Plastic article or earthenware shaping or treating: apparatus – Endless casting surface and cooperating harvesting means
Reexamination Certificate
1999-05-26
2002-02-05
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Endless casting surface and cooperating harvesting means
C425S337000, C425S371000, C425S372000, C425S373000
Reexamination Certificate
active
06343924
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
REFERENCE TO A “MICROFICHE APPENDIX”
Not Applicable.
BACKGROUND OF INVENTION
1. Fielf of Invention
The invention relates to an arrangement for the manufacture of plastic molded parts such as sheets, profiles or the like, with at least two containers holding a liquid monomeric component which via feed lines and a mixing arrangement are connected to a mold in which the liquid plastic material solidifies into a molded article.
2. Description of Related Prior Art
It is already known to manufacture molded plastic articles by mixing two monomeric components situated in separate vessels, in particular caprolactam melts, to which an activator or catalyst is added, and which are then heated to an appropriate temperature. In that case, the monomeric components are cast in liquid state into appropriately tempered molds where they are polymerized without pressure. A disadvantage of this known method is that the molded articles are not manufactured continuously, but that the dimensions are limited by the size of the molds into which the liquid monomeric components are cast. Since such molds cannot be made available in a large enough number of different dimensions, the molded articles thus manufactured must be subsequently treated, in particular they must be cut to the desired size, which results in wastes that cannot be utilized. Furthermore, this known method as a rule leads to the formation of so-called feeder heads on the upper surfaces, similar to those formed in metal casting, which must be separated from the molded article after polymerization, which also requires an additional working process and leads to further waste.
BRIEF SUMMARY OF INVENTION
Object of the present invention is to create an arrangement for the manufacture of molded articles which allows the continuous manufacture and the simple adaptation to the desired dimensions of the molded articles to be made, so that the production of waste can be avoided, and the work required for manufacturing can be reduced and simplified. To achieve this objective, the invention recommends that the mold is provided with two revolving conveyor belts running parallel to each other and arranged at a distance of each other, and that a distributor means is provided that feeds the liquid plastic material into the intake gap between the conveyor belts. If, as in the known method, the molded articles are formed from two polymerized monomeric components, it is advantageous to provide at least four containers, so that it is possible to switch to one container pair while the other pair becomes empty, thus avoiding the necessity to interrupt the continuous manufacturing process. The distributor means is used to distribute the liquid plastic material evenly across the entire width of the intake gap and subsequently moved on across the two conveyor belts whose length is designed so that this plastic material solidifies and is polymerized while it is being moved, and the finished solidified molded article exits from the outlet gap of the two conveyor belts.
It is practical to provide the feed line, preferably in the area where it leads into the distributor means, with a casting valve so that the quantity of the liquid plastic material can be adjusted by regulating the valve opening time, thus adapting the quantity to whatever is in demand.
It is practical for the conveyor belts to be downwardly inclined from the distributor means, and advantageously the incline can be adjusted. This ensures that the entire width of the conveyor belts can be loaded by the distributor means, and the occurrence of skips due to an insufficient material supply can be avoided. When the incline is adjustable, it can be adapted in particular to the thickness of the molded articles to be manufactured, which corresponds to the distance between the two conveyor belts. To manufacture molded articles of different thickness, it is therefore only necessary to make the distance between the two conveyor belts adjustable, which can be achieved without difficulty by mounting the deflection rollers on adjustable trestles.
According to a preferred embodiment of the invention, a sealing member, for example made of silicone rubber, is provided in the area of the two longitudinal edges of at least one conveyor belt. This sealing member may, for example, be formed of a compressible elastic hollow section which, due to its elasticity, can adapt itself to distances of different size between the two conveyor belts. By changing the position of the sealing members on the conveyor belt, the width of molded element to be manufactured can be changed without difficulty. Thus, the arrangement according to the invention makes it possible and simple to vary the thickness as well as the width of the molded elements to be manufactured.
To allow a simple change in the position of the sealing members, these lie loosely on the conveyor belt, according to another characteristic of the invention, and they are fixed in their position thanks to the support straps abutting on their outsides, which are supported by guides fastened to the conveyor belt preferably in the form of rivets. To change the position of the sealing members, only the support straps must be exchanged. These support straps also serve the purpose of preventing the lateral deflection of the elastic sealing members and thus to ensure that an exact lateral delineation is created for the molded articles to be manufactured.
When the manufactured molded articles are sheet-shaped, the liquid plastic material is fed by the distribution means directly to the inlet gap between the conveyor belts, whereby the shape of the sheet-shaped molded articles is determined by the distance between the conveyor belts and the distance between the sealing members. However, the present invention also allows the manufacture of molded articles which are not sheet-shaped, i.e. for example of profiles with a round or angular cross section. To manufacture such profiles according to the invention, cavities corresponding to the profiles to be manufactured, preferably made of silicone rubber, can be arranged between the two conveyor belts, and the liquid plastic material is then fed into those cavities. These mold sections are divided, with one part supported on the upper conveyor belt and one part on the lower conveyor belt. Each mold part is continuous and revolves with one of the two conveyor belts, while a closed mold is created which forms the mold for the cavities. Again, the molded articles can be fixed against lateral displacement via the guides fastened to the conveyor belt.
It is practical for the distributor means to consist of a tube system emptying into the inlet gap. If in the manufacture of thick sheets, the inlet gap between the two conveyor belts is large enough, it is possible that the distributor means extends into the space between the two conveyor belts without touching the belts, in which case no other lateral delineation is necessary. However, when the inlet gap is small, it is not possible to let the distributor means formed by the tube system extend between the two conveyor belts without touching the conveyor belts. In that case, stationary sealing members, preferably of triangular profile, must be provided to act as lateral limitation for the inlet gap.
It is practical for the distributor means to be provided with measuring contacts for measuring the quantity of the liquid plastic material fed into the intake gap, whereby the measuring contacts are preferably actively connected to the casting valve. In that case, the supply of the liquid plastic material is regulated via the casting valve, depending on the amount of liquid plastic material fed into the intake gap, i.e. when the maximum amount is reached, the casting valve closes, and when the minimum amount is reached, the casting valve opens. With such a control, the conveyor belts are driven at a constant speed that is precisely adjusted to the desired dose. However, the casting valve may also be open all the time, so th
Del Sole Joseph S
Firma Ploytech Klepsch & Co. GmbH
Nguyen Nam
Pitney Hardin Kipp & Szuch LLP
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