Thermal Forming of Refractory Alloy Surgical Needles

Abstract

A method of thermal forming of refractory alloy suture needles is disclosed. Needle blanks made from refractory alloys are used to form surgical needles, which are heated to a temperature above the ductile to brittle transition temperature but below the recrystallization temperature of the refractory alloy. The heated needle blanks are then mechanically formed into a surgical needle.

1 . A method of forming a refractory alloy into a surgical needle, said method comprising:
 providing an alloy metal needle blank, said needle blank comprising a refractory metal alloy;   heating at least a section of the needle blank to a temperature above the ductile to a brittle transition temperature, but below the recrystallization temperature of the alloy; and,   mechanically forming the needle blank into a surgical needle.   
   
   
       2 . The method of  claim 1  wherein the temperature is between about 100° C. to about 1600° C. 
   
   
       3 . The method of  claim 1  wherein the temperature is between about 600° C. and about 1400° C. 
   
   
       4 . The method of  claim 1  wherein the elongation to break of the alloy is increased to exceed 5%. 
   
   
       5 . The method of  claim 1  wherein the forming operation is selected from the group consisting of needle body forming, needle point coining, needle channel coining, and needle curving. 
   
   
       6 . The method of  claim 1  wherein the alloy has a Rhenium concentration comprising of about 0% to about 30% 
   
   
       7 . The method of  claim 1  wherein the needle is heated using hot gas jets. 
   
   
       8 . The method of  claim 1  wherein the needle is heated using a resistive heating element. 
   
   
       9 . The method of  claim 1  wherein the needle is heated by contacting electrodes to the needle blank and causing an electrical current to flow through the needle blank. 
   
   
       10 . The method of  claim 1  wherein the needle is in an oxygen free atmosphere when at an elevated temperature. 
   
   
       11 . The method of  claim 10  wherein the oxygen free atmosphere is a shielding gas or combination of shielding gases selected from the group consisting of nitrogen, argon, helium, and hydrogen. 
   
   
       12 . The method of  claim 1  wherein the refractory alloy comprises Tungsten and one or more elements selected from the group consisting of Rhenium, Molybdenum, Tantalum, Titanium, Yttrium, Zirconium, and Niobium. 
   
   
       13 . The method of  claim 1  wherein the refractory alloy comprises Molybdenum and one or more elements selected from the group consisting of Rhenium, Tungsten, Tantalum, Osmium, Iridium, Yttrium, Zirconium, and Niobium. 
   
   
       14 . The method of  claim 1  wherein the refractory alloy is Tungsten-Rhenium (W—Re). 
   
   
       15 . The method of  claim 14  wherein the W—Re alloy has a rhenium concentration less than 30% and preferably 26% or less. 
   
   
       16 . The method of  claim 14  wherein the temperature of the W—Re alloy is elevated to between 100° C. and 1600° C. and more preferably between about 600° C. and 1400° C. where the forming operation is selected from the group consisting of coining, flattening, channel forming, point forming, and curving. 
   
   
       17 . The method of  claim 1  wherein the alloy needle blank is heated by a method selected from the group consisting of resistive heating, radiant heat, induction coils, and hot gas streams. 
   
   
       18 . A surgical needle comprising a refractory alloy wherein the needle can be re-shaped more than 1.0 times without breaking. 
   
   
       19 . The needle of  claim 18  wherein the suture needle made from a refractory alloy wire is work hardened to a tensile strength greater than 2500 MPa and thermal formed.