Metal founding – Process – Shaping a forming surface
Patent
1995-11-29
1997-07-22
Batten, Jr., J. Reed
Metal founding
Process
Shaping a forming surface
164 9, 164 97, B22C 904, B22D 1914
Patent
active
056495854
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for producing fiber composite investment castings.
DISCUSSION OF CONVENTIONAL ART
A process for producing investment castings is known, wherein a pattern is formed by using a pattern material, a ceramic mold is formed around the pattern, the pattern material is subsequently melted off, burned out and/or gasified and finally, liquid metal is introduced into the mold.
According to such a process, investment castings of very complex geometry can be produced. Owing to such a geometry and due to the fact that the ceramic mold formed according to this process does only resist relatively low pressures when introducing the liquid metal into the mold, the use of reinforcing fibers, i.e. the production of fiber composite investment castings, is not yet in practice.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a process which permits the production of fiber composite investment castings with tolerable production expenditure.
In case of a process of the above-mentioned kind, this object is solved, according to the invention, by producing at least one preliminary pattern body of fibers and a pattern material, which is then used as part of a pattern or the pattern itself, then forming a ceramic mold around the pattern, and subsequently introducing metal in liquid, liquid-solid or powdery form into the mold, wherein, in case of an introduction in powdery form, the metal is at least partially liquefied in the mold. Such a preliminary body offers a far-reaching freedom of design. This means that the preliminary body can readily be adapted to the casting to be produced. Thus, the fiber orientation and the material reinforcement in the casting intended through them can be achieved purposefully at the desired sites.
DETAILED DESCRIPTION OF THE INVENTION
According to the process of the invention, the pattern material is removed by melting off and/or burning out and/or gasifying and/or releasing.
According to the process of the invention, fibers having special mechanical and/or physical and/or chemical properties are used. This means that the fibers can be selected with respect to the respectively desired properties.
According to the process of the invention, mineral fibers are used as fibers. These may be Al.sub.2 O.sub.3 or SiC fibers, which, e.g., are 10 .mu.m thick. Handling such fibers may present a danger to health if these fibers are bare. According to the present process, however, it is possible to mechanically make up such fibers into preliminary bodies. When handling these preliminary bodies, these fibers, however, are then enclosed by the pattern material and do therefore no longer present a danger to health.
According to the process of the invention, the fibers are used in the form of a bundle of monofilaments or multifilaments, or as wovens, nonwovens or fiberwoven fabrics, or as fiber parisons. The selection among the possibilities given herein can be made according to the respective shapes and requirements of the casting to be produced.
According the process of the invention, wax is used as pattern material. This pattern material is the one which is used most often and which can, as a rule, be treated most easily. Only a relatively low energy expenditure is required to remove it from the mold.
Further, the process according to the invention can be performed such that synthetic resin is used as pattern material. Due to the selected fibers and also with respect to the respective three-dimensional shape, this pattern material can be particularly suited for special applications.
According to the process of the invention, the preliminary body is released from the pattern material at its ends or edges, and the thus bare fiber sections, when forming the ceramic mold, are fixedly embedded therein. Thus, the preliminary body can be placed particularly exactly in the mold and thus in the casting to be produced.
Further, the process according to the invention can be performed such that the preliminary body is adapted to the
REFERENCES:
patent: 4476916 (1984-10-01), Nusbaum
patent: 5394930 (1995-03-01), Kennerknecht
Abstract of Japanese Patent Publication 4-089155 Published Mar. 23, 1992.
Abstract of Japanese Patent Publication 4-143063 Published May 18, 1992.
Neussl Eric
Nolte Markus
Schaedlich-Stubenrauch Juergen
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