Luminescent Braze Preforms

Abstract

A braze preform is provided that includes a filler metal and a luminescent material that covers at least a portion of the filler metal and that can luminesce when exposed to a black light. The luminescent material may include a luminescent ink and a solvent that are mixed together before being applied to filler metal. Presence of the braze preform may be determined using automated equipment by detecting luminescence of the braze preform with a sensor. A decision may be made on whether to advance a parts assembly for brazing based on the determination of presence or absence of the braze preform on such parts assembly.

What is claimed is: 
     
         1 . A braze preform comprising:
 a filler metal; and   a luminescent material that can luminesce when exposed to a black light, the luminescent material covering at least a portion of the filler metal.   
     
     
         2 . The braze preform of  claim 1 , wherein the luminescent material comprises equal to or less than 0.15% total weight of the braze preform after the luminescent material is fully cured. 
     
     
         3 . The braze preform of  claim 2 , wherein the braze preform is a brazing ring. 
     
     
         4 . The braze preform of  claim 2 , wherein the luminescent material includes a luminescent ink and a solvent that are mixed together before being applied to the filler metal. 
     
     
         5 . The braze preform of  claim 3 , wherein the luminescent ink is an optical brightener. 
     
     
         6 . The braze preform of  claim 3 , wherein the solvent is a non-flammable solvent. 
     
     
         7 . The braze preform of  claim 3 , wherein the luminescent ink is about 30% of the weight of the luminescent material before being applied to the filler metal and the solvent is about 70% of the weight of the luminescent material before being applied to the filler metal. 
     
     
         8 . The braze preform of  claim 3 , wherein the luminescent ink is about 10-50% of the weight of the luminescent material before being applied to the filler metal. 
     
     
         9 . The braze preform of  claim 3 , wherein the solvent is about 50-90% of the weight of the luminescent material before being applied to the filler metal. 
     
     
         10 . The braze preform of  claim 3 , wherein the luminescent material is soluble in a braze pool without introducing contamination in the form of inclusions, porosity, and voids in a brazed joint. 
     
     
         11 . The braze preform of  claim 3 , wherein a brazed joint is created with the braze preform to withstand a tensile strength of at least 32,000 psi. 
     
     
         12 . The braze preform of  claim 3 , wherein a brazed joint is created with braze preform to join a first tube with a second tube and the brazed joint can withstand a pressure within the first and second tube of 25,000 psi without a failure. 
     
     
         13 . The braze preform of  claim 2 , wherein the luminescent material is combined with a flux to produce a luminescent flux in the form of a powder or paste. 
     
     
         14 . The braze preform of  claim 2 , wherein the luminescent material is mixed homogeneously with the filler metal to produce a luminescent filler metal. 
     
     
         15 . The braze preform of  claim 3 , wherein the braze preform is used in heating, ventilation, an conditioning, valves, thermostatic valves, and hose applications. 
     
     
         16 . The braze preform of  claim 3 , further including:
 a first alloy piece;   a second alloy piece;   the braze preform connected to both the first and second alloy piece to form a workpiece; and wherein   heat is applied to the workpiece in a braze furnace comprising hydrogen or a hydrogen and nitrogen mixture between 1200-2000 degrees Fahrenheit without the use of flux for period of time including 15 minutes or less.   
     
     
         17 . The braze preform of  claim 16 , wherein the braze preform joins the first alloy piece with the second alloy piece by melting in the braze furnace and then solidifying on both the first and second alloy pieces to form a brazed workpiece. 
     
     
         18 . The braze preform  claim 17 . wherein the brazed workpiece is free of a contamination from the luminescent ink. 
     
     
         19 . A system for brazing multiple components to each other, the system comprising:
 a braze preform that includes,
 a filler metal; and 
 a luminescent material that covers at least a portion of the filler metal; 
   multiple components that are assembled to each other so that the brazing ring engages each of the multiple components;   a light source emitting light that can cause the luminescent material of the brazing ring to luminesce; and   a sensor that can detect luminescence and is positioned with respect to the brazing rings so as to detect the luminescence of the brazing ring.   
     
     
         20 . The system of  claim 20 , further including a plurality of shields defining an enclosure allowing only the light from the light source to enter the enclosure. 
     
     
         21 . The system of  claim 21 , wherein the sensor s a UV sensor. 
     
     
         22 . A method of determining whether to perform a brazing procedure, the method comprising:
 treating a braze preform with a luminescent material;   assembling the braze preform to a component to be subjected to a brazing procedure;   directing a light toward the component to be subjected to a brazing procedure;   detecting the luminescent material at the parts assembly;   determining presence or absence of the brazing preform on the component to be subjected to a brazing procedure based on detection of the luminescent material; and   determining whether to perform a brazing procedure to the determined presence or absence of the brazing preform.   
     
     
         23 . A method of detecting presence or absence of a brazing material during an assembly process, the method comprising:
 applying a luminescent material to a brazing filler metal;   creating a parts assembly that will be subjected to a brazing procedure by:
 assembling the brazing filler metal to a first component of the parts assembly; 
 assembling the first component of the parts assembly to a second component of the parts assembly; 
 creating an enclosure preventing shielding the parts assembly from secondary light sources; 
   directing an ultra violet light toward the parts assembly;   detecting the luminescent material at the parts assembly; and   determining brazing filler metal presence based on detection of the luminescent material.   
     
     
         24 . The method of  claim 24 , further comprising sending the parts assembly to at least one of a subsequent assembly station and a brazing station when the luminescent material is detected. 
     
     
         25 . A method of joining multiple components by brazing, the method comprising:
 applying a luminescent material to a brazing filler metal;   assembling the brazing filler metal to a first component to be brazed;   detecting the luminescent material;   assembling a second component to the first component so that the brazing filler metal engages both of the first and second components; and   brazing the first and second components to each other.   
     
     
         26 . The method of  claim 26 , wherein the luminescent material is detected after the first and second components are assembled to each other and before the first and second components are brazed to each other. 
     
     
         27 . The method of  claim 27 , wherein the brazing step occurs in a brazing furnace. 
     
     
         28 . The method of  claim 28 , wherein at least one of the assembling steps is performed in an assembly station of a facility having a first light source and the detecting step is performed in a detecting station of the facility having a second light source that is different from the first light source. 
     
     
         29 . The method of  claim 28 , wherein the second light source is a black light. 
     
     
         30 . The method of  claim 29 , further comprising blocking at least some light being emitted from the first light source with a shield that reduces the amount of light from the first light source that can illuminate the brazing filler metal. 
     
     
         31 . The method of  claim 30 , wherein multiple interconnected shields define an enclosure that blocks at least some light being emitted from the first light source. 
     
     
         32 . The method of  claim 30 , wherein the brazing the first and second components to each other step further includes producing a brazed joint free of contamination including inclusions, voids, porosity, slag, and spatter. 
     
     
         33 . The method of  claim 33 , further comprising verifying the brazed joint is free of contamination with a helium leak check.