DE19929761A1 - Core for components consists of a hollow molding with a single hollow body formed by applying a suspension of a powdered first base material and binder onto the surface of a support material to form a cladding layer, and sintering - Google Patents

Abstract

Core for components consists of a hollow molding with a single hollow body formed by applying a suspension of a powdered first base material and binder onto the surface of a support material to form a cladding layer, and reinforcing by sintering.

Description

The invention relates to a core and a manufacturing method for components with ge closed cavity profile, the components being produced using the casting process the, with the features of in the preambles of claims 1, 2, 21 and 22 described genera.

The manufacture of cores for components with a closed cavity profile leaves execute for cast components by means of various casting processes. It can permanent forms or lost forms are used in all these cases len is the core before pouring the melt using brackets in the Mold cavity introduced. For this purpose, conventional molds are used Core supports or supports specially adapted to the respective casting process stanchions used.

The use of cores for components with a closed cavity profile is a requirement to be met today, for example in lightweight construction. A casting tech nik with cavity profile and core offers the possibility of thin in component design to produce wall components with struts and different wall thicknesses gene, despite a weight reduction achieved by inserting a core represent high-strength components that have high rigidity with minimal weight and  weight reduction due to a thin outer wall of the casting chen. Castings with a closed profile are usually much stiffer and lighter than open profiles and external ribs and beads for reinforcement fung. Above all, cast components with high rigidity, high torsion and bending moments have to be transmitted, are often considered as closed hollow bodies Made from thin sheet metal shells or cast from aluminum materials.

For the manufacture of components it is in the gravitational casting process and Nieder State of the art die casting process, a cavity profile with sand cores, Insert wax, polystyrene and other materials into the respective mold. These cores are either cast in through existing openings after casting removed the wall of the cast component or leave it there. From DE 41 16 837 C2 is a torsion bar stabilizer for motor vehicles, which consists of a There is a U-shaped tube with reinforcement inside. The Ge The subject of DE 41 16 837 is that the reinforcements from after Bending and internal shot peening of the tube at least in its curvature range internally stiff and / or volume-constant core fillings a flowable or free-flowing agent, which after the application foams and / or cures. The core filling fills the entire pipe. The core filling exercises at least in the highly stressed curvature areas a support effect is sufficient and thus acts as a cross-sectional deformation of the Tube against load.

DE 195 01 508 C1 describes a component for the chassis of a motor vehicle previously known, which consists of die-cast aluminum and a cavity profile points, in the cavity of which there is a core made of aluminum foam. In a Die cast aluminum cores are introduced, which after the Pressing the liquid aluminum into the mold in the aluminum component  die casting remain. The core made of aluminum foam consists of a Mi aluminum powder with a blowing agent, and this mixture becomes Foaming in the core mold heated to a temperature of about 800 ° C where at this temperature the gas enclosed in the blowing agent is released is so that it is similar to polyurethane foam, and the aluminum foaming powder. At the same time, aluminum grains are baked together, so that a foamy mass fills the contour of the core shape. The frothy According to the information in DE 195 01 508, the mass has a closed porosity and withstands pressures above 30 bar. The core of foamed Aluminum is used in the less stressed areas in the inner wall of the casting Stuffed so that an eveni between the core and the tool long distance remains in the desired wall thickness. Disadvantages of using Metal foams as well as aluminum foams for the production of hollow spaces show up due to the low strength of the foam bubbles at ent speaking casting conditions that lead to a collapse of the foam structure ren. Another disadvantage is that the metal due to the high pressure partially melt into the pore structure of the metal foam made of aluminum penetrates and thereby at least partially fills the cavities. The intrusion or the destruction of the foam bubbles in metal foams is once caused by this gently that the cell walls of the metal foams have no exact spherical shape, d. H. in principle, they can only withstand relatively low pressures. On the other hand, has shown that the walls of the metal foam bubbles are still small perfora have ions that cannot withstand high pressure during casting.

Finally, metal foams also have the disadvantage that the thickness of the walls the metal foams can not be adjusted and therefore the walls of these Foam membranes do not withstand very high pressures, as they usually do are required for die casting processes. The cores made of metal foams can therefore the high flow rates of the melt when filling the  Do not withstand the mold because the flow rate of the liquid The melt at the gate is usually between 30 and 70 m / s. Beyond that metal foams can also withstand the high pressures in the die-casting process not to be resisted during the holding phase, as these pressures exceed 50 bar are. The liquid melt can therefore, as already stated, to at least partially in the pore structure of the metal foams and fills there through at least part of the cavities of the core of the casting.

There is also a method for producing hollow metallic bodies in Known spherical shape, in which, for example, directly on polymeric carrier materials or after a possible surface treatment galvanic metallic Layers are deposited. These metallic hollow bodies have in common that it has so far gained no practical significance, primarily for cost reasons have, because the finished metallic hollow spheres must first be produced sen, which are then arranged in further process steps to each other and by Sin tern, soldering or gluing to the desired structure. This me Tall hollow bodies have the disadvantage that the only less technically in interesting but electrodepositable metals can be produced. Another disadvantage of the metallic hollow body is the fact that when Heat treatment of the hollow metal spheres is the polymeric carrier mat decompose and when the carrier materials escape, a hole in the Hollow body remains. These hollow bodies must then be replaced by others Treatment still be sealed so that the metal melt during the Pouring can not penetrate the hollow body. On a galvanic way Metal hollow bodies are produced in the production of larger wall thicknesses Hollow bodies can only be produced with very expensive effort.  

It is therefore an object of the present invention, a simple, inexpensive and core suitable for mass production and a method of manufacture provide this core for components with a closed cast To create cavity profile, which is pore-free and thus gastight, fer ner a reduction in core weight and at the same time an increase in the egg Stiffness allowed especially in the die casting process, beyond that from even the highest pressures during the holding pressure phase of the casting process Die casting processes can withstand and also a variable extent allows the integration of the core in the cast component.

These tasks are inventively by the in the characterizing Tei len of claims 1, 2, 21 and 22 specified features. Advantage Adherent developments of the subject matter of the invention are in the features of Subclaims 3 to 20 and 23 to 40 characterized.

The advantages of the invention consist in particular in the invention Interaction of the features that a hollow mold is used as the core and the mold hollow body consists of at least one single hollow body, wherein the single hollow body arises from the fact that on the outer surface of a carrier fes a suspension of a powdery first base material component and of a binder for initially forming a cladding layer for a single hollow body green is applied. Then the individual thus formed hollow green body through a sintering process to a through the original Form of the shell layer of the carrier molded single hollow body solidified. It can, if the first base material component used sintering up to Pore closure does not allow a second base in this first embodiment material component with lower melting point to the first base material component can be added. The binder and the carrier can in the  Heating in the course of the energy supply for the sintering process by the temporarily porous shell layer of the carrier escape before melting the Be components of the second base material component is the microporo still present density of the cladding layer until the pore is closed when the melting temperature is reached the second base material component are sealed while the powder shaped components of the first base material component because of its higher Do not melt the melting point, but only with the neighboring ones Crosslink components of the first base material component. By adding towards a lower melting point compared to the first base material component The second basic component is a completely gas-tight single hollow by sintering body generated.

The same advantage of producing one up to the pore closure of the microporosity sintered and gas-tight single hollow body can also be used with a second one Achieve embodiment in which instead of the second base material com component the application of an additional coating layer occurs. In doing so, between two or on the existing cladding layer for the single hollow body green body an additional cladding layer using an additional variant of the first Base material component applied. The additional variant of the first base The material component is made of the same material as the first material Component manufactured and differs, however, in that the powder Components of the additional variant of the first base material component are finer are crushed as the large powder components of the previous ones Cladding layers from the first base material component. Even with this finer zer The smallest variant of the first base material component can be found in the envelope layer of the single hollow body green body present microporosity down to the pores close the end. Would the single hollow body only be chopped from the finely nert powdery components of the variant of the first base material compo  If they were to produce nente, the production of the cores would be very expensive and thus unwelcome become economic. That is why the normal cladding layers from the first Ba Sismaterial component made only from coarsely crushed powder components and is therefore inexpensive to manufacture. Even if several normal Envelopes from only roughly crushed first base material components can be applied to each other, even after sintering, an open Wed Croporosity be present in the shell of the single hollow body. Only by the addition of either a second base material component with low Melting point as the powder components of the first base material components or by coating with an additional coating layer from an additional Vari ante the first material component with finely crushed powder components can be a pore closure and thus a gas tightness of the individual hollow body achieve that when using the single hollow body as a hollow mold for one Core in a component of die casting technology is absolutely necessary because of the high pressures prevailing there, especially in the holding phase, with over 50 bar so that the cores can withstand these conditions. Another Advantage is the changeability of the thickness of the wall indicated above Single hollow body either by varying the length of the coating time or by applying several enveloping layers one above the other, so that the compressive strength of the individual hollow bodies required in the respective application can be achieved by increasing the wall thickness.

A reduction in the weight of the core and thus the casting with a hollow spatial profile is achieved in that from the single hollow body green body the binder and also the carrier during the heating process at Sintering can escape, leaving only the outer walls of the original Single hollow body remain. Beyond that, however, there is a high inherent rate ability of the core is achieved in that the outer surfaces of the carrier materials of the one  hollow cell green parts in a defined and from a stable geometric Form are built. For example, the shape of the carriers and thus the resulting shape of the single hollow body can be designed as a ball. On also very stable single hollow body can by a corresponding shape of the Carrier material, for example, be formed as an ellipse or in any other for such a purpose appropriate design, the stresses of the respective has grown in use. Is the single hollow body out as a ball forms, so several individual hollow bodies together to form a hollow body measure by first applying the suspension layers to the Single hollow body green compacts are applied. Several single hollow body green ge are then cold in a mold before the start of the sintering process filling tool filled, the shaping tool the shape of the tailored to the respective application hollow green body, so of the core to be inserted into the casting. The green hollow body blank then stands out from numerous spherical single hollow body green bodies the shape of the shaping tool in the cold state in the desired Core shape are brought. Then the green body of the mold is sined tert, so that after the end of sintering, a hollow mold is formed, the corresponding to the number of single hollow body green compacts from individual hollow bodies exists, which are connected by the sintering, but all on hollow cell bodies each contain a cavity.

The shaping of the hollow moldings in the mold can be advantageous ting tool by pressure with a stamp on all individual cavities perform body greening. If single hollow bodies in spherical shape are used, so they form on the outer sides of a one made of several individual hollow bodies Molded hollow body pore-like depressions between the individual hollow bodies pern, which are themselves dense. By applying pressure with the  Stamps on the individual hollow body can be used in the manufacture of the molded hollow body now the diameter and its resulting from the outside Extending the depth of the pore-like depressions between the individual hollow bodies control with regard to the size and depth of these pores deepening. The range of size and depth of the pore-like ver depressions can go as far as their total closure, by correspondingly stronger Pressure is exerted so that the single hollow body green parts deform until the Depressions are closed. The number of pore-shaped depressions the outside of a green body and thus the hollow body the individual hollow can be changed by changing the size or the diameter body greenlings vary. The changeability of the pore-shaped depressions on the outside of a hollow mold body allows a variable extent the integration of the core in the melt of the cast component. Depending on how deep and wide the pore-like depressions are according to the requirements a particularly high or a lower one for the respective application Degree of integration of the core consisting of a hollow mold body in the Cast component, d. H. possible with the surrounding melt.

The base material and the base material components for the production of the A hollow cell body and the hollow mold body are preferably made of metal and / or ceramic powder components. The processing of this materia Lines to individual hollow bodies enable the density of the base material to be broad Limits to vary. At the same time, a extensive adaptation to the operating requirements are carried out at for example with regard to high temperature strength or resistance in corrosive media, but also with regard to the demand for statistical reliability Liquidity and predictability of the hollow body or core, which often comes to an end rigid cross sections can be used. Become the single hollow  body and the hollow body made of several individual hollow bodies Single hollow body green compacts are made, so the detour over the manufacture a separate metallic single ball as with the galvanic methods layer formation avoided. Since the manufacture of the single hollow body and Molded hollow body does not take place via a liquid phase, no signifi can edged accumulations of material in cell corners, so that the individual generated hollow body structures in the mold hollow body in a spherical shape in a positive manner use the principle of inserting material primarily in the spherical edges where it contributes most to the increase in strength.

The invention will be explained in more detail below on the basis of exemplary embodiments explained.

A core according to the invention for components with a closed cavity profile is in its structure and production described below. During construction parts are castings that are used in a wide variety of casting processes can be produced. Special requirements for a core for castings to create a cavity profile, the die casting process, which the jewei flow around the cores at high flow rate when filling the mold and where the cores have extreme pressures especially in the holding phase have to withstand more than 50 bar. A core according to the invention is out a molded hollow body, this hollow body only in extreme cases can consist of a single hollow body. In the case of an extreme bela Stung as in the die casting process, however, it is advantageous to the individual hollow body to build in a defined and from a stable geometric shape, like that is the case for example with a ball. The structure of the single hollow body takes place over a carrier, which in the case of extreme stress, such as outlined above, has a spherical shape. That means balls are made  the lightest possible carrier material such as expanded styrene used on the outer surface of a suspension from a powdery he Most base material component, which is mixed with a binder, up brings. After drying the suspension is on the spherical carrier a coating layer of the powder material of the base material component and the Binder formed, the spherical carrier with the cladding layer forms in front of the Sintering a so-called single hollow body green body. The strength of through the Suspension applied cladding layer and thus the thickness of the wall of the individual Hollow body green can now be changed by one by a Suspensi on layer formed from base material and binder on the carrier further enveloping layers are applied to the single hollow body green or by varying the length of the coating time. The thickness of the cladding layers and thus the thickness of the wall of the individual hollow body depends on the pressure loads on the individual hollow body when pouring in the respective individual case be exercised by. At high pressures, you become the wall of the individual Reinforce the hollow body with several or a thicker covering layer accordingly.

In a first embodiment according to the invention, there is the base mat rial from a powdery first base material component. It can be a second Base material component can be added. When the first base material com component consists for example of powdered iron base material, contains the single hollow body still has a microporosity after sintering. This micro porosity, if the first base material component used sinters to does not allow for pore closure, can be invented in two different ways Eliminate properly. Once the first base material component is left a second base material component supplied in the form of a liquid Me talls is formed, such as copper. The sintered single hollow bodies are treated by soaking in the liquid metal until the pores are closed  and so gas-tight, the second base material component having a lower one Has melting point as the first base material component. The second way to Sealing of the microporosity in the individual hollow after sintering bodies that are made of an iron material, for example, consists of that the single hollow body is coated with a second base material component and then a second sintering process until the pore is closed are trained, the second base material component also having a low has a higher melting point than the first base material component and second base material component again, for example, as a copper material is chosen. The coating in the second way of the individual hollow body can For example, by rolling in fine copper powder, the Zu administration of an adhesive may be appropriate. That in the second sintering process Liquid copper powder in the form of the coating on the single hollow body the microporosity then infiltrates when the melting point of the copper is reached the wall of the single hollow body. The by applying a suspension from a powdery first base material component and binder on the outside surface of the carrier layer formed is initially not porous. By the heating process begins during sintering, this layer begins po to become red when the binder components contained therein decompose, which et what can be the case at 250 °. The between the metal or ceramic powder part The remaining binder remains ensure the cohesion of the base material components and thus for a sufficiently stable shell for the next loading to be able to carry out steps. By decomposing the binder parts except for certain binder residues between the powder particles of the base material component, the covering layer applied to the carrier material becomes porous. By this then porous coating layer escapes at a higher temperature level Carrier z. B. Styrofoam or any other desired carrier material about a temperature of 400 ° C. At the subsequent tempera  ture increase during sintering, the diffusion processes between the Metal powder parts of the base material components, in which there are metallic Build bridges between the powder components. This creates a metallic cal envelope around the carrier. The escape of the binder and on closing the carrier material of the single hollow body green body is therefore possible because the decomposition temperature of the binder is below the decomposition temperature of the carrier is determined and the decomposition temperature of the carrier is again selected so that the decomposition temperature of the carrier below the melting points of the respective base materials or base material com components for the single hollow body green bodies. Specifically, that means at the start of melting of the second powdery base material components te is before and during the duration of the sintering process with increasing energy pouring and heating first the binder and then the carrier due to the temporarily porous covering layer of the individual in the course of the sintering process hollow green body escaped. At the end of the sintering process, the on zelhohlkörpergrünling then through the original shape of the envelope of the Carrier shaped shape, which by the base material components and Sintering is solidified.

To reduce the weight of the kernel and increase the egg To achieve rigidity and thus the compressive strength, it is advantageous to form core-forming shaped bodies from several single hollow body green bodies.

This is done in a shaping tool in which the single hollow body green be filled in cold and by pressure from egg stamp on all single hollow body green bodies take the shape of the core, for which the shaping tool is designed, the hollow mold body green body is produced from the single hollow body green bodies in the cold state, while it has been common until now, the connection of the individual balls by heating  the balls and the existing pressure. The existing one Pressure was created by re-foaming z. B. of styrofoam in a heated form. With the help of the shaping tool it is therefore possible to match one to the respective to form coordinated hollow body green body application. The To cohesion of the single hollow body green parts in the forming tool by dissolving the coating or the binder before or during the Pressurization by means of the stamp in the shaping tool. By doing Shaping tools can be made suitable, for example, by porous mold walls th solvent to the single hollow body green bodies in the interior of the shaping tool are fed. A firm connection of the single hollow body green Successful drying is achieved by drying the loosened layers achieved. There may be an accelerated evaporation of the solvent by heating and / or flow through the mold with a suitable gaseous medium order to be achieved. After the formation of the green body in the The shaping tool is sintered using the same methods, as schil above for the single hollow body green sheets in the manufacture have been changed and will therefore not be repeated. With the ge described manufacturing process for hollow moldings can also be a sta biler and flat connection of the spherical single hollow bodies with each other achieve so that the core formed as a hollow body has a high permanent change has self-resistance. Such hollow moldings became several million Load changes exposed to swelling pressure loads without an external che damage or setting behavior was recognizable, with an outstanding deformation behavior under pressure load could be observed.

A second embodiment for creating a core for components with ge closed cavity profile for components manufactured in the casting process in that a thin additional coating layer on the single hollow body green  Use of an additional variant of the first base material component brought. There is the additional variant of the first base material component made of the same material as the first base material compo nente itself. The powder components of the additional variant of the first base mat rial components differ in the finer size reduction of the powder parts compared to the roughly held powder components of the previous one Cladding layers from the first base material component of the single hollow body green lings. The crushing of powder components of the base material components is very expensive, so they were put on the outer surface of the carrier materials often brought cladding layers thick according to practical requirements Layers used only roughly crushed powder parts, for example must be generated by grinding. Since the cladding layers have already been cut only from the first base material component together with the binder a microporosity coating on the support for the individual hollow green body result, are now very inventive feature finely crushed powder components in the form of the variant of the first base material component added to the base material mixture. These very finely chopped Powder components of the variant of the first base material settle in during sintering the existing open pores of the other cladding layers from only roughly zer smaller powder components. This will make these pores in the normal envelope layers closed and there is a non-porous and therefore for the use in casting processes, especially die casting processes with high pressures and temperatures of the required gas-tight hollow bodies by the sintering. These individual hollow bodies can be combined into several in one mold Molded hollow body are formed under external pressure and thus ent form the speaking core for a casting. By applying only one tens of additional coating layers on the inside of the carrier material, between two from the first Base material component formed cladding layers or on the outside  Envelope will be great cost savings when crushing the powder components of the additional variant of the first base material component light, since only small amounts of powder components of the additional variant of the the first base material component for the application of the additional coating layer are necessary, while for the other coarse envelopes, the coarse ones first base material component for building the load-bearing walls of the single hollow body is used, which forms the largest part of the wall material. A as The core of the hollow molded body can, however, also consist of only one single cell hollow body exist, which directly describes the cavity of the core. there can the outer shape of the outer surface of the single hollow body once by Aus Embossings are formed in a form for the carrier or on the other hand can the core shape from a larger than the hollow mold Ma material block be formed from a carrier, in both cases the shape of the one hollow body is tailored to the specific application. From a existing single hollow bodies can be cast during the casting process use ren, for example with low filling speed and small Casting pressure work, and thus the laminar and turbulence-free mold filling in rising pour is possible. In addition to gravity die casting, there is also the never derdruckkokillenguß for such consist of a single hollow body de Molded hollow body suitable as an area of application.

A shaped hollow body formed as a core can, however, also be made from a loose Ver consist of individual hollow bodies. The outer shape of a loose Compound of single hollow bodies existing hollow body is by a Be limit means achieved that the loose bond of single hollow bodies around closes. This limiting means can be used, for example, as a cage, net or in any other suitable shape be formed, which as a limitation of a loose Ver Bund of individual hollow bodies is suitable for a shaped hollow body.  

Essential to the invention for the present subject matter is the combination of the features of creating single hollow body green sheets by coating a carrier with a suspension of base material and binder, the then deforming the single hollow body green bodies in the cold state in a molding tool to form a green hollow body, the covering layers are initially usually provided with pores. Another feature of this combination is the sintering of the green compacts of both the single hollow body and the shape hollow body with Be matched to different melting temperatures components, such as the rising melting temperature chain with the lowest Most melting binder, then the carrier, then the second base material component up to the highest melting point for the powdery first base material component, the components of which are only sintered together by diffusion become. The base material and the base material components can be in Powder form made of metals and / or ceramics. The adaptation to the Be operating temperatures of the castings or to the other requirements of the castings is done by selecting different base materials, dimensioning the Single hollow body and the production of different suitable geometri orders. This allows special tailor-made custom Form shaft combinations for every application. For the execution of the Cast or the casting on the one hand and for the manufacture of the individual hollow body on the other hand, different materials can be used. That's the way it is possible to produce cores consisting of hollow moldings, which from a whose material is made up of the molten cast iron and in this way the extreme Stresses related to temperature or other parameters during casting can withstand.  

The castings provided with a core according to the invention impair through their inner cavities formed by the core differently than with convents tional cores in no way the casting. When making the mold hollow bodies have the prevailing ambient pressure at room temperature. Due to the described specifically adjustable wall thickness of the individual hollow bodies NEN these must be interpreted accordingly so that they are not in the heating tion close to the casting temperature or the heat treatment temperature of the casting partly expand or even leak and the gas pressure in the casting Let the component escape. It can be caused at any time by the during the Sintering process in the manufacture of the individual hollow bodies and the hollow moldings prevailing atmosphere different pressures from the negative pressure inside half the single hollow body or molded hollow body up to the vacuum in this hollow train bodies. This is made possible by the fact that the carrier material is removed brought enveloping layers of the single hollow body green bodies and the shaped hollow body green compacts are at times porous in the course of the sintering process and therefore always because the selected atmospheric pressure then also within that at the end of the sinter process hermetically sealed single hollow body is preserved. The one The setting of negative pressure or vacuum in the interior enables even thin ones Ren cladding layers of the individual hollow body an expansion of the hollow body in the Er to prevent heating, as is the case, for example, in the heat treatment of Castings occurs. A single hollow body in spherical shape, from which the mold hollow body is constructed overall, is so pressure-resistant that by casting applied pressure and the resulting thermal expansion Pushing or denting can be prevented safely.

The hollow moldings are made up of several spherical individual hollow bodies forms, so pore-like recesses arise on the outer sides of the hollow moldings exercises. The diameter and the resulting from the outside  Extending the depth of the pore-like depressions between the individual hollow bodies is changeable, while the individual hollow bodies themselves are gas-tight. It However, the pore-like depressions can be sized and extended by exerting pressure in the shaping tool on the hollow mold change pergrünling. The single hollow body green bodies are deformed and the diameter changes depending on the amount of pressure applied and the depth of the pore-like depressions until they finally come together like this be pressed that between several single hollow body green bodies pore-like depressions directed towards the interior of the green hollow body completely shut off. The number of these pore-like depressions on the Au ßenseiten the mold hollow body can be changed by changing the size of the hollow cell bodies such as their diameter size vary. Depending on Diameter and depth of the pore-like depressions can be the extent of Change the integration of the hollow molded body formed as a core in the casting or improve. Are spherical single hollow bodies in the manufacture of the as Core-shaped hollow body used, so the resulting po ren-like depressions even under disordered structures different in size. This means that with statistically packed single hollow bodies There is a high uniformity of this pore size in the mold hollow body and depth results. The structures of the spherical individual hollow bodies easy to calculate in the mold hollow body, so that it is possible, for example, the Effect of density and size of pore-like depressions on the egg properties of the core structure relative to the compact material of the casting to calculate. The resulting uniform size of the pore-like depressions in the case of spherical individual hollow bodies in the molded hollow body, a high level is guaranteed statistical security in the calculation, so that, for example, required Minimum strengths of the core can be safely observed, for example as is not possible with metallic foams from the prior art.  

example 1 Support structure made of aluminum and manufactured in sand casting (Machine molding process)

The production of support elements for various machine applications Mechanical engineering can be carried out using sand casting techniques. With these The process is either clay-bound molding sand or chemically bound Quartz sand used. To increase rigidity while reducing it of the component weight, it turns out to make sense to use the conventional rib construction tion through closed profiles from a hollow hollow body made of alloys based on aluminum, iron or titanium. The as Molded hollow body is made with conventional core supports in the Mold fixed, the minimum wall thickness of the outer casting skin that on this can be achieved is in the range of approximately 2 mm. Due to the procedural period of time between the insertion of the hollow mold, the Closing the mold and casting are adhering to the pre-selected Insertion temperature of the hollow mold at the usual casting temperatures between 700 ° and 750 ° C special requirements.

Example 2 Cast iron machine stand and sand cast manufacturing (Hand molding process)

The weight of large castings for heavy machinery can be Introduction of hollow moldings designed as a core while maintaining the Properties of the large casting are reduced. Press stand, machine bed ten and similar components are in bentonite or furan resin-bonded forms cast, which are made by machine. Because of the aluminum high casting temperature is the use of a hollow mold  bodies made of refractory materials based on iron, nickel and titanium required, the casting temperature of cast iron with ball and lamella phit is between 1300 ° and 1500 ° C depending on the composition. The cores Molded hollow bodies are, for example, with conventional core support zen fixed in the mold. Due to the metallostatic pressure and the very Slow cooling and solidification is the fixation of the core Molded hollow body is a central point of the process.

Example 3

Motor mount for passenger cars and lightweight structures made of aluminum um, which are manufactured in gravity die casting.

In gravity die casting, both lost shapes and duration can occur form are used. The molded hollow body formed as a core is also various brackets fixed in the mold. The laminar and turbulence-free Mold filling, which is achieved in the rising casting, ensures the uniform Wetting of the shaped body designed as a core by the melt. Because of the low filling speed and the comparatively low casting pressure are only small requirements for the fixation of the Core executed molded hollow body.

Example 4

Manufacture of large-area lightweight components using the die-casting process.

The high metal speed of the melt and the high casting pressure difficult the exact positioning of the shaped hollow body formed as a core decisive for die casting. These circumstances are dealt with by a form concept this counts both the position of the hollow mold body designed as a core and considering its attachment. The shape made from single hollow bodies Hollow bodies have a high strength according to the invention, so they are  for the production of large-area lightweight components made of aluminum and magne well suited.

Example 5 Squeeze casting

This is due to the slow mold filling and the high degree of densification Squeeze casting process for the production of high quality components made of different material combinations. The local reinforcement of Piston bottoms by pouring ceramic preforms were already in the Production scale realized. The application of this pouring procedure of hollow moldings designed as a core in complex components is in shape Filling speeds below 1 m / s comparable to low-pressure die casting. In principle, however, the high post-compression opens up the possibility of components to be able to produce largely pore-free with longer flow paths.

Claims (40)

1. core for components with a closed cavity profile, the components being produced by the casting process and the cavity profile being filled with a preformed core, and the core is supported in the casting mold with holding means, characterized in that a hollow mold body is used as the core, and that the mold hollow body consists of at least one single hollow body, that by applying a suspension of a powdery first base material component and binder on the outer surface of a carrier material, at least one shell layer is formed for a single hollow body green body, and that the single hollow body green body is then sintered to one by the original shape of the cladding layer of the carrier shaped single hollow body is solidified. 2. Core for components with a closed cavity profile, the components in Casting process are produced and the cavity profile with a pre molded core is filled, also the core in the mold with holding means is supported characterized, that a hollow mold is used as the core, and that the hollow mold consists at least of a single hollow body that by the application a suspension of a powdery first base material component and binder on the outer surface of a carrier at least one shell layer is formed for a single hollow green body that an application  using an additional coating layer on the single hollow body green body an additional variant of the first base material component that the additional variant of the first base material component from the same There is material like the first base material component, but the pul components of the additional variant of the first base material component are finely crushed than the coarse powder components of the others Cladding layers from the first base material component of the single hollow body greenlings, and that then the single hollow body greenling by one Sintering process to a through the original shape of the cladding layer of the Trä gerstoffes shaped single hollow body is solidified. 3. Core according to claim 1 and 2, characterized, that in the manufacture of the mold hollow body from a single hollow body the shape of the outer surface of the single hollow body by stamping in a form for the carrier or by molding the core form from egg nem larger than the molded hollow body block of material made of carrier Fabric is tailored to the application. 4. core according to one or more of claims 1 to 3, characterized, that the outer surface of the carrier material of the single hollow green body in defi nier and executed from a stable geometric shape. 5. core according to one or more of claims 1, 2, 4, characterized, that the shape of the carrier and thus the resulting shape of the Single hollow body is designed as a ball.   6. core according to one or more of claims 1, 2, 4, characterized, that the shape of the carrier and thus the resulting shape of the Single hollow body is designed as an ellipse. 7. core according to one or more of claims 1, 2, 4, 5, 6, characterized, that the molded hollow body be from a loose composite of individual hollow bodies stands, and that the outer shape of the from a loose union of single existing hollow hollow body by a limiting means is enveloped. 8. Core according to one or more of claims 1, 2, 4, 5, 6, 7 characterized, that the limiting means is designed as a cage, net or the like. 9. core according to one or more of claims 1 to 8, characterized, that in the period of the sintering process with increasing warming, the first Binder except for binder residues and then the carrier volatile the, and that this through the porous in the course of the sintering process Shell layer escape from the single hollow body green body that the decomposition temperature of the binder below that of the carrier, and that the Decomposition temperature of the carrier below the melting point of the or of the respective base materials for the single hollow body green bodies.   10. core according to one or more of claims 1 to 9, characterized, that the thickness of the wall of the individual hollow body is changeable, that the wall thickness is varied by the length of the coating time or by Auf bring one or more additional cladding layers onto the single cavity body green is changed. 11. core according to one or more of claims 1 to 10, characterized, that during the duration of the sintering process to produce the single hollow body per from the single hollow body green bodies and the shaped hollow body from the Hollow body green body with a shaping tool each on the Requirements of the planned application are coordinated and changeable atmospheric pressure is adjustable. 12. core according to one or more of claims 1 to 11, characterized, that during the sintering process to produce the individual hollow body and shape hollow body prevailing atmospheric pressure as negative pressure or as a vacuum is trained. 13. Core according to one or more of claims 1 to 12, characterized, that after the application of one or more formed from a suspension several hollow green bodies before the start of the Sintering process in the cold state in a shaping tool Shape of a shaped hollow body tailored to the respective application pergrünling be formed, and that after pretreatment with Lösemit  the shape of the green hollow body parts to dissolve the coating layer in the molding tool by external pressure by means of a Stamp is done on the single hollow body green bodies. 14. core according to one or more of claims 1 to 13, characterized, that the one on the outer sides made of several individual hollow bodies pore-like depressions are formed with respect to their Diameter and their resulting from the outside Extent of depth between the individual hollow bodies in the manufacture of the Molded hollow body controllable and thus change the size and depth are designed such that pressure in the shaping tool the molded hollow body green body for the deformation of its single hollow body Grünlingen is exercised. 15. core according to one or more of claims 1 to 14, characterized, that from the single hollow body green compacts of the mold hollow body practiced pressure is such that between several individual hollow body the pore arti executed to the inside of the green hollow body are closed to recesses. 16. core according to one or more of claims 1 to 15, characterized, that the number of pore-like depressions on the outside of the mold hollow body is variable by changing the size of the individual hollow body.   17. core according to one or more of claims 1 to 16, characterized, that the base material and the base material components made of metal and / or Ceramics exist in the form of powder components. 18. Core according to one or more of claims 1 to 17, characterized, that for the execution of the casting or casting on the one hand and for the manufacture different hollow materials used on the other hand different materials become. 19. Core according to one or more of claims 1, 3 to 18, characterized, that the formed from the first base material component and after Sintering a single hollow body with a microporosity with a second base material component are merged that the second Base material component has a lower melting point than that ste base material component that the second base material component in Form of a liquid metal is formed and that the individual hollow body who is treated by soaking in the liquid metal until the pores are closed the. 20. Core according to one or more of claims 1, 3 to 18, characterized, that the formed from the first powdery base material component and after the sintering still a single hollow body having microporosity per together with a second powdery base material component leads that the second base material component a lower  Melting point has as the first base material component that the single hollow body coated with the second base material component and on then subjected to a second sintering process until the pores are closed becomes. 21. A method of making a core for closed cavity components Raumprofil, whereby the components are manufactured in the casting process and that Cavity profile is filled with a preformed core, further the core in the mold is supported with holding means, characterized, that a hollow mold is used as the core, and that the hollow mold at least consists of a single hollow body that on the outer surface a carrier, a suspension of a powdery first base material component and binder for forming at least one shell layer is applied for a single hollow green body, and that on closing the single hollow green body to one by the original Shape of the cladding layer of the carrier shaped single hollow body sintered becomes. 22. A method of making a core for closed cavity components Raumprofil, whereby the components are manufactured in the casting process and that Cavity profile is filled with a preformed core, further the core in the mold is supported with holding means, characterized, that a hollow mold is used as the core, and that the hollow mold consists at least of a single hollow body that by applying one Suspension from a powdery first base material component and Binder on the outer surface of a carrier at least one envelope  layer for a single hollow body green body creates an additional covering layer on the single hollow body green body using an additional Vari ante the first base material component that the additional Che variant of the first base material component made of the same material like the first base material component, however, the powder inventory parts of the additional variant of the first base material component finer zer are smaller than the coarse powder components of the other casing layers from the first base material component of the single hollow body green lings, and that then the single hollow body green to one through the original shape of the cladding layer of the carrier-shaped single hollow body is sintered. 23. The method according to claim 21 and 22, characterized, that in the manufacture of the mold hollow body from a single hollow body the shape of the outer surface of the single hollow body by stamping in a form for the carrier or by molding the core form from egg nem larger than the molded hollow body block of material made of carrier fabric is tailored to the application. 24. The method according to one or more of claims 21 and 22, characterized, that the outer surface of the carrier material of the single hollow green body in defi nier and executed from a stable geometric shape. 25. The method according to one or more of claims 21, 22, 24, characterized,  that the shape of the carrier and thus the resulting shape of the Single hollow body is designed as a ball. 26. The method according to one or more of claims 21, 22, 24, characterized, that the shape of the carrier and thus the resulting shape of the Single hollow body is designed as an ellipse. 27. The method according to one or more of claims 21 to 26, characterized, that in the period of the sintering process with increasing warming, the first Binder except for binder residues and then the carrier volatile the, and that this through the porous in the course of the sintering process Shell layer escape from the single hollow body green body that the decomposition temperature of the binder below that of the carrier, and that the Decomposition temperature of the carrier below the melting point of the or of the respective base materials for the single hollow body green bodies. 28. The method according to one or more of claims 21 to 27, characterized, that the thickness of the wall of the individual hollow bodies is changed in that the wall thickness is varied by the length of the coating time or by applying one or more additional coating layers on the Single hollow green body is changed. 29. The method according to one or more of claims 21 to 28, characterized,  that during the duration of the sintering process to produce the single hollow body per from the single hollow body green bodies and the shaped hollow body from the Hollow body green body with a shaping tool each on the Requirements of the planned application are coordinated and changeable atmospheric pressure is set. 30. The method according to one or more of claims 21 to 29, characterized, that during the sintering process to produce the individual hollow body and shape hollow body prevailing atmospheric pressure as negative pressure or as a vacuum is set. 31. The method according to one or more of claims 21 to 30, characterized, that after the application of one or more formed from a suspension several hollow green bodies before the start of the Sintering process in the cold state in a shaping tool Shape of a shaped hollow body tailored to the respective application pergrünling be formed, and that after pretreatment with Lösemit the shape of the green hollow body parts to dissolve the coating layer in the molding tool by external pressure on the individual hollow green bodies. 32. The method according to one or more of claims 21 to 31, characterized, that the one on the outer sides made of several individual hollow bodies pore-like depressions are formed with respect to their Diameter and their resulting from the outside  Extent of depth between the individual hollow bodies in the manufacture of the Molded hollow body controllable and thus change the size and depth are designed such that pressure in the shaping tool the molded hollow body green body for the deformation of its single hollow body Grünlingen is exercised. 33. The method according to one or more of claims 21 to 32, characterized, that from the single hollow body green compacts of the mold hollow body practiced pressure is such that between several individual hollow body the pore arti executed to the inside of the green hollow body are closed to recesses. 34. The method according to one or more of claims 21 to 33, characterized, that the number of pore-like depressions on the outside of the mold hollow body is variable by changing the size of the individual hollow body. 35. The method according to one or more of claims 21 to 34, characterized, that the base material and the base material components made of metal and / or Ceramics exist in the form of powder components. 36. The method according to one or more of claims 21 to 35, characterized, that for the execution of the casting or casting on the one hand and for the manufacture different hollow materials used on the other hand different materials become.   37. The method according to one or more of claims 21, 23 to 26, characterized, that the formed from the first base material component and after Sintering a single hollow body with a microporosity with a second base material component are merged that the second Base material component has a lower melting point than that ste base material component that the second base material component in Form of a liquid metal is formed and that the individual hollow body who is treated by soaking in the liquid metal until the pores are closed the. 38. The method according to one or more of claims 21, 23 to 36, characterized, that the formed from the first powdery base material component and after the sintering still a single hollow body having microporosity per together with a second powdery base material component leads that the second base material component a lower Melting point has as the first base material component that the single hollow body coated with the second base material component and on then subjected to a second sintering process until the pores are closed becomes. 39. component that is produced by casting, characterized, that it has a cavity profile, in the cavity of which is a core guided mold hollow body according to claims 1 to 20.   40. casting method for producing a component according to claim 39, characterized, that in the mold or the tool, a hollow mold designed as a core is introduced according to claims 1 to 20, after the casting process remains in the component.