Apparatus and Method for Performing Welding at Elevated Temperature

Abstract

A welding apparatus includes a workpiece housing having a window therethrough and having a welding access therethrough for a welder to an interior of the workpiece housing. The workpiece housing is metallic with a heat insulation on an internal surface thereof. A lamp heat source is directed through the window and at the workpiece in the interior of the workpiece housing. A gas source delivers a controllable flow of a shielding gas to the interior of the workpiece housing. A temperature sensor senses a temperature of the workpiece within the interior of the workpiece housing. A feedback controller controls the power to the lamp heat source responsive to the temperature of the workpiece. To perform welding, the workpiece is placed into the interior of workpiece housing to have its temperature sensed by the temperature sensor, and the gas source is operated to envelope the workpiece in the shielding gas.

1 . Apparatus for performing welding on a workpiece at elevated temperature, comprising: 
 a workpiece housing having a window therethrough and having a welding access therethrough for a welder to an interior of the workpiece housing, wherein the interior of the workpiece housing is sized to receive the workpiece therein, and wherein the workpiece housing is metallic with a heat insulation on an internal surface thereof;    a lamp heat source directed through the window and at the workpiece in the interior of the workpiece housing;    a gas source that delivers a controllable flow of a shielding gas to the interior of the workpiece housing;    a temperature sensor that senses a temperature of the workpiece within the interior of the workpiece housing; and    a feedback controller having a setpoint input and an input responsive to the temperature sensor, wherein the feedback controller controls the power to the lamp heat source responsive to the temperature of the workpiece.    
   
   
       2 . The apparatus of  claim 1 , wherein the workpiece housing is made of a stainless steel.  
   
   
       3 . The apparatus of  claim 1 , wherein the workpiece housing has a wall having an interior shape that is curved in its corners to avoid dead gas spaces in the corners.  
   
   
       4 . The apparatus of  claim 1 , wherein the workpiece housing has a removable top cover that provides the welding access.  
   
   
       5 . The apparatus of  claim 1 , wherein the heat insulation is a ceramic thermal barrier coating.  
   
   
       6 . The apparatus of  claim 1 , wherein the window is made of quartz.  
   
   
       7 . The apparatus of  claim 1 , wherein the lamp heat source comprises at least two quartz lamps, and 
 a cooled lamp housing in which the quartz lamps are received.    
   
   
       8 . The apparatus of  claim 1 , wherein the lamp heat source comprises 
 a lamp having a lamp output beam, and    a support upon which the lamp is supported, wherein the support is adjustable to establish an angle of incidence of the lamp output beam upon the workpiece and a distance of the lamp from the workpiece.    
   
   
       9 . The apparatus of  claim 1 , wherein the temperature sensor is selected from the group consisting of a pyrometer and a thermocouple.  
   
   
       10 . The apparatus of  claim 1 , wherein the gas source comprises a gas distribution structure in a bottom of the workpiece housing.  
   
   
       11 . (canceled)  
   
   
       12 . (canceled)  
   
   
       13 . (canceled)  
   
   
       14 . A method for welding a workpiece at elevated temperature, comprising the steps of 
 furnishing the workpiece;    furnishing a welding apparatus comprising: 
 a workpiece housing having a window therethrough and having a welding access therethrough for a welder to an interior of the workpiece housing, wherein the interior of the workpiece housing is sized to receive the workpiece therein, and wherein the workpiece housing is metallic with a heat insulation on an internal surface thereof;  
 a lamp heat source directed through the window and at the workpiece in the interior of the workpiece housing;  
 a gas source that delivers a controllable flow of a shielding gas to the interior of the workpiece housing;  
 a temperature sensor that senses a temperature of the workpiece within the interior of the workpiece housing;  
 a feedback controller having a setpoint input and an input responsive to the temperature sensor, wherein the feedback controller controls the power to the lamp heat source responsive to the temperature of the workpiece; and  
 a welder that may be positioned to weld the workpiece through the welding access;  
   placing the workpiece into the interior of the workpiece housing so as to have its temperature sensed by the temperature sensor;    operating the gas source to envelope the workpiece in the shielding gas;    heating the workpiece by powering the lamp heat source responsive to the setpoint input and to the temperature of the workpiece; and    welding the workpiece using the welder.    
   
   
       15 . The method of  claim 14 , wherein the step of furnishing the workpiece includes the step of 
 furnishing a component of a gas turbine engine as the workpiece.    
   
   
       16 . The method of  claim 14 , wherein the step of heating includes the step of performing a pre-welding heat treatment of the workpiece prior to the step of welding.  
   
   
       17 . The method of  claim 14 , wherein the step of heating includes the step of maintaining the workpiece at a welding temperature during the step of welding.  
   
   
       18 . The method of  claim 14 , wherein the step of heating includes the step of performing a post-welding heat treatment of the workpiece after the step of welding.  
   
   
       19 . The apparatus of  claim 1 , wherein the window is in a side of the workpiece housing and the welding access is through a top of the workpiece housing.  
   
   
       20 . The apparatus of  claim 1 , further including: 
 a welder having access to the interior of the workpiece housing through the welding access.