Abstract:
A system for delivering a coolant fluid to a workpiece has a reservoir for retaining the fluid, a pump for delivering fluid from the reservoir, a supply line in communication with the workpiece and a diverter valve. A bypass line is in communication with the diverter valve, and the valve may be utilized to deliver fluid from the reservoir to the workpiece or to bypass the workpiece and circulate fluid back to the reservoir. The system also includes a fluid return line for conveying fluid from the workpiece back to the reservoir.

Description:
RELATED APPLICATION  
       [0001]     This patent claims priority of U.S. Provisional Patent Application Ser. No. 60/537,695 filed Jan. 20, 2004, and entitled “Method and Apparatus for the Continuous Fabrication of Shaped, Hardened, Steel Articles” which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to methods and apparatus for fabricating metal articles. More specifically, the invention relates to a method and apparatus for the continuous fabrication of metal articles. Most specifically, the invention relates to a coolant delivery system which may be employed in a process for the manufacture of metal articles.  
       BACKGROUND OF THE INVENTION  
       [0003]     Roll-forming is used with advantage in the fabrication of a number of variously configured metal objects. In a roll-forming process, a sheet of metal, typically steel, is continuously fed through a series of roller dies which progressively bend, stretch and shape the sheet into a body having a preselected cross-sectional profile. Roll-forming steps can be readily incorporated into continuous fabrication processes, and such techniques are widely used for the fabrication of various automotive components. Roll-forming processes, with a few notable exceptions, generally cannot be used to shape the longitudinal dimension of articles, and this does limit the utility of roll-forming techniques to some degree.  
         [0004]     Other metal forming processes such as bending, stamping, forging, hydroforming, die-forming, post-forming and the like can be utilized to shape metal articles. Also, processes such as heat treating, nitriding, quenching and tempering may be employed to control hardness or other properties of metal articles. As will be explained hereinbelow, the present invention combines roll-forming with other metal shaping and treating processes to provide an integrated, continuous system and process for producing shaped metal articles.  
         [0005]     Automobiles and other motor vehicles generally include a number of protective members therein such as bumper beams and side intrusion beams. These members must be high strength, and are preferably light in weight and low in cost. Bumper and intrusion beams are, as a consequence, often fabricated from folded, sheet steel members having a cross-sectional profile which may be of a C shape or of a closed, boxlike or circular cross section. Ideally, such members are relatively light in weight, of high strength, and low in cost. As will be detailed hereinbelow, one aspect of the present invention provides a continuous manufacturing process and apparatus for producing particularly configured high strength steel items such as bumper beams and side intrusion bars for motor vehicles. The method and apparatus of this embodiment of the present invention rely upon a combination of roll-forming and other processing operations carried out on a continuous basis utilizing coiled sheet steel. Unlike many roll-forming processes, the process of the present invention can be used to fabricate relatively complex shapes. Further aspects of the present invention include a coolant fluid delivery system, such as a quench fluid delivery system, which may be utilized in the aforementioned fabrication system as well as in other systems. These and other details of the present invention will be apparent from the drawings, discussion and description which follow.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0006]     Disclosed herein is a system for delivering a coolant fluid to a workpiece. The system includes a fluid supply line which is disposed and operative to convey the fluid to the workpiece. The system further includes a coolant fluid supply station having a reservoir for retaining a coolant fluid therein; a pumping station in fluid communication with the reservoir for pumping a fluid from the reservoir; a diverter valve disposed downstream from the pumping station; and a bypass line which establishes fluid communication between the diverter valve and the reservoir. The diverter valve is operable to selectively establish a fluid flow either between the pumping station and a fluid supply line so that fluid is delivered from the reservoir to the workpiece or between the pumping station and the bypass line so that fluid which is pumped from the reservoir is returned thereto. The system further includes a return line which is disposed and operative to return a coolant fluid from the workpiece to the reservoir.  
         [0007]     In some instances, the pumping station includes at least two pumps, and these pumps may be disposed in a parallel fluid flow relationship. The system may be configured so that the pumping station operates continuously when the system is in operation.  
         [0008]     The system may also include a preheater for warming the fluid before it is delivered to the workpiece as well as a heat exchanger for extracting heat from the fluid. In particular embodiments, quick connect couplings may be employed to join the various components of the system. The system may further include a controller, such as a microprocessor-based controller which is operative to, among other things, sense the temperature of the fluid and/or various components of the system or workpiece, and control the system accordingly.  
         [0009]     Also disclosed are specific embodiments in which the cooling system may be implemented. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic depiction of a portion of one embodiment of apparatus for carrying out the method of the present invention;  
         [0011]      FIG. 2  is a schematic depiction of another portion of the apparatus;  
         [0012]      FIG. 3  is a schematic depiction of a number of roll-formed members which are passing through the apparatus of the present invention;  
         [0013]      FIG. 4  is a schematic depiction of yet another portion of the apparatus;  
         [0014]      FIG. 5  is a depiction of the final portion of the apparatus showing roll and die-formed parts passing out of the apparatus; and  
         [0015]      FIG. 6  is a schematic diagram of a quench fluid delivery system which may be used in the practice of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     The present invention, in its most general form, comprises an apparatus for carrying out the continuous production of shaped metal members. The parts are preferably produced, on a continuous basis, from coiled webs of metal feedstock. The apparatus includes a payout station which supports a coiled web of metal and feeds that web to the other stations of the system. Downstream of the payout station is a roll-forming station which includes a plurality of roll-forming dies therein. The roll-forming station is operable to receive the web on a continuous basis and to form the web into a continuous, elongated body having a preselected cross-sectional profile. The system includes a cutting station, which is downstream of the roll-forming station, which is operable to cut the continuous, elongated body into a plurality of members each having the preselected cross-sectional profile. A heating station or other such processing station is downstream of the cutting station, and it is operable to alter a physical characteristic of the steel comprising the article. For example, when the metal being formed is steel and the processing station is a heating station, it can function to heat the steel to a temperature sufficient to effect a metallurgical transition; as for example by heating it above its austenizing temperature. In the illustrated embodiment, a die-forming station is disposed downstream of the heating station, and it is operable to receive the heated members from the heating station and to carry out a forming operation thereupon. Since the metal is relatively hot, and in a fairly plastic state, such operations can be implemented very easily. The die-forming station is further operative to quench the heated, formed, members. This quenching may be accomplished in the die by the use of a cooling fluid such as a water-based fluid. The quenching locks in a particular metallurgical phase, such as a martensitic phase, which at least partially hardens the steel thereby providing a hardened steel part.  
         [0017]     This general system of the present invention may be employed to fabricate a variety of parts, and the particular configuration of system will depend, to some degree, upon the parts being fabricated. For purposes of illustration, the method of the present invention will be described in detail, with regard to one specific apparatus and process for the fabrication of hardened steel bumper beams. It is to be understood that a system of this type may be used to fabricate other items such as door beams, frame members, seat backs and other structural components. Also, the system may be employed to fabricate items from other metals such as aluminum.  
         [0018]      FIGS. 1-6  depict this particular system. Referring now to  FIG. 1 , there is shown a first portion of the system in which a coil of steel  10  is supported in a payout station which serves to feed a web of steel  14 , on a continuous basis, to the remainder of the system. The steel may, in some instances, be coated so as to control corrosion during downstream processing, particularly during the heating and quenching steps. The coating may be organic or inorganic, and aluminum coated steel is one preferred material.  
         [0019]     In the illustrated embodiment, the web of steel  14  passes to a flattening station  16  which serves to flatten the web  14 , typically through the use of a set of rollers. The flattening station  16  may be dispensed with, depending upon the quality of the steel employed and/or downstream processing requirements. After exiting the flattening station  16 , the web, in this embodiment, proceeds on to a punching and shaping station  18 . Again, this station is optional; however, it functions to carry out one or more shaping operations on the web  14 . These operations can include punching a number of openings in the web and/or forming embossed or coined features on the web. These openings and features can provide attachment points, screw holes, reinforcements, or pierce points which facilitate downstream cutting operations and the like. These features can also be used to “tune” the resiliency, crushability and/or other physical parameters of the finished product. By control of the geometry and placement of these features, finished parts having precisely shaped and positioned features and/or physical parameters may be produced in the process.  
         [0020]     As will be seen from  FIG. 1 , a first  20   a  and second  20   b  slack loop are formed in the web. These loops accommodate the punching and shaping station which, in this embodiment, requires that the web be stationary during the time the punching and/or shaping operations are carried out. By use of the slack loops  20   a ,  20   b , the web  14  may be continuously fed while allowing portions to stop for punching and shaping. The fact that portions of the web may halt during processing does not negate the fact that this is a continuous process. In other embodiments, the punching and shaping operations may be carried out on a moving web by the use of a roller die or similar apparatus.  
         [0021]     Although not illustrated, the system may include dual payout stations wherein the end of one coil of steel may be welded or affixed to the beginning of another. This arrangement will allow for “on the run” replacement of coils, the slack loops will permit the system to run continuously during coil changes.  
         [0022]     Downstream of the punching/shaping station  18  is an edge conditioning station  22 . This station trims the edges of the web  14  to remove any irregularities therefrom. This station may be disposed upstream of the punching and shaping station  18 , or it may be dispensed with completely, depending on the quality of the steel and the requirements of the process.  
         [0023]     The system will preferably include one or more centering stations for keeping the center line of the web aligned with the center lines of the various stations. This centering is particularly important when punched or shaped features are included in the web, since it assures that the features will be properly placed in the finished article. The centering may be accomplished by mechanical members which engage the edges of the web. Centering may also be accomplished by systems having optical sensors, electronic sensors or other non-contact sensors. A centering station  19  may be associated with the punching/shaping station  18 , as well as with the edge conditioning  22  and roll forming stations  24 .  
         [0024]     Referring now to  FIG. 2 , there is shown another portion of the process, and as will be seen, the web  14 , having features formed thereupon in the punching and shaping station, proceeds on to a roll-forming station  24 . While this station  24  is shown in schematic form, it will be understood by one of skill in the art that it includes a plurality of roll-forming dies which progressively bend and shape the web  14  as it passes therethrough. As mentioned above, the roll-forming station will generally include a centering apparatus which is either associated with, or upstream of, the station for assuring that the web  14  is centered on the rollers as it passes therethrough. This is particularly important when preformed structural features of the web are incorporated into the final product.  
         [0025]     As is shown in  FIG. 2 , the web  14  enters the roll-forming station and exits therefrom as a continuous, elongated body  26  having a preselected cross-sectional profile, which in this instance is a generally C-shaped profile. Downstream of the roll-forming station  24  is a joining station which functions to join the two free edges, or other portions of the continuous, shaped, elongated body  26  to one another or to other portions of the roll-formed body so as to form a closed cross-sectional profile. In this embodiment, joining is accomplished by a welding station  28 , although it is to be understood that joining could be accomplished by soldering, adhesives, mechanical interlocking or the like. The welding station may be dispensed with in particular instances, or may be disposed in another portion of the apparatus. Welding may be accomplished by any number of techniques which are compatible with a continuously moving body. Some of the preferred techniques are induction welding, arc welding (including TIG and MIG welding), spot welding, gas welding, and resistance welding, among others.  
         [0026]     In some instances, the system may include several welding and roll-forming stations, depending on the configuration of the profile being fabricated. For example, a first roll-forming station may shape a portion of the profile, and a first, midstream welding station will then join parts of the profile together, after which a second roll-forming station will further shape the profile; and following that, a second welding station will join the remaining parts of the profile. Clearly, yet other stations may likewise be included in the system. Following joining, the continuous, elongated shaped body  26  passes on to a cutting station  30  in which it is cut to preselected lengths so as to produce a number of members, each having the preselected profile of the elongated body  26 . Cutting may be facilitated by preformed piercings formed in the web at the punching/shaping station  18  or by piercings formed in a separate upstream station (not shown). Cutting may be accomplished “on the fly” using available technology. The cutting station may be programmed to cut all of the members to the same length, or it may be operational to cut members to varying lengths, depending upon process requirements. In some instances, further operations, such as punching, stamping and the like, may be carried out on the workpiece either before, during or after the cutting by including further stations in the line. As noted above, in some embodiments of the invention, the members may be cut before being welded.  
         [0027]     Referring now to  FIG. 3 , there is shown a plurality of cut members  32   a - 32   d  passing along, in series, through the apparatus of the present invention. It should be noted that members  32   a  and  32   b  are shorter in length than members  32   c  and  32   d . These members  32  pass, in series, to a series/parallel feeder station  34  which collects these serially disposed members, and groups them into a plurality of groups, each group having at least two of the members therein. As shown in  FIG. 4 , the series parallel feeder has grouped the members  32  into two separate groups  36   a ,  36   b , each group  36   a ,  36   b  including four members. As is further shown in  FIG. 4 , the system includes an inspection/rejection station  38  which receives the groups  36   a ,  36   b  and inspects the members thereof to determine if they meet certain preselected criteria. Members not meeting these standards are rejected; and, as is shown in  FIG. 4 , member  32   a  has been rejected. The inspection station can also carry out a marking function wherein it operates to place identifying indicia on the parts. Such markings may indicate part numbers, tracking numbers, identity of the coil of steel from which the part was made, dates, customer numbers and the like. Marking may be accomplished by the use of high temperature ink, etching, mechanical means such as punching, scribing or engraving, or by use of a laser, electric arc or the like.  
         [0028]     Following inspection, the groups of parts, for example group  36   a  and  36   b , are sequentially fed into a metallurgical furnace  40 . The furnace maintains the parts at an elevated temperature which is sufficient to bring about a metallurgical transformation in the metallic members loaded therein. In the particular process illustrated herein, this metallurgical transition is an austenizing transition, and in that regard, the parts are heated to a temperature in excess of 900° C. It is to be understood that the term “furnace” is used herein in its broadest sense to encompass all types of heating stations which can maintain the parts at an elevated temperature. As such, the furnace may include combustion heated furnaces, arc furnaces, resistance heated furnaces, as well as stations which heat parts by induction or radiant heating.  
         [0029]     As illustrated, the furnace includes a sequence controller  42  which operates to regulate the residence time and ejection of parts from the furnace  40 . As is further illustrated, the furnace  40  may also include an atmosphere controller  44  therein for providing a preselected atmosphere in the furnace. Typically, this atmosphere may be an inert gas atmosphere such as an argon atmosphere, a reducing atmosphere, or a nitriding atmosphere. In some operations, depending upon the nature of the metal being formed, it may be desirable to have an oxidizing atmosphere in the furnace, and such could also be accomplished by the atmosphere controller  44 .  
         [0030]     Referring now to  FIG. 5 , and following the appropriate heat treatment in the furnace  40 , heated parts, for example parts  36   a  and  36   b , are ejected from the furnace, and while being maintained at an elevated temperature, are transferred to a pair of quenching dies  46   a ,  46   b . Transfer is preferably accomplished by a robotic transfer feeder  52 . These dies receive and shape the heated parts therein. The dies may shape the longitudinal profile of the parts as shown in the figures, or they may serve to hold and stabilize the roll-formed profile during quenching. Given the fact that the metal is heated, shaping is accomplished relatively easily and this fact is reflected in the design and construction of the dies. In some instances, the atmosphere between the furnace  40  and dies  46  may be controlled so as to prevent oxidation or other unwanted reactions of the heated parts. In yet other instances, welding operations may be carried out on the part while it is still at an elevated temperature. The welding may be carried out in the furnace, after the part exits the furnace, or in the die.  
         [0031]     Following shaping, the parts are quenched within the die, typically by introducing a quench fluid into the dies through inlet  54 . The quench fluid is typically a liquid, and generally a water-based liquid, although other quenching media may be employed as is known in the art. The quenching step hardens the metal and locks in the shape imposed thereupon by the die-forming step. As is shown in  FIG. 5 , finished, formed, hardened metal parts  50   a ,  50   b  are ejected from the forming dies  46   a ,  46   b.    
         [0032]     Within the scope of the present invention, a number of different systems may be employed to deliver quench fluid to the dies. Referring now to  FIG. 6 , there is shown one particular system which may be employed in the present invention. As shown therein, quench fluid is introduced into a die  46  through a fluid inlet  54 , and moved therefrom by an outlet  56 . In this embodiment, the inlet  54  and outlet  56  are connected to the remainder of the quench fluid system by quick connect couplings  58 , which facilitate removal and replacement of die units. The quench system of  FIG. 6  includes a holding tank  60  which may include heaters or coolers (not shown) for maintaining the fluid at a preselected temperature. The quench fluid exits the holding tank by an outlet  62 . In this embodiment, a pair of pumps  64   a ,  64   b  disposed in series operate to convey quench fluid from the holding tank  60  through the remainder of the system. While the pumping may be accomplished by a single pump, inclusion of a second pump provides for redundancy in the system which increases its reliability and allows for maintenance without requiring shutdown. In one mode of operation of this system most, and in some instances all, of the pumping function is carried out by a single pump at a given time, with the second pump being held in reserve. If one of the pumps fails, the second pump will come on line, thereby maintaining coolant flow while allowing the first pump to be repaired or replaced.  
         [0033]     The system of  FIG. 6  includes a diverter valve  68  downstream of the pumps  64   a ,  64   b . The diverter valve  68  operates to selectively convey quench fluid to the die  46  or to a bypass return line  70 . When the valve  68  is in a first position, the quench fluid passes from the pumps  64  to the die  46  by an inlet line  72 , which in this embodiment includes a preheater  74  therein. The preheater functions to ensure that the quench fluid is at an appropriate temperature to effectively carry out quenching operations in the die  46 . After the quench fluid has passed through the die  46  it exits via the die outlet  56  and returns back to the holding tank  60  via a return line  76 . In the  FIG. 6  embodiment, a heat exchanger  78  is associated with the return lines  76 , and is operative to extract heat from the returning quench fluid prior to its entry into the holding tank  60 . In other variations of the system, the heat exchanger  78  may be eliminated or disposed with the holding tank  60 . Extracted waste heat from the heat exchanger  78  may be employed to heat other process fluids and/or provide ambient heating to the workplace. In particular embodiments, the heat exchanger may be coupled into the system by quick connect couplings so as to facilitate its removal for cleaning or service. In particular instances, a number of separate heat exchange units may be included in the system, and the fluid may be selectably conveyed to one or more of the heat exchangers.  
         [0034]     When the diverter valve  68  is in a second position, quench fluid bypasses the die and returns directly to the holding tank via the diverter line  70 . By using an arrangement of this type, the system can be operated so that the pump or pumps  64  operate continuously to maintain a flow of fluid. This keeps the pressure of the system constant and in balance and avoids starting and stopping the pumps which is detrimental to pump life and which can cause fluid hammering in the system which can damage the system or the die. In addition, this allows for quick on/off control of fluid flow thereby increasing the accuracy of the quenching process. Fluid flow can be further facilitated by tuning the inlet and outlet ports  54  and  56  respectively of the die to accommodate a smooth fluid flow.  
         [0035]     Operation of the quench system is preferably under control of a microprocessor-based quench controller  80  which directly controls the operation of the pump  64   a ,  64   b , valve  68  and preheater  74 . The controller  80  will preferably obtain pressure and/or temperature data from various components of the system including the die  46  or other workpiece, the fluid itself, the preheater  74 , the holding tank  60 , pump  64   a ,  64   b  and valve  68  among other things. Other versions and modifications of the system of  FIG. 6  may likewise be implemented in embodiments of the present invention.  
         [0036]     While the foregoing has described the fluid delivery system of the present invention in the context of a specific fabrication system, the invention may be implemented in other systems. The system may be used outside of a die forming operation. For example, the system may be used to deliver a quenchant to a forging station, a heat treating station, a bending station or the like. Also, the system may be utilized to deliver a coolant fluid which is not used in a quenching operation. Accordingly, the term “workpiece” is to be interpreted broadly so as to cover articles of manufacture as well as tooling utilized for the manufacture of the articles. Also, the coolant fluid is to be interpreted to include quenchants as well as other coolant fluids.  
         [0037]     The foregoing is illustrative of one particular embodiment of the present invention. It is to be understood that numerous modifications and variations thereof may be implemented. For example, the series/parallel feeder may be further operational to separate parts by length, and group the parts into length-based groups for charging into the furnace. In other embodiments, the furnace  40  may be programmed to provide different residence times for different parts charged thereinto, and in that regard may have plural feed and ejection systems which operate independently of one another. In yet other embodiments, the furnace may have a waste heat collector associated therewith. This collector could, for example, gather heated air from the immediate environment of the furnace and use that heat to warm process water or to supplement the heat for the workplace. Also, the die-forming and quenching station may include a plurality of different dies, and the system may be operational to charge specific parts into specific dies, depending upon the length and/or profile of the parts. In such embodiments, it will be desirable to standardize certain of the dimensions of the dies or other tooling so as to allow diverse tooling to be employed in the system at the same time. For example, if the forming dies are all of the same height and all have the same length of travel, adjustments to the press will not need to be made when dies are changed, also several different dies may be utilized at the same time.  
         [0038]     Also, while the foregoing system has been described as incorporating a die-forming station and method, other embodiments may incorporate forming processes such as bending, stamping, forging, hydroforming, post-forming and the like. Also in yet other embodiments, the formed members may be otherwise treated in the processing station so as to alter a physical characteristic of the steel with or without further changing their shape. For example, the articles may be heat treated, nitrided, hardened or otherwise processed in the station. Still other modifications and variations will be apparent to those of skill in the art in view of the teaching herein.  
         [0039]     In view of the foregoing, it is to be understood that the drawings, discussion and description presented herein are illustrative of specific embodiments of the present invention, but are not meant to be limitations upon the practice thereof. It is the following claims, including all equivalents, which define the scope of the invention.