Sintering furnace

Abstract

According to one aspect, embodiments herein provide a furnace for debinding and sintering additively manufactured parts comprising a unitarily formed retort having at least one open side, a heater for heating a sintering volume within the retort to a debinding temperature and to a sintering temperature, an end cap sealing the at least one open side, a forming gas line penetrating the end cap for supplying forming gas at a flowrate, and a heat exchanger within the retort, outside the sintering volume, and adjacent a heated wall of the retort, the heat exchanger having an inlet connected to the forming gas line and an outlet to the sintering volume, wherein the heat exchanger includes a heat exchange tube length sufficient to heat the forming gas to within 20 degrees Celsius of the sintering temperature before the forming gas exits the outlet.

What is claimed is: 
     
       1. A furnace for debinding and sintering additively manufactured parts, comprising:
 a tubular retort having at least one open side; 
 a heater, outside of the tubular retort, for heating a sintering volume within the tubular retort to a debinding temperature and to a sintering temperature; 
 an end cap sealing the at least one open side; 
 a forming gas line penetrating the end cap for supplying forming gas at a flowrate; and 
 a heat exchanger within the tubular retort, outside the sintering volume, and adjacent a wall of the tubular retort that is constructed and arranged to be heated by the heater, the heat exchanger having an inlet connected to the forming gas line and an outlet to the sintering volume, wherein the heat exchanger includes a tube length sufficient to heat the forming gas to within 20 degrees Celsius of the sintering temperature before the forming gas exits the outlet, 
 wherein at least a portion of the heat exchanger is disposed between the heater and a sidewall of the retort. 
 
     
     
       2. The furnace according to  claim 1 , further comprising:
 a pressure control mechanism, including a vacuum pump, coupled to the retort and configured to control pressure in the retort. 
 
     
     
       3. The furnace according to  claim 2 , further comprising a control system configured to:
 control the flowrate of the forming gas; 
 operate the pressure control mechanism to control the pressure in the retort; and 
 control a level of heat provided by the heater to the sintering volume. 
 
     
     
       4. The furnace according to  claim 3 , further comprising:
 a moisture sensor configured to sense an amount of moisture in the sintering volume and to be in communication with the control system; and 
 a Liquid Petroleum Gas (LPG) sensor configured to sense an amount of hydrocarbon gas in the sintering volume and to be in communication with the control system. 
 
     
     
       5. The furnace according to  claim 1 , further comprising:
 a series of baffle shields adjacent the end cap and configured to reduce a temperature between the sintering volume and the end cap. 
 
     
     
       6. The furnace according to  claim 5 , further comprising:
 a dip tube penetrating the series of baffle shields to the sintering volume and configured to remove debinding decomposition gas from the sintering volume. 
 
     
     
       7. The furnace according to  claim 6 , further comprising:
 an inert purge gas supply penetrating the end cap and having an outlet at the end cap, the inert purge gas supply configured to introduce a purge gas between the series of baffle shields and the end cap that keeps the debinding decomposition gas away from walls of the retort adjacent the end cap. 
 
     
     
       8. The furnace according to  claim 1 , wherein the heat exchanger is formed as a stainless-steel tube having an exchange tube length greater than the length of the sintering volume.