Metal founding – Process – Shaping a forming surface
Patent
1985-10-01
1987-09-22
Batten, Jr., J. Reed
Metal founding
Process
Shaping a forming surface
164 71, 164 34, 164 44, 164 45, 164246, 164249, B22C 702, B22C 904
Patent
active
046948791
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for producing castings with partially nonconforming contours.
BACKGROUND OF THE INVENTION
For molding nonconforming contours, which means undercuts in the mold it is common to work with loose parts. After the removal of the main part of the pattern, these are drawn into the created hollow space of the mold and then also removed, in order to be reassembled with the main part of the pattern. In the case of relatively narrow molds loose parts can not be used since the hollow space of the mold is not sufficiently wide. Here, separate cores have to be inserted in the produced mold.
Another possibility for molding nonconforming contours is offered by the technique according to which gasifiable models fill the mold. Hereby, the model within the mold is destroyed before or during casting. The application of this process is limited by the stability of the synthetic foam to be used which opposes relatively low resistance during the hardening of the molding material. This can lead to distortions and dimensional aberrations of the castings. For each casting a new model has to be made which then is completely gasified. Relatively large gas quantities have to be evacuated during the casting. The residues on the surface of the casting can deteriorate the quality of the casting.
Accordingly, it is the object of this invention to provide a process in which castings with nonconforming contours can be produced without the aforementioned disadvantages.
SUMMARY OF THE INVENTION
The foregoing objects have been achieved by a method wherein there is employed a pattern having a combination of gasifiable pattern parts for the molding of nonconforming contours and of reusable pattern parts. After molding, only the reusable pattern parts are withdrawn from the mold whereas the gasifiable pattern parts are destroyed during casting. More specifically, the method is intended for producing cast products with ribs. The pattern employed therefor has ribs with L- and/or T-shaped cross sections. In this method, only the vertical rib webs are withdrawn from the mold after molding and utilized as reusable pattern parts. Horizontal rib flanges are destroyed as gasifiable pattern parts during casting.
A further aspect of the invention is the use of a pattern made of gasifiable and reusable pattern parts which is covered with a foil embedded in a binder free molding material. The so-obtained mold is connected to a vacuum source prior to the removal and construction of the pattern parts.
The present invention retains advantages of both the known methods wherein both reusable and gasifiable patterns are used. Yet, in comparison to the method in which the mold is filled with gasifiable models, the precise dimensioning is ensured here because the functional dimensions, the conforming contours and the support parts for the gasifiable pattern segments are made of inherently stable materials. It is not necessary to gasify large volumes during casting. The flowability of the metal is improved thereby, since it is opposed by reduced gas pressure and the gases can be more easily evacuated. Also, the residues in the hollow space of the mold are reduced, improving considerably the surface of the casting. Besides, the efforts and the costs related to the hereto known process for the production of molds filled with patterns are considerably reduced.
In comparison with the known molding technique wth reusable patterns possibilities to shape forms which come closer to the requirements are created, since the method is not tied down to conformity. Loose parts which have to be then removed from the mold can be eliminated. Contours which are technically quite difficult to produce can be easily manufactured without cores. This leads to reduction of production costs and to the elimination of error sources.
The process according to the invention reaches its full advantage when used in combination with the known vacuum molding technique. This molding process is suitable for the production of castings requi
REFERENCES:
patent: 3063113 (1962-11-01), Operhall et al.
patent: 3552480 (1971-01-01), Harris
patent: 3624758 (1971-11-01), Harris
patent: 3842899 (1974-10-01), Hauser-Lienhard
Batten, Jr. J. Reed
Buderus Aktiengesellschaft
Dubno Herbert
Ross Karl F.
LandOfFree
Process for producing castings does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing castings, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing castings will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2053216