Plastic and nonmetallic article shaping or treating: processes – Carbonizing to form article – Agglomeration or accretion
Patent
1982-12-20
1985-01-15
Parrish, John A.
Plastic and nonmetallic article shaping or treating: processes
Carbonizing to form article
Agglomeration or accretion
264 44, 264 60, B29H 720
Patent
active
044938055
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a new and improved method of, and apparatus for, manufacturing a light construction element, particularly a cover plate.
The present invention relates specifically to a new and improved method of, and apparatus for, manufacturing a light construction element, particularly a cover plate, in which a blank comprising an upper layer of an expandable first clay material and a lower layer of a second clay material which is incapable of expanding at least in the range of the expansion temperature of the first clay material is fired in an oven such that the first clay material expands and is sintered to the second clay material at the interconnecting surface.
The initially mentioned subjects are known as, for example, from British Patent No. 1,279,980 and German Patent Publication No. 1,933,421, respectively. In the procedure as described therein, for instance, a layer of an expandable first clay material is arranged on a layer consisting of a second clay material which is not capable of expansion at the swelling temperature of the first clay material. There the layer of the second clay material is introduced into a mold and, then, the first clay material is deposited thereupon in the form of particles or pieces. Such method, however, did not render useful results since, on the one hand, a large surface is formed which oxidizes on firing and, thereby, prevents swelling due to the cavities intermediate the particles and, on the other hand, due to the cavities the heat transfer is too poor to ensure sufficient and particularly uniform swelling. Due to the cavities the further described radiation heating cannot become sufficiently effective, particularly, since the side walls of the mold also have a cooling action.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind it is a primary object of the present invention to provide a new method of, and apparatus for, manufacturing a light construction element, particularly a cover plate, which enables or at least improves the manufacture of such light construction elements.
Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the method of the present development is manifested by the features that, the upper layer is designed as a dimensionally or form-stable massive body and the blank is expanded and fired resting on its lower layer without the use of a mold.
By designing the upper layer of the blank as a form-stable massive body the surface of the layer is kept small, on the one hand, whereby optimum heat absorption and uniform expansion through a great thickness are achieved. Due to the form-stability of the first layer, furthermore, a mold wall can be dispensed with, whereby cooling of the blank is avoided and the heat supply and the expansion process are further improved and the adherence of the expanded body to the mold is avoided. The method ensures uniform expansion through a great thickness of the blank so that, for example, an increase in volume to the sevenfold of the unexpanded layer is possible.
Advantageously, the clay material of the first layer contains porosity generating agents which are known and may comprise, for instance, burn-out materials like particles of wood, coal, paper, cork, rice shells and the like. However, styropor is specifically advantageous since it acts as an absorbing agent for heat absorption. The porosity generating agents are spherically shaped with further advantage.
The manufacture of the light construction element is particularly simple and economical since the two clay material layers can be combined in a simple manner by extrusion to form a blank.
Preferably, at least one of the layers prior to extrusion is provided with a clay suspension. The second layer of material which is not expandable at the expansion temperature of the first clay material retains the form stability and may serve readily as a carrier for the first clay material during the expansion process so
REFERENCES:
patent: 1448684 (1923-03-01), Beecher
patent: 1459357 (1923-06-01), Booze
patent: 4187266 (1980-02-01), Greskovich
Sporkenbach Gustav-Adolf
Suetterlin Dieter
Keller Holding AG
Kleeman Werner W.
Parrish John A.
Sporkenbach Gustav-Adolf
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