Electric heating – Metal heating – By arc
Reexamination Certificate
2000-03-31
2001-12-04
Paschall, Mark (Department: 3742)
Electric heating
Metal heating
By arc
C219S121440, C219S121540, C219S121390
Reexamination Certificate
active
06326583
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed towards an apparatus and process for controlling a plasma arc torch. More particularly, the present invention relates to a control apparatus which regulates the supply of preflow, plasma, shield gases, and post flow supplied to a plasma arc torch.
BACKGROUND OF THE INVENTION
The operation of conventional plasma arc torches is well known and understood by those having ordinary skill in the art. The basic components of these torches are a body, an electrode, mounted in the body, a nozzle defining an orifice for a plasma arc, a source of an ionizable gas, and an electrical supply for producing an arc in the gas.
Initiation of a torch start up sequence involves supplying an electrical current to the electrode, typically a cathode, and the pilot arc is initiated in a pre-flow supply of ionizable gas between the electrode and the nozzle. A flow of a plasma gas is then directed from the electrode to the work piece, wherein the work piece defines the anode and a plasma arc is generated from the electrode to the work piece. Suitable ionizable gases include non-reactive gases such as nitrogen, or reactive gases such as oxygen or air. Shield gases are also employed to increase the efficiency and efficacy of the torch cutting process.
The control and regulation of the various supply gases (preflow, plasma and shield) is needed in order to obtain a high quality, economical cut. Improper supply gas pressures may damage or shorten the shorten the operating life of the torch nozzle and electrode components.
Torch operators frequently rely upon cutting charts to help determine proper combinations of gas and pressure with respect to the work piece material, thickness of the workpiece, operating currents, and desired plasma gas and gas pressures. Frequently, an operator may change an operating parameter without full realization of how the adjustment may impact other attributes of the torch performance. Frequently, operator adjustments lead to less than optimal performance which in turn increases operating costs and contribute to a shortened torch component life.
SUMMARY OF THE INVENTION
It is therefor a principal object of the present invention to provide an apparatus and process for the optimal control of the supply of operating gases to a plasma arc torch. In so doing, the longevity of consumable parts such as electrodes, nozzles, and shields is increased.
An additional object of the invention is to provide an apparatus and process which automatically presets pre-flow, plasma, shielding, and post flow gas pressures for a selected material and thickness.
Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In accordance with this invention, an apparatus is provided which permits the automated selection and continuous monitoring of the supply gases used to control a plasma arc torch. In one embodiment of this invention, a supply gas controller for a plasma arc torch is provided in which a user accessible console provides a user interface keypad for selecting menu options, default values, and manual inputting of select parameters. A console housing defines a plurality of gas inlet ports, each inlet port adapted for receiving a source of a pressurized gas such as nitrogen, air, oxygen, or other useful gas. A plurality of solenoid gas valves, each valve having an inlet and an outlet, are retained within the console housing and are used to establish a fluid flow between each inlet gas port and an inlet of a corresponding solenoid gas valve. The solenoid gas valves are responsive to signals from a microprocessor. The microprocessor may thereby regulate the gas selection and flow through the solenoid gas valves.
An outlet of each solenoid gas valve is in fluid communication with at least one of a plurality of pressure regulators. A pressure regulator is, in turn, in communication with a corresponding gas outlet port, namely a pre-flow outlet, a plasma outlet, a post flow outlet, and a shield outlet. For instance, a pressure regulator which supplies a gas under pressure to a pre-flow exit port of the console receives the gas from an external pressurized source. A pressure regulator which supplies a plasma gas flow receives the plasma gas from any one of a number of solenoid valves depending on the plasma gas selected. Similarly, a pressure regulator which supplies the shield gas outlet is in selective communication with a plurality of solenoid valves for receiving a pressurized gas suitable for use as a shield gas.
A microprocessor, responsive to a signal from the user interface, provides a control mechanism for the solenoid gas valves as well as each pressure regulator. In response to an input from the user interface, for example the type and thickness of material to be cut, the microprocessor automatically selects the type and pressure of each of the supply gasses and automatically initiates and controls the supply of the gasses during the cutting operation. In addition, arc current is also determined and automatically transmitted to the power source. The settings for the type and pressure of the supply gasses may be considered “default” settings for a selected type and thickness of material. The microprocessor stores such default settings in a memory or library. Additionally, the microprocessor may prompt the user that certain operational parameters, such as arc voltage, pierce height, cutting height, etc., are available to transmit to a torch height control apparatus, such as the INOVA torch height control made by Innerlogic, Inc. The microprocessor may also provide certain recommended settings, such as cutting speed, and the like.
Once the system has selected the appropriate settings and any required selections or settings have been made by the user, the microprocessor initiates and controls the cutting operation. For example, the microprocessor initiates a pre-flow gas, for example air, via a solenoid valve. The pre-flow gas is directed to its respective pressure regulator and then directed out of an outlet port of the console. Similarly, the appropriate plasma gas is directed via the appropriate solenoid valve to the corresponding plasma gas pressure regulator at the proper time. A similar control process occurs for the shield gas and post flow gas. The microprocessor additionally controls the supply pressure of each gas which is released from any of the pressure regulators, i.e., the pre-flow gas, the plasma gas, the post flow gas, and the shield gas, to the respective outlet ports.
The present invention also includes a useful automated gas flow control process for supplying pre-flow, plasma, shield, and post flow gasses to a plasma arc torch and may including the following steps:
selecting a material workpiece substrate;
providing a thickness value of the substrate;
based on the type and thickness of material, automatically selecting sources for the supply gasses and setting pressure settings for the gasses, the supply gasses including pre-flow, plasma, shield, and post flow gasses;
automatically calculating certain cutting parameter values preferably including but not limited to arc voltage, torch travel speed, cutting height, and a piercing height value and making such values available for use by a torch height control apparatus;
automatically setting and supplying arc current to the power source;
supplying the selected pre-flow gas at the selected pressure to the plasma arc torch in response to a start-up sequence;
supplying the selected plasma gas at the selected pressure to the plasma arc torch in response to the start-up sequence;
supplying the shield gas at the selected pressure to the plasma arc torch in response to the start-up sequence;
maintaining the selected plasma gas and shield gas at the respective pressures; and
upon shut down, supplying the post flow gas at the selected pressure.
Yet another embodiment of the invention is directed to a process of controlling the supply gas and gas
Hardwick J. Travis
Hardwick Steven F.
Newcomb David L.
Dority & Manning PA
Innerlogic, Inc.
Paschall Mark
LandOfFree
Gas control system for a plasma arc torch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas control system for a plasma arc torch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas control system for a plasma arc torch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2568893