WO2012172062A1

WO2012172062A1 - Casting tool and method for producing a casting tool

Info

Publication number: WO2012172062A1
Application number: PCT/EP2012/061470
Authority: WO
Inventors: Karl-Heinz Horsmann
Original assignee: E.G.O. Elektro-Gerätebau GmbH
Priority date: 2011-06-17
Filing date: 2012-06-15
Publication date: 2012-12-20
Also published as: EP2720815A1; DE102011077711A1

Abstract

A casting tool or a mold for cast metal for shaping the exterior of a cast body has a shaped portion. At least one part of the casting tool consists of a clay mineral or silicate material, said part adjoining the shaped portion or forming a part of the shaped portion. The clay mineral or silicate material can be vermiculite, perlite, or expanded glass for example.

Description

Casting tool and method for producing a casting tool

Field of application and state of the art

The invention relates to a casting tool for metal casting for the outer shaping of a cast body by means of a molding in the casting tool. Furthermore, the invention relates to a method for producing a casting tool.

Such casting molds or molds made of cast or cast metal have long been known. In an at least two-part casting tool liquid metal is poured in the closed state and then hardens or solidifies relatively quickly, among other things, because the thermal mass of the casting tool is greater than that of the casting to be produced. Above all, on the surface of the cast body, the liquid metal is cooled by the casting tool until it solidifies.

The disadvantage here is that in casting process or a casting process for particularly thin-walled cast body, for example, with cavities, channels or the like, solidifies the filled liquid metal relatively quickly. As a result, it can not spread so well and evenly, so that in such castings either disturbing geometric constraints must be accepted or irregularities on the outside or in appearance structural weaknesses can occur.

Task and solution

The invention has for its object to provide an aforementioned casting tool and a method for its preparation, which can be solved with the problems of the prior art and in particular, an advantageous, practicable and easy to use casting tool can be created.

This object is achieved by a casting tool having the features of claim 1 and a method for producing a casting tool having the features of claims 9 or 11. Advantageous and preferred embodiments of the invention are the subject of the other claims and are explained in more detail below. Some of the features are described only for the casting tool or only one of the methods. However, they should be able to apply regardless of both the casting tool and for the procedures. The wording of the claims is incorporated herein by express reference.

According to the invention it is provided that at least a part of the casting tool, which adjoins the molding or forms part of the molding, consists of a different material with significantly lower heat capacity with sufficient thermal resistance. This is particularly advantageous a clay mineral or sheet silicate or silicate material such as vermiculite, perlite or expanded glass. This means that in a first basic embodiment of the invention no longer the entire casting tool is made of metal, but just a part of the other material. Furthermore, these other materials are all lighter than metal, as is commonly used for casting tools, so that advantageously also the weight of the entire casting tool is lower, which among other things allows easier handling. In addition, the heat capacity is lower, so that liquid metal does not solidify so quickly. The materials mentioned, such as clay mineral or phyllosilicate and silicate material have a sufficient thermal resistance at the temperatures that occur during metal casting. Furthermore, they are also very good thermal insulation materials known so that the liquid metal coming into contact with them during the casting process does not cool so quickly.

In an advantageous embodiment of the invention it is provided that the part is formed of a different material than the other casting tool as an insert, which is inserted into the casting tool otherwise made of metal. As a result, this part, which is naturally far less resistant to multiple continuous use of the casting tool than one made of metal, can be easily replaced with a new one. It is also possible to provide several such inserts on a casting tool made of metal. They may be integrally formed or advantageously separated from each other or each with a metal region in between. The condition should be met that the metal volume of the casting tool is still greater than the volume of the inserts of the other material or clay mineral or silicate material. Finally, the mechanical stability of the casting tool, which is of great importance, depends on the metal content and can thus be ensured.

Advantageously, a said insert made of clay mineral or silicate material is provided at a position of the molding of the casting tool, which determines a part of the outer surface or surface of the finished casting. It is precisely here that the aforementioned advantage can be achieved that the course and thus the distribution of the liquid metal is as good as possible, especially at the subsequently optically visible and potentially functionally significant surface of the cast body. If a casting has several such critical regions, then either a slightly larger part of the casting tool, which affects some of these points, can be made of the other material.

Advantageously, such areas of the cast body, which later lie outward or can be seen, only then by an aforementioned part another material, such as clay mineral or silicate material, formed in the casting mold, if it does not depend on the optical surface quality in detail with respect to surface roughness. This is usually optimal for metal as a material for the casting tool, because very smooth, if desired. In the alternative materials, however, especially in a silicate material in the form of compressed vermiculite, perlite or expanded glass, however, usually no such smooth surface can be created, which in the case of castings, which must be treated on the surface in any case, not disturbing is.

Advantageously, such a part of the casting tool is formed by a material other than metal or an insert made of clay mineral or silicate material is used, on which the finished cast body should have relatively thin wall thicknesses or has complicated, very strongly varying surfaces. This can also be the case, for example, with a hollow cast body with a cast core. Under certain circumstances, the casting core can also be formed from a material other than metal, for example with a lower heat capacity, such as molding sand or the like.

An advantage of using a material such as clay mineral or phyllosilicate or silicate material is also compared to known molding sand in that even the heat capacity is still significantly higher than that of the inventive materials mentioned here. Furthermore, as a result of the binder used, molding sand is usually made unstable by the temperature during casting or the mold formed by it is destroyed at the latest when the finished cast body is removed, so that the insert in the casting tool would have to be re-produced over and over again. This is obviously more expensive than inserting a prescribed insert into a casting tool and then at least a few times, for example, 10 times to 20 times or even more often to use without having to replace it. Finally, molding sand can outgas on heating, which is sometimes disturbing.

In an advantageous embodiment of the invention, the silicate material comprises expanded vermiculite, preferably exclusively expanded vermiculite. Its properties with regard to stability after compression, thermal heat capacity and above all thermal resistance are particularly good. Such an insert also has a harder and more durable surface.

The clay mineral or silicate material used for the insert is bound or solidified with a binder. If possible, this binder should be heat-resistant such that even the areas which come in contact with the liquid metal at temperatures of 500 ° C to 1000 ° C, retain their shape and do not dissolve or over-wear.

In an alternative second basic embodiment of the invention, it is possible that the entire casting tool consists of clay mineral or silicate material and not just one or more parts thereof. Then a casting tool may no longer be durable, but can be made easily and much cheaper than metal. This is especially useful where prototypes or small series parts are manufactured.

In a further embodiment of the invention, not only a newly manufactured casting tool as described above partly consist of a material other than metal, for example by means of said inserts. Above all, it is also possible, so to speak, to take a used casting tool, which consists entirely of metal, and to remove or mill out certain areas. These areas are advantageously the aforementioned, which in terms of the casting Surface and / or wall thickness can be critical. In the milled areas then an aforementioned use of the other material can be used as metal. Thus, the casting tool is then ready to use.

Alternatively, so casting tools can be quasi repaired or made reusable by just worn out critical points are removed and replaced by the aforementioned inserts. In this way, a casting tool can be made from an existing casting tool, which may not be usable for normal known use or is no longer good enough.

Even if these mentioned inserts of a material other than the metal of the casting tool by far do not hold as long as if it consists of metal, these inserts can very easily be made in a molding of appropriate material and also relatively easily used in a casting tool and be fixed in it.

Alternatively, a casting tool may be manufactured right from the beginning for use with at least one such insert of a material other than that of the casting tool by releasing, from the beginning, the areas into which an aforesaid insert is to be inserted later.

In a further embodiment of the invention, it is also possible that in a cast body with a tubular portion, for example, should have relatively thin wall sections, not all around an aforementioned insert of clay mineral or silicate material is used, which may mean an overall low mechanical or dimensional stability would for the casting tool. Here can may then be provided by appropriate inserts under circumstances that a umfangsmaßige division into an area of the metal of the casting tool on the one hand and the other material on the other hand by appropriate inserts is present, so that ultimately a kind of mixed result is achievable, so at least slightly improved flowability of pouring metal in these critical areas, so that the result is still better than with a casting tool exclusively made of metal. However, this is only one possibility of several, albeit a beneficial one, and their use depends on the concrete shape of the casting as well as the quality requirements.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application in individual sections as well as intermediate headings do not limit the statements made thereunder in their generality.

Brief description of the drawings

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

1 is a plan view of a lower Kokillenhälfte for pouring a sanitary fitting with two inserts of vermiculite,

Fig. 2 shows a section through the mold half of Fig. 1 in the region of the two insert parts and Fig. 3 shows a further section showing the lower Kokillenhälfte and the upper Kokillenhälfte in an area outside the insert parts.

Detailed description of the embodiment

In Fig. 1, a lower Kokillenhälfte 13 is shown as a casting tool 1 1 in plan view. It has a molding 16, in which a sanitary fitting or a main body of a sanitary fitting is to be produced by casting. A first region 16a of the molding thereby forms a later vertical basic body of the sanitary fitting and a second region 16b protruding therefrom and extending approximately horizontally, as can be clearly seen. In extension of the main body according to the first region 16a, a control lever is later placed in the finished sanitary fitting. As can be seen in conjunction with the illustrations of FIGS. 2 and 3, both the first region 16a and the second region 16b are rounded. The first region 16a is formed substantially circular and slightly tapered, while the second region 16b is formed rounded flattened according to the outlet pipe, starting from the first region 16a ever flatter.

As has been explained above, a relatively small wall thickness is to be achieved in the second region 16b corresponding to the outlet pipe of the sanitary fitting. For this purpose, two recesses 18a left and 18b right are provided in the lower die half 13, which merge into each other with the same width, but this does not necessarily have to be so. In the recesses 18a and 18b above inserts 20a and 20b are accurately inserted, which consist of a prescribed material, in particular blown vermiculite. As can be seen in particular from the synopsis with FIG. 2 in section A, the shape of the outlet tube corresponding to the second region 16b is determined in its area exclusively by the vermiculite inserts 20a and 20b. Here, the outlet pipe according to the second region 16b is to have relatively small wall thicknesses, so that the above-mentioned advantages of slower solidification of the casting material on such vermiculite inserts can be used particularly well here. It is self-evident that a mirror-symmetrical upper mold half 14 is placed on the lower mold half 13 shown in FIG. 2, as shown in FIG. 3 in the other section B also. This means that in the upper mold half 14, two inserts of clay material or vermiculite not shown here are present, which then complete the molding 16.

Not shown in the sectional views according to FIGS. 2 and 3 is an inner casting core, which is held in the mold 16 in a known manner.

The inserts 20a and 20b may be held in the recesses 18a and 18b by press fit alone. Alternatively, retaining pins or even screw connections can be provided.

As has been explained in the introduction, the inserts 20a and 20b can be provided from the beginning in the casting tool 1 1 and the mold halves 13 and 14, just to achieve the advantage of possible lower wall thicknesses with good casting quality for the casting such as a sanitary fitting can. In certain molds or press molds, which can easily be imagined by the person skilled in the art, the inserts 20a and 20b can then be newly produced after wear and replaced in the casting tool 11. Alternatively, a casting tool which has already been worn out in a particularly stressed area or which is no longer fit for use can be provided with recesses 18 into which the inserts 20 are then inserted. Thus, the casting tool can still be used on itself.

From Fig. 2 it can also be seen that the inserts 20a and 20b do not reach to the bottom of the lower die half 13, but end a piece before it. Thus, the bottom is continuously formed by the material or metal of the lower die half 13, which of course significantly improves the overall stability.

Claims

claims

Casting tool, in particular mold, for metal casting for the outer shaping of a cast body by means of a molding, characterized in that at least a part of the casting tool which adjoins the molding or forms part of a clay mineral or silicate material such as vermiculite, perlite or expanded glass ,

Casting tool according to claim 1, characterized in that the part of clay mineral or silicate material is designed as an insert in an otherwise existing metal casting tool, wherein preferably the metal volume of the casting tool is greater than the volume of clay mineral or silicate material and in particular more such inserts are provided on a casting tool made of metal.

Casting tool according to claim 1 or 2, characterized in that the insert of clay mineral or silicate material is provided at such a position of the molding of the casting tool that it forms part of the outer surface or surface of the finished cast body.

Casting tool according to one of the preceding claims, characterized in that at least one insert made of clay mineral or silicate material is provided at a region of the casting tool, on which the cast body should have relatively thin wall thicknesses, in particular in a hollow cast body with a cast core.

5. Casting tool according to one of the preceding claims, characterized in that the clay mineral or silicate material at least partially billowed vermiculite, preferably exclusively bloated vermiculite.

6. Casting tool according to one of the preceding claims, characterized in that the clay mineral or silicate material is bonded or solidified with a heat-resistant binder.

7. Casting tool according to one of the preceding claims, characterized in that it is made of a ready-to-use, completely made of metal casting tool by removing or milling certain areas, in which then an insert of clay mineral or silicate material according to claim 2 is used, preferably the insert is provided at such a location of the molding of the casting tool that it forms part of the outer surface or surface of the finished cast body.

8. Casting tool according to claim 1, characterized in that the entire casting tool consists of clay mineral or silicate material.

9. A method for producing a casting tool for metal casting for the outer shaping of a cast body by means of a molding, characterized in that in the casting tool made of metal, a region, in particular a region which forms part of the outer surface or surface of the finished cast body, is removed and for the remote area an insert or a part consisting of clay mineral or silicate material is used.

10. The method according to claim 9, characterized in that the insert or the part of clay mineral or silicate material forms a part of the molding.

1 1. A method for producing a casting mold for metal casting for the outer molding of a cast body by means of a molding, wherein the casting tool is at least partially made of metal, characterized in that a portion of a finish-usable casting tool is removed from metal, in particular in areas which in the finished cast body whose outer surface or surface form, and the removed areas are replaced by correspondingly shaped inserts or parts of clay mineral or silicate material, which give the same shape.