Patents by Inventor Lifeng Luo

Lifeng Luo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5317126
    Abstract: In a plasma arc cutting torch a flow of plasma gas is bypassed out of a plasma chamber, preferably at an annular gap between a pre-orifice in an inner nozzle piece and an exit nozzle orifice in an outer nozzle piece. A bypass channel formed between the inner and outer nozzle pieces directs the bypass flow to atmosphere. A metering valve or restricting orifice remote from the gap controls the amount of the bypass flow and delays the response of changes in the flow parameters in the plasma chamber to changes in the bypass flow. The pre-orifice and nozzle orifice are positioned and dimensioned to optimize the mass flow velocity and the strength of a vortex-type flow at the pre-orifice, thereby creating a virtual nozzle immediately below the electrode. The gas flow in the plasma chamber is highly uniform and very steady.
    Type: Grant
    Filed: January 14, 1992
    Date of Patent: May 31, 1994
    Assignee: Hypertherm, Inc.
    Inventors: Richard W. Couch, Jr., Nicholas A. Sanders, Lifeng Luo, John Sobr, Patrik Backander
  • Patent number: 5310988
    Abstract: The diameter of a hafnium insert press fit into the bottom end of a copper electrode varies as a function of the level of current carried by the electrode. The diameter is the minimum necessary to support emission at that current level while also protecting the copper body against attack by the arc. The insert is generally circular and preferably extends completely through the bottom wall to a circulating flow of cooling water at a hollow interior of the electrode. The bottom wall includes an annular recess in a portion of the copper wall surrounding the insert. A coolant inlet tube extends into the recess in a spaced relationship to provide a high flow velocity of the coolant over the interior rear surface of the electrode.
    Type: Grant
    Filed: May 20, 1992
    Date of Patent: May 10, 1994
    Assignee: Hypertherm, Inc.
    Inventors: Richard W. Couch, Jr., Nichols A. Sanders, Lifeng Luo, Zhipeng Lu, Patrik Backander, John Sobr
  • Patent number: 5170033
    Abstract: A process and apparatus for reducing wear of an electrode in a plasma arc torch involves providing a substantial pressure drop in a flow of plasma gas from the torch to a plasma arc chamber defined by the electrode and a nozzle. The pressure drop is immediately before the plasma arc chamber. There is also a small, localized supply of the plasma gas located between the pressure drop and the plasma chamber. The supply is sufficient to stabilize the arc when the gas flow is cut off upstream of the pressure drop and the arc current is cut off very shortly thereafter. The pressure drop is small enough to permit an adequate flow of plasma gas to the plasma arc chamber during normal operations, but large enough to isolate residual gas in the torch from the plasma arc chamber when the arc current is cut off. The apparatus is preferably a swirl ring with an annular pre-chamber fed by a set of choke holes to feed gas to the chamber and create the pressure drop.
    Type: Grant
    Filed: April 12, 1991
    Date of Patent: December 8, 1992
    Assignee: Hypertherm, Inc.
    Inventors: Richard W. Couch, Jr., Lifeng Luo, Nicholas A. Sanders
  • Patent number: 5166494
    Abstract: A process and apparatus for reducing wear of an electrode in a plasma arc torch involves altering the gas flow in a plasma chamber surrounding the electrode immediately before and continuing after cutting of the current that sustains the arc. The altering includes closing off the gas flow upstream of the chamber, switching from a swirling flow to a radial/axial flow through the plasma chamber, reducing the arc current level in conjunction with either of the above, the venting the plasma chamber to rapidly change the gas flow and pressure in the chamber. The interval is sufficient to reduce electrode wear, but short enough that the arc remains stabilized until cut-off. In the flow stop mode, a solenoid valve is placed on an inlet tube for the plasma gas. Flow altering also occurs on start up. A gas preflow is established prior to pilot arc ignition. On transfer, the flow increases to its full operating value in conjunction with an increase in the arc current. The preflow can be axial, or partially axial.
    Type: Grant
    Filed: April 12, 1991
    Date of Patent: November 24, 1992
    Assignee: Hypertherm, Inc.
    Inventors: Lifeng Luo, Nicholas A. Sanders, Richard W. Couch, Jr.
  • Patent number: 5070227
    Abstract: A process and apparatus for reducing wear of an electrode in a plasma arc torch involves altering the gas flow in a plasma chamber surrounding the electrode immediately before and continuing after cutting of the current that sustains the arc. The altering includes closing off the gas flow upstream of the chamber, switching from a swirling flow to a radial/axial flow through the plasma chamber, reducing the arc current level in conjunction with either of the above, and venting the plasma chamber to rapidly change the gas flow and pressure in the chamber. The interval is sufficient to reduce electrode wear, but short enough that the arc remains stabilized until cut-off. In the flow stop mode, a solenoid valve is placed on an inlet tube for the plasma gas. For venting, a vent tube and another solenoid valve are added to the torch.
    Type: Grant
    Filed: April 24, 1990
    Date of Patent: December 3, 1991
    Assignee: Hypertherm, Inc.
    Inventors: Lifeng Luo, Nicholas A. Sanders, Richard W. Couch, Jr.