EP1361009A1 - Mould for producing a casting piece using moulding base material and method for producing a mould - Google Patents

Abstract

Casting mold comprises an outer first mold support (4), an outer second mold support (5), a molded body arranged between the mold supports, and an inner layer (12) made from the mold base material applied in areas of the molded body to form a casting hollow chamber. Preferred Features: The molded body has a first half (13) fixed to the first mold support and a second half (14) fixed to the second mold support. The molded body halves lie over each other when the casting mold is closed. The molded body has a number of modular molded body segments (16), preferably made from high temperature resistant material, such as graphite, tungsten carbide or steel.

Description

The invention relates to a mold for producing a casting under Use of basic molding material and a method for producing a such a mold.

Castings, which often have a complicated shape, are usually made in so-called "lost" forms or made in permanent forms. At the Pour into lost molds, usually from a mineral refractory, granular base material such as B. quartz sand or chrome ore sand as well a binder and often also from other additives for improvement of the raw material properties, the mold after casting destroyed by unpacking. In connection with the pouring in lost molds is first a model of the metal casting, Made of wood, plaster or plastic. The model forms the outer contour of the property. The model is basically reusable. to Manufacturing the mold will be the top and bottom of the model in one Molding box, namely an upper box and a lower box, positioned and surrounded with the basic molding material. After compaction and curing of the mold raw material, the model parts are drawn from the sand mold. Then the top and bottom boxes are placed one above the other. The This completes the negative form.

Casting is particularly useful for high-melting Fe-based alloys used with lost forms. Disadvantage when casting with lost Molding is that after each casting process not only a new mold is made must be, but that the reprocessing or disposal of the Mold base material after casting with a high technical and financial expense. It is important in this context in particular, that the mold boxes for the production of the molds usually have a standard format, so that especially with small castings Relatively large amount of mold base is needed to make the mold to be able to manufacture.

Another disadvantage of casting with lost molds is that Cooling segments cannot be positioned exactly. Cooling segments in a lost form, usually to build up a temperature gradient and used to set a controlled solidification. hereby should the feed flow to the "feeder zone" start from the "end zone" of a casting be relieved. Cooling segments are loosely attached to the model in each Box created and fixed by the surrounding raw material. The exact positioning can be done during the compression of the base material of the cooling segment are lost. The exact positioning of Cooling segments are especially useful when casting thin-walled castings of considerable importance.

When casting in permanent molds, thousands to hundreds of thousands of casts can be made achieve with the same shaping device. Permanent forms have an excellent Significance for the comparatively low-melting non-ferrous metal casting materials achieved because the thermal stress that the Permanent molds set limits due to relatively low casting temperatures for Non-ferrous metals is acceptable. Cast iron materials and steel can in principle can also be cast in permanent forms, however, the associated is Cost of manufacture and maintenance due to the used Molded materials (e.g. graphite, sintered metals, ceramic materials) very high. Suitable for casting cast iron materials and steel Permanent forms are therefore very expensive and due to the high thermal load resulting cracks or due to local melting the shape very susceptible to wear.

The object of the present invention is therefore a casting mold and a To provide methods of making a mold, whereby a simple and inexpensive casting of cast iron materials and steel is possible.

According to the invention, the aforementioned object is achieved by a casting mold, which an outer first mold carrier and an outer second mold carrier has, wherein a molded body is provided between the mold carriers and wherein at least partially an inner layer on the molded body Mold base material is provided to form the casting cavity. According to the method is an alternative to producing the casting mold according to the invention provided that the layer thickness of the base material is dependent the wall thickness of the casting to be cast and / or depending on the Solidification behavior and thus also the temperature of the mold introduced melt is selected. In an alternative embodiment is the basic molding material on a modular, in particular Mold carrier fastened mold body half pneumatically by air impulses applied.

Although the type of the casting mold according to the invention is also a lost form arises compared to the prior art essential advantages. Due to the arranged between the mold carriers Shaped body, at least the negative mold or the casting cavity essentially specifies is only a smaller amount of mold base required to produce the actual negative form. Therefore in contrast to the prior art, only a smaller amount is obtained Mold base material with every pouring process. This is especially true for thin-walled ones Castings with a wall thickness between 1 and 10 mm are important. When casting such thin-walled castings, only one falls lower amount of heat from the base material during solidification must be included. The binder of the basic molding material therefore burns only at a depth of a few centimeters. The invention is now accurate exploited this fact and accordingly the layer thickness of the applied molding material depending on the wall thickness of the to be cast Cast part and / or depending on the solidification behavior or Temperature of the melt introduced into the casting mold selected. hereby ultimately, in the optimal case, only the amount of basic molding material is necessary, which is required for technical reasons when casting. In contrast is it in the prior art so that just small or thin-walled Castings have significant amounts of base molding material after casting would still be usable, be recycled. This is not only with increased and in itself unnecessary costs for the Mold raw material connected, but also with a high level of plant technology Reprocessing effort. Higher energy costs also fall on. In addition, the design of the sand preparation of the foundry more complex due to the large amounts of sand. Eventually arise in the prior art large amounts of dusts, which is not just one Can cause environmental pollution, but also increased costs for the Disposal.

However, the use of the molded body according to the invention offers still more Benefits. Since the molded body, which already specifies the negative basic shape, already accounts for a large part of the volume between the mold carriers and consequently only small amounts of sand are required to produce a mold, can achieve significantly shorter cycle times for the production of the casting mold become. Furthermore, it is straightforward in the casting mold according to the invention possible to attach cooling segments to the mold carrier or molded body, so that there is an exact positioning, which, as stated at the beginning, is essential for the production of thin-walled castings. In addition, it is also easily possible that the molded body - with appropriate Material selection - at least in some areas the function of a Cooling segment takes over, namely in areas that are not or only with a small layer of mold base are coated.

Small clock marks can be realized in particular in that the application of the mold base layer to the molded body or the individual Molded body halves are supported by air flow. This can also easily the thickness of the sand layer according to the requirements of a controlled solidification can be set. After applying the Layer, the mold halves are then placed on top of each other, so that the Mold is closed.

It has also been found that when using metallic and / or ceramic mold carriers and a metallic molded body a considerable stabilization of the shape results, which is just for the manufacturing Thin-walled castings are important where tight manufacturing tolerances are observed Need to become.

Of particular advantage in connection with the present invention is to build the molded body modularly, so that it consists of one A plurality of molded body segments. Through this modular Setup makes it easy to add individual modules and thus specify the negative basic shape for the casting cavity. The final The form base material then becomes negative form insofar as it is on the molded body is applied, formed.

Preferred embodiments of the invention result from the subclaims.

Fig.1

eine Querschnittsansicht einer ersten Ausführungsform einer erfindungsgemäßen Gießform,

Fig. 2

eine weitere Querschnittsansicht der Gießform aus Fig. 1,

Fig. 3

eine Querschnittsansicht einer zweiten Ausführungsform einer erfindungsgemäßen Gießform,

Fig. 4

eine weitere Querschnittsansicht der Gießform aus Fig. 3,

Fig. 5

eine Querschnittsansicht einer dritten Ausführungsform einer erfindungsgemäßen Gießform,

Fig. 6

eine weitere Querschnittsansicht der Gießform aus Fig. 5,

Fig. 7

eine Querschnittsansicht einer vierten Ausführungsform einer erfindungsgemäßen Gießform,

Fig. 8

eine weitere Querschnittsansicht der Gießform aus Fig. 7,

Fig. 9

eine Querschnittsansicht einer fünften Ausführungsform einer erfindungsgemäßen Gießform,

Fig. 10

eine weitere Querschnittsansicht der Gießform aus Fig. 9,

Fig. 11

eine Querschnittsansicht einer sechsten Ausführungsform einer erfindungsgemäßen Gießform und

Fig. 12

eine Querschnittsansicht einer siebten Ausführungsform einer erfindungsgemäßen Gießform.

Preferred embodiments of the invention are explained below with reference to the drawing. It shows

Fig.1

2 shows a cross-sectional view of a first embodiment of a casting mold according to the invention,

Fig. 2

2 shows a further cross-sectional view of the casting mold from FIG. 1,

Fig. 3

2 shows a cross-sectional view of a second embodiment of a casting mold according to the invention,

Fig. 4

3 shows a further cross-sectional view of the casting mold from FIG. 3,

Fig. 5

2 shows a cross-sectional view of a third embodiment of a casting mold according to the invention,

Fig. 6

5 shows a further cross-sectional view of the casting mold from FIG. 5,

Fig. 7

2 shows a cross-sectional view of a fourth embodiment of a casting mold according to the invention,

Fig. 8

7 shows a further cross-sectional view of the casting mold from FIG. 7,

Fig. 9

2 shows a cross-sectional view of a fifth embodiment of a casting mold according to the invention,

Fig. 10

7 shows a further cross-sectional view of the casting mold from FIG. 9,

Fig. 11

a cross-sectional view of a sixth embodiment of a mold according to the invention and

Fig. 12

a cross-sectional view of a seventh embodiment of a mold according to the invention.

In each of the figures there is a casting mold 1 for producing one Cast part 2 shown using raw material 3. In which The basic molding material is, in a manner known per se, mineral, refractory, granular material, such as sand, with a binder and optionally other additives. By using mold raw material it is in the case of the casting mold 1, a "type" shape was lost Shape".

The casting mold 1 has an outer first mold carrier 4 and an outer one second mold carrier 5. The mold carriers 4 and 5 are the upper and lower limits of the mold 1 in a horizontal arrangement. It it goes without saying that the casting mold is of course also inclined or vertical can be arranged. If the mold 1 is arranged vertically the mold carriers 4, 5 are also on the outside, but are then on the right and arranged on the left. The following explanations refer to the same Way to the right-left arrangement of the mold carrier, albeit only the top-bottom arrangement of the mold carrier is shown and described. The same applies to the rest of the mold halves described below 13, 14. There is a molded body between the mold carriers 4, 5 6, which usually consists of metal, but at least in some areas can also consist of ceramic. The molded body 6 lies with its outer sides 7, 8 on the inner surfaces 9, 10 of the mold carriers 4, 5. The inner surface 11 of the molded body 6 is profiled and corresponds at least essentially the outer contour of the casting 2. The inner surface 11 of the molded body 6 forms thus a negative preform or an outer preform. On the inside surface 11 of the molded body 6 is at least partially a layer 12 of the basic molding material 3 applied to form the casting cavity, not specified in detail. The layer thickness varies from 0 mm to a maximum of 100 mm and can have any intermediate value without an enumeration in individual would be required.

Although in the individual figures the entire inner surface of the molded body 6 is coated with mold base material 3, it may be pointed out that from For technical reasons, it is basically also possible to use individual surface areas not to coat. This will be discussed in more detail below. Otherwise, it is the case in the illustrated embodiments that the layer 12 of molding material 3 also partially directly on the inner surface 10 of the lower mold carrier 5 is applied. This goes without saying with certain castings 2 also in the area of the upper mold carrier 4 possible, although this is not shown here.

As can be seen from the individual figures, the molded body 6 has a first one Molded body half 13 and a second molded body half 14. The upper Molded body half 13 is attached to the upper mold carrier 4, while the lower mold half 14 is attached to the lower mold carrier 5. In the closed In any case, the mold halves 13, 14 are in the state of the casting mold 1 in their outer edge region 15 on each other, so that the casting mold 1 is closed in this area.

Especially from Figures 11 and 12 it follows that the molded body 6 a A plurality of mold carrier segments 16, in particular of modular design having. The modular structure makes it possible, if necessary, individual Shaped body segments 16 to add or remove to a variation of To achieve thickness of layer 12 to meet the requirements of directed solidification to meet. In the present case, modular also means that the shaped body segments 16 are constructed in a modular manner, that is to say the lengths, Widths and / or heights of the individual shaped body segments 16 one on the other their dimensions are matched, which means that a certain basic dimension n is provided and all dimensions are an integral multiple of the basic dimension n are. The individual molded body elements 16 are each with the respective Mold carrier 4, 5 firmly connected. Is it for realizing a particular Negative mold or negative preform required, molded body elements To arrange 16 on top of each other, it is understood that in this case the relevant molded body elements 16 attached to each other, in particular screwed are. Otherwise, the shaped body segments can be on the outer sides 7, 8 16 and on the inner surfaces 9, 10 of the mold carriers 4, 5 corresponding Guide elements, such as pegs and grooves, can be provided to a exact positioning of the individual shaped body segments 16 or the shaped body halves 13, 14 to ensure the mold carriers 4, 5. Because of the modular structure of the molded body 6, it is easily possible to corresponding Always suitable guide or positioning elements on the relevant one To provide components.

In the individual exemplary embodiments, the shaped body segments 16 are as massive blocks executed. The massive execution leads to a comparatively heavy weight of both the top box 17, which results from the upper mold carrier 4, the upper mold body half 13 and the applied Layer 3 composed, as well as the lower box 18, the lower Mold carrier 5, the lower mold body half 14 and that applied thereon Layer 12 has. For certain applications, one is comparative high weight of the top box is an advantage. In the illustrated Embodiments, the mold 1 is used in low pressure casting. The mold 1 is filled from below, namely via a Opening 19, usually referred to as a gate, in the lower mold carrier 5. Due to the massive design of the upper half of the molded body 13 and that the resulting high dead weight can cause the upper box to “float” 17 can be prevented during casting. Additional means of holding down the upper box 17 or a clamping of the mold 1 can be saved.

It is not shown that the shaped body segments 16 on the respective Mold carrier 4, 5 facing side to save weight even with cavities, Recesses and the like can be provided. This leaves then a weight saving can be achieved, depending on the casting process or application - desired and necessary.

In the embodiment shown in Figures 3 and 4, it is the case that on the molded body 6 on the inner surface 11, that is to say on the base material 3 facing side fixing aids 20 to prevent accidental Detachment of the base material 3 from the molded body 6 are provided. Both Fixing aids 20 are, for example, projections in the manner of monier iron, a loosening of the molding sand due to vibrations prevent in the foundry. Instead of monier iron, it is fundamental also possible, fixing aids in the manner of surface profiling of the inner surface 11 of the molded body 6 to provide a better connection of the To obtain basic molding material 3 with the shaped body 6.

The molded body 6 itself or the individual molded body segments 16 exist preferably made of a high temperature resistant material, such as in particular Graphite, tungsten carbide or steel. Such a choice of materials is in the Rule required because the molded body 6 is subject to high thermal stress subject to casting. In contrast, the mold carriers 4, 5 can cheaper materials are made because of the thermal stress of this Components are usually significantly lower.

In the embodiments shown in Figures 11 and 12 is both one cooling segment each on the upper mold carrier 4 and on the lower mold carrier 5 21 attached. Due to the direct attachment of the cooling segments 21 on the mold carriers 4, 5 there is an exact positioning of these segments, what with regard to a controlled solidification especially with thin-walled Castings is of considerable importance. Draw the cooling segments 21 is characterized by the fact that at least some areas do not have a layer 12 on them Mold base material 3 is applied and therefore from the cooling segments 21 heat energy is dissipated very quickly. Ultimately, it is the Cooling segments 21 around molded body segments 16, which are not or only partially heat insulating molding material 3 is applied.

As can be seen from the individual representations, the basic molding material 3 is included different layer thickness on the molded body 6 or the inner surface 11 applied. In areas where the melt has been liquid for as long as possible should remain, the layer thickness is greater, so that there is a heat insulating Effect. In areas where there is a lot of material of the casting 2 and / or solidification as quickly as possible is the layer thickness very low or in these areas it is entirely based on molding material 3, as in the embodiments according to the figures 11 and 12 in the area of the cooling segments 21 is the case. In any case the thickness of layer 12 can meet the requirements of directed solidification accordingly, taking into account the wall thickness of the casting to be cast 1 can be set and thus optimized.

Even if this is not shown in detail, the basic molding material 3 even pneumatically, in particular through air pulses, i.e. with high Speed and at high pressure, on the inner surface 11 of the molded body 6 applied. The basic molding material 3 is quasi on the shaped body 6 shot up. In this way, the desired one can be set exactly and in the shortest possible time Realize layer thickness. In view of this very quick application of the Mold base 3 on the molded body 6 are not shown in the molded body 6 Openings with a small opening width for discharging air in the case of airflow assisted Application of the basic molding material 3 is provided. The basic mold 3 is fully automatic in the desired layer thickness, which is usually is in the one-digit centimeter range, applied due to the binder contained in the raw material 3, a very quickly Consolidation results. Because of this way of making the negative mold achieve very short cycle times for the production of the mold 1, especially only a very small amount of base material 3 applied to the molded body 6 must become.

As can be seen from the individual figures, the mold carriers 4, 5 are each plate-shaped as so-called base plates. Ultimately take over the base plates merely the supporting function for the molded body 6, which can be any size, but not over the base plates should survive. The invention thus offers the possibility of standardized To use base plates on which, depending on the cast part to be produced, larger ones or smaller shaped bodies 6 are attached. Because of the plate-shaped Forming the mold carriers 4, 5, these only form the upper and lower Completion of the casting mold 1. The casting mold 1 is on the side through the molded body 6 or the superimposed mold body halves 13, 14 limited.

As previously stated, in the present case it is located in the lower mold carrier 5 an opening 19 for filling the mold 1. Basically it is also possible, a corresponding opening in the upper mold carrier 4 or laterally to provide on the molded body 6. The gates are arranged under Taking into account the chosen casting process, the mold 1 in addition to low-pressure casting, also for gravity and Die casting as well as for tilt casting can be used.

In any case, it offers itself, in the area of the gate and / or one Not shown feeder of the mold 1 an insert 22 made of heat-resistant Provide material as shown in Figure 12. The stake can consist of molded raw material or commercially available insulating materials. It is not shown that the insert 22 is basically also on the outside can survive.

In the embodiment shown in Figures 5 and 6 is in the range the opening 19 is provided with cooling. In the present case, the cooling has at least one guided past the gate and preferably essentially surrounding cooling channel 23 for guiding a cooling medium. In the present case, the cooling duct 23 is located in the lower mold carrier 5, see above that this and in particular the area of the opening 19 is cooled. Procedurally, cooling is activated towards the end of the casting process. The resulting cooling effect is used to build up a controlled solidification or used to set a rapid solidification in the area of the opening 19. The rapid solidification in the area of the opening 19 is necessary in order to Using short cycle times, the still liquid metal runs out of the To prevent opening 19. As cooling media supplied via the cooling channel 23 and preferably carried out in a cycle, all suitable gaseous or liquid materials can be used.

Furthermore, it should be noted that the arrangement of the cooling in the area of the opening 19 there is also independent inventive significance, So regardless of the implementation of the molded body 6 and the applied Layer 12 of molding base 3.

FIGS. 7 and 8 show that one of the mold carriers is present on the lower mold carrier 5, means for coupling with the associated Pouring device are provided. In the present case, the coupling means around recesses 24, in the corresponding hooks or projections the casting device engage when the mold 1 on the casting device is positioned. It goes without saying that it is basically also is possible, in addition or only on the upper mold carrier 4 corresponding Provide recesses.

FIGS. 9 and 10 show that both on the upper mold carrier 4 and on the lower mold carrier 5 guide means 25, 26 are provided in order to be able to move and position the mold carriers 4, 5 in a simple manner. In the illustrated embodiment, the guide means 25 around an elongated, laterally protruding from the lower mold carrier 5 Leading projection, while the guide means 26 is a A plurality of laterally protruding guide pieces.

The manufacture of a casting mold 1 is carried out in such a way that first on the respective Mold carrier 4, 5, the molded body segments 16 and with the help of appropriate Positioning or form-locking means are positioned exactly. Then the shaped body segments 16 with the respective mold carrier 4, 5 firmly connected. Then the basic molding material 3 is dependent on the wall thickness of the casting to be produced required layer thickness applied pneumatically by air pulses. The required layer thickness The expert is responsible for achieving a controlled solidification Taking into account his expertise based on the above parameters. Basically, it applies that in areas where as late as possible solidification is to take place, a large layer thickness is selected while very low in areas where the melt should solidify quickly until there should be no layer thickness. In cases where the Melt directly with cooling segments 21 or shaped body segments 16 comes into contact, there is ultimately a combination of metallic Permanent form and lost form. After the layer 12 is applied the mold halves 13, 14 placed one on top of the other so that the casting mold 1 is closed and melt can be introduced.

Claims (14)

Casting mold (1) for producing a casting (2) using Mold base material (3), with an outer first mold carrier (4), an outer second mold carrier (5), one arranged between the mold carrier (4, 5) Shaped body (6) and one on the shaped body (6) at least in regions applied inner layer (12) made of molding material (3) to form the Casting cavity. Casting mold according to claim 1, characterized in that the shaped body (6) has a first shaped body half (13) fastened to the first shaped carrier (4) and a second shaped body half (14) fastened to the second shaped carrier (5) and that the shaped body halves (13 , 14) rest on one another in the closed state of the casting mold (1). Casting mold according to claim 1 or 2, characterized in that the shaped body (6) has a plurality of modularly constructed shaped body segments (16), in particular made of a high temperature-resistant material, such as in particular graphite, tungsten carbide or steel, and that, preferably, shaped body segments (16 ) are provided on the side facing the mold carrier (4, 5) with recesses, cavities or the like, or that molded body segments (16) are designed as solid blocks. Casting mold according to one of the preceding claims, characterized in that fixing aids (20) are provided on the shaped body (6) on the side facing the basic molding material (3) to prevent the unintentional detachment of the basic molding material (3) from the shaped body (6). Casting mold according to one of the preceding claims, characterized in that at least one cooling segment (21) is attached to the first mold carrier (4), to the second mold carrier (5) and / or to the mold body (6). Casting mold according to one of the preceding claims, characterized in that form-locking means for exact positioning are provided between the mold carriers (4, 5) and the molded body (6). Casting mold according to one of the preceding claims, characterized in that the base material (3) is applied to the shaped body (6) with a different layer thickness. Casting mold according to one of the preceding claims, characterized in that the molding material (3) is applied pneumatically to the molding (6) by air pulses and that, preferably, openings in the molding (6) have a small opening width for discharging air during the airflow-assisted application of the molding material ( 3) are provided. Casting mold according to one of the preceding claims, characterized in that the first mold carrier (4) and / or the second mold carrier (5) are / is designed as a base plate. Casting mold according to one of the preceding claims, characterized in that at least one opening (19) is provided on one of the mold carriers (4, 5) as a gate for filling the casting mold (1), that an insert is preferably inserted into the opening (19) (22) made of high-temperature-resistant material is used, that, preferably, cooling is provided in the mold carrier (4, 5) in the region of the opening (19), that, preferably, the cooling at least one cooling duct (23 ) for guiding a cooling medium. Casting mold according to one of the preceding claims, characterized in that on at least one mold carrier (4, 5) means for coupling to the associated casting device and / or laterally guide means (25, 26) for moving and / or positioning the casting mold (1) and / or the mold carrier (4, 5) are provided. Use of the casting mold (1) according to one of the preceding claims for gravity, low pressure, die casting and tilting casting. A process for producing a casting mold using the base material, characterized in that the layer thickness of the base material is selected as a function of the wall thickness of the casting to be cast and / or as a function of the solidification behavior of the melt introduced into the mold. A process for the production of a casting mold using the basic molding material, characterized in that the basic molding material is applied pneumatically by means of air impulses to a half of the shaped body, in particular a modular one, fastened on a mold carrier.

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