Cutting water table and methods of use
View Patent ↗A water table for cutting metallic materials comprises an upper water pool supported above a false vessel bottom. The surface of the upper pool water volume is regulated relative to workpiece support rails secured above the upper pool surface. An actual vessel bottom is positioned below the false bottom and supports a lower pool volume. Bearing directly upon the lower pool surface is an enclosed air pressure volume regulated by an air supply source. The upper and lower pool volumes are hydraulically linked by flow conduits. A frangible rupture disc in a pressure release vent assures an absolute pressure limit within the air volume to avoid over-pressurization or under-pressurization of the water table.
1. A metal cutting water table comprising:
a vessel comprising a primary water volume located beneath a plurality of support rails, wherein the support rails are secured to the vessel in parallel alignment along a common support plane, wherein the vessel additionally comprises a secondary water volume beneath the primary water volume, and wherein the primary water volume and the secondary water volume are hydraulically linked by a plurality of water conduits;
a true bottom below a false bottom, wherein the false bottom extends parallel with the common support plane;
an air volume bearing upon the secondary water volume to support a predetermined surface level for the primary water volume;
an air control conduit for controlling additions and reductions of air in the air volume;
a pressure relief conduit opening into the air volume; and
a rupture disc closing the pressure relief conduit, wherein the rupture disc ruptures to open the pressure relief conduit at a pressure differential across the rupture disc that is equal to or exceeding a predetermined value.
2. The metal cutting water table of claim 1 , wherein a volume of space is between the false bottom and the true bottom, and wherein the volume of space is divided between the air volume and the secondary water volume.
3. The metal cutting water table of claim 2 , wherein the water conduits penetrate the false bottom and extend downwardly through the secondary water volume.
4. The metal cutting water table of claim 3 , comprising a gap between the water conduits and the true bottom, wherein the secondary water volume flows into the water conduits through the gap.
5. The metal cutting water table of claim 1 , wherein the rupture disc comprises a calibrated flange plate that ruptures at the predetermined value of the pressure differential to release pressure in the air volume.
6. The metal cutting water table of claim 1 , wherein the rupture disc comprises polytetrafluoroethylene.
7. The metal cutting water table of claim 1 , wherein the rupture disc is secured to the pressure relief conduit with a flange connection, bolt connection, threaded connection, or combinations thereof.
8. The metal cutting water table of claim 1 , wherein the air control conduit comprises a first valve and a second valve, wherein the first valve actuates to add air to the air volume, and wherein the second valve actuates to remove air from the air volume.
9. A method of preventing destructive over pressure in a plasma arc cutting table, wherein the method comprises the steps of:
securing a primary water volume positioned beneath a plurality of workpiece support rails to a water holding vessel in parallel alignment against a workpiece support plane;
positioning the primary water volume elevationally above a secondary water volume and hydraulically linking the primary water volume to the secondary water volume via a plurality of water conduits;
bearing a pressurized volume of air upon the secondary water volume to sustain a predetermined surface level for the primary water volume, the pressurized volume of air being provided above a true bottom of the water holding vessel and below a false bottom of the water holding vessel, the false bottom extending parallel with the workpiece support plane;
controlling a supply of air, pumped into the pressurized air volume, relative to a predetermined surface level for the primary water volume; and
closing a pressure relief conduit in communication with the pressurized air volume with a rupture disc that opens the pressure relief conduit at a pressure differential across the rupture disc that is equal to or exceeding a predetermined value.
10. The method of claim 9 , further comprising the step of selecting a rupture disc that is calibrated to fail at the predetermined pressure differential.
11. The method of claim 9 , wherein the step of positioning the primary water volume elevationally above a secondary water volume is accomplished by the step of bearing a pressurized volume of air upon the secondary water volume.
12. The method of claim 9 , wherein the step of controlling a supply of air pumped into the pressurized air volume further comprises controlling the supply of air independently of the use of the rupture disc.
13. The method of claim 12 , wherein the step of controlling a supply of air pumped into the pressurized air volume further comprises actuating a first valve to increase the supply of air to the pressurized air volume, and actuating a second valve to release the supply of air within the pressurized air volume.
14. The method of claim 13 , wherein the steps of actuating the first valve and actuating the second valve are controlled by a sensor in accordance with the predetermined surface level.
15. The method of claim 9 , wherein the step of closing the pressure relief conduit with the rupture disc further comprises connecting the rupture disc to the pressure relief conduit with a flange connection, bolt connection, threaded connection, or combinations thereof.
16. The method of claim 9 , wherein the step of bearing a pressurized volume of air upon the secondary water volume to sustain the predetermined surface level is accomplished by forcing a portion of the secondary water volume upward through the plurality of water conduits that are physically separated from the pressurized air volume.