EP3119545A1

EP3119545A1 - Method for casting castings

Info

Publication number: EP3119545A1
Application number: EP15738697.0A
Authority: EP
Inventors: Klaus Arnold; Dirk Rogowski; Jürgen Schmidt; Rolf SÜSSMANN
Original assignee: Fritz Winter Eisengiesserei GmbH and Co KG
Current assignee: Fritz Winter Eisengiesserei GmbH and Co KG
Priority date: 2014-07-30
Filing date: 2015-07-20
Publication date: 2017-01-25
Anticipated expiration: 2035-07-20
Also published as: CN106536083A; WO2016016035A1; CA2948750C; KR20170028392A; BR112016023696B8; ES2759264T3; DK3119545T3; JP2017525570A; RS65376B1; EP3597329A1; HRP20192115T1; BR112016023696B1; KR101845505B1; JP6275324B2; PL3119545T3; PT3119545T; CA2948750A1; EP3597329C0; MX2016012496A; US9890439B2

Abstract

The invention relates to a method for casting castings, wherein a casting mold is provided, which consists of one or more casting mold parts or casting mold cores, which are produced from a mold material, which consists of core sand, binder, and optional additives. The casting mold (2) is encased in a housing in such a way that a filling space (10) is formed between an inner surface segment of the housing and an associated outer surface segment of the casting mold (2). The filling space (10) is then filled with a free-flowing filling material (F) and metal melt is poured into the casting mold (2). In conjunction with the pouring in of the metal melt, the casting mold begins to radiate heat. As a result of the input of heat by means of the metal melt, the binder of the mold material begins to evaporate and to burn. The binder thus loses the effect thereof and the casting mold (2) disintegrates. According to the invention, the filling material (F) has such a low bulk density that a gas flow (S1, S2) can flow through the filling material packing formed from the filling material (F) in the filling space. During the filling of the filling space, the filling material (F) has a minimum temperature, proceeding from which the temperature of the filling material (F) rises due to process heat, which is formed by the heat radiated by the casting mold (2) and by the heat released during the burning of the binder, to above a limit temperature at which the binder evaporating out ignites and burns.

Description

Method for casting castings

The invention relates to a method for casting cast parts, in which a molten metal is poured into a casting mold, which surrounds a cavity forming the casting to be produced, wherein the casting mold consists of one or more mold parts or cores as a lost mold. The mold parts or casting cores are formed from a molding material which consists of a core sand, a binder and optionally one or more additives for adjusting certain properties of the molding material.

In conventional methods of this kind is

usually first the cast of the casting

Mold provided whose cores and moldings have been prefabricated in separate operations. The casting mold can be composed as a so-called "core package" of a plurality of casting cores.

In the same way it is possible to use casting molds which are composed, for example, of only two mold halves, in which the mold cavity forming the casting is formed, wherein mold cores may also be present in order to image recesses, cavities, channels and the like in the casting , Typical examples of castings with a

are produced according to the invention are

Cylinder crankcase and cylinder heads. For larger and highly stressed engines, they are made of cast iron by sand casting.

As molding material for the outer end of the mold forming moldings are in the field of

Iron casting usually quartz sands, mixed with

Bentonites, lustrous carbon formers and water

used. By contrast, the casting cores reproducing the internal cavities and channels of the casting are usually formed from commercially available core sands, which are filled with an organic or inorganic binder, eg. B. with a synthetic resin or water glass, are mixed.

Regardless of the nature of the core sands and binders, the basic principle in the production of molds formed from molding materials of the above-mentioned type is that after shaping the binder by a suitable thermal or chemical treatment

is cured, so that the grains of the core sand stick together and is ensured over a sufficient period of the dimensional stability of the respective molded part or core.

Especially when casting large - volume castings of cast iron on the casting mold after pouring the

Molten metal load-bearing internal pressure be very high. In order to absorb this pressure and to reliably avoid bursting of the casting mold, either thick-walled, large-volume casting molds or supporting structures

are used, which support the mold on its outside.

One possibility of such a support structure is an enclosure which is slipped over the mold. The enclosure is usually formed in the manner of a jacket, which the casting mold on their

Surrounds peripheral sides, but on its upper side has a sufficiently large opening to allow the pouring of the melt into the mold. The enclosure is dimensioned so that after filling at least in the decisive for the support of the mold sections between the inner surfaces of the housing and the outer surfaces of the mold remains a filling space. This filling space is filled with a free-flowing filling material, so that a large-area support of the respective surface portion is ensured at the housing. Here as uniform as possible filling of the filling space, an equally uniform

Contact the mold with the filler and a correspondingly uniform support of the

To achieve fragile Gießformstoffs be as a product usually fine-grained, free-flowing

Fillers, such as sand or steel gravel, used, which have a high bulk density. After filling, the contents are additionally compacted. The aim here is to produce a very compact filling material, which in the manner of an incompressible monolith direct

Ensures transfer of support forces from the housing to the casting mold. The molten metal is poured into the mold at high temperature, so that the mold parts and cores from which the mold is composed, are heated strongly. As a result, the

Casting mold to radiate heat. If the temperature of the mold exceeds a certain minimum temperature, the binder of the molding material begins to evaporate and burn with the release of further heat. The binder loses its effect. As a result of this decomposition of the binder, the bonding of the grains of the molding material from which the mold parts and cores of the mold are made is lost, and the mold or its parts made of molding material and cores disintegrate into individual fragments.

It is known from practice that this effect can be used for demoulding the casting from the respective casting mold. For example, from the

EP 0 546 210 B2 or EP 0 612 276 B2

Heat treatment of castings known in which the mold with the castings in one

continuous process flow from the casting heat in a heat treatment furnace. When passing through the furnace, the mold and the castings will be exposed for a sufficiently long duration to a temperature at which the

Heat treatment set desired state of the casting. At the same time the temperature is the

Heat treatment chosen so that the binder of the molding material decomposes. The then automatically falling from the casting, consisting of molding fragments of the mold are still in the heat treatment furnace in a Sandbed caught. There they linger over a certain period of time, around the disintegration of the fragments of the

Casting mold parts and cores continue to drive. The crushing of the falling off of the mold molding material fragments can be supported by the fact that the

Sand bed by blowing in a hot gas stream

is fluidized. The enough crushed

Formstoffbruchstücke finally one

Processed, in which the core sand so

that it can ■ be used for the production of new mold parts and cores.

The well-known approach to demolding and

Treatment of casting castings

required molds has been proven in practice in the casting of parts for internal combustion engines made of aluminum in large quantities. However, it requires a furnace of considerable length and a handling of the molds and castings, which is at

bulky parts or molds proves to be costly, which require additional support through an enclosure of the type described above. This is especially true for such castings, which are to be produced in small and medium quantities of cast iron.

Against this background, the object of the invention was to provide a method which with optimized Energieeffiziens and in a particularly economical way, the casting production of castings

allows. - -

The invention has achieved this object by the method specified in claim 1.

Advantageous embodiments of the invention are set forth in the dependent claims and will become hereafter as the general inventive concept in detail

explained.

The invention thus provides a method for casting castings, wherein a

Molten metal is poured into a mold, which encloses a cavity forming the casting to be produced. The mold is as a lost form

formed, which is composed of one or more mold parts or cores. These mold parts are each formed from a molding material consisting of a core sand, a binder and optionally one or more additives for adjusting certain properties of the

Formstoffs exists.

The method according to the invention comprises the following

Work steps:

- Providing the mold;

- Elnhausen the mold into a housing to form a filling space between at least one

Inner surface portion of the housing and an associated outer surface portion of the mold;

- filling the filling space with a free-flowing medium;

Pouring the molten metal into the casting mold, - -

wherein the mold commences, along with the pouring of the molten metal, to radiate heat resulting from the heat input caused by the molten metal, and

- As a result of the effect caused by the molten metal heat input, the binder of the molding material begins to evaporate and burn, so that it loses its effect and the mold breaks up into fragments.

According to the invention, the filling material filled in the filling space now has such a low bulk density that the product formed there after filling of the filling space from the filling material

Füllgutpackung is flowed through by a gas flow.

In addition, the filling material in the method according to the invention when filling the filling space to a minimum temperature, starting from the temperature of the filling material by process heat, by the radiated heat from the mold and by the combustion of the binder

released heat is formed, up over one

Limit temperature of 700 ° C increases.

The method according to the invention is therefore based on the idea to use the filling material in the sense of a heat storage and to temper and form this heat storage so that the decomposition of the binder of the molding material from which the mold parts and cores of the mold are made, already during the Dwell time in the enclosure by

Temperature effect is largely decomposed.

In this way it is achieved that the parts made of molding material and cores of the mold so far in Fragments are crumbled that these fragments of

Drop casting and the casting after removal of the enclosure at least in the region of its outer surfaces is largely free of adhering moldings or cores.

At the same time are also the cores

disintegrate, which form channels or cavities in the interior of the casting, so that the core sand and the molded fragments of these cores trickle either automatically in the enclosure from the casting or in a conventional manner, for example by mechanical methods such as shaking, or by rinsing with a suitable fluid can be removed from the casting.

The present invention filled in the formed between the casting and housing filling space filling material is free-flowing, so that it also completely fills the filling space when in the area of the outer surfaces of the mold undercuts, cavities and the like are present.

It is crucial that according to the invention, the filling material has a bulk density which is so low that it is also after filling the filling space and optionally

carried out compression of the filled into the filling space filling material is still flowed through by a gas flow.

According to the invention, therefore, in contrast to the above-mentioned prior art expressly no highly compressed

Pack produced in the filling space, although an optimal

Supporting the mold ensures, however, largely gas impermeable. Rather, the filling material used according to the invention is to be selected such that it is suitable for a - -

Gas flow is permeable, which sets, for example, as a result of thermal convection. This occurs when the mold is heated by the molten metal poured into it and the vaporizing binder components of the molding material of the mold parts and cores begin to evaporate and begin to burn with the release of heat.

If there is talk here of a vaporizing and burning binder, then there are always those

Meant binder components that become vaporous by the application of heat and are combustible. This does not exclude that other binder components remain in solid or other form, for example as cracking products in the mold and there optimally also decomposed by heat influence.

The inventively provided flowability of the filled into the filling material with a gas flow creates not only the possibility that the evaporating from the mold binder in the region of the medium itself burns and thereby further heating the contents, but additionally allows the supply of oxygen, the Combustor combustion supported. In this way, the filling material is fed through the over the molten metal and through the

Burning the binder heated process heat to a temperature that is so high that the coming into contact with the contents, emerging from the mold

Binder proportions of the moldings and cores burn or thermally decomposed at least so that they no longer have the environmental damaging effect or deducted as exhaust from the enclosure and an exhaust gas purification can be supplied. - -

The pre-tempered product according to the invention is preferably at a short time interval before casting the

Molten metal introduced into the filling space to

Minimize temperature losses.

After a sufficient concentration of combustible outgassing of the molding material has been achieved in the filling space, the combustion starts due to the contact with the heated product. The combustion of the emerging from the mold

Binders progresses and the contents are kept warm for so long. This process continues until only small quantities of binder escape from the casting mold so that no combustible atmosphere forms in the enclosure. However, the hot medium now holds in the manner of a heat storage a temperature above the limit temperature at which it comes to the combustion of the binder. The mold lingers

Accordingly, at least also at this temperature, so that remaining in the mold binder residues are thermally decomposed.

Casting molds whose shaped parts and cores are made of molding material which is bound by an organic binder are particularly suitable for the process according to the invention. For this purpose, for example, commercially available solvent-containing binder or such binder in question, the effect of which is triggered by a chemical reaction. Appropriate

Binder systems are today used in the so-called "cold-box process".

In practice, the limit temperature is 700 ° C., especially when processing cast iron melt. At above 700 ° C burn in particular safe organic binders. At the same time, at these temperatures other pollutants are released from the mold

leak, oxidized or otherwise harmless

made. The same applies to the in the casting mold as a result of the temperature-induced decomposition of the binder adjusting cracking products, which are also at such high

Safely decompose temperatures.

According to the invention, the contents to a certain

Preheated temperature is filled in the filling space, it is achieved that the filling material due to the supplied process heat to a lying above the limit temperature

Temperature heats up. Practical experiments have shown here that a minimum temperature of 500 ° C is sufficient when filling into the filling space.

Along with the exit, the combustion and the

Decomposition of the binder, the molding material shaped parts and cores of the mold disintegrate into loose fragments, the

either disposed of after removal of the housing and a treatment can be supplied or, advantageously, already during the between the casting of the

Molten metal and the removal of the housing transient residence time can be deducted from the enclosure. For this purpose, the mold placed on a sieve and the trickling down through the sieve plate fragments of

Mold are caught. Practically, the openings of the sieve plate are designed so that the

Fragments of the casting mold and the contents trickle together through the sieve bottom, collected, processed and separated from each other after the preparation. This has the - -

Advantage that no loose filling material is more in the housing is available when the housing is removed.

The enclosure of the mold can accordingly by a mold surrounding the mold with a sufficient for the formation of the filling space distance, from a thermal

insulating and sufficiently dimensionally stable material existing coat, acting as a perforated screen plate

Support plate on which the mold is placed, and a likewise thermally insulating lid may be formed, which is placed after filling the mold. In order to enable a controlled discharge of the exhaust gases forming in the filling space, an exhaust gas opening may additionally be provided.

Also in the method according to the invention, in the

Be filled filling material filled to produce a bias between the mold and the enclosure, through which a secure, positionally accurate cohesion of the mold is guaranteed even if the mold than from a variety of moldings and cores

composite core package is formed. As mentioned, however, due to the low bulk density, even with such a compacted filling material the flowability is secured with a gas stream.

The effectiveness of the present invention achieved destruction of the moldings and cores of the mold can be further increased by not only the contents, but also the mold itself is designed to flow through gas. For this purpose, channels can be deliberately introduced into the casting mold, through which the hot exhaust gas forming in the filling space or correspondingly preheated oxygen-containing gas flows. In this way, a rapid evaporation, combustion and other thermal decomposition of the molding material binder is also within the mold. The disintegration of the mold is thus additionally accelerated.

Targeted channels introduced into the mold may also be used to quench or accelerate certain zones on or in the casting

Avoid cooling in order to achieve certain properties of the casting in the respective zone.

In a filling material according to the invention, the bias is transmitted by the contacting grains of the medium after the compression. In order to avoid despite the invention required gas permeability of the contents that move the grains of the contents uncontrollably, the housing can be assigned to its the mold

Be provided inside surface with a textured surface on which the abutting against this surface grains are at least partially positively supported.

The contents should at the same time have a low suitability for storing heat, so that the product heats up quickly and can be kept at a temperature above the limit temperature for as long as possible.

Optimal for the purposes of the invention suitable filling thus combines a low bulk density with a low specific heat capacity of the material from which the items that make up the contents are made. - -

Practical investigations have shown here that product in which the product P from bulk density Sd and specific heat capacity cp of the material from which the contents

is not more than 1 kJ / dm ³ K.

(P = Sd x cp 1 kJ / dm ³ K), wherein product, in which the product P = Sd x cp is at most 0.5 kJ / dm ³ K, is particularly well suited.

Regardless of whether a compaction is carried out, granules or other granular bulk material have proven to be good as filling material. Such bulk materials with bulk densities of max. 4 kg / dm ³ , in particular less than 1 kg / dm ³ or even less than 0.5 kg / dm ³ , for the inventive

Purposes particularly suitable.

Is a granular, pourable and pourable filling

used, it has proved in practical experiments to be beneficial if the average diameter of the grains is 1.5 - 100 mm, with optimal filling material is used, the particle sizes are in the range of 1.5 - 40 mm.

It shows contents, made of materials with a

specific heat capacity of max. 1 kJ / kgK, ideally less than 0.5 kJ / kgK, is an optimum heating and heat storage behavior for the invention.

As a product, in principle, all thermally stable bulk materials are suitable, which are the above

Meet conditions and are sufficiently temperature resistant. For this purpose, in particular non-metallic

Bulk materials, such as granules of ceramic materials. These can be irregularly shaped, spherical or with cavities - -

be provided to a good Durchgasung filled in the filling material at the same time lower

To achieve heat storage property. Also, the contents may consist of annular or polygonal elements that touch each other only in point contact upon contact, so that between them enough space remains to ensure a good flow.

To avoid having it through the optional one

Gas inlet into the enclosure led oxygen-containing gas stream comes to a cooling of the filling material, the gas stream, before it enters the filling space on a

be heated above room temperature temperature. Optimal way is the temperature of the

Gas flow at least at the level of the minimum temperature of the medium. For the heating of the gas stream, for example, the hot exhaust gas can be used, which is deducted from the enclosure. For this purpose, a known heat exchanger can be used. If a sieve bottom is provided, over which the fragments of the mold, if necessary together with the

Fillings can get out of the enclosure, the oxygen-containing gas stream can also be passed through this sieve tray. This not only has the advantage of a

large-scale introduction, but also causes the supplied gas stream is heated by contact with the hot, trickling out of the housing molding material fragments and the equally hot contents.

Alternatively or additionally, it is also conceivable, a

Partial flow of the exhaust stream to be mixed with the oxygen-containing gas stream and return the resulting hot gas mixture in the filling space. For this it can be useful that the oxygen-containing gas stream fed into the filling space consists of 10 to 90% by volume of waste gas.

The oxygen-containing gas stream supplied to the filling space may be, for example, ambient air.

The oxygen-containing gas stream fed to the filling space can be formed by means of a suitably formed flow as a result of the heat convection within the filling space

Inlet are sucked into the filling space. Alternatively, it is of course also conceivable to introduce the gas flow by means of a blower or the like with a certain pressure in the filling space.

An optional control of the gas flow introduced into the filling space may be dependent on the housing

exiting exhaust gas volume flow to avoid the formation of excess pressure in the atmosphere prevailing in the filling space. For this purpose, the respective gas inlet can be equipped with a mechanism which regulates the supply air as a function of the flow velocity. Suitable for this purpose is, for example, a known per se

Pendulum flap, which is suspended and loaded so that the flow pressure of the gas flow passing in

Depending on counterweights regulates the flow rate and thus the combustion air supply automatically.

It is also conceivable to carry out an exhaust gas measurement at the exhaust gas outlet and the oxygen-containing gas stream in

Depending on the result of this measurement to regulate complete combustion of the binder and the other possibly to escape from the mold escaping gases in the filling space.

A minimization of pollutant emissions can during

inventive method also be achieved in that the enclosure with a catalyst device for

Decomposition of pollutants contained in the combustion products of the binder is equipped.

The exposed after demolding according to the invention

Casting can after the disintegration of the mold a

Undergo heat treatment, in accordance with it

a controlled cooling curve is cooled in a conventional manner controlled to produce a certain state of the casting.

Of course, in accordance with the invention

Procedure simultaneously housed several molds together in a housing and this

Molds in parallel or in tight time to each other

following sequence be filled with molten metal.

In principle, the method according to the invention is suitable for any type of metallic casting materials, during their processing a sufficiently high process heat

arises. The invention is particularly suitable

Method for producing castings from cast iron, because due to the high temperature of the cast iron melt that for the combustion of the binder according to the invention

envisaged temperatures reached particularly safe

become. In particular, can be in inventive - -

Way GJL, GJS and GJV cast iron materials as well

Process steel casting.

If it is mentioned here that the mold used in the invention consists of molded parts or cores, which are formed from molding material, so this concludes

Of course, the ability to produce within such a mold items, such as chills, supports and the like, made of other materials. It is only crucial that the mold contains so much molding material volume that it comes in the course of pouring the respective molten metal for evaporation of binder, which then burns in the filling space and heats up the contents so far that it has one for a

As far as possible complete decomposition of the binder of the molding material sufficient duration over the

Limit temperature maintains temperature.

The cleaning of the exiting from the housing provided according to the exhaust stream can thereby

take place that the flammable substances still present in the exhaust gas are post-combusted in an exhaust air combustion. The heat released in turn can be used to guide the person into the enclosure

preheat oxygen-containing gas stream.

If with several casting molds according to the invention

parallel to each other castings are produced according to the invention, it may be useful if the molds together with their assigned housings in a tunnel or the like and the forming exhaust gases via a common

Exhaust line to be dissipated.

The inventive method is particularly suitable for the casting production of

Cylinder crankcases and cylinder heads for

Internal combustion engines. Especially if the

relevant components intended for commercial vehicles, they have and for their preparation respectively

required mold on a comparatively large volume, in which the advantages of the invention

Approach particularly clearly.

The core sand fragments obtained according to the invention, when they emerge from the enclosure, are usually still so hot that they can be comminuted in a conventional grinder without additional heat input.

If the core sand fragments are present as a mixture with the contents, the separation takes place after the grinding. This is very simple, because the grain size of the core sand obtained after milling is much smaller than the grain size of the medium. The grinder can be designed so that it is a mechanical

Preconditioning of the core sand causes. Such preconditioning can consist, for example, in the fact that the surface roughness of the sand grains is increased by the contact of the core sand with the product granules and thus the adhesion of the binder to the core sand is improved in the subsequent processing into a molded part or core. The regenerated sand obtained after the preparation can be mixed in a conventional manner with new sand.

Hereinafter, the invention with reference to a

Embodiment illustrative drawing explained in more detail. Their figures show each schematically:

Fig. 1 flowchart that the

process according to the invention;

Fig. 2-8 a thermoreactor in different phases of the implementation of the invention

Each method in a section along its longitudinal axis;

Fig. 9 the open to remove the casting

Thermoreactor in a Figures 2 - 8 corresponding view;

10 shows a device for cooling a

Casting;

11 shows the finished casting;

Fig. 12 is a collecting container of the thermal reactor in a Figures 2-8 corresponding

View ;

13 shows a grinder for regenerating core sand in a section guer to its longitudinal axis. 14 shows a casting mold for casting a casting in a manner corresponding to FIGS

View ;

Fig. 15 is a filled with contents reservoir of the figures 8 corresponding

View .

In Fig. 1 is a diagram of the circuit shown in the execution of the invention

Procedure results. It starts with

Casting parts and cores made of molding material, the new, previously unused core sand, z. As quartz sand, and a conventional binder, for example, a commercial cold box binder is mixed. Likewise, new filler material, for example, ceramic granules with a mean particle size of 1.5 - 25 mm, used for the first use of the

required minimum temperature, z. B. 500 ° C, must be heated before it can be used. Furthermore, these starting materials can be reused in the circulation, as explained below.

The thermoreactor T shown in FIGS. 2-8 in different phases of the method according to the invention has a screen plate 1, on which a casting mold 2 prepared for casting an iron casting melt is provided

is placed. The casting mold 2 is intended for the casting production of a casting G, which in the present example is a cylinder crankcase for a commercial vehicle engine. - -

The mold 2 is in a conventional manner as

Core package of a variety of external outer cores or moldings and lying inside

arranged arranged cores. In addition, the casting mold 2 may comprise components made of steel or other indestructible materials. These include, for example, cooling molds and the like, which are arranged in the mold 2 to a through

accelerated solidification of each coming in contact with the molten metal melt a directed

Solidification of the casting G to achieve.

The casting mold 2 delimits a mold cavity 3 from the environment U into which the iron casting melt is poured off to form the casting G. The molten iron flows through a gate system into the

Mold cavity 3, which is not shown here for clarity.

The cores and moldings of the mold 2 are in

conventional manner in the cold-box process of a conventional molding material, which is a mixture of a commercially available core sand, an equally commercially available organic binder and optionally added additives, the

For example, serve the better wetting of the grains of the core sand by the binder. From the molding material, the cores and moldings of the mold 2 are formed. Subsequently, the obtained cores and moldings are gassed with a reaction gas to cure the binder by a chemical reaction and - -

thereby the cores and moldings the necessary

To give dimensional stability.

The screen plate 1 is with its edge on one

encircling edge shoulder 4 of a collecting container 5

supported. In the surrounding AufStandfläche of the

Randabsatzes 4, a sealing element 6 is incorporated.

After the mold 2 is positioned on the screen plate 1, a likewise to the thermoreactor T is

belonging enclosure 7 is set to the peripheral edge paragraph 4 of the collection container 5. The housing 7 is formed in the manner of a hood and encases the mold 2 at its outer peripheral surfaces 8. In this case, the

Extent of the space bounded by the housing 7 an excess over the circumference of the mold 2, so that after placing the housing 7 on the sieve plate 1 between the outer peripheral surface of the mold 2 and the inner surface 9 of the housing 7 a filling space 10 is formed. With her the collection container. 5

assigned edge sits the enclosure on the

Sealing element 6, so that a tight closure of the filling space 10 with respect to the environment U is ensured here. The enclosure consists of a thermally insulating material, which may consist of several layers, of which one layer ensures the necessary dimensional stability of the enclosure 7 and another layer thermal insulation. At its upper side, the housing 7 delimits a large opening 11, via which the casting mold 2 can be filled with cast iron melt and the filling space 10 with filling material F (FIG. 3). For filling the filling chamber 10 with a granular formed as granular and tempered to a temperature Tmin of at least 500 ° C filling material F is a

Reservoir V positioned above the opening 11, from which one then the hot medium F via a

Dispensing system 12 can trickle into the filling space 10 (Fig. 4).

When the filling process is completed, the filled in the filling space 10 filling package can be compacted if necessary. Subsequently, a lid 13 is placed on the opening 11, which also has an opening 14, through which the cast iron melt can be filled in the mold 2 (Fig. 5).

The casting of the iron casting melt then takes place in the casting mold 2 (FIG. 6).

In the meantime, a gas inlet 15 formed in the lower edge area of the housing 7 can be used

oxygen-containing ambient air enter the filling space 10. Likewise, ambient air, which passes through an access 16 into the collecting container 5, is sucked through the sieve bottom 1 into the filling space 10 (FIG. 7).

The deliberate destruction of the casting mold 2, which starts with casting of the iron casting melt, and the associated demolding of the casting G takes place in two phases.

In the first phase, solvent contained in the binder evaporates. The emerging from the mold 2 vaporous solvent reaches in the filling chamber 10, a concentration at which it ignites automatically and

burns. Due to the released heat, the granular, to a temperature Tmin of about 500 ° C.

heated contents F heated beyond the limit temperature TGrenz of 700 ° C until its temperature reaches the maximum temperature Tmax of approximately 900 ° C.

When the concentration of the mold 2

evaporating binder components for an independent combustion is no longer sufficient, takes over the thus heated contents the function of a heat storage, by which the temperature of the mold 2 and in the filling chamber 10 is maintained at a temperature above the threshold of 700 ° C level. In this way, the combustion keeps emerging from the mold 2

Binder components and other potential

Pollutants until no more binder from the mold 2 evaporates. The then possibly still emerging from the mold 2 vaporous substances are oxidized by the prevailing in the filling chamber 10 high temperature or rendered harmless in any other way.

Likewise contribute to the completeness of the combustion of the casting mold 2 passing gases

oxygen-containing, formed from ambient air

Gas streams S1, S2, which via the gas inlet 15 and the sieve bottom 1 in the filling space 10 of the housing. 7

reach .

Since the bulk density of the product F is so low that even after compression a good gas permeability of the filling material package 10 present in the filling space

is guaranteed, a good mixing of the emerging from the mold 2 gases with the oxygen for its combustion-providing gas streams S1, S2 is ensured. At the same time, the filling material pack in the filling space 10 supports the casting mold 2 on its peripheral surfaces and thus prevents the break-through of the mold

Cast iron melt.

The flow through the gases emerging from the casting mold 2 through the filling material F causes a good mixing with the supplied gas flow S1, S2, a longer residence time and a good reactivity. The

Casting mold 2 is thus heated both by the combustion of the binder system and the heat introduced by the metal poured into the casting mold 2, as well as by the preheated filling material F. As a result, the moldings and cores of the mold 2

cohesive binder system almost completely

destroyed. The moldings and cores then break up into fragments B or individual grains of sand.

The fragments B and the loose sand fall through the sieve tray 1 in the sump 5 and is collected there. Depending on the progress of the destruction of the casting mold 2, the sieve bottom 1 can be opened in such a way that contents F also enter the collecting container 5 (FIG. 8).

For optimal combustion of outgassing of the mold 2 gases and for the regeneration of the

Kernsandes already in the enclosure are the - -

Temperatures of product F and the gases flowing in the filling chamber 10 optimally each well above 700 ° C. The conditions in the thermoreactor T are designed so that the regeneration process and the

Exhaust gas treatment independently of system availability run independently. Determining and set sizes are the starting temperature of the filler F, the oxygen-containing gas streams S1, S2 flowing in via the gas inlet 15 and the inlet 16, and the casting mold 2 itself.

The progress of the destruction of the casting mold 2 and the solidification course of the cast iron melt poured into the casting mold 2 are adapted to each other so that the casting G is sufficiently solidified when the disintegration of the casting mold 2 begins.

After the casting mold 2 has essentially completely disintegrated, the collecting container 5 with the molding material / product mixture contained in it is separated from the sieve bottom 1 and the housing 7 likewise removed from the sieve bottom 1. The largely sanded casting G is now freely accessible and can in a this

provided tunnel-like space 17 controlled

are cooled (Fig. 10). Due to the process, the casting G has a high picking temperature at which the austenite transformation is not yet completed and rapid cooling would lead to residual stresses and thus to cracks. For that reason, that will

Cast G in a cooling tunnel 17 slowly cooled according to the glow curves during stress relief annealing. The supplied cooling air is measured so that the

Cooling profile is achieved product-specific.

The still contained in the container 5, still hot mixture of filling material F, core sand and fragments B is in a grinder 18, which may be, for example, a rotary tube, mixed intensively and mixed with sufficient oxidation air, so that

possibly still existing binder residues

afterburn. In this process step, the contents F of core sand can be separated and both fed to a separate cooling. Such

Nachregenerierung ensures the safe adherence to a complete combustion of the binder system and prepares additionally by mechanical friction the

Core sand surface for good adhesion of the binder for reuse as core sand.

The resulting core sand is cooled down to near room temperature and, after fractionation, recycled to casting moldings or casting cores for a new casting mold 2.

The contents F, however, on the intended

Start temperature Tmin cooled and in the circuit for refilling the filling chamber 10 in the

Reservoir V filled.

The amount of in the filling space 10 as gas streams S1, S2 conducted combustion air is controlled by mechanically adjustable flaps or slide, with which the Öffnungsguerschnitte the gas inlet 15 and of the access 16 can be adjusted. The respective

Adjustment can first be determined via the stoichiometrically required amount of air for combustion of the binder system and then finely adjusted via measurements of CO, NO x and 02 at here formed by the opening 14 of the lid 13 exhaust outlet 19, which is formed in the lid 13 and on the in the filling chamber 10 resulting exhaust gases are discharged from the enclosure 7.

As is apparent from Fig. 16, in the filling space 10th

Immediately after casting by the evaporation of the solvent from the binder system of the mold 2 and the other evaporations of the mold 2 a high through the curve KSchadstoff shown

Pollutant concentration reached, even at

Room temperatures would burn independently. The limit KGrenz, from at room temperature a

Pollutant concentration is reached, which is combustible, is shown in Fig. 16 by the dotted line

specified. Because of the high minimum temperature Tmin of 500 ° C, which prevails in the filling chamber 10 through the introduced there hot filling F, the combustion of the reaching into the filling chamber 10 from the mold 2 but already at a much lower gas

Concentration (see Fig. 16).

Due to the combustion within the granulate in phase 1, the granules heat up and its temperature TFüllgut exceeds after a short time

Limit temperature TGrenz of 700 ° C, in the organic substances known to be at sufficient oxygen content oxidize independently and thus burn. The course of the temperature TFüllgut is shown in Fig. 16 as a dashed line.

This phase ("phase 1") intensive combustion of the evaporating from the mold 2 binder continues until the concentration KSchadstoff of reaching into the filling chamber 10 from the mold 2, essentially formed by the vaporizing binder combustible gases decreases so much that at Room temperature no combustion would take place.

Due to the high product temperature of more than 700 ° C, as described above, this oxidation or

Combustion in the subsequent phase 2 still continued, with the released heat

is sufficient to further increase the temperature of the medium 10 until the maximum temperature Tmax is reached. At this temperature, the contents remain 10 until the decomposition process of the mold 2 has progressed so far that no significant outgassing more

take place, the mold 2 is divided into small pieces and the mold residues fall into the container 5. However, as long as 10 combustion processes take place in the filling space, so much heat still arises that the

Filled material F remains for a sufficiently long period of time in a range whose upper limit is the temperature Tmax and the lower limit of the temperature is TGrenz.

According to the invention is thus by the choice of

Temperature at which the filling material is filled in the filling space 10, the time at which the limit temperature - -

TGrenz of 700 ° C is exceeded, so set that this is reached before by low

Pollutant concentrations KSchadstoff the process of combustion in the filling space 10 no longer takes place reliably with the necessary intensity. The then highly heated filling material F then ensures that the decomposition and residual combustion of the gases still evaporating from the casting mold 2 takes place, even if the concentration of combustible gases present in the filling space per se would be too low at temperatures below the temperature TGrenz.

It could be proven that with in the

Mold 2 contained evaporative and combustible substances so much chemical energy is available for combustion that product temperatures of well over 1,000 ° C could be achieved. In this case, however, the cooling of the casting would be far

delayed, so that long residence times would be necessary. This too can be due to the starting temperature

are determined, with which the contents F is filled in the filling space 10. Likewise, too strong

Temperature increase by an increase of then as

Cooling air acting gas streams S1, S2 can be prevented.

In the choice of the product F, in which it is

For example, is ceramic filler, care is taken that the individual grains of the filling F have a high compressive strength to absorb the compressive forces during casting and to keep the abrasion loss as low as possible in circulation. Another one

Selection criterion is a low heat capacity in Combination with the bulk density of the product F to get a temperature rise above the 700 ° C as quickly as possible from phase 1. Due to the oxidation in the bulk material, with adapted combustion air supply and relatively low temperature, a nitrogen oxide formation is largely avoided.

Since the exiting exhaust gases according to the invention in

Essentially even in the first phase the

Heating up the filling material results in a

Temperature profile within the bed, which ensures clean combustion. The combustion air follows due to the resulting in the filling chamber 10

Wärmekonvektionsströmung a vertical upward direction and the outgassing of pollutants from the mold 2 due to the strong vapor formation in the first phase of a horizontal direction in the filling package into it. By crossing the gas streams within the product F good mixing is ensured.

In the region above the casting mold 2, the gas streams are then rectified and can sufficiently afterburn in the hottest region of the exhaust system in the combustion chamber between the lid 13 and filling F before exiting the exhaust outlet 19 above the sprue.

In an example calculation, on the basis of the parameters and material values given in Table 1 for a process according to the invention, the heat energy Qa released by the cooling of the melt and the combustion of the binder as well as for the heating of the contents and the heating of the core sand of the mold required heat energy Qb has been determined.

It has been assumed that a gray cast melt is poured into a mold as a melt, the moldings and cores are made in the conventional cold box process of molding material, the

conventional core sand, d. H. made of quartz sand, and for this purpose just as common binder.

Simplifying it has also been assumed that the

Casting metal after casting gives off its heat to the casting mold and the filling material and that the chemical energy inherent in the binder used in the form of

Heat of combustion is completely available for heating the medium.

The dissipated to solidify the melt

Melt heat Hfus is then calculated according to the formula

Hfus = m _Schme i _Z ex hfus x 1/1000 MJ / kJ thus in the present example too

Hfus = 170kg x 96kJ / kg x 1/1000 MJ / kJ = 16.3MJ.

The heat energy Qal, released from the melt during cooling, is then calculated according to the formula

Qal = cp x ΔΤ xmx 1/1000 MJ / kJ - Hfus in the present example with ΔΤ = (T1 - T2) = (850K - 1500K) = -650K too

Qal = 950 J / kgK x -650K x 170kg x 1/1000 MJ / kJ - 16.3 J Qal = -121MJ.

In a corresponding calculation results from the combustion of the binder contained in the molding material released heat energy Qa2 according to the formula

Qa2 = hi xm _Bi Direction (-1) to

Qa2 = 30MJ / kg x 4kg x (-1) = -120MJ.

The sum of the released heat energy Qa = Qal + Qa2 is then -241MJ.

The time required for the heating of the core sand of the mold from the temperature Tl to the temperature T2

Heat energy Qbl is calculated according to the formula

Qbl = Cp kernel X (T2 - Tl) X m _Ke rnsand

TO

Qbl = 835 J / kgK x (800K - 20K) x 255kg = 166 [MJ].

The same applies to the warming of the

Core sand of the mold from the temperature Tl to the temperature T2 required heat energy Qb2 according to the formula Qb2 = cpFuugu _t x (T2 - Tl) xm _FU1 i _good to

Qb2 = 754 J / kgK x (800K - 500K) x 125kg = 28 [MJ].

The core sand of the casting mold, which was initially at a room temperature of 20 ° C., and the filling material filled with the temperature T 1 of 500 ° C. to the final temperature T 2 of 800 ° C. required heating

Heat requirement Qb = Qbl + Qb2 is then total

Qb = 166MJ + 28MJ = 194MJ.

According to the parameters given in Table 1, as a result of the heat input through the melt and the combustion of the binder emerging from the casting mold, a heating of the filling material F and of the

Compensation of tolerances and losses available energy surplus of 47 MJ.

The determination given in Table 1 of an energy balance achievable during the casting of a gray cast iron molten metal casting shows that a significant excess thermal energy capacity is present when conventional moldings based on a conventional binder system and using quartz sand are used. The supplied oxygen-containing

Gas streams S1, S2 are in this consideration

neglected, since their influence is energetically very low. In Table 2 are different bulk materials, which in terms of their temperature resistance

principle for use as filling material in question, the bulk densities SD, the specific

Heat capacities cp and the product P = Sd x cp

specified. It turns out that, for example, steel gravel has a significantly lower specific heat capacity cp than a ceramic granulate of the type mentioned here, but a clearly too high bulk density

has, according to the invention prescribed

To ensure gas permeability of the intended in the filling space around the mold Füllgutpackung.

- -

REFERENCE NUMBERS

1 sieve plate

2 mold

3 mold cavity

4 peripheral edge heel

5 collection containers

6 sealing element

7 enclosure (housing)

8 peripheral surfaces of the mold 2

9 Inner surface of the enclosure 7

10 filling space

11 opening of the enclosure

12 distribution system

13 lids

14 Opening the lid 13

15 gas inlet

16 access

17 cooling tunnel

18 grinder

19 exhaust outlet

B fragments

F contents

G casting

S1, S2 oxygen-containing gas streams

T thermoreactor

U environment

V reservoir

Table 1

Table 2

Claims

PATENT APPLICATIONS

A method of casting castings (G) in which a molten metal is poured into a mold enclosing a cavity (3) forming the casting to be produced, the mold (2) being a lost mold of one or more mold parts or consists of a molding material consisting of a core sand, a binder and optionally one or more additives for the adjustment of certain

Properties of the molding material, comprising the following steps:

- Providing the mold (2);

- Elnhausen the mold (2) in a housing (7) to form a filling space (10) between at least one inner surface portion (9) of the housing (7) and an associated outer surface portion (8) of the mold (2);

- filling the filling space (10) with a free-flowing filling material (F);

Pouring the molten metal into the casting mold (2),

- Wherein the mold (2) associated with the

Pouring the molten metal begins to radiate heat, which is the result of the effected by the hot molten metal heat input, and - as a result of the molten metal

caused heat input of the binder of the molding material to evaporate and burn begins, so that it loses its effect and the mold (2) breaks down into fragments (B), characterized in that in the filling space (10) filled contents (F) such a small Bulk density has that after filling of the filling space (10) there formed from the filling material (F) Füllgutpackung of a gas flow (S1, S2)

is flowed through, and that the filling material (F) during filling of the filling space (10) has a minimum temperature (Tmin), starting from which the temperature of the filling material (F) by process heat, by the from the mold (2) radiated heat and by the heat released during combustion of the binder is formed until it rises above a limit temperature (limit) at which the binder evaporating from the casting mold (2) and coming into contact with the filling material (F) ignites and starts burning.

2. The method of claim 1, d a d u r c h

characterized in that the product P of bulk density Sd and specific heat capacity cp is at most 1 kJ / dm ³ K.

3. Method according to one of the preceding claims,

characterized in that the bulk density Sd max. 4 kg / dm ³ .

4. Method according to one of the preceding claims, characterized in that the filling material (F) has a specific heat capacity cp of max. 1 kJ / kgK possesses.

5. The method according to any one of the preceding claims,

The product (F) is formed from granules having a mean diameter of 1.5-100 mm.

6. The method according to any one of the preceding claims,

The temperature of the product to be filled (F) during filling of the product (s)

Filling space (10) is at least 500 ° C.

7. The method according to any one of the preceding claims,

The limit temperature (limit) is 700 ° C.

8. Method according to one of the preceding claims,

d a d u r c h e c e n e, the enclosure includes a gas inlet (15) and a gas inlet

Exhaust outlet (19) and d a s s that in the filling space

(10) contained contents (F) at least temporarily and ^' sections of an oxygen-containing gas stream

(S1, S2) is flowed through.

9. The method of claim 7, d a d u r c h

In other words, the gas stream (S1, S2) is heated to a temperature above room temperature.

10. The method according to any one of claims 7 to 9,

d a d u r c h e k e n c i n e, the gas flow (S1, S2) is dependent on the

Exhaust outlet (19) exiting exhaust gas volume flow

is regulated.

11. The method according to any one of claims 7 to 10,

In the exhaust gas outlet (19), an exhaust gas measurement is carried out and the gas flow (S1, S2) is regulated as a function of the result of this measurement.

12. The method according to any one of claims 7 to 11,

That is, a partial flow of the combustion gases leaving the exhaust gas outlet (19) is mixed with the oxygen-containing gas stream (S1, S2) and the resulting mixture is passed into the housing (7).

13. The method according to any one of the preceding claims,

characterized in that the housing (7) with a catalyst device for Decomposition of pollutants contained in the combustion products of the binder is equipped.

14. The method according to any one of the preceding claims,

The casting mold (2) is placed on a sieve bottom (1), and the fragments (B) of the casting mold (2) and the filling material (F) trickle together through the sieve bottom (1), collected, processed and after the

Preparation be separated from each other.

15. The method according to any one of the preceding claims,

The casting (G), after the disintegration of the casting mold (2), undergoes a heat treatment in which it is cooled in a controlled manner in accordance with a specific cooling curve, the casting (G) is subjected to a heat treatment.