Systems and methods for manufacturing orthodontic appliances

Abstract

A system for debinding a green body in the form of an orthodontic appliance may include a pressure vessel configured to contain a supercritical fluid. A source of a fluid chemical may be coupled to the pressure vessel to supply the fluid chemical to the pressure vessel. A heat source may be configured to heat the fluid chemical. A pump may pressurize the fluid chemical to at least the supercritical pressure. A collection vessel is coupled to the pressure vessel to capture the binder removed from the green bodies as at least the pressure of the supercritical fluid is reduced. A method of manufacturing an orthodontic appliance includes exposing green bodies including particles and a binder to a supercritical fluid to remove at least some of the binder from the green bodies, and collecting the removed binder from the supercritical fluid as the supercritical fluid transitions to a non-supercritical fluid.

What is claimed is: 
     
         1 . A system for debinding a green body in the form of an orthodontic appliance comprising:
 a pressure vessel configured to contain a plurality of green bodies, including sinterable particles and a binder, and a supercritical fluid capable of removing the binder from the green bodies;   a liquid supply system coupled to the pressure vessel and configured to supply a fluid chemical to the pressure vessel;   a collection vessel coupled to the pressure vessel for receiving the fluid chemical and the binder removed from the green bodies, the collection vessel being configured to capture the binder removed from the green bodies;   a tube between the pressure vessel and the collection vessel for flowing the fluid chemical and the binder from the pressure vessel to the collection vessel; and   a heater proximate the tube for heating the binder as the binder flows through the tube.   
     
     
         2 . The system of  claim 1 , wherein the tube is less than 2.5 feet long. 
     
     
         3 . The system of  claim 1 , wherein the tube is larger than ⅛ inch in diameter. 
     
     
         4 . The system of  claim 1 , wherein the tube is about ¼ inch in diameter. 
     
     
         5 . The system of  claim 1 , wherein the liquid supply system includes a source of the fluid chemical coupled to the pressure vessel and configured to supply the fluid chemical to the pressure vessel. 
     
     
         6 . The system of  claim 1 , wherein the liquid supply system includes a heat source configured to heat the fluid chemical to at least a supercritical temperature of the fluid chemical. 
     
     
         7 . The system of  claim 6 , wherein the liquid supply system includes a pump configured to pressurize the fluid chemical to at least a supercritical pressure of the fluid chemical, the combination of the supercritical pressure and supercritical temperature being sufficient to form the supercritical fluid in contact with the binder of the green bodies; 
     
     
         8 . The system of  claim 7 , further including a source of compressed air coupled to the pump and configured to supply pressurized air to the pump. 
     
     
         9 . The system of  claim 1 , further including a pressure regulator in the tube and configured to control a pressure of the fluid chemical in the tube. 
     
     
         10 . The system of  claim 1 , further including a heater proximate the collection vessel and configured to heat binder in the collection vessel to a temperature at which the binder is flowable. 
     
     
         11 . The system of  claim 1 , further including a vent line fluidly coupled to the collection vessel and configured to vent fluid from the collection vessel to atmosphere. 
     
     
         12 . The system of  claim 11 , further including a flow meter coupled to the vent line and configured to measure fluid flow between the collection vessel and the atmosphere. 
     
     
         13 . The system of  claim 1 , further including a drain line coupled to the collection vessel and configured to flow binder from the collection vessel. 
     
     
         14 . The system of  claim 1 , further including a relief valve coupled to the collection vessel and configured to prevent over pressurization of the collection vessel. 
     
     
         15 . The system of  claim 1  further including an outlet valve coupled to the pressure vessel between the pressure vessel and the collection vessel and configured to be automatically opened and closed. 
     
     
         16 . The system of  claim 1  further including an inlet valve coupled to the pressure vessel between the source of the fluid chemical and the pressure vessel and configured to be automatically opened and closed. 
     
     
         17 . The system of  claim 1  further including an auto vent valve coupled to the pressure vessel at or near an outlet of the pressure vessel and configured to vent the pressure vessel to atmosphere. 
     
     
         18 . The system of  claim 1  further including a rupture disc directly coupled to an outlet of the pressure vessel and configured to vent to atmosphere when the pressure vessel is over pressurized. 
     
     
         19 . A system for using a supercritical fluid during debinding of a green body, the system comprising:
 a pressure vessel configured to contain a plurality of green bodies, including sinterable particles and a binder;   a collection vessel coupled to the pressure vessel for receiving a fluid chemical and the binder removed from the green bodies in the pressure vessel;   a tube between the pressure vessel to the collection vessel; and   a heater proximate the tube for heating the binder that separates from the fluid chemical as the fluid chemical flows through the tube toward the collection vessel.   
     
     
         20 . The system of  claim 1 , wherein the tube is less than 2.5 feet long and is larger than ⅛ inch in diameter.