EP2563537B2 - Method and device by which moulding compound to be processed is kept moist during the production of cores - Google Patents

Description

The invention relates to a method according to claim 1, for the production of cores for foundry purposes wherein molding material or sand and at least one binder which is at least predominantly inorganic, water-soluble and / or hygroscopic, are mixed by means of a mixing device and wherein this mixture by means of a feeder at least one sand storage unit is fed to a core production device.

The invention further relates to a device according to claim 6, for the production of cores for foundry purposes with a mixing device for mixing molding material or sand and a binder which is at least predominantly inorganic, water-soluble and / or hygroscopic, and with a feed device for conveying the mixture to a sand storage unit of a core manufacturing apparatus.

Advantageous developments of the invention are specified in the subclaims.

Such a method and a comparable device are known from WO 03/022 487 A1 and from the WO 2007/062 706 A1 known.

To avoid crusting of the molding material or sand in the firing hood of a core shooting machine, it is from the WO 03/22 487 A1 It is known to bring a moisture carrier in contact with filling elements, which may be, for example, an absorbent material impregnated with liquid or water, in order to create a moist atmosphere which is as avoidable as possible during shaping shooting. As a result, however, the reject opening and the mixture of sand and binder may become too wet, which may lead to adulteration of this mixture. Further, the WO 03/22 487 A1 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 disadvantages already mentioned in the region of the reject or discharge opening of a core shooter.

Also from the WO 2007/062 706 A1 It is known to supply liquid or moisture in the region of a shooting unit to a core shooting machine in order to prevent premature curing of the mixture of core sand or molding material and binder in the area of the broke opening or broke openings.

However, it may happen that during the mixing process and then in the binder originally contained moisture escapes, so that the mixture dries and encrusted in places, which on the one hand complicate the further transport and supply of the mixture to Kernherstellungsvorrichtung and on the other hand, the mixing device and the downstream feeder and the Can cause contamination of the sand storage unit. Even the core production device itself can be clogged by clumping mixture. Scrap, production stoppage and a high cleaning effort of the entire plant - from the mixing device to the core production device - can be the result.

So far, these problems are reduced by short cleaning intervals, by cooling the mixture or optionally by increasing the binder content, ie by additional effort.

It is therefore the object to provide a method and a device of the type mentioned, in which an early drying and crusting of the mixture and the associated contamination of the mixing device and / or the feeder and / or sand storage unit is largely avoided.

To achieve this object, the method defined at the outset according to claim 1 provides that the mixture-free region of the mixing device at least temporarily during the mixing process and the mixing-free region of the feeding device located between the mixing device and the core-producing device and the mixture-free region of the sand-storing unit behind the feeding device and before the core or mold making device moistened or kept moist, with the amounts of moisture for each area individually sized and fed. By moistening sets in the areas mentioned a high humidity, which can prevent or reduce evaporation or leakage of moisture from the mixture. Thus, the mixture can not fully or partially cure or dry or form encrustations. Soiling of the mixing device and the feeder and also the sand storage unit, but also the core manufacturing device, so can be reduced and / or the necessary cleaning intervals are extended. This fact can in particular have a positive effect on the productivity of the core production process and, in addition, the cleaning intervals can be extended and the cleaning costs can be reduced.

According to the invention, it is provided that the mixture-free region of the mixing device is at least temporarily moistened or kept moist, at least during the mixing process. Especially by the mixing process moisture could escape from the mixture in the mixture-free area. By moistening the mixture-free area can be easily prevented that moisture escapes from the mixture, it dries on parts the mixing device and soiling the blender.

In addition, it may be favorable if evaporation or escape of moisture from the mixture is reduced or prevented by keeping the humidity above the mixture by supplying moisture, in particular to about 70% to 100%, preferably to about 80% to 100 % is kept. Such humidity values minimize the moisture gradient between the mixture and the air surrounding the mixture, thereby largely preventing the release of moisture from the mixture to the air by evaporation and concomitant undesired curing of the mixture.

It is possible that the serving for wetting liquid or serving for wetting water is atomized by means of ultrasound to a floatable aerosol and the mixing device and the feeder and the sand supply unit is supplied. In this case, the aerosol which can be suspended has such small liquid constituents that they can directly evaporate and increase the humidity without first condensing and without condensing as condensate in the mixing device and the feed device and the sand storage unit. The size of the fluid particles produced by ultrasound may be on the order of 0.01 mm or less. At the same time a sufficiently high humidity is achieved, which can prevent the drying of the sand-binder mixture. Both the mixing process as well as the supply and the storage of the Sandbindergemisch can be done reliably.

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 generator (s) and / or by changing the voltage of the ultrasound generator (s). In this way, the amount of airborne aerosol, with which the mixing device and the sand storage unit is moistened, adapt to the existing conditions such as atmospheric humidity, size of the volume to be humidified and ambient temperature.

A particularly expedient embodiment of the method according to the invention can be that the suspended aerosol is formed and fed via several lines of the mixing device and the feed device and the sand storage unit. The generation of the aerosol thus happens outside of the mixing, feeding and the sand storage unit. For the preparation of the aerosol so no additional space is needed in the mixing, feeding and the sand storage unit. Nevertheless, it is possible to provide a sufficiently high humidity, so that drying of the sand-binder mixture can be avoided, but without supplying too much liquid, whereby in particular the binder could possibly be washed out or dissolved.

To achieve the object, the device defined at the outset according to claim 6, characterized in that provided on the mixing device and on the feeding device and the sand storage unit whose inside acting or in the interior of which moistening device is provided, so that the amount of moisture for each area individually - and can be fed. With the aid of the moistening device, the generation and maintenance of the desired air humidity can be achieved in a particularly simple manner so that the risk of drying due to moisture loss of the mixture in the mixing device and in the feed device and / or in the sand storage unit can be reduced. This can favorably reduce the contamination of the mixing device and the feeder and the sand storage unit, but also the downstream core manufacturing device.

It is possible that the moistening device has at least one ultrasound transmitter in the form of an ultrasonic atomizer for water or for a liquid containing in particular water. The invention thus makes use of the fact or knowledge that with ultrasonic atomizers water or a liquid containing water can be atomized in such a way that the individual droplets can be smaller than 20 thousandths of a millimeter or even smaller than 10 thousandths of a millimeter, so that they change into atmospheric moisture and precipitating hardly or hardly as a moisture film on parts of the mixing device and the feeder and the sand storage unit.

It is particularly advantageous if the / the ultrasonic atomizer and a corresponding liquid reservoir are spatially separated from the mixing device and from the feeder and from the sand storage unit and connected to the areas to be humidified via at least one pipe or hose. Experiments have shown that the floating aerosol formed by an ultrasonic atomizer from water or from a liquid containing water can be easily transported over several meters through such a conduit to provide at the desired location sufficiently humid air, drying the mixture of sand or molding material and Binder prevents in particular in the mixing device itself, the feeder and the sand storage unit, but without too much wet this mixture. The liquid reservoir with the ultrasound transmitters can thus advantageously at a point of the core shooter or be placed near this machine, where there is enough space for it.

According to the invention, it is provided that the mixing device, the feed device and the sand storage unit are each connected to the moistening device via a pipe or hose line. With separate pipe or hose lines for the individual device areas, moist air can be introduced individually to the individual process steps into the mixing device, the feed device and the sand storage unit. Thus it can be prevented with even greater certainty that the Sandbindergemisch loses moisture in one of the aforementioned areas, dries and dirty them.

According to the invention, it is provided that the number of ultrasonic atomizers corresponds at least to the number of pipe or hose lines and at least one ultrasonic atomizer is provided per pipe or hose line. With at least one ultrasonic atomizer per pipeline, it is possible that even with different humidity values in the areas to be moistened, a sufficient amount of liquid can be atomized and fed to the respective areas in order to prevent drying and crusting of the mixture.

In addition, it may be favorable if, for conveying the moisture or the aerosol from the ultrasonic atomizers to the mixing device and feed device and sand storage unit, a fan or a compressed gas connection is arranged in particular above the liquid surface in the liquid reservoir. Although the aerosol could flow to the mixing device and feed device and sand supply unit, especially with relatively short lines due to its autogenous pressure, a fan or compressed gas connection can improve this flow or also allow a greater distance of the ultrasonic atomizer from the areas of the device to be supplied with moist air , Furthermore, height differences between the ultrasonic atomizer and the said areas of the device at the core shooting device can be overcome by a fan and / or a compressed gas connection. Above all, the aerosol can also be conveyed upwards, so that the ultrasonic atomizer can also be arranged deeper with the liquid reservoir, where as a rule there is sufficient space therefor. In addition, in such an arrangement is advantageous that a possibly occurring condensate on the inner walls of the tube or hose in which the aerosol is transported, can flow back down into the liquid reservoir.

A modified embodiment of the invention may provide that the feed device is at least one movable transport bucket. With a movable transport bucket as a feeder, it is possible to transport the sand-binder mixture from the mixing device to the sand storage unit of the core or mold manufacturing device over longer distances.

An embodiment of the invention will be described in more detail below with reference to the drawing. The single FIGURE shows a schematic representation of a longitudinal section of a mixing device, a feeder and a sand storage unit with pending Kern- or Formherstellungsvorrichtung and a moistening device with two Ultraschallzerstäubern and liquid reservoir and three supply lines, one to the mixing device, one to the feeder and one to the sand storage unit runs.

A generally designated 1 apparatus for producing molds or cores, in the embodiment for the production of cores for foundry purposes, comprises a mixing device 20 with a mixing tool 22 for producing a mixture M by mixing molding material or sand and a binder, a feeder 30 for Forwarding the mixture M to a sand storage unit 40 with a closure device 42 and a core manufacturing device 50 on.

For moistening the air in the device 1 is a moistening device 2 with two Ultraschallzerstäubern 60 for water or for a particular water-containing liquid 71 and a liquid reservoir 70. With the help of these Ultraschallzerstäuber 60, the liquid 71 can be atomized to a fine aerosol. This aerosol is indicated by the two cloud fungi 61 in the interior of the liquid reservoir 70 in the figure.

An embodiment of the device, not shown, but can also provide that three ultrasonic atomizers 60 are provided, one of which is assigned to one of the three pipes 81, 82 and 83, so so for the liquid supply in the areas to be humidified per pipe 81, 82 and 83 at least one ultrasonic atomizer is available. Thus, the amount of moisture for each area can be individually sized and fed.

It can also be seen from the figure that the moistening device 2 with the ultrasonic atomizers 60 and the liquid reservoir 70 is spatially separated from the mixing device 20, the feed device 30 and the sand storage unit 40, but connected to the areas to be moistened via conduits 81, 82 and 83 are, which extend directly from the liquid reservoir 70 in said areas of the device 1 and provide therewith moist areas for mixing-free areas 21, 31 and 41. In the exemplary embodiment, not only the mixing device 20, but also the feed unit 30 and the sand storage unit 40 at least temporarily each have a mixture-free region 31 and 41.

In addition, a fan 90 and a compressed gas connection 10 can be seen in the liquid-free region of the liquid reservoir 70. Either the fan 90 or the compressed gas port 10, or both, are preferably used to transport and transport the aerosol prepared by the ultrasonic atomizers 60 via the pipelines 81, 82 and 83 to the mixing device 20, the feed device 30 and the sand storage unit 40.

Via the pipes 81, 82 and 83, sufficiently humid air above the mixture M is blown into the mixing device 20, the feed device 30 and the sand storage unit 40, so that the mixture M can not harden and dry in any of the three regions of the device 1, which is the Prevent contamination of the device 1 and thereby improves the uninterrupted operation of the device 1 and increases the quality of the sand cores produced.

A modified, not shown embodiment of the device 1 may provide that the feeder 30 is at least one transport bucket that can be moved, for example by means of a railroad or with a crane between the mixing device 20 and sand storage unit 40. In particular, for bridging larger distances between the mixing device 20 and the sand storage unit 40, this may be favorable.

In order to produce cores for foundry purposes from a mixture M of molding material or sand and at least one binder, the mixture M is mixed by means of a mixing device 20 and supplied by means of a feeder 30 at least one sand storage unit 40 a Kernherstellungsvorrichtung 50, wherein the mixture-free region 21 of the mixing device 20th at least temporarily, and the feed device 30 and the sand storage unit 40 located between the mixing device 20 and the core or mold making device 50 are humidified or held moist behind the feed device 30 and before the core manufacturing device 50 by means of a liquid 71, wherein the liquid 71 to be humidified is replaced by at least atomizing an ultrasonic atomizer 60 into a suspended aerosol and supplying it to the mixing device 20 and the feeder 30 and the sand storage unit 40 via pipes 81, 82 and 83.

Claims (10)

1. Method for producing cores for casting purposes, in which casting compound or sand and at least one binder, which is at least predominantly inorganic, water-soluble and/or hygroscopic, are mixed using a mixing device (20), and in which said mixture (M) is fed to at least one sand storage unit (40) of a core production device (50) with the aid of a feed device (30), characterised in that a mixture-free region (21) of the mixing device (20), at least temporarily at least during the mixing process, and a mixture-free region (31) of the feed device (30), said region being situated between the mixing device (20) and the core production device (50), and a mixture-free region (41) of the sand storage unit (40) downstream of the feed device (30) and upstream of the core production device (50) are moistened or kept moist, and the mixing device (20), the feed device (30) and the sand storage unit (40) are each connected to a liquid reservoir (70) via a pipe or hose (81, 82, 83), and at least one ultrasonic atomiser (60) is provided per pipe or hose (81, 82, 83), and the number of ultrasonic atomisers (60) at least corresponds to the number of pipes and hoses (81, 82, 83), such that the moisture amounts for the individual regions are measured and supplied individually.
2. Method according to Claim 1, characterised in that moisture is prevented from evaporating or escaping from the mixture (M) in that the humidity above the mixture (M) is kept at approximately 70% to 100% or at approximately 80% to 100% by supplying moisture.
3. Method according to either of Claims 1 and 2, characterised in that the liquid (71) used for moistening or the water used for moistening is atomised by ultrasound to form an aerosol capable of floating and is fed to the mixing device (20) and to the feed device (30) and to the sand storage unit (40).
4. Method according to any one of Claims 1 to 3, characterised in that the aerosol formed from the liquid (71) and the size of the volumetric flow provided with the aerosol are adjusted by changing the pulse packets emitted by the ultrasonic generators and/or by changing the voltage of the ultrasonic generator (s).
5. Method according to any one of Claims 1 to 4, characterised in that the aerosol capable of floating is formed and fed via a plurality of lines (81, 82, 83) to the mixing device (20) and to the feed device (30) and to the sand storage unit (40).
6. Device for producing cores for casting purposes, having a mixing device (20) for mixing casting compound or sand and a binder, which is at least predominantly inorganic, water-soluble and/or hygroscopic, and having a feed device (30) for conducting the mixture (M) to a sand storage unit (40) of a core production device (50), characterised in that a moistening device (2) is provided on the mixing device (20) and on the feed device (30) and on the sand storage unit (40), said moistening device loading the interior or opening into the interior of said devices and unit, and the mixing device (20), the feed device (30) and the sand storage unit (40) are each connected to a liquid reservoir (70) via a pipe or hose (81, 82, 83), and at least one ultrasonic atomiser (60) is provided per pipe or hose (81, 82, 83), and the number of ultrasonic atomisers (60) at least corresponds to the number of pipes and hoses (81, 82, 83), such that the moisture amounts for the individual regions can be measured and supplied individually.
7. Device according to Claim 6, characterised in that the moistening device (2) has at least one ultrasonic generator in the form of an ultrasonic atomiser (60) for water or for a liquid (71) in particular containing water.
8. Device according to Claim 6 or 7, characterised in that the ultrasonic atomisers (60) and an associated liquid reservoir (70) are arranged spatially separate from the mixing device (20) and from the feed device (30) and from the sand storage unit (40) and are connected to the region (s) to be moistened via at least one pipe or hose (81, 82, 83).
9. Device according to either one of Claims 7 and 8, characterised in that to convey the moisture or the aerosol from the ultrasonic atomisers (60) to the mixing device (20) and feed device (30) and sand storage unit (40), a ventilator (90) or a compressed gas connection (10) is arranged in the liquid reservoir (70), in particular above the liquid surface.
10. Device according to any one of Claims 7 to 9, characterised in that the feed device (30) is at least one mobile transport bucket.

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