EP1957218B1 - Method and device for producing moulds or cores, in particular for foundry purposes - Google Patents

Abstract

The production of molds or cores by blasting a mixture of sand and binder through orifices (7) in a blasting plate (5) into a mold or core tool (8) and wetting the mixture between blasts comprises ultrasonically atomizing the wetting liquid (15) and supplying the resulting aerosol to a blasting unit (2). An independent claim is also included for an apparatus for the production of molds or cores from a mixture of sand and binder, comprising a blasting unit consisting of a blast pipe (3) and a blast head (4) with a blasting plate having orifices, and an ultrasonic atomizer for water or aqueous liquid connected to the blasting plate orifices.

Description

The invention relates to a method for producing molds or cores, in particular for foundry purposes, from a mixture of sand or molding material and a binder, which is in particular water-soluble and / or hygroscopic, wherein the mixture by means of at least one shooting unit from this in a shooting process by at least a scrap opening disposed on a shooting plate is shot into a forming or core tool and then cured, wherein at least between two firing operations the area of the broke opening is moistened and / or kept moist by means of a liquid or water.

The invention further relates to an apparatus for producing molds or cores, in particular for foundry purposes, from a mixture of sand or molding material and a preferably inorganic binder, which is in particular water-soluble and / or hygroscopic, with at least one shooting unit having a shooting tube and a shooting head, wherein at the shooting head a shooting plate with at least one reject opening and a device for the moistening are provided, in particular for carrying out the aforementioned method.

Such a method and a comparable device are out DE 103 40 491 B3 known. It is provided for the realization of the method that the moisture is supplied as a finely divided or sprayed or atomized liquid. However, it has been shown that by doing so get much liquid in the area of the reject orifices or outlets and the binder from the mixture of sand and binder leach out or swamp out and / or make in the reject openings or outlets and shortly above it located mixture of sand and binder to moist, so that within the Mold or core tool differently moist mixture areas of sand or molding material and binder may be present, which can lead to irregularities of the mold or the core.

Out DE 101 44 193 C1 It is known to bring a moisture carrier in contact with filling elements, which may be, for example, impregnated with liquid or water, absorbent material to create a humid atmosphere during shooting. This also causes the reject opening and the mixture of sand and binder to become too wet, which can lead to adulteration of this mixture.

Further disclosed DE 101 44 193 C1 in that the supplied moisture should be effective as a condensate, which in turn can lead to excessive dilution of the mixture of sand and binder with the mentioned disadvantages in the region of the reject or discharge opening of a filling element.

There is therefore the object to provide a method and also a device of the type mentioned above, whereby premature curing of the mixture of core sand or molding material and binder in the area of broke or reject openings avoided and so a low-maintenance continuous operation is possible without the binder too moist or even flushed out.

To solve this problem sees the initially defined method in that the moistening liquid or moistening water is ultrasonically atomized to a buoyant aerosol and supplied to the region of the broke opening and / or the shooting unit or the shooting head.

It has been found that with the aid of ultrasound liquid, for example water-containing liquid or even water, can be transformed into a suspended aerosol whose liquid constituents are so small that they pass into atmospheric moisture without condensing and without condensate in the region knock down the reject opening for the sand-binder mixture. The size of the fluid particles produced by ultrasound may be on the order of 0.01 millimeters or less. At the same time a sufficiently high humidity is achieved, which prevents the drying of the sand-binder mixture, for example, between two shots, so that the individual shots can be done safely, without causing unevenly moist areas in the form or in the core.

The aerosol or the quantity of this aerosol which can be aerated and the size of the volumetric flow provided with the aerosol can be adjusted by changing the pulse packets delivered by the ultrasound transmitter (s) and / or by changing the voltage of the ultrasound transmitter (s). In this way, the amount of aerosol that can be aerated, which wets the area of the reject opening (s), can be adapted to existing conditions such as atmospheric humidity, number of rejected openings and ambient temperature.

A particularly expedient embodiment of the method according to the invention may consist in that the aerosol can be suspended formed at a distance from the / the reject openings and fed via a line of the / the reject openings. Thus, no space is required for the generation of the aerosol in the area of the shooting unit. Nevertheless, so much moisture can be provided within the air in the area of the reject openings that drying of the reject openings is avoided, but without supplying too much liquid, which in particular could possibly flush or loosen the binder.

Another particularly advantageous embodiment of the method according to the invention can be that the sand supply in the shooting tube and / or in the shooting head is moistened with a liquid aerosol. The shooting tube and / or the shooting head can therefore also be connected via one or more lines with an ultrasonic atomizer for liquid or water, so that the sand supply and in particular its surface, which could otherwise possibly form a crust, are moistened, but without drenched What can be done in addition to direct humidification of the reject opening or instead as indirect humidification of the reject opening.

To achieve the object, the device defined at the outset is characterized in that it comprises at least one ultrasonic atomizer for water or for a liquid containing in particular water, and that this ultrasonic atomizer is in communication with the reject orifices. Thus, the invention makes use of the fact or knowledge that with ultrasound donors water or a water-containing liquid can be atomized such that the individual droplets can be less than 20 thousandths of a millimeter or even less than 10 thousandths of a millimeter, so that they in humidity and do not precipitate as a moisture film on parts of the shooting unit and in particular in the area of the reject opening.

In this case, it is particularly expedient if the ultrasonic transmitter (s) and the associated liquid reservoir are spatially separated from the shooting unit and connected to the region of the reject opening (s) via at least one pipe or hose line. Experiments have shown that the floating aerosol formed by an ultrasonic atomizer made of water or of a liquid containing water can be easily transported over several meters through such a conduit to then provide sufficiently humid air at the or the reject openings, which drying of the mixture of sand or mold material and binder prevented in particular in the reject openings, but without too much wet this mixture. Thus, the liquid reservoir with ultrasound generator can advantageously be arranged at a location of the forming or core shooter or near this machine, where sufficient space is available for it.

For conveying the aerosol from the ultrasonic atomizer (s) to the discharge opening or openings of the shooting unit, a fan and / or a pressure connection can be arranged in particular above the liquid surface of the liquid reservoir. Although the aerosol could flow to the reject openings especially with a relatively short line due to its autogenous pressure, a fan or a compressed gas connection can improve this flow or also allow a greater distance of the ultrasonic transmitter from the reject openings. Furthermore, by a fan and / or a compressed gas connection height differences between overcome the ultrasonic atomizer and the shooting plate or any other destination of the aerosol on the core shooting machine. Above all, the aerosol can also be conveyed upwards so that the ultrasound transmitter can also be arranged deeper with the liquid reservoir, where as a rule there is sufficient space therefor. It is advantageous in this case that any condensate which may occur can flow back down into the reservoir on the inner walls of the pipe or hose in which the aerosol is transported.

It is particularly expedient if the liquid reservoir is a closed liquid container and is under pressure by a fan arranged in or on one of its walls or effective there and / or pressure connection. Accordingly, the aerosol generated by an ultrasonic atomizer can be transported to the place of its destination.

It is particularly advantageous if one or more, for example, two ultrasonic atomizers are provided on the liquid reservoir. The surface of the liquid reservoir and the liquid contained therein can be correspondingly large and a corresponding amount of aerosol can be generated, so that correspondingly large shooting units can be kept moist at several places at the same time.

The shooting head may include a movable guard having a scavenging hood having the aerosol port removable or movable away from the individual shots, and the connecting line from the ultrasonic atomizer and liquid reservoir to the guard may be a telescoping tube or a hose. Thus, the possibility remains, a movable protection device and flushing hood to provide, since it can be connected to the movable line, which can join the movements of the protective device.

It can be advantageous if the shooting tube and / or the shooting head of the shooting unit is / are connected via one or more lines to the ultrasonic atomizer and the liquid reservoir. As a result, a crust formation on the surface of the sand stock can be avoided, especially in the shooting tube. Furthermore, the sand supply can thereby be specifically moistened in such a way that only a small or possibly no moisture supply at the exit or shooting opening is no longer necessary, but the moisture is supplied to the region of the reject opening via the sand reservoir. Thus, direct or indirect delivery of the aerosol to the reject port (s) may be provided, with a combination of both promising the best results.

An embodiment of the invention will be described in more detail below with reference to the drawing. The only figure shows
in a schematic representation of a longitudinal section through a shooting unit for supplying a mixture of sand or molding material and a binder to a likewise schematically shown in vertical section core tool, wherein on a belonging to the shooting unit protection device with gas flushing hood on the one hand and on a belonging to the shooting unit shooting on the other hand respectively opens a conduit that comes from a liquid container with ultrasonic atomizers and is used to moisten the reject opening and the sand stock.

A designated as a whole with 1 device for the production of molds or cores, in the embodiment for the production of cores for foundry purposes, from a mixture M of sand or a molding material and a particular water-soluble or hygroscopic binder has a designated as a whole with 2 shooting unit, to which essentially comprises a shooting tube 3 receiving the mixture M with a firing head 4.

At the lower end of the shooting head 4, a shooting plate 5 is arranged, over which the mixture M lies, which are fired in a shooting operation by at least one shooting nozzle 6 with reject opening 7 and - in the embodiment - another Ausschöffhung 7 from the shooting unit 2 in a core tool 8 can. In a known manner, the shooting tube 3 is pressurized from above, so that the mixture M driven by the shooting nozzle 6, which fits into an inlet opening 9 of the core tool 8, from the space located above the shooting plate 5 and in the core tool 8 is provided for receiving the mixture provided space 14 and this fills.

In the drawing, the device 1 is shown in the state after a shooting operation, that is, shooting unit 2 and core tool 8 are separated and spaced from each other.

So that in the meantime not remaining up to a next shot in the shooting nozzle 6 or reject opening 7 remaining mixture residues and the mixture above the shooting plate 5 M crust and especially the reject openings 7 are not clogged by partially cured mixture, they are moistened in the following manner ,

Between the shooting unit 2 and the core tool 8 is a wegbewegbare protection device 10 with a gas purging hood 11 is provided. The protective device 10 has a cavity 12. When it is connected to the shooting plate 5 as shown, it engages over these and in particular the reject openings 7 and also the shooting nozzle 6, which projects into the cavity 12. In this case, the cavity 12 is closed relative to the shooting plate 5 gas-tight or almost gas-tight relative to the environment.

The figure further shows a reservoir 13 for liquid 15 and two ultrasonic atomizers 16 acting on this liquid 15 and connected to the liquid reservoir 13, so that the water-containing or water-containing liquid 15 can be transformed into a suspended aerosol is indicated as "cloud mushroom" 17 above the surface of the liquid 15.

The ultrasonic atomizer 16 and the liquid reservoir 13 are connected via a line 18 to the cavity 12 of the protective device 10 and thus to the reject openings 7, so that the moistened by the suspended aerosol, but are not wetted by precipitating water.

It can be seen that the ultrasonic atomizers 16 and the liquid reservoir 13 are spatially separated from the shooting unit 2 and connected to the region of the reject openings 7 via a pipe or hose line 18. Thus, the generation of the floating aerosol 17 may take place at a location that provides sufficient space therefor.

To transport the aerosol 17 from the ultrasonic atomizers 16 and the liquid reservoir 13 to the or the reject openings 7 of the shooting unit 2 is in the embodiment a Fan 19 and a pressure port 20 indicated, both possibilities can be provided simultaneously or alternatively. In this case, the fan 19 and / or the pressure port 20 are above the surface of the liquid 15 in the liquid reservoir 13, which is designed as a closed liquid container, so above the liquid 15 by the fan 19 or the compressed gas port 20 serving for the transport of the aerosol 17 Overpressure can occur. The compressed gas connection 20 or the fan 19 are arranged on or in a wall 21 of the liquid reservoir 13 formed as a liquid container.

It can be seen in the exemplary embodiment that at the liquid reservoir 13, two ultrasonic atomizers 16 are provided, which are covered by the liquid 15 and thus can produce two "aerosol clouds" 17, both of which can be conveyed in the direction of arrow Pf in the conduit 18.

Since the protective device 10 with the gas purging hood 11 is movable relative to the shooting unit 2 and the shooting plate 5, the leading to her line 18 is designed as a hose that can join in appropriate movements. Thus, the protective device 10 belonging to the shooting head 4 and the shooting plate 5 can be removed from the shooting plate 5 and moved away with the flushing cap 11 despite the connection for the aerosol and despite the line 18 leading to this connection for the individual shots.

It can be seen in the drawing that the line 18 has a branch 22 and another line strand 23 leads to and into the shooting tube 3, so that the aerosol formed by the ultrasonic atomizers 16 can also be transported in or over the mixture M to the Surface of this supply of Prevent mixture from encrusting. In addition, the entire mixture can be kept moist from the outset, which can prevent crusting in the shooting openings 7.

With the device 1 according to the invention, it is thus possible to atomize the moistening liquid 15, for example water, by means of ultrasound into a suspended aerosol and to supply it directly or indirectly to the region of the reject opening 7 or the reject openings 7. The direct feed takes place in the embodiment via the line 18 and the protective device 10 with the cavity 12 and the indirect supply via the wiring harness 23 and the shooting tube. 3

In a manner not shown here, the aerosol and the size of the volume flow provided with the aerosol can be adjusted by changing the pulse packets emitted by the ultrasound transmitters 16 and / or by changing the voltage of the ultrasound transmitters 16.

Since the shooting unit 2 is connected via the hose line 18 and the wiring harness 23 to the liquid reservoir 13 and the ultrasonic atomizers 16, the suspended aerosol is formed at a distance from the reject openings 7 and directed thereto via the mentioned lines.

The ultrasonically generated aerosol 17 results in such small liquid particles that they pass into humidity and so can be used to moisten the mixture M at least in the region of the reject openings 7, but without being deposited as moisture and the mixture M may even be soaked unevenly and possibly Flush out or loosen binder.

To produce molds or cores for foundry purposes from a mixture M of molding material or sand and a binder, the mixture M by means of at least one shooting unit 2 from this or from a shooting tube 3 and a shooting head 4 by at least one disposed on a shooting plate 5 reject opening 7 in a molding or core tool 8 shot, wherein at least between two shooting operations, the area of the reject opening 7 is moistened by a liquid and / or kept moist, wherein the serving for wetting liquid 15 atomized by means of at least one ultrasonic atomizer 16 to a buoyant aerosol and the reject opening. 7 is supplied directly or indirectly, for example via a line 18 and / or 23.

Claims (11)

1. Method for producing moulds or cores, particularly for foundry purposes, from a mixture (M) of sand or moulding material and a binder which is, in particular, inorganic, water-soluble and/or hygroscopic, the mixture (M) being fired into a mould or core tool (8) by means of at least one firing unit (2) and from said unit, in a firing process, through at least one discharge opening (7) arranged on a firing plate (5), and then being hardened, while at least between two firing processes the area of the discharge opening (7) is moistened and/or kept moist with a liquid or water, characterised in that the liquid (15) used for the moistening or the water used for the moistening is nebulised into a suspended aerosol by the use of ultrasound and is supplied to the area of the discharge opening (7) and/or the firing unit (2) or the firing head.
2. Method according to claim 1, characterised in that the aerosol and the size of the flow volume comprising the aerosol is adjusted by varying the pulse packages emitted by the ultrasound emitter(s) (16) and/or by varying the voltage of the ultrasound emitter(s) (16).
3. Method according to claim 1 or 2, characterised in that the suspended aerosol is formed at a spacing from the discharge opening(s) and is supplied to the discharge opening(s) through a line.
4. Method according to one of claims 1 to 3, characterised in that the supply of sand in the firing tube and/or in the firing head is moistened with a liquid aerosol.
5. Apparatus (1) for producing moulds or cores, particularly for foundry purposes, from a mixture of sand or moulding material and a preferably inorganic binder which is, in particular, water-soluble and/or hygroscopic, with at least one firing unit (2) comprising a firing tube (3) and a firing head (4), while on the firing head (4) are provided a firing plate (5) with at least one discharge opening (7) and a device for moistening it, in particular for carrying out the method according to one of claims 1 to 4, characterised in that the apparatus (1) has at least one ultrasound nebuliser (16) for water or for a liquid (15) that contains water, in particular, and in that this ultrasound nebuliser (16) is connected to the discharge opening(s) (7).
6. Apparatus according to claim 5, characterised in that the ultrasound nebuliser(s) (16) and the associated liquid reservoir (13) are arranged spatially separate from the firing unit (2) and is or are connected to the region of the discharge opening(s) (7) via at least one pipe or hose (18).
7. Apparatus according to claim 5 or 6, characterised in that in order to convey the aerosol (17) from the ultrasound nebuliser(s) (16) to the discharge opening(s) (7) of the firing unit (2), a blower (19) and/or a pressure connection (20) is/are provided, in particular, above the surface of the liquid in the liquid reservoir (13).
8. Apparatus according to one of claims 5 to 7, characterised in that the liquid reservoir (13) is a sealed liquid container and is kept at elevated pressure by a blower (19) preferably arranged in or on one of its walls (21) or acting thereon and/or by a pressure connection (20).
9. Apparatus according to one of claims 5 to 8, characterised in that one or more, for example two, ultrasound nebulisers (16) are provided on the liquid reservoir (13).
10. Apparatus according to one of claims 5 to 9, characterised in that associated with the firing head (4) is a movable protecting device (10) with a rinsing cowling (11) which comprises the connection for the aerosol and which can be taken off or removed for the individual firings, and in that the connecting line from the ultrasound nebuliser (16) and liquid reservoir to the protecting device is a telescopic tube or a hose.
11. Apparatus according to one of claims 5 to 10, characterised in that the firing tube and/or the firing head of the firing unit is or are connected to the ultrasound nebuliser (16) and the liquid reservoir via one or more lines.

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