Metal founding – Process – Disposition of a gaseous or projected particulate molten...
Patent
1984-02-28
1985-09-17
Lin, Kuang Y.
Metal founding
Process
Disposition of a gaseous or projected particulate molten...
164 761, 164 98, B22D 2300, B22D 1904
Patent
active
045414742
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for manufacturing a moulding plunger for hollow glass objects.
In the hollow glass industry, moulding plungers are used which are formed by a hollow body having a rounded form at its conical end, the internal cavity of these plungers being intended for permitting the cooling thereof by means of a fluid. in order to manufacture objects, such as bottles, at a very high rate, by means of automatic machines.
Such plungers have to have a wall which is as thin as possible, in order to impose on them a high value of the thermal transmission coefficient, permitting a high cooling efficiency, while having a mechanical resistance which is sufficient to withstand the stresses to which they are subjected while they are being used.
Hitherto, as moulding punches for glass objects, hollow bodies have been used, which are formed by a support element of a ferrous metal, for example, of steel or cast iron, especially grey cast iron, of which those parts of the external surface particularly exposed to mechanical wear and to the effects of corrosion at high temperature resulting from contact with the molten glass, are covered with a protective layer of a suitable material, for example, of certain metallic alloys, mixtures of metal and ceramics or even of ceramic materials.
In such plungers, it is not possible to decrease the thickness of the wall of the support element to below a certain limit, which is higher than that which would correspond to the limit of mechanical resistance because, for very small wall thicknesses, the lack of homogeneity as regards the structure of the ferrous material of the support element and also its moderate resistance to the thermal stresses would cause disturbances in respect of the protective surface layer.
One process is known for the manufacture of hollow bodies having a thin wall, constituting a self-supporting structure, which consists in forming a layer of material (this formation being generally effected by projecting a powder or a suspension of powder in a liquid) on a support coated with an intermediate layer of a substance which is soluble or fusible under conditions in which the external layer, intended to form the wall of the hollow body, is not subjected to any modification, and in then detaching this external layer from the support after dissolving or melting the substance which forms the intermediate layer. However, this process has the disadvantage that, for obtaining bodies which have a certain mechanical resistance, it is necessary to carry out a heat-densifying treatment of the external layer formed on the support. Now it is only possible for this treatment to be carried out when this layer is still on the said support, and this implies that it is necessary, first of all, to separate this layer from the support and to transport the "green body" as thus formed by this layer into a densifying device (for example, a sintering furnace), and this represents a delicate and expensive operation.
The object of the invention is to overcome the disadvantages which have just been mentioned, by making it possible to obtain a moulding plunger formed by a hollow body with a thin wall, but having an appreciable mechanical resistance.
To this end, the process according to the invention has the features which are set out in claims.
The invention will be better understood by reference to the following detailed description as regards how the process according to the invention is carried into effect, and by reference to the accompanying drawings, in which:
FIG. 1 is a partial section of the assembly, which is formed by a support member, a member serving as a base for the plunger and a compact layer of material formed by heat projection, and
FIG. 2 is a sectional view of the moulding plunger, after mutual separation of the support member and of the layer of material formed by heat projection.
The first step in the process consists in forming, by heat projection, e.g., a thermal spray torch, a compact layer 3 of material on the end of a support element 1 an
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patent: 2449136 (1948-09-01), Pattison
patent: 2945273 (1960-07-01), Herzmark et al.
patent: 2966423 (1960-12-01), Shichman
patent: 3112540 (1963-12-01), Kaneko et al.
patent: 3204917 (1965-09-01), Richards
patent: 3921701 (1975-11-01), Cardone
Castolin S.A.
Lin Kuang Y.
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