Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Positioning of a mold part to form a cavity or controlling...
Patent
1990-12-06
1992-10-27
Lowe, James
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Positioning of a mold part to form a cavity or controlling...
7245311, 100269R, 264 65, 264122, 264123, 425149, 425352, 425419, B29C 4358, B28B 302, B30B 1516
Patent
active
051587238
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hydraulic pressing apparatus for exerting pressure on the bodies to be processed by virtue of hydraulic actuation means.
The bodies to be processed are ceramic tiles, ceramic plates and ceramic refractory bricks, or are made for example of the following materials, taken individually or in mixtures or in compounds with one another: metals, oxides or other metallic compounds, polymers, elastomers, carbon, biological materials of plant or animal origin, waste materials, special ceramic materials. Said materials may be in aggregate, granular, pulverized, solid, fluid or semi-fluid form. The term "special ceramic materials" defines all ceramic materials, except for ceramic plates, ceramic tiles and ceramic refractory bricks.
A preferred body to be processed is formed by pulverized solid ceramic material (in powder or granules), with low humidity, preferably up to 8%, which is compacted during the pressing operation so as to obtain a preformed solid body in the required shape, which is then sent to the successive thermal cooking operation.
Hydraulic actuation means for pressing are generally formed by one or more hydraulic cylinders. Hydraulic auxiliary actuation means, formed by hydraulic cylinders or motors, are furthermore often necessary.
Hydraulic devices in the field of the invention operate with an open hydraulic circuit, while hydraulic devices with closed hydraulic circuit do not relate to the field of the present invention. For the purposes of the present invention, a hydraulic circuit is termed open if the liquid, after working in the actuation means and before returning to the pump, is sent to a connecting line which is open towards the tank, while a hydraulic circuit is termed closed if the liquid, after working in the actuation means, returns directly to the pump and has no open connection towards the tank. The liquid is generally hydraulic oil.
Hydraulic devices in the field of the invention comprise: a positive-displacement pump operating with a direction of flow directed towards a delivery line, preferably with a flow-rate which is always substantially greater than zero, an actuation motor for the positive-displacement pump having a flywheel for accumulating kinetic energy, a tank for the liquid, with which the intake of the positive-displacement pump and the discharge of the hydraulic actuation means are connected, first directional control valve means connected to the delivery line in order to discharge the flow of the positive-displacement pump to the tank.
The term "directional control valve means" defines valve means which offer, in their open position, the minimum load loss and the maximum flow-rate.
The closure of said first valve means sends the flow of the positive-displacement pump to the hydraulic actuation means. The opening of the first valve means sends the flow of the positive-displacement pump to the tank. The flywheel accumulates kinetic energy during the open times of the first valve means and yields kinetic energy during the closure times of said first valve means.
The hydraulic devices in the field of the invention have the purpose of eliminating conventional hydraulic presses, which do not relate to the field of the invention. Conventional hydraulic presses in fact operate with a throttling valve connected to the delivery of the pump so as to discharge to the tank the excess flow always at maximum pressure, so that the pump constantly operates at its maximum pressure. Since the maximum flow and pressure are in any case insufficient for the actual pressing work, the pressing flow and pressure are reached by using hydraulic accumulators and pressure multipliers. Though said conventional hydraulic presses are by far the most widespread, they entail high power consumption, overheating of the liquid, high pressure hammers and reduced controllability of the speed of their movements. Other conventional hydraulic presses attempt to reduce power consumption without discharging the pump's total flow to the tank, using variable-displacement pumps and
REFERENCES:
patent: 3069742 (1962-12-01), Walchhutter
patent: 3359608 (1967-12-01), Walchhutter
patent: 3830615 (1974-08-01), Walchhutter
patent: 4363612 (1982-12-01), Walchhutter
patent: 4839119 (1989-06-01), Sterzel
Bossetti Renato
Walchhutter Ulrico
Lowe James
S.I.T.I Societa Impianti Tenmoelettrici Industrial S.p.A.
Walchhutter Ulrico
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