Apparatus and method of cryogenic cooling for high-energy cutting operations

Abstract

A cryogenic fluid jet is used in an apparatus and a method for remote cooling of a cutting tool engaged in machining a workpiece under high-energy conditions, such as high-speed machining, hard-turning, cutting of difficult to machine materials, and combinations thereof. The apparatus and method use a stabilized, free-expanding cryogenic fluid jet having a pulse cycle time less than or equal to about 10 seconds. The apparatus and method increase the cleanliness of machined parts and chips and machining productivity of hard but brittle tools, including but not limited to tools which should not be cooled with conventional cooling fluids.

1 . A method for cooling a cutting tool, comprising the steps of: 
 providing a supply of a cryogenic fluid; and    delivering a free-expanding stabilized jet of the cryogenic fluid to the cutting tool.    
     
     
         2 . A method as in  claim 1 , wherein the cutting tool has a cutting edge and wherein a means for delivering the free-expanding stabilized jet of the cryogenic fluid to the cutting tool has at least one discharge point spaced apart from the cutting edge by a distance greater than or equal to about 0.1 inches and less than about 3.0 inches.  
     
     
         3 . A method as in  claim 1 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a temperature below about minus 150 degrees Celsius (−150° C.).  
     
     
         4 . A method as in  claim 2 , wherein at least a portion of the cryogenic fluid has a pressure greater than or equal to about 25 psig and less than or equal to about 250 psig during or immediately prior to discharge from the at least one discharge point.  
     
     
         5 . A method as in  claim 1 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a substantially uniform mass flowrate greater than or equal to about 0.5 lbs/minute and less than or equal to about 5.0 lbs/minute.  
     
     
         6 . A method as in  claim 1 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a substantially uniform mass flowrate having a flow pulse cycle time less than or equal to about 10 seconds.  
     
     
         7 . A method as in  claim 1 , wherein the cutting tool has a rake surface and at least a portion of the free-expanding stabilized jet of the cryogenic fluid impinges on at least a portion of the rake surface.  
     
     
         8 . A method as in  claim 1 , wherein at least a portion of the cryogenic fluid is selected from a group consisting of liquid nitrogen, gaseous nitrogen, liquid argon, gaseous argon and mixtures thereof.  
     
     
         9 . A method as in  claim 1 , wherein at least a portion of the cutting tool has a traverse rupture strength (TRS) value of less than about 3000 MPa.  
     
     
         10 . A method as in  claim 1 , wherein the cutting tool is engaged in a high-energy chip-forming and workpiece-cutting operation.  
     
     
         11 . A method for machining a workpiece with a cutting tool using a method for cooling the cutting tool as in  claim 1 .  
     
     
         12 . A workpiece machined by a method as in  claim 11  and characterized by an improved surface.  
     
     
         13 . Recyclable chips obtained as a byproduct of a method as in  claim 11  and characterized by an improved purity.  
     
     
         14 . A method for cooling a workpiece, comprising the steps of: 
 providing a supply of a cryogenic fluid; and    delivering a free-expanding stabilized jet of the cryogenic fluid to the workpiece.    
     
     
         15 . A method for controlling cooling of a cutting tool during a cutting operation, comprising the steps of: 
 providing a supply of a cryogenic fluid;    delivering a flow of the cryogenic fluid to the cutting tool; and    regulating the flow of the cryogenic fluid to the cutting tool at a substantially uniform mass flowrate, whereby a frost coating is maintained on at least a portion of the cutting tool during substantially all of the cutting operation in an atmosphere having an ambient relative humidity in a range of about 30% to about 75% and an ambient temperature in a range of about 10° C. to about 25° C.    
     
     
         16 . A method as in  claim 15 , wherein the cutting tool is engaged in a high-energy chip-forming and workpiece-cutting operation.  
     
     
         17 . A method for machining a workpiece with a cutting tool using a method for controlling cooling of the cutting tool as in  claim 15 .  
     
     
         18 . A workpiece machined by a method as in  claim 17  and characterized by an improved surface.  
     
     
         19 . Recyclable chips obtained as a byproduct of a method as in  claim 17  and characterized by an improved purity.  
     
     
         20 . A method for cooling a cutting tool having a cutting edge, comprising the steps of: 
 providing a supply of a cryogenic fluid;    providing a nozzle adapted to discharge a jet of the cryogenic fluid, said nozzle having at least one discharge point spaced apart from the cutting edge by a distance greater than or equal to about 0.1 inches and less than about 3.0 inches; and    delivering a free-expanding stabilized jet of the cryogenic fluid from the discharge point to the cutting tool, wherein the cryogenic fluid has a temperature of about minus 150 degrees Celsius (−150° C.) at the discharge point.    
     
     
         21 . A method for controlling cooling of a cutting tool during a cutting operation, comprising the steps of: 
 providing a supply of a cryogenic fluid;    providing a nozzle adapted to discharge a flow of the cryogenic fluid, said nozzle having at least one discharge point spaced apart from the cutting tool;    delivering a flow of the cryogenic fluid from the discharge point to the cutting tool; and    regulating the flow of the cryogenic fluid to the cutting tool at a substantially uniform mass flowrate greater than or equal to about 0.5 lbs/minute and less than or equal to about 5.0 lbs/minute having a flow pulse cycle time less than or equal to about 10 seconds, whereby a frost coating is maintained on at least a portion of the cutting tool during substantially all of the cutting operation in an atmosphere having an ambient relative humidity in a range of about 30% to about 75% and an ambient temperature in a range of about 10° C. to about 25° C.    
     
     
         22 . An apparatus for cooling a cutting tool, comprising: 
 a supply of a cryogenic fluid; and    means for delivering a free-expanding stabilized jet of the cryogenic fluid to the cutting tool.    
     
     
         23 . An apparatus as in  claim 22 , wherein the cutting tool has a cutting edge and wherein the means for delivering the free-expanding stabilized jet of the cryogenic fluid to the cutting tool has at least one discharge point spaced apart from the cutting edge by a distance greater than or equal to about 0.1 inches and less than about 3.0 inches.  
     
     
         24 . An apparatus as in  claim 22 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a temperature below about minus 150 degrees Celsius (−150° C.).  
     
     
         25 . An apparatus as in  claim 23 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a pressure greater than or equal to about 25 psig and less than or equal to about 250 psig during or immediately prior to discharge from the at least one discharge point.  
     
     
         26 . An apparatus as in  claim 22 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a substantially uniform mass flowrate greater than or equal to about 0.5 lbs/minute and less than or equal to about 5.0 lbs/minute.  
     
     
         27 . An apparatus as in  claim 22 , wherein at least a portion of the free-expanding stabilized jet of the cryogenic fluid has a substantially uniform mass flowrate having a flow pulse cycle time less than or equal to about 10 seconds.  
     
     
         28 . An apparatus as in  claim 22 , wherein the cutting tool has a rake surface and at least a portion of the free-expanding stabilized jet of the cryogenic fluid impinges on at least a portion of the rake surface.  
     
     
         29 . An apparatus as in  claim 22 , wherein at least a portion of the cryogenic fluid is selected from a group consisting of liquid nitrogen, gaseous nitrogen, liquid argon, gaseous argon and mixtures thereof.  
     
     
         30 . An apparatus as in  claim 22 , wherein at least a portion of the cutting tool has a traverse rupture strength (TRS) value of less than about 3000 MPa.  
     
     
         31 . An apparatus as in  claim 22 , wherein the cutting tool is engaged in a high-energy chip-forming and workpiece-cutting operation.  
     
     
         32 . An apparatus for machining a workpiece with a cutting tool using an apparatus for cooling the cutting tool as in  claim 22 .  
     
     
         33 . A workpiece machined by an apparatus as in  claim 32  and characterized by an improved surface.  
     
     
         34 . Recyclable chips removed from a workpiece by an apparatus as in  claim 32  and characterized by an improved purity.  
     
     
         35 . An apparatus for cooling a workpiece, comprising: 
 a supply of a cryogenic fluid; and    means for delivering a free-expanding stabilized jet of the cryogenic fluid to the workpiece.    
     
     
         36 . An apparatus for controlling cooling of a cutting tool during a cutting operation, comprising: 
 a supply of a cryogenic fluid;    means for delivering a flow of the cryogenic fluid to the cutting tool; and    means for regulating the flow of the cryogenic fluid to the cutting tool at a substantially uniform mass flowrate, whereby a frost coating is maintained on at least a portion of the cutting tool during substantially all of the cutting operation in an atmosphere having an ambient relative humidity in a range of about 30% to about 75% and an ambient temperature in a range of about 10° C. to about 25° C.    
     
     
         37 . An apparatus as in  claim 36 , wherein the cutting tool is engaged in a high-energy chip-forming and workpiece-cutting operation.  
     
     
         38 . An apparatus for machining a workpiece with a cutting tool using a method for controlling cooling of the cutting tool as in  claim 36 .  
     
     
         39 . A workpiece machined by an apparatus as in  claim 38  and characterized by an improved surface.  
     
     
         40 . Recyclable chips removed from a workpiece by an apparatus as in  claim 38  and characterized by an improved purity.  
     
     
         41 . An apparatus for cooling a cutting tool having a cutting edge, comprising: 
 a supply of a cryogenic fluid;    a nozzle adapted to discharge a jet of the cryogenic fluid, said nozzle having at least one discharge point spaced apart from the cutting edge by a distance greater than or equal to about 0.1 inches and less than about 3.0 inches; and    means for delivering a free-expanding stabilized jet of the cryogenic fluid from the discharge point to the cutting tool, wherein the cryogenic fluid has a temperature of about minus 150 degrees Celsius (−150° C.) at the discharge point.    
     
     
         42 . An apparatus for controlling cooling of a cutting tool during a cutting operation, comprising: 
 a supply of a cryogenic fluid;    a nozzle adapted to discharge a flow of the cryogenic fluid, said nozzle having at least one discharge point spaced apart from the cutting tool;    means for delivering a flow of the cryogenic fluid from the discharge point to the cutting tool; and    means for regulating the flow of the cryogenic fluid to the cutting tool at a substantially uniform mass flowrate greater than or equal to about 0.5 lbs/minute and less than or equal to about 5.0 lbs/minute having a flow pulse cycle time less than or equal to about 10 seconds, whereby a frost coating is maintained on at least a portion of the cutting tool during substantially all of the cutting operation in an atmosphere having an ambient relative humidity in a range of about 30% to about 75% and an ambient temperature in a range of about 10° C. to about 25° C.