Fluid sprinkling – spraying – and diffusing – Including supply holder for material – Conveyer for fluent solid in holder
Reexamination Certificate
2001-01-09
2004-01-13
Hwu, Davis (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including supply holder for material
Conveyer for fluent solid in holder
C239S329000, C239S310000, C239S311000
Reexamination Certificate
active
06676039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to waterjet cutting systems and more particularly to abrasive feed systems for same.
2. Description of the Prior Art
Waterjet cutting is well known and involves the use of pure high pressure waterjets containing abrasive particles being used to cut or peen materials such as stainless steel. Various types of abrasive materials are used including ice crystals. Such systems are known and examples of same are found in various U.S. patents.
One system shown in U.S. Pat. No. 5,778,713 teaches the use of abrasive material waterjet devices underwater for peening and not waterjet cutting.
Another system is shown in U.S. Pat. No. 5,211,752 to Allerton. Which teaches an abrasive material waterjet cutting application other than underwater cutting.
The above described abrasive waterjet (AWJ) processes require that the cutting abrasive be metered to the cutting nozzle at a constant rate. During some applications the abrasive must be delivered to the nozzle from a hopper at great distances such as 100 feet or more. This same abrasive must still be metered to a constant known flow rate. All of the known existing systems, require that the abrasive metering system be located close to the cutting nozzle, usually within 5 feet, and depend on the vacuum created in the nozzle to pull the metered abrasive into the high pressure jet. Other abrasive metering devices are known which use various embodiments for trying to maintain a constant flow of abrasive to the cutting nozzle.
One example is found in U.S. Pat. No. 4,478,368 which teaches the transport of abrasive to a waterjet nozzle from a pressurized container. The flow from the pressurized abrasive container is controlled by a control valve and a pressure regulator with the line pressure being measured by a pressure meter.
Another example is found in U.S. Pat. No. 5,320,289 which teaches the transport of abrasive material to a waterjet using a vacuum assist line under the control of a controller to meter the flow of abrasive from a hopper.
Yet another example is seen in U.S. Pat. No. 5,854,744 which teaches the transport of abrasive to a waterjet using a vibrating hopper controlled by a controller.
None of these prior art systems assure the constant flow of abrasive under varying external pressure conditions found at the opening of the discharge tank or at the hopper or other container for the abrasive. Thus a system was needed for discharging abrasive to the cutting nozzle which was independent of these external pressure variations.
SUMMARY OF THE INVENTION
The present invention solves the problems associated with prior art abrasive delivery systems to the cutting nozzle and others, by providing an improved abrasive delivery system (
10
) for delivering an abrasive material (
14
) to a cutting nozzle (not shown) which will have no external pressure effects varying the abrasive delivery.
To accomplish this, the system (
10
) of the present invention uses a pressurized container or hopper (
12
) and a delivery hose (
18
) to transport the abrasive material (
14
) to the nozzle. Pressure regulated air is delivered to the hose inlet and the hopper at a pressure adequate to push the suspended abrasive through the required length of hose. The classical flow orifice is used to regulate the flow of abrasive as it exits the hopper. Since the pressure is maintained equal above and below the orifice, it does not influence the abrasive flow through it.
As the process requires greater abrasive flow, the flow orifice is changed to a larger diameter and pressure is increased as necessary to move the abrasive. The advantage of this system is the metering device is located at the hopper and is not a separate unit.
In view of the foregoing it will be seen that one aspect of the present disclosure is to provide an abrasive delivery system to waterjet cutting nozzles having a constant abrasive flow for differing external pressures.
Another aspect of the present invention is to provide an abrasive delivery system to waterjet cutting nozzles having no pressure difference between the abrasive holding tank and the abrasive delivery orifice.
Yet another aspect of the present invention is to provide an abrasive delivery system to waterjet cutting nozzles having a abrasive container and metering nozzle in close proximity to one another even if the cutting nozzle is connected at a distance therefrom.
REFERENCES:
patent: 4250908 (1981-02-01), Velie
patent: 4512515 (1985-04-01), Tenney
patent: 4534427 (1985-08-01), Wang et al.
patent: 4594924 (1986-06-01), Windisch
patent: 4821467 (1989-04-01), Woodson et al.
patent: 5133500 (1992-07-01), Simpson
patent: 5150690 (1992-09-01), Carter et al.
patent: 5213263 (1993-05-01), Corona
patent: 5785127 (1998-07-01), Miller, Sr.
patent: 6220529 (2001-04-01), Xu
Gould Michael C.
Lindsey Orville L.
Framatome ANP Inc.
Hwu Davis
Watas Vytas R.
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