Process and device for controlling a vessel for pouring liquid under low pressure in a repeated manner

Claim 1

In a process for controlling a liquid in a liquid-containing vessel having a pouring tube having an end portion defining an outlet and an opposite end portion immersed in the liquid, for a repeated pouring of the liquid under a low pressure into sand moulds, each of which moulds comprises at least one mould cavity and a liquid inlet passageway, combined with means for precluding a return flow of the liquid from the mould cavity after the liquid has filled said cavity, said liquid being controlled by means of a driving gas under pressure supplied to the interior of the vessel above the liquid in the vessel; the improvement comprising in combination the steps of: placing the mould on said outlet of the tube to enable the supply of the liquid to the cavity by way of said passageway; supplying said gas under a first pressure to the interior of the vessel above the liquid to raise the liquid in the tube; detecting the arrival of the liquid at a predetermined level in the tube; stopping the flow of the gas under said first pressure when said predetermined level is reached; measuring the pressure of the gas above the liquid in the vessel to detect a second pressure representing the pressure of the gas when said predetermined level of the liquid in the tube is reached; supplying the gas to the interior of the vessel above the liquid at a pressure which creates a third pressure in the vessel which is higher by a predetermined amount than said second pressure and at a predetermined rate of flow so as to raise the level of the liquid in the tube beyond said predetermined level and fill the cavity of the mould during a predetermined time; maintaining said third pressure for a predetermined period so as to allow said means for precluding return of the liquid to operate; reducing the pressure of the gas above the liquid inside the vessel so as to bring the level of the liquid in the tube down to substantially said predetermined level and create conditions for a further pouring procedure for a second mould placed on said outlet of the tube.

Claim 5

A device for controlling a closed liquid-containing vessel for repeatedly pouring the liquid from the vessel under a low pressure into sand moulds, each of which sand moulds comprises at least one mould cavity and a liquid inlet passageway which is combined with means for precluding a return flow of the liquid from the mould cavity after the liquid has filled said cavity, the device comprising an upwardly extending pouring tube having a lower end portion immersed in the liquid in the vessel and an upper end portion extending out of the vessel and defining a liquid outlet for receiving the mould so as to supply the liquid to said cavity via said tube outlet and said inlet passageway of the mould, a source of gas under pressure, an inlet communicating with the interior of the vessel above the liquid, an outlet communicating with the interior of the vessel above the liquid, first conduit means putting the source in communication with said inlet, second conduit means putting the source in communication with said inlet, pressure-reducing first valve means inserted in the first conduit means for supplying the gas to the vessel at a first pressure, pressure-reducing second valve means inserted in the second conduit means, means inserted in the second conduit means for producing a given rate of flow of the gas in the second conduit means, detector means associated with the tube for detecting a predetermined level of the liquid in the tube, a pressure sensor for responding to a second pressure of the gas prevailing in the vessel above the liquid and representing the pressure of the gas when the liquid is at said predetermined level in the tube, exhaust valve means associated with said outlet for controlling the discharge of the gas from the vessel, the detector means being associated with the first valve means and operative to close the first valve means when the liquid reaches said predetermined level in the tube, the second valve means being associated with the pressure sensor for producing a third pressure of the gas in the vessel which is higher than said second pressure by a predetermined amount, means being associated with the second conduit means for maintaining said third pressure for a given period to allow said means for precluding a return flow of the liquid to operate, and the exhaust valve means being associated with one of two elements consisting of the pressure sensor and the detector means for reducing the gas pressure in the vessel and bringing the liquid in the tube down to substantially said predetermined level for putting the device in a condition for filling a following mould.

Claim 6

A device for controlling a closed liquid-containing vessel for repeatedly pouring the liquid from the vessel under a low pressure into sand moulds, each of which sand moulds comprises at least one mould cavity and a liquid inlet passageway which is combined with means for precluding a return flow of the liquid from the mould cavity after the liquid has filled said cavity, the device comprising an upwardly extending pouring tube having a lower end portion immersed in the liquid in the vessel and an upper end portion extending out of the vessel and defining a liquid outlet for receiving the mould so as to supply the liquid to said cavity via said tube outlet and said inlet passageway of the mould, a source of gas under pressure, an inlet communicating with the interior of the vessel above the liquid, an outlet communicating with the interior of the vessel above the liquid, first conduit means putting the source in communication with said inlet, second conduit means putting the source in communication with said inlet, pressure-reducing first valve means inserted in the first conduit means for supplying the gas to the vessel at a first pressure, pressure-reducing second valve means inserted in the second conduit means, means inserted in the second conduit means for producing a given rate of flow of the gas in the second conduit means, detector means associated with the tube for detecting a predetermined level of the liquid in the tube, a pressure sensor for responding to a second pressure of the gas prevailing in the vessel above the liquid and representing the pressure of the gas when the liquid is at said predetermined level in the tube, exhaust valve means associated with said outlet for controlling the discharge of the gas from the vessel, the detector means being associated with the first valve means and operative to close the first valve means when the liquid reaches said predetermined level in the tube, the second valve means being associated with the pressure sensor for producing a third pressure of the gas in the vessel which is higher than said second pressure by a predetermined amount, means being associated with the second conduit means for maintaining said third pressure for a given period to allow said means for precluding a return flow of the liquid to operate, and the exhaust valve means being associated with one of two elements consisting of the pressure sensor and the detector means for reducing the gas pressure in the vessel and bringing the liquid in the tube down to substantially said predetermined level for putting the device in a condition for filling a following mould.