Patent Abstract:
Method of forming a workpiece comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, and moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; and (c) providing a jet of cryogenic fluid and impinging essentially all of the jet of cryogenic fluid on a surface of the tool.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     The configuration of a solid material workpiece can be altered by processes in which material is removed from the workpiece, in which the workpiece is separated into multiple pieces with or without the removal of material, or in which the shape of the workpiece is altered without any significant material removal. Exemplary shaping processes include, for example, machining/turning, grinding, drilling, tapping, sawing, milling, and planing. In these shaping processes, material is removed from the workpiece during the process. In a forming process, the shape, thickness, diameter, or any other physical configuration of the workpiece is altered without any significant material removal, or the workpiece is separated into multiple pieces without any significant material removal. Typical forming processes include, for example, extruding, stamping, profiling, bending, slitting, shearing, drawing, forging, and punching. Any of these processes can be applied to solid metallic or non-metallic materials.  
         [0002]     Forming processes are characterized by forcible contact of a tool with the workpiece in which the tool deforms the workpiece. In the process, external heat is generated by surface friction between the tool and the workpiece, and internal heat is generated by deformation of the workpiece material. In order to prevent overheating of the tool and workpiece, a coolant or a combined lubricant/coolant fluid such as a water-oil emulsion can be applied to the tool and/or workpiece. The cooling and lubrication properties of a coolant/lubricant fluid are critical in decreasing tool wear and extending tool life. Cooling and lubrication also are important in achieving the desired size, finish, and shape of the workpiece. A secondary function of the coolant/lubricant may be to prevent marring of the finished surface. Various additives and surfactants can be added to the coolant and lubricant fluids to enhance performance. In certain applications, particularly metalworking applications, cryogenic fluids are used to provide effective cooling.  
         [0003]     These processes have been well-developed and are widely used on metals, plastics, and other materials in various manufacturing industries. While the art of forming of materials is well-developed, there remains a need for further innovation and improvements in forming processes. This need is addressed by the embodiments of the present invention as described below and defined by the claims that follow.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     An embodiment of the invention relates to a method of forming a workpiece comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, and moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; and (c) providing a jet of cryogenic fluid and impinging essentially all of the jet of cryogenic fluid on a surface of the tool.  
         [0005]     The workpiece may be plastically deformed by the tool. The workpiece may be separated into two or more pieces by the tool. A lubricant may be applied to any area on a surface of the tool and/or to any area on a surface of the workpiece. The lubricant may comprise a powder entrained in the jet of cryogenic fluid; alternatively, the lubricant may be a liquid sprayed onto the tool and/or workpiece in combination with impinging essentially all of the jet of cryogenic fluid on a surface of the tool. When a lubricant is used, the surface energy of the tool and/or the workpiece may be less than about 38 milliNewtons per meter (38 mN/m). The amount of lubricant applied to the tool and/or the workpiece may be less than about 100 milligrams per square foot. The lubricant may be a solid or semi-solid and the lubricant may be applied by pressing or smearing onto the tool and/or workpiece. The workpiece may comprise metal.  
         [0006]     Typically, essentially no cooling of the workpiece is effected by impingement of the jet of cryogenic fluid on a surface of the tool. The cryogenic fluid may be selected from the group consisting of nitrogen, argon, carbon dioxide, and mixtures thereof.  
         [0007]     The forming method may be selected from the group consisting of contour and profile roll forming, power spinning, roll forging, orbital forging, shoe-type pinch rolling, alligator shearing, guillotine shearing, punch parting, rotary shearing, line shearing, slitting, wire and rod drawing, tube drawing, moving mandrel drawing, punch drawing, moving insert straightening, die and punch press bending, hammer forming, and die forging.  
         [0008]     Another embodiment of the invention includes a method of forming a workpiece comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, and moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; and (c) providing a jet of cryogenic fluid and impinging at least a portion of the jet of cryogenic fluid on a surface of the tool while impinging essentially none of the jet of cryogenic fluid on the workpiece.  
         [0009]     An alternative embodiment of the invention relates to a method of forming a workpiece comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; (c) providing a jet of cryogenic fluid and impinging at least a portion of the jet of cryogenic fluid on a surface of the tool; and (d) terminating contact of the tool and workpiece; wherein the geometric average temperature of the tool may be less than the geometric average temperature of the workpiece. The forming method may be selected from the group consisting of contour and profile roll forming, power spinning, roll forging, orbital forging, shoe-type pinch rolling, alligator shearing, guillotine shearing, punch parting, rotary shearing, line shearing, slitting, wire and rod drawing, tube drawing, moving mandrel drawing, punch drawing, moving insert straightening, die and punch press bending, hammer forming, and die forging.  
         [0010]     Another alternative embodiment of the invention includes a shaped article made by a method comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, and moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; (c) providing a jet of cryogenic fluid and impinging essentially all of the jet of cryogenic fluid on a surface of the tool; and (d) forming the workpiece into a final shape to provide the shaped article.  
         [0011]     A related embodiment of the invention includes a shaped article made by a method comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, and moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; (c) providing a jet of cryogenic fluid and impinging at least a portion of the jet of a jet of cryogenic fluid on a surface of the tool while impinging essentially none of the jet of cryogenic fluid on the workpiece; and (d) forming the workpiece into a final shape to provide the shaped article.  
         [0012]     Another related embodiment relates to-a shaped article made by a method comprising (a) providing a tool and a workpiece, wherein the workpiece has an initial shape; (b) placing the workpiece and the tool in contact, applying force to the tool and/or the workpiece, moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece by forming; (c) providing a jet of cryogenic fluid and impinging at least a portion of the jet of cryogenic fluid on a surface of the tool; and (c) forming the workpiece into a final shape to provide the shaped article; and terminating the contact of the tool and the shaped article; wherein the geometric average of the temperature of the tool may be less than the geometric average of the temperature of the shaped article.  
         [0013]     A final embodiment of the invention relates to an apparatus for processing a workpiece comprising (a) a tool and a workpiece, wherein the workpiece has an initial shape; (b) means for placing the workpiece and the tool in contact to form an interface, means for applying force to the tool and/or the workpiece, and means for moving the tool and/or the workpiece to effect a change in the initial shape of the workpiece; and (c) a cryogenic fluid application system adapted for providing a jet of cryogenic fluid and impinging essentially all of the jet of cryogenic fluid on a surface of the tool. The forming apparatus may be selected from the group consisting of contour and profile roll forming systems, power spinning systems, roll forging systems, orbital forging systems, shoe-type pinch rolling systems, alligator shearing systems, guillotine shearing systems, punch parting systems, rotary shearing systems, line shearing systems, slitting systems, wire and rod drawing systems, tube drawing systems, moving mandrel drawing systems, punch drawing systems, moving insert straightening systems, die and punch press bending systems, hammer forming systems, and die forging systems. 
     
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0014]      FIG. 1A  is a schematic diagram of the splash pattern of a water or oil-based coolant stream that impinges on a target surface.  
         [0015]      FIG. 1B  is a schematic diagram of the splash pattern of a cryogenic fluid coolant stream that impinges on a target surface.  
         [0016]      FIG. 2A  is a schematic diagram of a contour and profile roll forming system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0017]      FIG. 2B  is a schematic diagram of a power spinning system prior to workpiece deformation illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0018]      FIG. 2C  is a schematic diagram of a power spinning system following workpiece deformation illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0019]      FIG. 3  is a schematic diagram of a roll forging system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0020]      FIG. 4  is a schematic diagram of an orbital forging system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0021]      FIG. 5  is a schematic diagram of a shoe-type pinch rolling system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0022]      FIG. 6  is a schematic diagram of an alligator shearing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0023]      FIG. 7  is a schematic diagram of a guillotine shearing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0024]      FIG. 8  is a schematic diagram of a punch parting system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0025]      FIG. 9  is a schematic diagram of a rotary shearing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0026]      FIG. 10  is a schematic diagram of a shearing line system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0027]      FIG. 11  is a schematic diagram of a slitting line system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0028]      FIG. 12  is a schematic diagram of a wire and rod drawing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0029]      FIG. 13  is a schematic diagram of a tube drawing (sinking) system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0030]      FIG. 14  is a schematic diagram of a moving mandrel drawing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0031]      FIG. 15  is a schematic diagram of a punch drawing system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0032]      FIG. 16  is a schematic diagram of a moving insert straightening system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0033]      FIGS. 17A, 17B ,  17 C, and  17 D are schematic diagrams of die and punch press bending systems illustrating the locations of cryogenic fluid application according to an embodiment of the invention.  
         [0034]      FIG. 18  is a schematic diagram of a hammer forming system illustrating the location of cryogenic fluid application according to an embodiment of the invention.  
         [0035]      FIG. 19  is a schematic diagram of a die-forging system illustrating the location of cryogenic fluid application according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     Forming operations modify the geometry of a work material or workpiece by plastic deformation and/or shearing under the contact stress of a tool sliding in some fashion over the surface of the work material or workpiece. This relative motion or sliding of the work material and the tool surfaces may result in localized heating, tool surface softening, wear, and seizures or fractures. Effective cooling of the surface and reduction of adhesive sticking between the tool and the work material have been recognized as critical for achieving high production rates., and the conventional solution involves application of lubricating coolants, oils, metallic soaps, and greases to the surfaces of the work material and the tool. The most frequently used lubricating media include straight and compounded oils with sulfur and chlorine, graphite, wax, fluorinated polymer additives, solvents, surfactants, phosphorus, molybdenum disulfide, and biocides. Typical examples of metal forming operations which involve these lubricating media include blanking, piercing, slitting, drawing, spinning, roll forming, and forging. Due to recently recognized negative effects of these lubricants on health, environment, and process economics, which increase costs of cleaning operations, it is desired to minimize or eliminate these lubricants.  
         [0037]     The embodiments of the present invention eliminate or at least minimize the usage of lubricating media without affecting the conventional metal forming rate by replacing or augmenting them with completely innocuous, environmentally-friendly, and clean cryogenic gases. Although not lubricating, the cryogenic gases in the gas-phase, liquid-phase, and multi-phase form can cool the surface of the tool to the point at which the loss of tool hardness and increase in friction coefficient are arrested, and forming may be carried out more effectively than in the case of a completely dry operation. The effect of cooling on hardness, strength, and impact resistance of metals is increased because conductive and convective heat transfer is enhanced by the large temperature difference between the cryogenic cooling medium and the target material. Thus the embodiments of the invention utilize the impingement of a fast-moving cryogenic jet (or jets) on the surface of the forming tool while avoiding or minimizing contact of the cryogen with the work material. This allows the tool to retain the desired hardness and strength while the work material is free to soften and plastically flow or shear during forming.  
         [0038]     In experimental work supporting development of the embodiments of the invention, it was discovered that an expanding cryogenic jet does not splash after impacting a tool surface, and as a result does not contact and cool the work material. This selective cooling of the tool but not the work material thus is possible by proper application of a cryogenic fluid using methods described herein. The methods may be applied to metal forming operations in which cryogenic coolant is aimed at the tool surface only such that the work material in proximity of the tool is not cooled significantly. Typically, the temperature of the work material is above the freezing point of water. In some embodiments, the geometric average temperature of the tool is less than the geometric average temperature of the work material or workpiece. In other embodiments, the geometric average temperature of the tool is above the geometric average temperature of the workpiece but below a temperature at which the tool properties (for example, hardness) are adversely affected.  
         [0039]     The impingement of conventional and cryogenic fluid streams on the surface of a workpiece is illustrated in  FIGS. 1A and 1B , respectively. In  FIG. 1A , nozzle  1  discharges spray or jet  2  of a cooling liquid (typically at or near ambient temperature) that impinges upon surface  3 . The liquid may be water, oil, a water/oil emulsion, or other similar liquid. As the liquid impinges upon and cools the surface, splash zone  3  is formed and liquid droplets  5  are rejected outward from the splash zone. Some vaporization may occur in splash zone  3 , but the major portion of the coolant remains in the liquid phase. When surface  3  is a surface of a tool in contact with a workpiece (not shown), these droplets may fall on the workpiece and cool the workpiece.  
         [0040]     In  FIG. 1B , nozzle  6  discharges spray or jet  7  of a cryogenic fluid that impinges upon and cools surface  8 . An intense vaporization zone  9  is formed wherein essentially all cryogenic fluid that is in the liquid phase in the zone is vaporized, and no significant amount of unvaporized liquid is rejected outward from this zone. When surface  8  is a surface of a tool in contact with a workpiece (not shown), essentially no cooling of the workpiece is caused by residual cryogenic liquid rejected from the vaporization zone.  
         [0041]     When lubricants are used in conjunction with cryogenic cooling of the tool, methods can be used to minimize the quantity of the lubricants. In one embodiment, microscopic quantities of oil mist may be co-sprayed toward the surface of the tool or toward the surfaces of both the tool and the work material while the cryogenic fluid is sprayed on the tool. Alternatively or additionally, finely-divided particles of lubricant material may be suspended in the cryogenic fluid sprayed on the tool surface. In another embodiment, microscopic quantities of solid lubricant may be smeared over the tool or both the tool and work material surfaces.  
         [0042]     Due to recently-recognized negative effects of conventional lubricants on health, the environment, and process economics, the costs of operations to clean formed articles have increased significantly. It is desired, therefore, to reduce or eliminate these lubricants. The embodiments of the invention eliminate or at least minimize the use of lubricating media without affecting the conventional metal forming rate by using innocuous, environmentally-friendly, and clean cryogenic fluids in the forming process.  
         [0043]     In the present disclosure, the term “forming” is defined as a process in which the shape of a workpiece or work material is changed by contact with a tool without the removal of material from the workpiece or without the removal of any significant amount of material from the workpiece. A very small and insignificant amount of material may be worn off the workpiece by friction between the tool and workpiece. In a forming process, in contrast with a shaping process, there is no deliberate removal of material from the workpiece by grinding, milling, planing, sawing, drilling, machining, and the like.  
         [0044]     In the present disclosure, the term “cryogenic fluid” means a gas, a liquid, solid particles, or any mixture thereof at temperatures below about minus 100° C. Cryogenic fluids for use in embodiments of the present invention may comprise, for example, nitrogen, argon, carbon dioxide, or mixtures thereof. A lubricant is defined as any of various oily liquids and/or greasy solids that reduce friction, heat, and wear when applied to parts that are in movable contact. The lubricant may be essentially water-free, or alternatively may contain water. Exemplary lubricants for use in embodiments of the present invention include, but are not limited to, Quakerol-800, a lubricating fluid available from Quaker Chemical Corp.; Gulf Stainless Metal Oils produced by Gulf Lubricants; Rolube 6001 fluids for forming non-ferrous metals available from General Chemical Corp.; and a range of other, mineral, synthetic, or soluble oil fluids and wax suspensions formulated for forming, rolling, cutting, and grinding operations. Oil-water emulsions may be considered as lubricants when used in embodiments of the invention.  
         [0045]     The terms “apply”, “applying”, or “applied” as used for a cryogenic fluid mean spraying, jetting, or otherwise directing the fluid to contact and cool any external surface of a tool while the workpiece and the tool are in contact. In a cyclic forming process, in which the tool and workpiece are in intermittent contact, the fluid also may be applied to the tool during at least a portion of the time period when there is no tool/workpiece contact. The terms “apply”, “applying”, or “applied” as used for a liquid lubricant mean spraying, jetting, flooding, misting, or otherwise directing the lubricant to contact the surface of a tool or workpiece and to penetrate and/or fill the microscopic regions formed by the surface asperities on the tool and/or workpiece. The terms “apply”, “applying”, or “applied” as used for a solid or semi-solid lubricant mean pressing, rubbing, smearing, or otherwise directing the solid lubricant to contact the surface of a tool or workpiece and to penetrate and/or fill the microscopic regions formed by the surface asperities on the tool and/or workpiece.  
         [0046]     The term “surface” as used in reference to a tool or a workpiece means any external surface of the tool or workpiece. The term “area” as used in reference to a tool or a workpiece refers to a region on any external surface of the tool or workpiece.  
         [0047]     When a jet of cryogenic fluid is applied to the surface of a tool, essentially all of the jet impinges on a surface of the tool. The term “essentially all” means that at least 90% of the fluid in the jet impinges on the tool surface. Essentially none of the jet of cryogenic fluid impinges on the workpiece. The term “essentially none” means that less that 10% of the jet of cryogenic fluid impinges on the workpiece. Essentially no cooling of the workpiece is effected by impingement of the jet of cryogenic fluid on the tool. The term “essentially no cooling” means that the geometric average temperature of the workpiece, which may be affected by small amounts of stray cryogenic fluid from the tool surface, changes by less than 10° C. due to contact with this stray cryogenic fluid.  
         [0048]     The indefinite articles “a” and “an” as used herein mean one or more when applied to any feature in embodiments of the present invention described in the specification and claims. The use of “a” and “an” does not limit the meaning to a single feature unless such a limit is specifically stated. The definite article “the” preceding singular or plural nouns or noun phrases denotes a particular specified feature or particular specified features and may have a singular or plural connotation depending upon the context in which it is used. The adjective “any” means one, some, or all indiscriminately of whatever quantity. The term “and/or” placed between a first entity and a second entity means one of (1) the first entity, (2) the second entity, and (3) the first entity and the second entity.  
         [0049]     The geometric average temperature of a workpiece is defined as an arithmetic average of the temperature at discrete points located on the workpiece surface (i.e., the portion of the workpiece surface that comes into contact with the tool surface) during a forming cycle averaged for the time length of the forming cycle.  
         [0050]     The geometric average temperature of a tool is defined as an arithmetic average of the temperature at discrete points located on the work surface of the tool (i.e., the portion of the tool surface that comes into contact with the workpiece surface) during a forming cycle averaged for the time length of the forming cycle. For a rotating tool, the discrete points located on the work surface of the tool are the points located on and/or immediately near the perimeter of the tool, and the time length of the forming cycle is the time required for one full revolution of this tool. For an intermittently operating tool (for example, a punch, forming hammer, shearing blade, and the like), the discrete points located on the work surface of the tool are the points located on and/or immediately near the tool face that contacts the workpiece, and the time length of the forming cycle is the time required for moving in, contacting the workpiece, and withdrawing the tool from the workpiece.  
         [0051]     The embodiments of the invention are based on the beneficial effect of cryogenic cooling to increase hardness and plastic flow resistance while reducing impact resistance of the tool material. Heat transfer required for cooling can be both conductive and convective, and can be enhanced by the large temperature difference between the cryogenic fluid and the initially ambient temperature of the tool material. Thus, the process utilizes the impingement of a fast-expanding cryogenic jet (or jets) on the surface of the forming tool while avoiding or minimizing the contact of the cryogenic fluid with the workpiece or work material. In this process, the forming tool retains the desired hardness and strength while the work material is thermally unconstrained, i.e., is free to soften under the tool pressure and plastically flow or shear during the forming process.  
         [0052]     The temperature of the tool surface may be at or below room temperature, and the allowable lower temperature limit depends on the properties of the tool material. For carbon tool steels and ferritic-martensitic tool steels, the lower temperature limit should be in the range of about minus 30° C. to about minus 50° C., since temperatures below this range would fall under the ductile-brittle transition point of those steels and result in undesired tool embrittlement. In the case of tungsten and/or molybdenum carbide and other hard tool materials, designed to operate within their brittle regimes, the lower temperature limit can be equal to the cryogenic jet temperature.  
         [0053]     The cryogenic fluid used for cooling the tool surface can comprise a gas-phase, liquid-phase, solid-phase, or multi-phase stream. The cryogenic fluid may be nitrogen, argon, carbon dioxide, or any mixture of these. The fluid may be liquid, vapor, or multi-phase and may contain solid particles. An advantageous cryogenic fluid is a jet of saturated boiling liquid nitrogen, which produces a large thermal gradient at the tool surface and promotes very rapid cooling of the surface. The process used in the embodiments of the present invention is made possible by an unexpected behavior of such a jet. When the jet (which consists of many very fine liquid droplets in a cryo-vapor envelope) impinges on a tool surface, the jet boils off or evaporates at the point of impact and does not splash away to cool adjacent surfaces and components. Such a jet can be conveniently used for selective cooling of tool surface without undesired cooling of the work material. This observed jet behavior contrasts with that of water or oil-based conventional coolant jets, which tend to splash off and impinge on surrounding surfaces.  
         [0054]     Certain work materials (e.g., aluminum) and certain operations (e.g., drawing), as well as aggressive forming conditions, may require the use of minute quantities of lubricating material at the interface between the tool and the work material to prevent frictional welding. In these cases, the cryogenic fluid jet and the lubricating material may be applied simultaneously. The lubricating material may be a microscopic quantity of vegetable oil mist co-sprayed with the cryogen. During experimental tests, co-spraying oil with cryogen did not cause a fog of oil, possibly due to the fact that the cryogen cooled and caused the oil droplets to become tacky. This enabled the oil droplets to stick to the target surface better than in the absence of cryogenic cooling, and oily fogs were not formed as are observed in the conventional art of ambient lubricant spraying.  
         [0055]     The lubricating material may be a suspension of micron- and submicron-sized powder suspended in the cryogenic fluid jet, whether the jet is liquid or gaseous. Such fine powders act as a boundary lubricating, dry medium, and can be combined with the cryogenic jet cooling. Finally, the micro-lubricating medium may be a microscopic quantity of solid material that is smeared over the surface of the tool and/or work material by rubbing. The solid medium may be borax, boric acid, hexagonal boron nitride, or similar solids known reduce friction coefficients and prevent interfacial reactions.  
         [0056]     In general, boron-based lubricants may be used during forming of non-ferrous metal surfaces, e.g., aluminum surfaces, and in forming operations which should minimize carbon contamination, e.g., forming surfaces of tungsten or molybdenum emission electrodes operating in vacuum or in gaseous atmospheres. LuBoron LCC and BAGL are examples of liquid-phase, orthoboric acid-based lubricants available from Advanced Lubrication Technology, Inc.  
         [0057]     The lubricant should be applied in a very small or microscopic quantity such that the lubricant layer cannot be easily detected by visual examination of the covered surface with naked eye or magnifying glass. The presence of such a microlubricating layer may be detected by determining the surface energy of the lubricant-covered surface by any conventional test method, e.g., by spreading droplets of inks of known surface energy. For the embodiments of the present invention, the surface of a micro-lubricated work material or workpiece may have a surface energy of less than about 38 milliNewtons per meter (38 mN/m), and may be considered lubricant-free if the surface energy is above about 46 mN/m. In the case of oil-based lubricants, the amount of microlubricant required to reduce the energy from 46 to 38 mN/m can be less than about 100 milligrams per square foot of work and/or tool surface.  
         [0058]     Embodiments of the present invention may be applied to exemplary shaping processes such as, for example, the use of rotating tools for plastic deformation of a workpiece in contour and profile roll forming, power spinning, roll forging, orbital forging, and shoe-type pinch forming. The embodiments also may be applied in the exemplary use of (a) shearing and parting tools for separating workpieces in alligator shearing, guillotine shearing, punch parting, rotary shearing, shearing in a shearing line, and slitting; (b) drawing tools in punch drawing, wire and rod drawing, tube drawing, and moving mandrel drawing; and (c) stroke forming tools in die and punch press bending, moving insert straightening, hammer forming, and die forging. Other shaping processes not listed here also may be amenable to application of the embodiments of the present invention.  
         [0059]     An embodiment of the invention is illustrated in  FIG. 2A  for contour and profile roll forming. In this forming process, a flat feed workpiece (not shown) is fed between upper contour roller  101  and counter-rotating lower contour roller  102  to produce channeled formed product  103 . Cryogenic fluid  104  is fed to spray feed line and nozzle  105  to form jet  106  that impinges on upper contour roller  101 , thereby cooling the roller. Additionally or alternatively, cryogenic fluid  107  is fed to spray feed line and nozzle  108  to form jet  109  that impinges on lower contour roller  102 , thereby cooling the roller. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  104  and  107  and jets  106  and  109 , may impinge on the rollers. The use of the cryogenic fluid may cool each roller to a geometric average temperature that is less than the geometric average temperature of channeled formed product  103  following termination of contact of rollers  101  and  102  with formed product  103 .  
         [0060]     Another embodiment of the invention is illustrated in  FIGS. 2B and 2C  for power spinning. In this forming process, initial blank or workpiece  201  ( FIG. 2B ) is placed on top of mandrel  202  that is rotated by turntable  203 . Roller  205  contacts the rotating workpiece and is forced downward on the workpiece by vertical positioner  206 , thereby changing the shape of the workpiece to final shaped product  207  shown in  FIG. 2C   2 B. During shaping, cryogenic fluid  208  is fed to spray feed line and nozzle  209  to form jet  210  that impinges on roller  205 , thereby cooling the roller. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  208  and jet  210 , may impinge on the roller. The use of the cryogenic fluid may cool the roller to a geometric average temperature that is less than the geometric average temperature of final shaped product  207 .  
         [0061]     Another embodiment of the invention is illustrated in  FIG. 3  for roll forging. In this forming process, a flat feed workpiece (not shown) is fed on table  301  between upper roll die  302  and counter-rotating lower roll die  303  to produce a roll-forged product (not shown). Cryogenic fluid  304  is fed to spray feed line and nozzle  305  to form jet  306  that impinges on upper roll die  302 , thereby cooling the roll die. Additionally or alternatively, cryogenic fluid  307  is fed to spray feed line and nozzle  308  to form jet  309  that impinges on lower roll die  303 , thereby cooling the roll die. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  304  and  307  and jets  306  and  309 , may impinge on the rollers. The use of the cryogenic fluid may cool each roller to a geometric average temperature that is less than the geometric average temperature of the roll-forged product.  
         [0062]     Another embodiment of the invention is illustrated in  FIG. 4  for orbital forging. In this forming process, a flat feed workpiece (not shown) is initially placed on lower die  401 . Upper die  402  is lowered and pressed against the feed workpiece as the two dies rotate in the same direction. As upper die  402  (which is convex) is rotated against lower die  401  (which is concave), the feed workpiece is formed to produce orbitally-forged product piece  403 . Cryogenic fluid  404  is fed to spray feed line and nozzle  405  to form jet  406  that impinges on upper die  402 , thereby cooling the die. Additionally or alternatively, cryogenic fluid  407  is fed to spray feed line and nozzle  408  to form jet  409  that impinges on lower die  401 , thereby cooling the roll die. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  404  and  407  and jets  406  and  409 , may impinge on the dies. The use of the cryogenic fluid may cool each die to a geometric average temperature that is less than the geometric average temperature of orbitally-forged product  403 .  
         [0063]     Another embodiment of the invention is illustrated in  FIG. 5  for shoe-type pinch rolling. In this-forming process, workpiece  501  is placed on top of shoe  502  and is contacted by rollers  503 ,  504 , and  505 . The rollers and shoe are located to roll bend the workpiece as shown. During rolling, cryogenic fluid  506  is fed to spray feed line and nozzle  507  to form jet  508  that impinges on shoe  502 , thereby cooling the shoe. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  506  and jet  507 , may impinge on the shoe. The use of the cryogenic fluid may cool the shoe to a geometric average temperature that is less than the geometric average temperature of final roll-bent workpiece  509 .  
         [0064]     Another embodiment of the invention is illustrated in  FIG. 6  for alligator shearing. In this forming process, a feed workpiece (not shown) is placed between upper blade  601  and lower blade  602 . Upper blade moves downward against the workpiece, forcing it against lower blade  602 , thereby causing shearing forces that cut and separate a product piece (not shown) from the feed workpiece. During cutting, cryogenic fluid  603  is fed to spray feed line and nozzle  604  to form jet  605  that impinges on lower blade  602 , thereby cooling the blade. Alternatively or additionally, cryogenic fluid  606  is fed to spray feed line and nozzle  607  to form jet  608  that impinges on upper blade  601 , thereby cooling the blade. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  603  and  606  and jets  605  and  608 , may impinge on the blades. The use of the cryogenic fluid may cool each blade to a geometric average temperature that is less than the geometric average temperature of the product piece.  
         [0065]     Another embodiment of the invention is illustrated in  FIG. 7  for guillotine shearing. In this forming process, a feed workpiece (not shown) is placed between upper blade  701  and lower blade  702 . Upper blade moves downward against the workpiece, forcing it against lower blade  702 , thereby causing shearing forces that cut and separate a product piece (not shown) from the feed workpiece. During cutting, cryogenic fluid  703  is fed to spray feed line and nozzle  704  to form jet  705  that impinges on lower blade  702 , thereby cooling the blade. Additionally or alternatively, cryogenic fluid is fed to another spray feed line and nozzle (not seen behind upper blade  701  and bladeholder  706 ) to form a jet that impinges on the rear side of upper blade  701 , thereby cooling the blade. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  703  and jet  705 , as well as the fluid and jet cooling upper blade  701 , may impinge on the blades. The use of the cryogenic fluid may cool each blade to a geometric average temperature that is less than the geometric average temperature of the product piece.  
         [0066]     Another embodiment of the invention is illustrated in  FIG. 8  for punch parting. In this forming process, feed workpiece  801  is placed on a lower fixed support (not shown) having sufficient clearance to allow full vertical movement of punch  802 . The punch moves downward against the workpiece, forcing it against the lower fixed support, thereby causing shearing forces that cut and separate waste piece  803  from feed workpiece  801 , thereby forming product pieces  804   a  and  804   b.  During punching, cryogenic fluid  805  is fed to spray feed line and nozzle  806  to form jet  807  that impinges on punch  802 , thereby cooling the punch. Additionally or alternatively, cryogenic fluid may be fed to another spray feed line and nozzle (not shown behind punch  802 ) to form a jet that impinges on the rear side of punch, thereby cooling the punch. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  805  and jet  806 , as well as the fluid and jet cooling the back of punch  802 , may impinge on the punch. The use of the cryogenic fluid may cool the punch to a geometric average temperature that is less than the geometric average temperature of product piece.  
         [0067]     Another embodiment of the invention is illustrated in  FIG. 9  for rotary shearing. In this forming process, feed workpiece  901  is placed between upper rotary cutter  902  and lower rotary cutter  903 . Upper rotary cutter  902  moves downward against the workpiece, forcing it against lower rotary cutter  903 , thereby causing shearing forces that cut and separate a product piece (not shown) from feed workpiece  901 . During cutting, cryogenic fluid  904  is fed to spray feed line and nozzle  905  to form jet  906  that impinges on upper rotary cutter  902 , thereby cooling the cutter. Additionally or alternatively, cryogenic fluid is fed to spray feed line  907  and nozzle  908  to form jet  909  that impinges on lower rotary cutter  903 , thereby cooling the cutter. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  904  and  907  and jets  906  and  909 , may impinge on the rotary cutters. The use of the cryogenic fluid may cool each cutter to a geometric average temperature that is less than the geometric average temperature of the product piece.  
         [0068]     Another embodiment of the invention is illustrated in  FIG. 10  for shearing in a shearing line. In this forming process, coilstock  1001  is fed between straightening rolls  1003  and over hump table  1004 . Stationary shear  1005  cuts the straightened stock into product sheets that pass over gage table  1006  having a retractable stop and stacker that stacks the cut sheets  1007  as they are delivered from the gage table. Cryogenic fluid  1008  is fed to spray feed line and nozzle  1009  to form jet  1010  that impinges on the blade of stationary shear  1005 , thereby cooling the blade. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1008  and jet  1010 , may impinge on the blade. The use of the cryogenic fluid may cool the blade to a geometric average temperature that is less than the geometric average temperature of each product sheet that passes over gage table  1006 .  
         [0069]     Another embodiment of the invention is illustrated in  FIG. 11  for slitting in a slitting line. In this forming process, slitting is accomplished by feeding stock from uncoiler  1101  and passing uncoiled strip  1102  strip to slitter  1103 , where it passes between slightly overlapping circular blades  1104  mounted on rotating arbors. Slit product strips  1105  are taken up by recoiler  1106  for simultaneous coiling of all slit strips. Cryogenic fluid  1107  is fed to spray feed line and nozzle  1108  to form jet  1109  that impinges on the circular blades  1104 , thereby cooling the blades. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1107  and jet  1109 , may impinge on the blades. The use of the cryogenic fluid may cool the blades to a geometric average temperature that is less than the geometric average temperature of each product strip  1105 .  
         [0070]     Another embodiment of the invention is illustrated in  FIG. 12  for wire and rod drawing. In this forming process, feed workpiece  1201  having a given diameter is fed through die  1202  to deform the feed workpiece and reduce the diameter to yield drawn product  1203  having a reduced diameter. Cryogenic fluid  1204  is fed to spray feed line and nozzle  1205  to form jet  1206  that impinges on die  1202 , thereby cooling the die. Additional cryogenic fluid may be applied (not shown) at other radial locations on the die. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1204  and jet  1206  (and/or cryogenic fluid applied at other radial locations on the die) may impinge on the die. The use of the cryogenic fluid may cool die  1202  to a geometric average temperature that is less than the geometric average temperature of drawn product  1203 .  
         [0071]     Another embodiment of the invention is illustrated in  FIG. 13  for tube drawing or sinking. In this forming process, feed tubing workpiece  1301  having a given outer diameter is fed through die  1303  held in frame  1303  to deform the feed workpiece and reduce the diameter to yield drawn tube product  1304  having a reduced diameter. Cryogenic fluid  1305  is fed to spray feed line and nozzle  1306  to form jet  1307  that impinges on die  1302 , thereby cooling the die. Cryogenic fluid may be applied to any location on the die, including more than one location. In addition to or as an alternative to applying cryogenic fluid to the die, cryogenic fluid may be applied to any location on frame  1303  as illustrated by cryogenic fluid  1308 , feed line and nozzle  1309 , and jet  1310 . Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1305  and jet  1307  (and/or cryogenic fluid applied at other radial locations on the die and at locations on the frame) may impinge on the die and frame. The use of the cryogenic fluid may cool each of die  1302  and frame  1303  to a geometric average temperature that is less than the geometric average temperature of drawn product  1304 .  
         [0072]     Another embodiment of the invention is illustrated in  FIG. 14  for tube drawing with a moving mandrel. In this forming process, workpiece  1401  having a given outer diameter is pushed through die  1402  by moving mandrel  1403  to deform the feed workpiece and reduce the diameter to yield a final drawn product piece (not shown) having a reduced diameter. Cryogenic fluid  1404  is fed to exemplary spray feed line and nozzle  1405  to form jet  1406  that impinges on die  1402 , thereby cooling the die. Cryogenic fluid may be applied at any location (including more than one location) on the die. In addition to or as an alternative to applying cryogenic fluid to the die, cryogenic fluid may be applied to any location on mandrel  1403  as illustrated by cryogenic fluid  1407 , feed line and nozzle  1408 , and jet  1409 . This application may be done while the mandrel is at any position as it moves axially. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1404  and jet  1406  (and/or cryogenic fluid applied at other radial locations on the die and at locations on the frame) may impinge on the die and frame. The use of the cryogenic fluid may cool each of die  1302  and frame  1303  to a respective geometric average temperature that is less than the geometric average temperature of the final drawn product.  
         [0073]     Another embodiment of the invention is illustrated in  FIG. 15  for punch drawing with a moving punch. In this forming process, die  1501  is provided with receiving nest or locator  1502  to hold a blank feed workpiece (not shown). This blank workpiece is deformed by downward axial movement of punch  1503  through the die as shown to form product piece  1504 . Cryogenic fluid  1505  is fed to spray feed line and nozzle  1506  to form jet  1507  that impinges on die  1501 , thereby cooling the die. Cryogenic fluid may be applied to any location, including more than one location, on the die. In addition to or as an alternative to applying cryogenic fluid to the die, cryogenic fluid may be applied to any location on punch  1503  as illustrated by cryogenic fluid  1508 , feed line and nozzle  1509 , and jet  1510 . Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluid  1505  and jet  1507  (and/or cryogenic fluid applied at other locations on the die and at locations on the punch) may impinge on the die and punch. The use of the cryogenic fluid may cool each of die  1501  and punch  1503  to a respective geometric average temperature that is less than the geometric average temperature of product piece  1504 .  
         [0074]     Another embodiment of the invention is illustrated in  FIG. 16  for moving insert straightening. Workpiece  1601  is positioned between two rows of movable inserts  1602 , and  1603  situated in tool base  1604 . The workpiece is subjected to a series of reciprocal strokes by the movable inserts that overbend the workpiece by a preset amount. The amplitude of the movement is progressively reduced during the cycle until it approaches a straight line, at which point a final straight workpiece is produced. The degree of bending movement and the number of bending cycles are adjustable, and varying insert spacing is available to accommodate a wide range of soft or heat-treated components. Some or all of movable inserts  1602  and  1603  may be cooled with a cryogenic fluid. To illustrate this, there is shown cryogenic fluid  1605  fed to spray feed line and nozzle  1606  to form jet  1607  that impinges on one of inserts  1602 , thereby cooling the insert. For further illustration, there is shown cryogenic fluid  1608  fed to spray feed line and nozzle  1609  to form jet  1610  that impinges on one of inserts  1603 , thereby cooling the insert. Cryogenic fluid may be applied to any location on any insert. Essentially all of the cryogenic fluid, i.e., at least 90% of cryogenic fluids  1605  and  1608  and jets  1607  and  1610  (and cryogenic fluid applied at other locations on the inserts) may impinge on the inserts. The use of the cryogenic fluid may cool each of inserts to a respective geometric average temperature that is less than the geometric average temperature of the final straight workpiece.  
         [0075]     Additional embodiments of the invention are illustrated in  FIGS. 17A, 17B ,  17 C, and  17 D for press-brake forming. In this process, punches  1701 ,  1702 ,  1703 , and  1704 , respectively, are forced against dies  1705 ,  1706 ,  1707 , and  1708 , respectively, to produce formed workpieces  1709 ,  1710 ,  1711 , and  1712 , respectively. Cryogenic fluid may be applied to either or both of the punch and the die in each of  FIGS. 17A, 17B ,  17 C, and  17 D.  FIG. 17A  illustrates the application of cryogenic fluid  1713  via spray feed line and nozzle  1714  to form jet  1715  that impinges on punch  1701 , thereby cooling the punch. Also illustrated is the application of cryogenic fluid  1716  via spray feed line and nozzle  1717  to form jet  1718  that impinges on die  1705 , thereby cooling the die.  
         [0076]      FIG. 17B  illustrates the application of cryogenic fluid  1719  via spray feed line and nozzle  1720  to form jet  1721  that impinges on punch  1702 , thereby cooling the punch. Also illustrated is the application of cryogenic fluid  1722  via spray feed line and nozzle  1723  to form jet  1724  that impinges on die  1706 , thereby cooling the die.  
         [0077]      FIG. 17C  illustrates the application of cryogenic fluid  1725  via spray feed line and nozzle  1726  to form jet  1727  that impinges on punch  1703 , thereby cooling the punch. Also illustrated is the application of cryogenic fluid  1728  via spray feed line and nozzle  1729  to form jet  1730  that impinges on die  1707 , thereby cooling the die.  
         [0078]      FIG. 17D  illustrates the application of cryogenic fluid  1731  via spray feed line and nozzle  1732  to form jet  1733  that impinges on punch  1704 , thereby cooling the punch. Also illustrated is the application of cryogenic fluid  1734  via spray feed line and nozzle  1735  to form jet  1736  that impinges on die  1708 , thereby cooling the die.  
         [0079]     Cryogenic fluid may be applied to any location on any of the punches and dies in  FIGS. 17A, 17B ,  17 C, and  17 D. Essentially all of the cryogenic fluid, i.e., at least 90% of each cryogenic fluid and corresponding jet in  FIGS. 17A, 17B ,  17 C, and  17 D may impinge on the respective punch or die. The use of the cryogenic fluid may cool each punch and die to a respective geometric average temperature that is less than the geometric average temperature of the final formed workpiece.  
         [0080]     Another embodiment of the invention is illustrated in  FIG. 18  for drop hammer forming. In this process, a workpiece (not shown) is placed between punch  1801  and die  1802 , and the punch is lowered to press against the workpiece and the die one or more times, thereby forming the workpiece to yield a final formed article. This power drop hammer may be powered by compressed air in cylinder  1803 , which moves piston  1804 , connecting rod  1805 , and ram  1806  to lower punch  1801 . Cryogenic fluid may be applied to either or both of the punch and the die.  FIG. 18  illustrates the application of cryogenic fluid  1807  via spray feed line and nozzle  1808  to form jet  1809  that impinges on punch  1801 , thereby cooling the punch. Also illustrated is the application of cryogenic fluid  1810  via spray feed line and nozzle  1811  to form jet  1812  that impinges on die  1802 , thereby cooling the die. Essentially all of the cryogenic fluid, i.e., at least 90% of each cryogenic fluid and corresponding jet in  FIG. 18  may impinge on the respective punch or die. The use of the cryogenic fluid may cool the punch and die to a respective geometric average temperature that is less than the geometric average temperature of the final formed article.  
         [0081]     Another embodiment of the invention is illustrated in  FIG. 19  for open die forging. In this forming process, a workpiece (not shown) is placed between top die  1901  and bottom die  1902 , and the top die is lowered to press against the workpiece and the bottom die one or more times, thereby forming the workpiece to yield a final formed article. This open die forge may be powered by steam in cylinder  1903 , which moves piston rod  1904  and ram  1905  to move top die  1901  against bottom die  1902 . Cryogenic fluid may be applied to either or both of the punch and the die.  FIG. 19  illustrates the application of cryogenic fluid  1906  via spray feed line and nozzle  1907  to form jet  1908  that impinges on top die  1901 , thereby cooling the top die. Also illustrated is the application of cryogenic fluid  1909  via spray feed line and nozzle  1910  to form jet  1911  that impinges on lower die  1902 , thereby cooling the lower die. Essentially all of the cryogenic fluid, i.e., at least 90% of each cryogenic fluid and corresponding jet in  FIG. 19  may impinge on the respective dies. The use of the cryogenic fluid may cool each die to a respective geometric average temperature that is less than the geometric average temperature of the final formed article.  
         [0082]     In the illustrations described above with reference to  FIGS. 1-19 , the workpieces typically may be made of metal or metal alloys. Alternatively, any of the processes may be used with workpieces made of non-metallic materials capable of being plastically deformed, sheared, cut, or otherwise formed without the removal of material as defined above.  
         [0083]     The cryogenic fluid may be applied to the desired surface by spraying, jetting, or otherwise directing the fluid to contact and cool the surface of a tool. Any method known in the art may be used, and exemplary methods are described in U.S. Pat. Nos. 6,513,336 B2, 6,564,682 B1, and 6,675,622 B2 and in U.S. Patent Publications 20040237542 A1, 20050211029 A1, 20050016337 A1, 20050011201 A1, and 20040154443 A1, all of which are fully incorporated herein by reference.  
         [0084]     Any type of nozzle or open-ended tubing discharging a pressurized cryogenic liquid or multi-phase cryogenic fluid may be used. The thermodynamic condition of the discharged stream (i.e., the stream decompressed at the nozzle exit) typically is such that the discharge results in a partial vaporization of the liquid phase and at least partial disintegration of this liquid into fine, rapidly-moving cryogenic liquid droplets. Typical flow rates of the discharged cryogenic fluid may range from 0.25 to 1.0 lb per min per nozzle at typical supply pressures in the range of 20 to 220 psig. The discharged liquid and vapor typically are saturated at equilibrium at the discharge temperature and pressure; alternatively, the liquid may be slightly subcooled, typically by a few ° C. to about 20° C. below the saturation temperature at the given pressure.  
         [0085]     Any appropriate liquid lubricant may be used; the liquid lubricant may be essentially water-free, or alternatively may contain water. A liquid lubricant is liquid at temperatures in the range of about minus 40° C. to about plus 40° C. Oil-water emulsions may be used as lubricants in embodiments of the invention. Any commercially-available cutting oil or cutting fluid may be used to provide the lubricant. Exemplary liquid lubricants for use in embodiments of the present invention are given above.  
         [0086]     Solid lubricants (for example, paraffin wax) or semi-solid lubricants (for example, pumpable greases or other flowable materials) may be used instead of (or in addition to) liquid lubricants. A solid lubricant typically is solid at ambient temperatures or below, e.g., below about 40° C. Some solid lubricants may remain solid at temperatures above 40° C. Any appropriate solid or semi-solid lubricant may be used; the lubricant may be essentially water-free, or alternatively may contain water. Solid or semi-solid lubricants typically are applied by pressing, rubbing, smearing, or otherwise directing the solid lubricant to contact the surface of a tool or workpiece and to penetrate and/or fill the microscopic regions formed by the surface asperities. The area of the surface to which the solid or semi-solid lubricant is applied may be cooled in the same manner as described above for liquid lubricants. In most embodiments, the solid or semi-solid lubricant is applied before the area is cooled.

Technology Classification (CPC): 1