Method and apparatus for automatically controlling gas pressure for a plasma cutter

Abstract

A system for providing a dynamically controlled plasma cutting system includes a plasma cutting system having a proportional valve and a sensing device arrangement and a controller connected to this arrangement. The system is configured to dynamically control gas flow in a plasma torch. The system measures gas pressure at a proportional valve and makes necessary gas pressure adjustments in the system by way of controlling a drive signal sent to the proportional valve to control gas flow.

1 - 24 . (canceled) 
   
   
       25 . A method for extending the life of a torch consumable comprising:
 providing a first fluid line for supplying a plasma gas to the torch;   positioning a programmable control valve in the first fluid line adjacent the torch to control a flow of the plasma gas; and   manipulating the programmable control valve thereby
 a) controlling the flow of the plasma gas to the torch during operation of the torch; and 
 b) compensating for a volume in the first fluid line between the proportional solenoid control valve and the torch. 
   
   
   
       26 . The method of  claim 25  wherein a control output from a digital signal processor is used to adjust the programmable control valve to perform at least one of the controlling and the compensating steps. 
   
   
       27 . The method of  claim 25  wherein the programmable control valve is a proportional solenoid control valve. 
   
   
       28 . The method of  claim 26  further comprising a sensor disposed between the torch and the programmable control valve, such that the digital signal processor uses a signal from the sensor to adjust the control output to the programmable control valve. 
   
   
       29 . The method of  claim 28  wherein the sensor is at least one of a pressure sensor or a flow sensor. 
   
   
       30 . The method of  claim 25  further comprising the steps of:
 positioning a sensor in the first fluid line between the programmable control valve and the torch;   sensing a parameter in the first fluid line; and   using the sensed parameter to adjust the programmable control valve during the controlling step.   
   
   
       31 . A method for control of a gas flow to a plasma arc torch including a
 plasma chamber disposed within a torch body comprising:   providing a first fluid line for supplying a first gas to the torch;   positioning a programmable control valve in the first fluid line adjacent the torch to control a flow of the first gas; and   manipulating the programmable control valve thereby
 a) controlling the flow of the first gas to the torch during operation of the torch; and 
 b) compensating for a volume in the first fluid line between the programmable control valve and the torch. 
   
   
   
       32 . The method of  claim 31  wherein the programmable control valve is a proportional solenoid control valve. 
   
   
       33 . The method of  claim 31  wherein the first gas is a plasma gas that supplies the plasma chamber. 
   
   
       34 . The method of  claim 31  wherein a control output from a digital signal processor is used to adjust the programmable control valve to perform at least one of the controlling and the compensating steps. 
   
   
       35 . The method of  claim 34  further comprising a sensor disposed between the torch and the programmable control valve, such that the digital signal processor uses a signal from the sensor to adjust the control output to the programmable control valve. 
   
   
       36 . A plasma arc torch for cutting a workpiece, the plasma torch having a plasma gas source to supply a plasma chamber such that an electrical current passing between an electrode and a nozzle produces a plasma arc that exits the torch through a nozzle exit orifice, the plasma torch comprising:
 a means for sensing a parameter in a first fluid line that supplies a plasma gas from the plasma gas source; and   a means for controlling a flow of the plasma gas to the plasma chamber based on the sensed parameter using a programmable control valve disposed in the first fluid line adjacent the plasma torch.   
   
   
       37 . The plasma arc torch of  claim 36  wherein the programmable control valve is a proportional solenoid control valve. 
   
   
       38 . The plasma torch of  claim 36  wherein the sensed parameter is a pressure or a flow of the plasma gas. 
   
   
       39 . The plasma torch of  claim 36  wherein a control output from a digital signal processor is used to manipulate the programmable control valve. 
   
   
       40 . A plasma cutting system comprising:
 a power supply; and   a plasma arc torch for cutting a workpiece, the plasma torch having a plasma gas source to supply a plasma chamber such that an electrical current passing between an electrode and a nozzle produces a plasma arc that exits the torch through a nozzle exit orifice, the plasma torch comprising:   a means for sensing a parameter in a first fluid line that supplies a plasma gas from the plasma gas source; and   a means for controlling a flow of the plasma gas to the plasma chamber based on the sensed parameter using a programmable control valve disposed in the first fluid line adjacent the plasma torch.   
   
   
       41 . The plasma cutting system of  claim 40  wherein the programmable control valve is a proportional solenoid control valve. 
   
   
       42 . A plasma arc torch for cutting a workpiece, the plasma torch having a plasma gas source to supply a plasma chamber and a shield gas source to supply a shield gas to pass through a space between a nozzle and a shield, such that an electrical current passing between an electrode and a nozzle produces a plasma arc that exits the torch through a nozzle exit orifice, the plasma torch comprising:
 a means for sensing a parameter in a first fluid line that supplies at least one of a plasma gas from the plasma gas source or a shield gas from the shield gas source; and   a means for controlling a flow of the first gas based on the sensed parameter using a programmable control valve disposed in the first fluid line adjacent the plasma torch.   
   
   
       43 . The plasma arc torch of  claim 42  wherein the programmable control valve is directly coupled to the plasma arc torch. 
   
   
       44 . A method for control of a gas flow to a plasma arc torch including a plasma chamber disposed within a torch body comprising:
 providing a first fluid line for supplying a first gas to the torch;   positioning a programmable control valve in the first fluid line adjacent the torch to control a flow of the first gas; and   manipulating the programmable control valve thereby
 a) controlling the flow of the first gas to the torch during operation of the torch; and 
 b) compensating for a volume in the first fluid line between the programmable control valve and the torch. 
   
   
   
       45 . The method of  claim 44  wherein the programmable control valve is directly coupled to a torch body of the plasma arc torch.