Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Feed control of material en route to shaping area
Patent
1997-10-10
1999-08-24
Heitbrink, Tim
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Feed control of material en route to shaping area
264 404, 264 407, B29C 4582
Patent
active
059422580
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns an apparatus for delivering fluid materials consisting of at least two mutually reacting components, in particular casting resin, wherein the components are moved from piston-cylinder units associated with supply vessels to a mixing system. The piston-cylinder units are fitted with retraction means for the conveyor pistons, and a drive system to load the conveyor pistons with pressurized fluid is provided.
2. Description of Related Art
Apparatus for filling at least one casting mold with castable liquid media is known for instance from the German patent document 34 20 222 A1, wherein the components of the casting substance are fed by conveyor means to one mixing system, and from there, the casting substance moves to at least one casting mold. The conveyor means is a piston-cylinder system associated with a pullback cylinder to retract the conveyor piston of the piston-cylinder unit. The known metering system however is designed in such manner that the volume of the piston-cylinder unit is sufficient to fill only the particular casting mold associated with that system, thus, in the event of large casting molds, commensurately large piston-cylinder structures are required and hence correspondingly high costs are entailed. As a result the pressure-gelling apparatus is applicable only in a limited way and always must be matched to the particular requirements.
SUMMARY OF THE INVENTION
The object of the invention is to improve upon the apparatus of the prior art, such that it shall be applicable in standard model sizes and preferably shall offer good handling of the piston-cylinder units for the most diverse volumes of casting molds.
The apparatus of the invention is universally applicable for various castings' volumes. Depending on the volume of the casting, several strokes of the piston-cylinder units are carried out as a rule. The lower design limit for the displacement volume of the piston-cylinder unit is essentially set by the viscosity of the components to be conveyed and is determined by the stroke frequency of the conveyor piston relative to the required conveyance rate. As the viscosity increases, that is as the component becomes tougher in its liquid form, larger feed cross-sections to the piston-cylinder units are required in order to assure the filling of the product chambers of the piston-cylinder units within the time intervals determined by the stroke frequency. The feed cross-section becomes especially significant when only the static feed pressure of the supply vessel is acting on the component as the cylinder is being filled. The stroke frequency also affects the dimensioning of the displacement volume and is given by the quotient of conveyance rate and stroke volume. Contrasted with the essentially operationally dictated lower limit, the upper limit of the displacement of the piston-cylinder units will be determined in the invention both as a function of the required metering accuracy and the synchronous operation of the two piston-cylinder units as well as of system costs and handling. As the displacement or stroke volume of the piston-cylinder unit increases, the volume of the drive fluid must also increase commensurately. Thereby the elasticity of the total system, being the sum of the mechanical elasticity of drive-unit housing and piston-cylinder unit on one hand and the fluids' elasticity on the other hand, will also increase, and the metering accuracy is degraded. It must be borne in mind in this respect that the apparatus must be designed for conveyance pressures of 100 bars and more. Another criterion for the upper limit of the displacement volume are the costs of construction for the piston-cylinder units and of the total system. Another criterion is good handling of the individual components for instance for purposes of maintenance and repairs.
In a first advantageous embodiment of the invention, the displacement volume of the piston-cylinder units shall be between 0.1 and 4 ltrs, preferably about 1 lt
REFERENCES:
patent: 4167236 (1979-09-01), Taubenmann
patent: 4275822 (1981-06-01), Juffa et al.
patent: 4307760 (1981-12-01), Hauser
patent: 4565511 (1986-01-01), Ramisch
patent: 4611982 (1986-09-01), Haeuser et al.
patent: 4956133 (1990-09-01), Payne
Heitbrink Tim
Wilhelm Hedrich Vakuumanlagen GmbH & Co., KB
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