide arranged with the plug, taking the plug first in the transition between Opening position for sprue and pouring channel located. After filling the mold, it becomes a sand molding trained stopper by means of in the Form engaging external drive within the guide moved to the closed position in which the transition between the gate and the pouring channel from the plug is misplaced. The metallostatic acts in the closed position Pressure of the form across the guide on the Sealing plug so that it remains in its position.

Since the sealing plug is a separate molded part, there is only minimal abrasion on the guide or Sand moldings themselves, so that the risk of procrastination of molding sand particles in the pouring tube when resetting the melt is very low. Furthermore, the Sealing plugs are basically made of the same molding sand Manufacture like the mold itself, so that when it is processed of the molding sand is also worked up. Due to the separate prefabrication, the hardness of the Optimize sand molding according to the intended use.

In a preferred embodiment, the plug is in the Self-locking opening position held in the guide. The Self-locking can be done by a correspondingly tight fit supported by plugs and guide, if necessary due to frictional forces due to surface roughness realize.

In the case of horizontal shapes and roughly vertical The sealing plug can also be poured into the sprue Guide inserted and for example a step or The like. When the mold is filled, the plug becomes under the buoyancy of the melt in the Opening position raised, in which it seals in the guide, for example against a ring step or through conical formation of the guide against the guide surface seals.

Instead of molding sand, as already indicated above, the sand moldings forming the sealing plug also Core sand must be made. In both cases, you can surface smoothing by applying a size recommend.

In a further advantageous embodiment, that the guide is designed as a sleeve made of core sand and is inserted in preformed receptacles of the form, the sleeve opening radially into the pouring channel Has recesses for the melt transfer that by means of the sealing plug inserted in the sleeve are lockable.

By training the guide as a core made of core sand can better guide properties for the plug realize. Furthermore, this rifle greater strength, so that the on the plug acting thrust no danger to the Represent the guide bush. Furthermore, the rifle can same external dimensions and corresponding recordings in terms of arrangement and size of the recesses for the transfer of the melt to the respective Conditions to be adjusted. Because the can made of core sand exists, it also provides the usual sand preparation process is not a foreign body.

The guide-whether formed directly in the molding sand or as a core of core sand - extends from the Casting mold over the mold parting plane up to the other form, so that it is ensured that the cross The pouring channel lying at the gate can be closed completely is.

In the event that the leadership is deployed by one Rifle is formed, are in two forms one another provided receptacles for the rifle. Here The core sand can has the advantage that even with an offset of the shapes in the parting plane a linear, ensures smooth guidance for the sealing plug is.

As a precautionary measure, downstream of the sealing plug a particle filter integrated in the mold his. In the case of a separate guide bush, the Particle filter at the melt inlet of the can in this be used so that sleeve with plug and Particle filter into the mold in a single operation can be used.

In the case of horizontally lying shapes, the guide for the Sealing plug coaxial with the essentially vertically running gate and the pouring channel approximately formed horizontally in the shape below. In the shape above is then one with the Guide coaxial bore for the engagement of the drive of the sealing plug arranged from above. The The drive therefore engages from the one opposite the gate Page in the form.

For vertical molds with side sprue and the pouring channel runs approximately horizontally about vertical and is the plug with his Guide parallel above the gate and across the Pouring channel arranged. In this case, the flows Melt the mold first horizontally and then deflected vertically into the pouring channel, which after filling the shape of the plug which can be moved transversely to it is relocated.

For molds with multiple discrete mold cavities, the via a central gate with a star shape perpendicular to it arranged pouring channels are filled Guide with the sealing plug coaxial with the Arranged sprue and put the pouring channels on this Guide so that after filling all the mold cavities the pouring channels with a single plug can be relocated.

The drive for the plug is advantageous a pressure cylinder, the piston rod in a molded or mechanically inserted afterwards Hole engages in the shape. The drive can be preferably control so that the piston rod of the drive before filling the mold into a stopper against the pressure of the melt in the open position supporting standby position is movable.

Fig. 1 bis 4

eine schematische Ansicht einer ersten Ausführungsform in verschiedenen Positionen beim Gießen;

Fig. 5

eine vergrößerte Teilansicht ähnlich Fig. 1 in einer abgewandelten Ausführung;

Fig. 6

eine der Fig. 5 entsprechende Ansicht einer weiteren Ausführungsform;

Fig. 7

eine Draufsicht auf eine weitere Ausführungsform;

Fig. 8

eine Ausführungsform der Vorrichtung mit senkrecht stehenden Formen.

The invention is described below with the aid of some exemplary embodiments and with the aid of the drawing. The drawing shows:

1 to 4

is a schematic view of a first embodiment in different positions during casting;

Fig. 5

an enlarged partial view similar to Figure 1 in a modified embodiment.

Fig. 6

a view corresponding to FIG 5 of another embodiment.

Fig. 7

a plan view of a further embodiment;

Fig. 8

an embodiment of the device with vertical shapes.

In the drawing, the invention is in connection with Box shapes described, but it can be equally use in boxless forms.

1 to 5 is an example of a casting table 1 shown, which may be by means of a lifting cylinder 2 is tiltable. Below and next to the casting table 1 is a Melt container 3, optionally in the form of a holding furnace arranged. In the located in the melt container 3 and melt under pressure is immersed Pouring tube 4, which opens at the casting table.

On the casting table, the sand mold 5 is arranged, which at Embodiment shown from an upper box shape 6 and a lower box shape 7, in which a further Core 8 is inserted. Between the top box shape 6 and the lower box mold 7 and the mold core 8 is the Mold cavity 9 formed. The top box shape 6 has further in the mold parting plane 10 to the mold cavity 9 subsequent risers 11 on.

The bottom box shape 7 has on one side a essential vertical gate 12 to which about at right angles a pouring channel 13 connects in the area the deepest point of the mold cavity 9 opens into this. The pouring channel molded in from the mold parting plane 10 13 is in this embodiment by a core 14 inserted from the mold parting plane upwards limited. Such a core is only with very high castings with a correspondingly deep gate necessary. At flat castings, the pouring channel 13 directly in the mold parting plane.

In the shape of a guide 15 is also molded, the in the embodiment shown from an inserted Box is formed, which in turn is made from core sand is. The leadership can also directly in Molding sand of the mold can be formed. In the embodiment shown shows the guide designed as a bush 15 a radially open window 16 through which the Interior of the guide 15 with the pouring channel 13 in connection stands.

In the guide 15 is a plug 17, which as Shaped body is formed from molding sand or core sand. The Guide 15 and the plug 17 are so on top of each other adjusted that the plug 17 self-locking is held in the open position shown in Fig. 1. If necessary, it can also be glued in place. Downstream of the sealing plug 17 is a particle filter in the guide 15 18 used. The device also has an external drive 19, which in the embodiment shown is designed as a pressure medium cylinder, whose piston rod 20 in a coaxial with the sprue 12 Engage hole 21 in the upper box mold 6 can.

Fig. 1 shows the starting position before casting, in the the melt column standing in the pouring tube 4 is reset and is otherwise depressurized. Before the start of the casting process the piston rod 20 is extended so far that it is in System comes on the plug 17 and this against holds the melt pressure in position (Fig. 2). Subsequently the casting process begins. The melt rises from the Pouring tube 4 in the sprue and the guide 15 and from there via the window 16 and the pouring channel 13 into the mold cavity 9. If the mold cavity 9 is filled, the drive 19 controlled and moves the piston rod 20 to Plug 21 down until the window 16 in the Guide 15 is covered (Fig. 3). Immidiatly after the melt can be put back in the pouring tube and after extending the piston rod 20 into position 4, the shape is uncoupled from the pouring tube 4 and for example, one located next to the casting table 1 Transport track 22 are pushed. The casting station 1 to 4 can of course also in such Transport track 22 may be integrated.

With horizontal molds 5, the plug can 17 also sit with a game in the leadership and in the Starting position, for example, on the particle filter 18 lie on. When the melt rises in the gate 12 the plug 17 is raised by the buoyancy force, until he releases the recess 16 and in the Opening position on a ring step on the guide or at conical formation of the leadership sealing against the leadership supports. This will cause the air cushion above the Melting level minimized and in the narrowed filter cross section accelerated melt front calms down.

Fig. 5 shows a slightly modified compared to Figs. 1 to 4 Embodiment for flatter castings, where for identical parts, the reference numerals of FIGS. 1 to 4 are taken over. The guide 15 is here again made as a preformed sleeve from core sand, with is provided with a plurality of radially opening windows 16, one of which is aligned with the pouring channel 13. The guide 15 in turn receives the plug 17 and also on its opposite side the particle filter 18. Thus, guide 15, sealing plug 17 and pre-assemble particulate filter 18 and these Unit in a corresponding receptacle on the lower box shape 7 insert. The upper box shape 6 has one appropriate recording so that after adding the Upper box positioned the bushing 15 forming the guide is.

6 has the shape 5 several discrete mold cavities 9, as in multiple molds are common. In this case the gate is 12 centrally located and go from this essentially radially from the pouring channels 13. Sitting in the mold parting line again the guide 15 for the plug 17. The Guide 15 has at least two diametrically opposite Window 16, each with a pouring channel 13 correlate. The way it works is the same as with 1 to 4 with the difference that both mold cavity 9 via the gate 12 and the interior the guide 15 and the two pouring channels 13 simultaneously be filled. At the end of the casting process, the Plug 17 moved down until he both Window 16 moved.

Fig. 7 shows an embodiment of a form 5 with four discrete mold cavities 9 and a central one Sprue on which the pouring channels run perpendicular to it 13 start. It is coaxial with the gate a guide 15 in the form of a sleeve made of core sand four windows are used for each pouring channel 13. In the Guide 15, the plug 17 is slidable.

8 is the shape 5 placed vertically. This situation lies, for example then when the mold is transported on pallets 23 and tilted out of the transport route into the vertical becomes. In such a situation, the shape of the Poured side. For this purpose the pouring pipe runs 4 at least horizontally in its mold-side area and the gate 12 is also approximately horizontal. A bore 24 is formed in the mold on the sprue side, those in the mold parting area just like the other Form a receptacle for the guide 15 of the sealing plug 17 has. Furthermore is in the sprue-side form a pouring channel 25 is formed, which in this case approximately vertical and otherwise essentially perpendicular to Sprue runs. The particle filter 18 sits in this Fall at the transition from the sprue 12 into the pouring channel 25. Furthermore, the drive 19 is laterally with the form Piston rod 20 arranged which engages in the bore 24 and the plug 18 from that shown Open position after filling the mold in the closed position shifts.

In all embodiments, the plug is 15 arranged in the closed position so that the one acting on it metallostatic pressure of the form perpendicular to the guide acts, the plug in the same way in the Guide tense, so that an always effective closure given is.

Claims (19)

Device for increasing low pressure casting of Metals, especially light metals, in split Sand molds (5, 6, 7) with a sprue (12) in one of the two molds (7) to which the pouring tube (4) one Melt container (3) can be connected and with the deepest area of the mold cavity (9) stands, and with an integrated in the form (5) Sealing plug (17) after filling of the mold cavity (9) by means of an external, in the Form engaging drive (19) in the closed position can be brought, characterized in that between the gate (12) and the mold cavity (9) a pouring channel connecting these (13) at an angle to the Inlet is arranged, and that the plug (17) formed as a sand molding and in one molded guide (15) of the form (5) between an open position and a closed position in which he closes the pouring channel and the metallostatic Pressure of the melt in the mold perpendicular to the guide (15) acts on the sealing plug (17), displaceable is. Device according to claim 1, characterized in that the sealing plug (17) in the open position is held self-locking in the guide (15). Device according to claim 1, characterized in that with horizontal forms (5) the sealing plug (17) with play in the leadership (15) is inserted and when filling the form under the Buoyancy of the melt in the open position can be raised in which it seals against the guide. Device according to one of claims 1 to 3, characterized characterized in that the sand molding Molding sand is made. Device according to one of claims 1 to 3, characterized characterized in that the sand molding Core sand is made. Device according to claim 4 or 5, characterized in that that the sand molding with a size is smoothed. Device according to one of claims 1 to 6, characterized characterized that the guide as a rifle (15) formed from core sand and preformed Recordings of the form (5) is used, and that the Bush opening radially into the pouring channel (13) Has recesses (16) for the melt transfer, the by means of the inserted in the sleeve (15) Sealing plug (17) are closable. Device according to claim 7, characterized in that the guide (15) is different from the gate (12) having the mold (7) over the mold parting plane (10) extends into the other shape (6). Device according to claim 7 or 8, characterized in that that the sleeve (15) in a facing Recordings of both forms (6, 7) is arranged. Device according to one of claims 1 to 9, characterized characterized in that downstream of the sealing plug (17) a particle filter (18) arranged is. Device according to one of claims 1 to 10, characterized characterized in that the particle filter (18) on Melt feed of the sleeve (15) is arranged. Device according to claim 11, characterized in that the particle filter (18) in the sleeve (15) is inserted. Device according to one of claims 1 to 12, characterized in that lying horizontally Form (6, 7) the guide (15) for the sealing plug (17) coaxial with the essentially vertically running gate and the pouring channel (13) approximately horizontal in the shape below (7) are trained. Device according to claim 13, characterized in that in the above form (6) one with the Guide (15) coaxial bore (21) arranged in which the drive (19, 20) for the sealing plug (17) engages from above. Device according to one of claims 1 to 12, characterized in that when standing vertically Molds (5) with side gate and horizontal lying sprue (12) of the pouring channel (25) approximately vertically runs and the guide (15) with the plug (17) roughly parallel above the gate (12) and is arranged transversely to the pouring channel (25). Apparatus according to claim 15, characterized that in the form of the gate (12) and parallel to this one with the guide (15) for the Sealing plug (17) coaxial bore (24) is arranged, in which the drive (19, 20) for the Sealing plug from the side of the sprue intervenes. Device according to one of claims 1 to 16, characterized in that with forms (5) with several discrete mold cavities (9) and central Gating (12), the star-shaped pouring channels (13) connected to the mold cavities (9) the guide (15) with the plug (17) is arranged coaxially with the gate (12) and attach the pouring channels (13) to the guide (15). Device according to one of claims 1 to 17, characterized in that the drive for the Sealing plug (17) a pressure medium cylinder (19) the piston rod (20) is retractable into the mold (5) is. Device according to one of claims 1 to 18, characterized in that the piston rod (20) the drive (19) before filling the mold in a the plug (17) against the pressure of the Melt in the open position (12) supporting standby position is movable.

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