High-performance tool cooling system

Abstract

A shaping tool includes a cooling system having one or more cooling passages configured for enhanced cooling. The cooling passages provide latent heat cooling of a heated material that is in contact with a shaping surface of the tool. Cooling fluid flows along the cooling passages in a two-phase flow regime in which a portion of the cooling fluid is liquid and a portion of the cooling fluid is vapor. A two-phase portion of the cooling passage can be shaped to follow a three-dimensional contour of the shaping surface. Opposing walls of the cooling passage can be provided by passage surfaces of separately formed pieces of the tool. The latent heat cooling provided by suitably configured cooling channels extracts more heat from the material being shaped in the tool than traditional cooling systems.

1 . A tool for shaping a heated material, the tool comprising:
 a tool portion comprising a shaping surface that contacts the heated material during shaping, the shaping surface having a three-dimensional contour; and   a cooling passage formed in the tool portion and spaced from the shaping surface, a two-phase portion of the cooling passage being shaped to follow the three-dimensional contour of the shaping surface and being configured such that a cooling fluid flowing along the cooling passage undergoes two-phase fluid flow when extracting heat from the heated material.   
     
     
         2 . The tool of  claim 1 , wherein the tool portion comprises first and second separately formed pieces having first and second passage surfaces that oppose each other across the cooling passage and at least partially define the two-phase portion of the cooling passage. 
     
     
         3 . The tool of  claim 2 , wherein each of the first and second passage surfaces is a three-dimensional surface that is shaped to follow the three-dimensional contour of the shaping surface in the two-phase portion of the cooling passage. 
     
     
         4 . The tool of  claim 1 , wherein the two-phase portion of the cooling passage is configured such that Bo 0.5 Re≦160, where Bo is the Bond number and Re is the Reynolds number associated with the two-phase fluid flow. 
     
     
         5 . The tool of  claim 1 , wherein the two-phase portion of the cooling passage is configured such that vapor bubbles formed in the cooling fluid substantially span the distance between opposing walls of the cooling passage. 
     
     
         6 . The tool of  claim 1 , wherein the two-phase portion of the cooling passage is located between a first opening and a second opening and the distance between opposing walls of the cooling passage varies between the first and second openings. 
     
     
         7 . The tool of  claim 6 , wherein the cooling fluid is received from an external cooling fluid source at the first opening and expelled from the cooling passage at the second opening, the distance between the opposing walls being greater at the first opening than at the second opening. 
     
     
         8 . The tool of  claim 1 , wherein the two-phase portion of the cooling passage has a length defined between a first opening and a second opening and a width defined in a direction transverse to the lengthwise direction, the distance between opposing walls of the cooling passage being at least one order of magnitude less than both the length and the width of the cooling passage. 
     
     
         9 . The tool of  claim 1 , wherein the tool is a casting die comprising a cavity partially defined by the shaping surface when the tool is in a closed condition, the casting die being configured to receive molten metal in the cavity and the cooling passage being configured to extract heat from the molten metal to solidify the molten metal into a shaped article. 
     
     
         10 . The tool of  claim 1 , wherein the tool is a sheet metal forming die configured to receive sheet metal heated above a transition temperature while the tool is in an open condition and to form and quench the heated sheet metal when the tool is in a closed condition. 
     
     
         11 . A tool for shaping a heated material, the tool comprising:
 a tool portion comprising a plurality of separately formed pieces with passage surfaces and a shaping surface that contacts the heated material during shaping; and   a cooling passage formed in the tool portion and spaced from the shaping surface, wherein opposing walls of the cooling passage are provided by the passage surfaces of the separately formed pieces and are spaced apart such that a cooling fluid flowing along a two-phase portion of the cooling passage undergoes two-phase fluid flow when extracting heat from the heated material.   
     
     
         12 . The tool of  claim 11 , wherein each of the opposing walls has a three-dimensional shape in the two-phase portion of the cooling passage that follows the shape of the shaping surface. 
     
     
         13 . The tool of  claim 11 , wherein the two-phase portion of the cooling passage is configured such that Bo 0.5 Re≦160, where Bo is the Bond number and Re is the Reynolds number associated with the two-phase fluid flow. 
     
     
         14 . The tool of  claim 11 , wherein the two-phase portion the cooling passage is configured such that vapor bubbles formed in the cooling fluid substantially span the distance between the opposing walls. 
     
     
         15 . The tool of  claim 11 , wherein the two-phase portion of the cooling passage is located between a first opening and a second opening and the distance between the opposing walls of the cooling passage varies between the first and second openings. 
     
     
         16 . The tool of  claim 15 , wherein the cooling fluid is received from an external cooling fluid source at the first opening and expelled from the cooling passage at the second opening, the distance between the opposing walls being greater at the first opening than at the second opening. 
     
     
         17 . The tool of  claim 11 , wherein the two-phase portion of the cooling passage has a length defined between a first opening and a second opening and a width defined in a direction transverse to the lengthwise direction, the distance between the opposing walls of the cooling passage being at least one order of magnitude less than both the length and the width of the cooling passage. 
     
     
         18 . The tool of  claim 11 , wherein the tool is a casting die comprising a cavity partially defined by the shaping surface when the tool is in a closed condition, the casting die being configured to receive molten metal in the cavity and the cooling passage being configured to extract heat from the molten metal to solidify the molten metal into a shaped article. 
     
     
         19 . The tool of  claim 11 , wherein the tool is a sheet metal forming die configured to receive sheet metal heated above a transition temperature while the tool is in an open condition and to quench the heated sheet metal when the tool is in a closed condition. 
     
     
         20 . A method of shaping a heated material into a shaped article, comprising the steps of:
 (a) introducing the heated material into a shaping tool;   (b) contacting the heated material with a shaping surface of the shaping tool such that the heated material conforms to the shaping surface; and   (c) extracting heat from the heated material while the shaping tool is in a closed condition via latent heat cooling, wherein the extracted heat transforms liquid cooling fluid flowing along a cooling passage of the shaping tool to the vapor phase.   
     
     
         21 . The method of  claim 20 , wherein the shaping tool is a casting die and the heated material is molten metal introduced into a cavity of the shaping tool while the tool is in the closed condition, wherein step (c) includes extracting a sufficient amount of heat from the molten metal to solidify the molten metal into the shaped article. 
     
     
         22 . The method of  claim 20 , wherein the shaping tool is a sheet metal forming die and the heated material is sheet metal heated above a transformation temperature and introduced into the tool while the tool is in an open condition, wherein step (c) includes quenching the heated sheet metal. 
     
     
         23 . The method of  claim 22 , wherein the sheet metal comprises steel and step (c) includes inducing a martensitic transformation in the steel. 
     
     
         24 . The method of  claim 20 , further comprising controlling the flow of cooling fluid along the cooling passage in a manner that achieves bidirectional fluid flow, wherein cooling fluid in the liquid phase flows in one direction along the cooling passage and cooling fluid in the vapor phase flows in the opposite direction along the cooling passage.