Patent Publication Number: US-6220336-B1

Title: Adjustable molten metal feed system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of Patent Application Ser. No. 09/183,185, filed Oct. 30, 1998, now U.S. Pat. No. 6,095,383 which claims the benefit of Provisional Patent Application No. 60/063,897, filed Oct. 31. 1997. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to devices for the continuous casting of molten metals and more particularly, to an improved molten metal feed system and method for high productivity continuous casting. 
     BACKGROUND OF THE INVENTION 
     The formation and casting of metals and metal alloys of various kinds have been conducted for many years using commercial scale operations. For example, continuous twin roll casters, such as those shown in U.S. Pat. Nos. 2,790,216 and 4,054,173 are commonly used. The casters disclosed therein include an opposing pair of water cooled, counter-rotated and generally horizontally oriented casting rolls. Molten metal is routed through a feed system into the nip of the two rolls just prior to the closest approach of the rolls. Typically, the feed system includes an upstream head box and a feed tip nozzle. The metal is directed from the head box, through the feed tip nozzle and into the nip of the rolls. As the metal comes into contact with the water cooled casting rolls, heat is rapidly extracted and the metal begins to solidify. The solid metal is then compressed into a sheet as it passes through the gap between the caster rolls. 
     Conventional casting machines of this type are typically capable of producing 6 mm thick strips at productivity rates of approximately 1.7 tons/m width/hour. Recently, however, a new generation of casting machines has been developed for high speed, thin strip casting of molten metal. These new generation casters are capable of casting gauges of less than 1 mm. By developing the technology necessary to cast thinner and faster, it is possible to increase productivity and reduce the number of downstream rolling passes necessary. Specifically, this technology allows for great increases in productivity, greater casting capacity in addition to enhanced quality when compared with conventional casting machines. 
     In order to satisfy the more demanding requirements of this latest generation of casting machines, a need exits for an improved molten metal feed system. The feed systems currently being used on conventional casting machines have not been able to successfully handle the transition to higher production flow requirements. For example, the feed systems currently being used on conventional casting machines tend to produce uneven, and often turbulent flow through the feed tip nozzle when operated at increased speeds. This turbulence is caused by the presence of baffles, or spacers, within the feed tip nozzle. One or more baffles are typically incorporated along the width of the feed tip to help manipulate and direct the flow of molten metal through the tip. The use of such baffles is described in U.S. Pat. Nos. 4,303,181 and 4,641,767. Although this design has proven sufficient for conventional casting machines operating at nominal production rates, at increased speeds the presence of baffles in the feed tip produces eddy currents in the molten metal as it is being routed through the nozzle which in turn cause the flow to be turbulent. 
     Additionally, the feed systems currently in use with continuous casters tend to produce a large temperature gradient in the molten metal across the width of the strip. Prior to entering the feed tip nozzle, the molten metal travels through an upstream head box. Since the width of the head box is typically significantly less than the width of the feed tip nozzle, an uneven flow of molten metal may reach the feed tip. Specifically, molten metal may begin to flow through the center section of the feed tip nozzle before a sufficient amount of metal is present to begin flowing through the edges of the feed tip nozzle. Consequently, a temperature gradient is produced in the molten metal along the width of the feed tip nozzle where typically the temperature of the molten metal is greatest at the center of the feed tip nozzle. This temperature gradient affects the profile of the cast sheet. 
     These and other problems have been experienced when the existing feed system designs are used on machines operating in the high speed, thin gauge range. Many of the casting defects (e.g. buckling, starvation, etc.) experienced on the resulting cast sheet are due to these problems associated with the feed system design. Consequently, a need exists for a molten metal feed system for continuous casters capable of handling the more demanding requirements inherent in high speed, thin gauge casting. 
     SUMMARY OF THE INVENTION 
     The present invention, therefore, provides an improved molten metal feed system for continuous casters capable of handling the transition to the higher production requirements associated with high speed, thin gauge casting. Additionally, the molten metal feed system provided for by the present invention may be retrofitted for use with conventional casters, to significantly improve the productivity of conventional casters. 
     A baffleless feed tip nozzle is provided to eliminate the turbulence problems associated the presence of baffles in the feed tip. By eliminating the baffles it is possible for liquid metal flow to be introduced into the tip in a nonturbulent manner at rates sufficient enough to satisfy the increased production flow requirements. Additionally, the feed tip nozzle is adjustable in opening size to assist in the transition from conventional to thin gauge casting. The fixed tip opening of existing feed systems produces several problems during the transition from conventional to thin gauge casting. By removing the baffles from the nozzle, it is possible to provide the option of an adjustable feed tip opening. 
     A feed tip control system is provided with the adjustable feed tip to automatically adjust the size of the feed tip opening. In addition, a roll gap control system may also be provided for automatically adjusting the size of a roll gap between a pair of caster rolls downstream from the feed tip. This automatically adjusts the casters according to the feed tip opening size. A feed tip nozzle set-back control system is also provided to automatically adjusting a set-back of the feed tip nozzle from the caster rolls. The feed tip nozzle set-back control system is operatively coupled to either the feed tip control system or the roll gap control system for automatically adjusting the feed tip opening, the roll gap, and the set-back of the feed tip nozzle in relation to one another. 
     Upstream from the feed tip nozzle, a flow distributor board is provided along the width of the desired casting. The flow distributor board stabilizes and balance the metal flow before it passes into the downstream feed tip. The flow distributor board is housed within a distributor box between an upstream edge and a downstream edge. The flow distributor board generally separates the distributor box into a lower section and an upper section and is oriented generally transverse to the metal flow. The distributor box is insulated to prevent heat loss and may also include an insulated lid when casting larger widths. In addition, the distributor box is advantageously equipped with preheaters which further prevent heat loss. 
     As is conventionally known, molten metal is introduced into the lower portion of the distributor box from an upstream head box. As the liquid metal flows into the distributor box, it is forced to fill the entire width of the lower portion of the box due to the presence of the flow distributor board. More specifically, the molten metal is restricted to filling the width of the distributor box by a plurality of perforations spaced apart along the width of the flow distributor board. The perforations, including pores or channels of different shapes, sizes, and arrangement, hydrodynamically optimize the flow of the metal into the upper portion of the distributor box and into the feed tip. The metal permeates through the perforations along the flow distributor board at different rates depending on the pore or channel configuration. Therefore, it is possible to regulate the temperature gradient across the width of the cast sheet by stabilizing the flow of molten metal as it enters the feed tip nozzle. 
     Additionally, flow dividers are provided to permit the distributor box to be compartmentalized to form different effective widths. The flow dividers may be inserted into the upper portion of the distributor box, substantially transverse to the flow distributor board. It may be desirable to compartmentalize the distributor box in order to isolate different pore or channel configurations along the width of the flow distributor board. Therefore, the flow dividers may be used in concert with the flow distributor board to manipulate and/or balance the molten metal temperature gradient across the width of the feed tip nozzle. The ability to manipulate the metal flow and the temperature gradient across the effective full casting width may be used to alter and improve the strip profile of the resulting cast sheet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be appreciated as the same become better understood by reference to the following Detailed Description Of The Preferred Embodiments, when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view of a molten metal feed system for a continuous roll caster constructed according to the principles of the present invention; 
     FIG. 2 is a cross-sectional view of an alternate embodiment of the distributor box of FIG. 1, wherein the distributor box is closed; 
     FIG. 3 is a top view of the molten metal feed system of FIG. 1; 
     FIG. 4 is a perspective view of the feed system of FIG. 1; 
     FIG. 5 is a partial cross-sectional view of the feed system of FIG. 4 taken along line  5 — 5 ; 
     FIG. 6A is a perspective view of four exemplary flow distributor boards of the feed system of FIG. 1, each having a particular perforation or channel configuration; 
     FIG. 6B is an enlarged partial view showing one end of the flow distributor boards of FIG. 6A; 
     FIG. 7A is a side view of an embodiment of a cartridge assembly that may be used in connection with the molten metal feed system of FIG. 1; 
     FIG. 7B is a top view of the cartridge assembly of FIG. 7A, with the support bar rotated to better illustrate the assembly; 
     FIG. 8 is a partial front cross sectional view of the feed tip nozzle of FIG. 1; 
     FIG. 9 is an enlarged cross sectional view of the feed tip nozzle of FIG.  1  and further showing an embodiment of a feed tip opening adjustment mechanism; 
     FIG. 10 is an enlarged cross sectional view of the feed tip nozzle of FIG. 9 shown with the feed tip opening minimized; 
     FIG. 11 is side view schematically illustrating the relationship between the gap control system, tip positioning system, and tip nozzle orifice control; and 
     FIG. 12 is a side view of the distributor box of the feed system of FIG. 1 with flow dividers. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates in transverse cross-section a pair of water cooled rolls  10  of a conventional roll caster. The rotational axes (not shown) of the two rolls  10  are parallel and the rolls are driven in the direction of movement of metal through the continuous caster (to the right in FIG.  1 ). The rolls  10  can be powered by any source, and preferably they are rotated independently by motors, such as by a pair of DC motors (not shown). The rolls  10  are cooled, usually by a cooling liquid passing through circumferential channels formed between a solid steel core and a cylindrical shell shrunk onto the core, to provide a heat sink for the molten metal as is common in the industry. 
     A molten metal feed system  12  of the present invention delivers fluid metal  14  into the space or bite between the rolls  10  to proceed toward the nip  16  of the rolls. The nip  16  is that location where the rolls  10  are closest together, also referred to as the roll gap. Thus, the fluid metal  14  emerges from the feed system  12  and engages a surface  18  of the rolls  10 . Typically, the outer surfaces of the rolls  10  are cooled to provide a high heat transfer rate and produce rapid solidification of the metal  14 . The final freezing point of the metal  14  is normally just before the nip  16  of the casting rolls  10 . A frozen metal sheet  20  is thus formed continues through the gap between the rotating caster rolls  10 . This process reduced the frozen metal sheet  20  in thickness and forms a strip of solid metal  22  which leaves the rolls  10  on the opposite side from the feed system  12 . 
     In the illustrated embodiment, the feed system  12  is shown tilted upwardly at an angle β from horizontal or level, so that the metal  14  being cast travels slightly “up hill.” Preferably, this angle is about 15 degrees. To accommodate the angled orientation of the feed system, a center line  24  through the caster rolls  10  is rotated a substantially matching angle α from vertical. Alternatively, the feed system  12  may be oriented in a generally horizontal plane with the upper caster roll  10  directly above the lower roll. The molten metal feed system provided in the practice of this invention is suitable for use in almost any such orientation. 
     The present invention provides an improved feed system  12  particularly useful for continuous casting operations. The feed system  12  generally comprises a head box  26 , an open distributor box or distribution box  28  adjacent to and downstream from the head box, and a feed Lip nozzle  30  adjacent to and downstream from the distributor box. Molten metal is typically fed into the head box  26  from a holding furnace and transfer system (not shown) in which the metal alloy to be cast is maintained at the desired temperature. During casting, the metal  14  flows from the head box  26  into the distributor box  28  through an outlet  32  in a downstream edge  34  of the head box. A matching inlet  36  is located in an upstream edge  38  of the distributor box  28  for receiving the metal  14  from the head box  26 . From the distributor box  28 , the metal  14  flows through an outlet  46  in a downstream edge  48  of the distributor box into a feed path  40  between a pair of feed tip nozzle members  42 ,  44 . 
     The feed system  12  provided for in the present invention further contains several unique features and advantages, including: a distributor box lined with an insulative layer and incorporating an internal heating element: a flow distributor board for stabilizing and balancing the flow of molten metal being introduced into the feed tip nozzle; flow dividers for isolating various flow patterns through the flow distributor board; a baffleless feed tip nozzle with an adjustable feed tip opening, and an automative system for adjusting the size of the feed tip nozzle opening. These features function integrally together to form an improved molten metal feed system for high speed, thin gauge continuous casting. Each of these features is discussed in more detail below. 
     Insulated Distributor Box 
     In a presently preferred embodiment, the distributor box  28  is constructed from a structural material capable of withstanding high temperatures and the harsh casting environment as is known to those of skill in the art in casting. For example, the head box  28  may be constructed from a hardboard material such as a high density ceramic fiber board material. A suitable hardboard is supplied by BNZ Corporation under the trade name “Marinite BNZ A” or alternatively “Marinite BNZ A HP.” This hardboard has a density of about 65 pounds/cubic foot. 
     The distributor box  28  is then insulated with an insulating liner  50 . As illustrated, the liner  50  may be directly attached to the interior wall of the distributor box  28  using a high temperature adhesive and fasteners such as screws. However, attachment may also be through, rivets, bolts, machined connections or any other devices or methods as known to those of skill in working with insulative materials and casting machinery. 
     Preferably, the entire interior of the distributor box  28  is lined, including the bottom. However, heat loss from the distributor box  28  may advantageously be reduced by placing the liner  50  along at least one wall. By providing an insulative liner  50  on at least a portion of the distributor box  28 , the loss of heat from inside the box is reduced and operating efficiency and capacity is increased. 
     The insulative liner  50  comprises a material having a low thermal conductivity such as a low density board made from a ceramic fiber. This lower density board  50  does not have the mechanical strength of the hardboard but has a lower thermal conductivity and is thus, a better insulator. The low density board  50  preferably has a density of between about 10 pounds/cubic foot and about 30 pounds/cubic foot and more preferably, about 24 pounds/cubic foot. A suitable low density board  50  may, for example, be supplied by Western Industrial Ceramics, Inc. of California, under the trade name “MagnaBoard.” However, other insulative liners or insulating materials  50  may be used. 
     Referring now to FIG. 2, the distributor box  28  is shown equipped with a lid  51 . This embodiment is preferable when casting larger widths and may be required when casting full widths at modern production speeds. More specifically, when casting widths of at least 48 inches, a closed distributor box  28 , such as the box illustrated, is preferably used. However, a closed distributor box  28  may also be used for all continuous casting operations. When casting smaller widths, the lid  51  or other closed distributor box  28  is less necessary because less heat is lost. 
     As illustrated, the lid  51  is constructed in a similar fashion as the distributor box  28  and includes a hardboard portion and may also include an insulative liner portion  53 . The insulative liner portion  53  preferably extends into the distribution box  28  to at least ensure contact with flowing molten metal during casting operations. However, the insulative liner  53  may also be partially submerged in the metal to ensure proper insulating. Similar to the liner  50 , the lid liner  53  may also be constructed from a low density ceramic fiber board which is fastened to the structural hardboard portion. 
     The lid  51  may be coupled to the distribution box  28  in any number of ways. For example, the lid  51  may be screwed or latched to the distribution box  28 . Alternatively, the lid  51  may include a wedge shaped portion formed from a step shaped hardboard which extends inwardly into the box  28  to form a wedge fit. A gasket, such as a compressible ceramic fiber blanket gasket may be placed between the lid  51  and the box  28  to further limit heat loss. 
     Distributor Box Heater 
     Referring now back to FIG. 1, the distributor box  28  is normally preheated in a low temperature oven at approximately 400° F. However, desiccated hot air may also be used as is commonly known. If the distributor box  28  is not properly preheated it can cause heat distribution problems and out gassing, by picking up inherent moisture from the distribution box assembly. In addition, the use of air only has proven generally insufficient for adequately preheating the distributor box  28  prior to start-up. Therefore, it would be desirable to also preheat the distributor box  28  prior to start-up. 
     Referring now to FIG. 2, the illustrated embodiment incorporates a heating element  55  for preheating the distributor box  28 . As shown, the heating element  55  is an electrical heating element embedded within the insulative liner  50 . The heating element  55  may also be attached to the inner or outer side of the liner  50  as is known to those of skill in the art. When using a distributor box  28  with a lid  51 , the heating element is preferably embedded within the insulative portion  53 . This may eliminate the need for heating elements  55  within the sides of the distributor box  28 . 
     A preferred heating element  55  is an electrical heating member such as an electric wire type heater that is embedded within the insulative liner  53  just below the surface. The heating element  55  may be wire coils that are formed within the low density board  53  about ⅛ inch to ⅜ inches below the surface adjacent the molten metal. A suitable heating element  55 , such as a 220V single phase or 340V variable adjustment coiled heater element may be obtained from Western Industrial Ceramic, Inc. of California. However, other heating element types, sizes and locations may also be suitable as will be known to those of skill in the art. 
     Prior to start-up, the heating element  55  may be activated to preheat the interior of the distributor box  28 . Preferably, the distributor box  28  may be preheated to over 1,000° F. However, different preheat temperatures and durations may also be used depending upon casting and other conditions. 
     Flow Distributor Board 
     As described above, existing feed system designs tend to produce a large temperature gradient in the molten metal across the width of the strip or casting, due primarily to the layout of existing feed systems. The relative dimensions of the components of the feed system are best illustrated in FIGS. 3 through 5. The feed tip nozzle  30  generally defines a full casting width  58  and the width of the distributor box  28  is substantially the same as the feed tip nozzle. However, the head box  26  and the outlet  32  in the head box through which the molten metal  14  is introduced to the downstream portion of the feed system, are significantly narrower. 
     In an exemplary embodiment of the present invention, an approximately one inch by three inch slot outlet  32  is provided in the downstream edge of the head box  26 , through which the metal  14  flows into an approximately sixty-six inch wide distributor box  28 . As previously described, the difference in dimensions of the adjacent components of the feed system may produce an uneven flow of metal  14  into the feed tip nozzle  30  and a temperature gradient across the casting width  58 . 
     To minimize the flow differences and temperature gradients of the molten metal which flows from the distributor box  28  and into the feed tip nozzle, the present invention includes a flow distributor board  60  which is housed within the distributor box. The flow distributor board  60  is positioned between the upstream edge  38  and downstream edge  48  of the distributor box  28  and extends across an effective width of the box. Thus, the flow distributor board  60  defines a lower  62  and upper section  64  of the distributor box which effectively runs the entire length of the distributor box. 
     The flow distributor board  60  is positioned within the distributor box  28  to isolate the inlet  36  from the larger outlet  46 . The inlet  36  in the upstream edge  38  of the distributor box  28  is located in the lower section  62  of the distributor box and the outlet  46  in the downstream edge of the distributor box is located in the upper section. The presence of the flow distributor board  60  in the distributor box  28  restricts the molten metal  14  flowing into the lower section  62  to fill across the entire width  58  of the distributor box before passing through the flow distributor board to enter the upper section  64  and into the feed tip nozzle  30 . 
     A plurality of perforation or channels  66  are provided along the width of the distributor board  60  to permit metal flow into the feed tip nozzle  30 . As can be seen in FIGS. 6A and 6B, the perforations  66  consist of a plurality of openings spaced apart across the width of the board  60 . Alternatively, a single perforation, such as a channel  66  may be provided. Each of the perforations  66  passes from a lower surface  67  to an upper surface  69  to allow the molten metal  14  to pass therethrough. 
     Once the lower section  64  of the distributor box  28  has been filled, including across the entire width, the molten metal  14  in the lower section  62  of the distributor box is then forced upwards through the openings  66  in the flow distributor board  60  into the upper section  64  of the distributor box and into the feed tip nozzle  30 . The result is a uniform, even flow of metal into the feed tip nozzle  30  across the entire width of the tip. 
     Those skilled in the art should realize that it is possible to manipulate the flow pattern, including volume, speed and thermal equilibrium, of the metal by varying the size, shape and arrangement (collectively “the configuration”) of the perforations or channel(s)  66  in the flow distributor board  60 . It may be desirable to use different perforations or channel configurations, spacings, etc., depending on the particular casting. For example, the particular casting speed, alloy, casting gauge and even the tip width of the casting operation may effect the desired configuration. Examples of various configurations are shown in FIGS. 6A and 6B. The examples shown are merely illustrative, however, and in any way limit the range of configurations that may be used to-control and manipulate the metal flow with the present invention. 
     As mentioned above, the feed system  12  is preferably configured for tilt-up casting as best illustrated in FIG.  1 . The flow distributor board  60  is preferably oriented within the distributor box  28  parallel to the horizontal, regardless of the orientation of the entire feed system  12 . The flow distributor board  60  provided by the practice of the present invention, however, is suitable for use in other orientations. 
     In one embodiment, the flow distributor board  60  is wedged by a friction fit between the upstream and downstream edges  38  and  48  of the distributor box  28 . More specifically, the flow distributor board  60  is wedged between the opposing insulative liners  50  attached to the opposing edges  38  and  48 . A flow divider  68  or plurality of flow dividers may be used to help retain the distributor board  60  in the distributor box  28  during casting operations as will be described in greater detail below. However, any means well known in the art may be used to secure the distributor board  60  within the interior distributor box  28  to form the lower section  62  and the upper section  64 . 
     One of the difficulties associated with the use of a flow distributor board  60  is the removal and insertion of the board in the distributor box  28 , particularly during the casting operation. Therefore, in a presently preferred embodiment, a cartridge assembly  70  as best illustrated in FIGS. 7A and 7B is provided which includes the flow distributor board  60  coupled to a opposing and spaced apart vertical support units  72 . In addition, a support bar  74  having handles  76  extends between the vertical support units  72 . 
     The cartridge  70  is a removable assembly which is inserted or positioned into the distribution box  28 , preferably just after start-up, and can be removed or reinserted into the box at any time during the casting operation.. The cartridge  70  may be changed or altered, including changing the flow distribution board  60 , to modify the flow distribution. Different cartridges  70  may be used depending on the alloy, gauge, speed, and tip width of the casting process. By coupling the flow distributor board  60  to the handles  46  of the support bar  74 , an easy method for safely removing or inserting the flow distributor board  60  is provided. 
     As illustrated, two vertical support units  72  are coupled to the upper surface  69  of the flow distributor board  60 . The vertical support units  72  may be coupled to the flow distributor board  60  by any means well known in the art, such as by screws or other conventional fasteners. Those skilled in the art should realize that more or less vertical support units  72  may be alternatively utilized with the present invention. 
     The primary purpose of the vertical support units  72  is to facilitate the removal and insertion of the flow distributor board  60 , and not to compartmentalize the distributor box  28 . Therefore, the vertical support units  72  preferably include an aperture  78  that extends through the vertical support units so that molten metal flow through the upper section  64  of the distributor box  28  is not inhibited. However, the vertical support units  72  are preferably designed to receive an insert  80  to close of the aperture, such that each vertical support unit may also act as a flow divider, as described in more detail below. The inserts  80  may be inserted or removed from the vertical support units  72  at any time during the casting operation to control or manipulate the metal flow by compartmentalizing the distributor box  28 , without affecting the operation of the remaining cartridge assembly  70 . 
     To facilitate the control and manipulation of molten metal flow, different cartridge assemblies  70  having flow distributor boards  60  with different configurations are preferably available during the casting process. If a different molten metal flow is desired, the cartridge assembly  72  in the distributor box  28  can easily be removed using the handles  76  on the support bar  74 , and a different cartridge assembly  70 , having a flow distributor board  60  with the appropriate configuration for producing the desired molten metal flow, inserted into the distributor box without requiring stoppage of the casting process. 
     Baffleless Feed Tip Nozzle With an Adjustable Tip Opening 
     Referring now back to FIG. 1, the metal flow passes into the distributor box  28  and through the flow distributor board  60  prior to being introduced into the feed tip nozzle  30 . The feed tip nozzle  30  is adjacent to and downstream from the distributor box  28  and comprises a pair of elongated feed tip members  42 ,  44 , constituting, respectively the top and bottom members of the feed tip nozzle. The feed tip members  42 ,  44  are spaced apart defining the feed path  40  for the metal through the nozzle  30 . 
     The feed path  40  is preferably aligned with the outlet  46  in the downstream edge  48  of the distributor box  28  for receiving the metal flow once it has permeated through the distributor board  60 . The feed path  40  continues the length of the nozzle and concludes in a feed tip opening  82  having a total opening width corresponding approximately to the desired width of the sheet being cast. 
     Conventional end dams  92 , as best shown in FIGS. 3 and 8, close off both ends of the feed tip nozzle  30  and help define the width of the sheet being cast. Preferably, the end dams  92  are made from a compressible gasket material such as a laminate fiber paper material as commonly used in casting operations. End plates  84  may be used to maintain the end dams in position and prevent the nozzle members  42 ,  44  from being closed together. 
     The width of a sheet prepared in a typical manufacturing operation can differ from time to time and the maximum casting width is dependent on the width of the caster rolls  10 . A width of 1½ to 2 meters is common. 
     In a presently preferred embodiment, the feed tip nozzle members  42 , 44  are attached to a tip holder. The use of a tip holder may add needed rigidity and strength to the feed tip nozzle. The tip holder comprises a top plate  86  and a bottom plate  88 . A suitable top plate  86  may be constructed from a mild steel and a suitable bottom plate  88  from a meehanite casting for reduced warpage. However, other materials may be used as will be known to those of skill in the art of casting. The top feed tip nozzle member  42  is attached to the top tip holder plate  86  and the bottom feed tip nozzle member  44  is attached to the bottom tip holder plate  88 . 
     The nozzle members  42 ,  44  may be attached to the tip holders  86 ,  88  by any means well known in the art. In the embodiment illustrated in FIG. 8, ceramic plugs  90  are attached to the respective tip plate  86 ,  88 . Each plug  90  is threaded or otherwise adapted for attachment to a fastener  76  which couples each nozzle member  42 ,  44  to the respective tip holder  86 ,  88 . To reduce cost, the plugs  90  may be through drilled and threaded with the base being filled with a moldable ceramic fiber bond to form a smooth flow path surface. 
     The feed tip nozzle  30  provided for in the present invention is a baffleless feed tip nozzle. The term “baffleless” refers to the absence of baffles or spacers in the nozzle between the feed tip members  42 ,  44 . In contrast to most existing feed system designs, the feed path  40  is unobstructed by baffles for directing the flow of metal through the tip. Therefore, metal can be introduced to and directed through the tip  30  in a uniform, even flow at rates sufficient enough to satisfy the higher production flow requirements of high speed, thin gauge casting. In particular, no turbulence is experienced in the feed tip nozzle  30  despite the increased casting speeds. 
     Additionally, the feed tip nozzle  30  is adjustable, therefore providing nozzle orifice control. Specifically, it is possible to adjust the discharge gap or spacing  82  between the nozzle members  42 ,  44 . The adjustable tip orifice option allows the discharge gap  82  to be made larger for conventional gauge and made smaller for thin gauge casting, resulting in greater control over the entire casting process. Existing feed tip designs have a fixed tip opening which may cause problems during the transition from conventional to thin gauge casting (e.g. controlling the tip set-back, end dam failures, etc.). Thus, the baffleless feed tip design  30  allows the tip opening  82  to be adjustable during operation. 
     Referring now to FIG. 8, in conjunction with FIGS. 9 and 10, an embodiment of an automatic nozzle adjustment mechanism  95  for the feed tip opening  82  will be described. In particular, the nozzle gap or tip opening  82  is adjusted by moving the top tip holder plate  86  relative to the bottom tip holder plate  88 . More specifically, a drive system  97  is coupled to the feed system  12  and adapted to adjust the position of the top tip holder plate  86  relative to the bottom plate  88  (reference FIG.  4 ). The drive system  97 , which preferably includes a stepper motor and a gear reducer, is coupled to a mechanical system  99  which changes the relative position of the feed tip nozzle members  42 , 44 , and thus, the size of the feed tip opening  82 . 
     As illustrated in FIGS. 9 and 10, the drive system  97  is coupled to a shaft  100  which drives a male wedge  102 . The male wedge  102  slidably engages a fixed tapered female slide  104  which is coupled to the top tip holder plate  86 . The slide may be directly coupled to the upper tip holder plate  86 . The wedges  102  and  104  are shaped (angled) such that by advancing the male wedge  102  forward it increases the size of the feed tip opening  82  likewise, the feed tip opening decreases  82  relatively as the drive system  99  withdraws the wedge. Mechanical stops may be provided to prevent blockage of the nozzle tip opening  82  or an inappropriately large tip opening. 
     Preferably, the automatic nozzle adjustment mechanism  95  comprises a pair of marched motor/gear reducer assemblies  97  and mechanical wedge assemblies  99  which operate together. As illustrated, each drive system  97  may be placed on either side of the distributor box  28  and the respective wedge assembly  99  adjacent the respective side of the nozzle  30 . However, other automatic nozzle adjustment mechanisms may also be used as well as their placement relative to the feed system  12 . The operation of the automatic nozzle adjustment mechanism  95  may also be automated and linked to a smart system with feedback control as will be further described below. 
     Adjustment of the feed tip opening  82  may also be manually operated and controlled, such as through acme type screws which forcibly move the tip holders  86  and  88  relative to each other or alternatively drive the wedge assembly as described above. In addition, gauges, such as dial gauges may be used to confirm and properly adjust the gap  82 . However, any mechanical type system may be used to adjust the gap  82  as will be known to those of skill in the art. 
     Referring now, back to FIG. 3 in conjunction with FIG. 8, a compressible spacer gasket  78  is provided on each respective end of the distributor box  28 . The spacer gaskets  78  prevent end dam  92  run off as well as nozzle tip  30  damage during the transition from conventional to thin gauge casting. The spacer gasket  78  transitions from the narrower distributor box  28  to the wider feed tip nozzle  30 . The narrower distributor box  28  is used to provide a support location for the feed tip nozzle adjustment mechanism  97 . The compressible spacer gaskets  78  are preferably sections cut from a high temperature fiber paper, such as a laminate ceramic fiber paper gasket. However, other sealing materials may also be used as will be known to those of skill in the art. 
     Referring now to FIG. 11, conventional roll casters typically have a roll gap control system and a feed tip positioning system that work independently from one another. The roll gap control system permits adjusting the roll gap  16  (increasing the gap for higher gauges and decreasing the gap for lower gauges) at any time during the continuous casting operation. The feed tip positioning system permits adjusting the position of the feed tip nozzle, tip set-back  94  (moving if forward into the roll gap or moving backward out of the roll gap) at any time during the continuous casting operation. 
     In order to more accurately control the metal flow output during casting for any consistency, it would be advantageous to automate the control of the roll gap  16 , tip set-back  94 , and the size of the gap or spacing in the feed tip orifice  82 , such that the roll gap  16  would be the master variable, and the tip positioning and orifice size control would be the followers. In other words, the tip positioning and orifice control adjustment features of the caster system are electronically tied or looped, using a programmable logic controller (PLC) or other suitable means, to the roll gap control such that they automatically respond when a specific roll gap  16  is set. As a result, the roll gap  16 , tip set-back  94 , and feed tip orifice size  82  can be controlled independent of one another, or automatically in relation to one another. Such an automation feature will facilitate more precise control and repeatability in the casting process, which is necessary for optimum performance. 
     For example, referring to FIG. 11, if the roll gap  16  is reduced from 0.230 inches to 0.177 inches, then the tip set-back  94  of 2.250 inches and the feed tip orifice  82  of 0.270 inches would change either proportionately, or as programmed to allow for the required clearance. If this change is not made, the feed tip nozzle  30  could be broken as the rollers  10  close to decrease the roll gap  16 . If the roll gap  16  is reduced from 0.230 inches to 0.177 inches, but it is desired to maintain the same tip set-back  94  of 2.250 inches, then a feed tip  82  orifice change from 0.270 inches to 0.217 inches could be programmed to allow for the required clearance. Alternatively, if it is desired to maintain the tip  82  orifice at 0.270 inches as the roll gap  16  is reduced to 0.177 inches, then a tip set-back  94  change from 2.250 inches to 2.470 inches could be programmed to allow for the required clearance. 
     Those skilled in the art will realize that the precise relationship between the roll gap  16 , tip set-back  94 , and feed tip orifice size  82  will depend on a variety of parameters, including but not limited to: the alloy being cast, strip quality, extrusion requirement and maximum flow rate. Depending on the exact parameters, it may be desirable to adjust only the tip set-back  94 , only the feed tip orifice  82 , or both the tip set-back and the feed tip orifice. 
     Flow Dividers 
     In a presently preferred embodiment, flow dividers  68  are provided for controlling and manipulating the metal flow by compartmentalizing the distributor box  28  as best illustrated in FIGS. 4 and 5. This may be particularly desirable when different pore or channel configurations  66  are present along the width of the flow distributor board  60  (best shown in FIG.  6 B). The flow dividers  68  may be used to isolate the different perforation or channel configurations  66  on the distributor board  60  to prevent the mixing of the flow from the different configurations, to regulate the different flow rates, and to achieve a uniform temperature across the width of the distributor box  28  and thus, the feed nozzle tip  30 . It is a particular advantage of the flow dividers  68  that they allow the temperature gradient between compartments to be manipulated along the width of the flow distributor board  60  allowing the capability to alter the strip profile. 
     The flow dividers  68  are inserted into the distributor box  28  between the upstream  38  and downstream  48  edges of the distributor box, substantially transverse to the flow distributor board  60 . Adjustment slots  96  may be formed in the upstream and downstream edges of the distributor box for receiving the flow dividers  68 . Preferably, these adjustment slots are cut or otherwise formed within the insulative liner  50 . The flow dividers  68  are preferably shaped to match the cross section of the upper section  64  of the distributor box  28  and thus, prevent flow and define the effective width of the distributor box. 
     In the embodiment illustrated in FIG. 1 where the feed system  12  is oriented for “tilt-up” casting, a bottom edge  98  of the flow dividers  68  may need to be angled accordingly, as illustrated in FIG.  12 . For example, the bottom edge  98  should be angled to match the “tilt up angle.” It should be noted, however, that a variety of different shapes may be used for the flow dividers  68  of the present invention and the shape of the dividers will largely be dictated by the configuration of the feed system  12 , including the distribution box  28 , the alloy being cast, and the casting speed and width. Moreover, it should be realized that the desired flow pattern and the configuration of perforations  66  in the flow distributor board  60  may dictate the desired number and location of flow dividers  68 . Therefore, although FIG. 4 illustrates the use of two flow dividers  68 , the feed system  12  provided according to the principles of the present invention contemplates the use of more or less flow dividers as required. Likewise, although the flow dividers  68  illustrated in FIG. 4 are oriented substantially perpendicular to the edges  38 ,  48  of the distributor box  28 , in an alternate embodiment of the present invention, the flow dividers  68  may be angled relative to the edges of the distributor box. 
     With reference to FIG. 12, a handle  100  may be provided at a top edge of the flow dividers  68  to assist in the safe installation and removal of the board from the distributor box  28 . As shown, the handle  100  may extend beyond the open upper surface of the distributor box  28  to allow for easy installation and maintenance of the flow distributor boards  60 . 
     As described above, when the cartridge assembly  70  illustrated in FIGS. 7A and 7B is utilized with the present invention, inserts  80  may be inserted into the vertical support units  72  so that the vertical support units act as flow dividers  68 . Additional flow dividers  68  may be used in connection with the cartridge assembly  70  if necessary to provide a desired compartmentalization of the distributor box  28 . 
     Feed System Operation 
     An embodiment of operation of the feed system  12  provided for in the present invention and generally illustrated in FIG. 1, when used in a continuous casting operation will be described. The feed system  12  is preheated, preferably in an oven. The feed system  12  is removed from the oven or other preheater and the distributor box  28  is further preheated using the heating elements  55 . After sufficient preheat temperature is attained, molten metal  14  is allowed to flow into the lower section  62  of the distributor box  28  through the outlet  32  in the upstream headbox  26 . The presence of the flow distributor board  60  in the distributor box  28  restricts the flow of the molten metal  14  and forces the flow to fill the entire width of the distributor box before rising upward through the openings  66  in the flow distributor board  60  and into the upper section  64  of the distributor box. 
     The insulative lining  50  within the distributor box  28  prevents massive heat loss and cooling of the molten metal. The lid assembly  51  and attached liner  53  further prevent this heat loss from the molten metal  14  out of the box  28 . 
     After filling the lower section  62  of the distributor box  28 , the metal  14  flows through the perforations  66  into the upper section  64  of the box and then into the feed tip nozzle  30 . Through this process, the flow distributor board  60  helps stabilize and balance the metal flow along the entire effective casting width  58 . 
     As previously described, different perforation sizes, configurations and spacings or alternatively channel configuration  66  may be used depending on the particular speed and gauge of the casting operation. When necessary, the cartridge assembly  70  may be removed and replaced with a different cartridge assembly having a flow distributor board  60  with a different perforation or channel configuration  66 . 
     A temperature measuring device  104  is used to measure the temperature of the molten metal  14  which passes out of the distributor box  28  and through the feed tip nozzle  30 . Preferably, this temperature measuring device  104  comprises a plurality of thermocouples which extend into the flow path and provide feedback regarding the temperature of the molten metal. The thermocouples  104  are spaced apart across the casting width  58  to indicate whether the temperature gradient across the casting width is as desired. Thus, the thermocouples  104 , which may, for example, be five identical thermocouples spaced apart on approximately 17 inch centers, indicate whether the cartridge  70  and particularly, the flow distribution board  60  is stabilizing the flow and temperature gradient properly and whether is should be replaced with a flow distributor board having a different configuration of perforations. 
     In the illustrated embodiment, the thermocouples are embedded into the upper tip plate  86  and extend through the upper nozzle member  42  and into the metal flow path  40  approximately ¼ inch. The thermocouples are too small to create turbulence or eddie currents. The thermocouples  104  are run back to a computer or data logger (not shown) on a substantially continuous basis to allow constant monitoring of the flow temperature gradient across the casting width  58 . As will be known to those of skill in the art, other temperature measuring devices and methods may also be used to achieve similar or otherwise acceptable feedback information on the temperature gradient across the casting width  58 . 
     Flow dividers  68  may be inserted into the distributor box  28  to compartmentalize and define an effective width of the box and to isolate different configurations on the flow distributor board  60 . Use of the flow dividers  68  permits manipulation of the metal flow across the entire casting width  58  to allow, for example, altering the temperature gradient affecting the strip profile during operation. From the distributor box  28 , the metal flow is introduced into the feed path  40  of the feed tip nozzle  30 . 
     The feed tip nozzle  30  is baffleless which allows for a uniform, even flow of metal through the feed tip despite increases in casting speeds. Moreover, the tip opening  82  of the nozzle  30  is adjustable so that it may be increased or decreased during the transitions between conventional to thin gauge casting. Furthermore, the control of the roll gap  16 , tip set-back  94 , and feed tip opening  82  may be automated using motorized systems under computer control. Further, these control systems may be linked for synchronous and more efficient operation. 
     While various embodiments of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. For example, although the feed system of the present invention has been primarily described for use in high speed, thin gauge continuous casters, it should be realized that the feed system disclosed herein may be retrofitted for use with conventional casters. Even at nominal production rates, the improved feed system will significantly improve the productivity of conventional casters. It is, therefore, to be understood that within the scope of the appended claims, this invention may be practiced otherwise than as specifically described.