Abstract:
A method of manufacturing a component in a die casting cell that includes a die casting system according to an exemplary aspect of the present disclosure includes, among other things, isolating a first chamber from a second chamber of the die casting system, melting a charge of material in the first chamber, sealing the second chamber relative to the first chamber, and simultaneously injecting the charge of material within the second chamber to cast the component and melting a second charge of material within the first chamber.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 13/030,225, filed Feb. 18, 2011. 
    
    
     BACKGROUND 
     This disclosure relates generally to die casting systems, and more particularly to a die casting system and cell. 
     Casting is a known technique used to yield near net-shaped components. For example, investment casting is often used in the gas turbine engine industry to manufacture near net-shaped components, such as blades and vanes having relatively complex geometries. A component is investment cast by pouring molten metal into a ceramic shell having a cavity in the shape of the component to be cast. Generally, the shape of the component to be cast is derived from a wax pattern or SLA pattern that defines the shape of the component. The investment casting process is capital intensive, requires significant manual labor and can be time intensive to produce the final component. 
     Die casting offers another known casting technique. Die casting involves injecting molten metal directly into a reusable die to yield a near net shaped component. The cycle time to melt an alloy for use in the die casting process is relatively high. Accordingly, the cycle time can affect the length of time the die casing system components are subjected to relatively high thermal loads and stresses during the die casting process. 
     SUMMARY 
     A method of manufacturing a component in a die casting cell that includes a die casting system according to an exemplary aspect of the present disclosure includes, among other things, isolating a first chamber from a second chamber of the die casting system, melting a charge of material in the first chamber, sealing the second chamber relative to the first chamber, and simultaneously injecting the charge of material within the second chamber to cast the component and melting a second charge of material within the first chamber. 
     In a further non-limiting embodiment of the foregoing method, the method includes removing the component from the die with a robot, delivering the component to a post-cast station with the robot, and performing a secondary operation on the component at the post-cast station. 
     In a further non-limiting embodiment of either of the foregoing methods, the method includes melting the charge of material into molten metal with at least one electron beam melting gun. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of melting includes preheating the charge of material with the at least one electron beam melting gun, focusing a beam of the at least one electron beam melting gun onto a tip of the charge of material and melting the charge of material into a crucible. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of melting includes superheating the charge of material within the crucible. 
     In a further non-limiting embodiment of any of the foregoing methods, the method includes applying a vacuum to the first chamber and the second chamber. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of isolating includes closing an isolation valve to separate the first chamber from the second chamber. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of sealing includes closing a shut-off mechanism to seal a shot tube of the die casting system from a melting system of the die casting system. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of melting includes communicating the charge of material to the first chamber and positioning the charge of material relative to a melting unit. 
     In a further non-limiting embodiment of any of the foregoing methods, the step of simultaneously injecting the charge of material within the second chamber to cast the component and melting the second charge of material with the first chamber includes actuating a shot tube plunger to force the charge of material into a die of the die casting system within the second chamber and melting the second charge of material with a melting unit housed in the first chamber. 
     A method of manufacturing a component in a die casting cell that includes a die casting system according to another exemplary aspect of the present disclosure includes, among other things, isolating a first chamber from a second chamber of the die casting system, drawing a vacuum in the first chamber, melting a charge of material within the first chamber, communicating the charge of material to a shot tube of the die casting system and injecting the charge of material into a die of the die casting system to cast the component. 
     In a further non-limiting embodiment of the foregoing method, the step of isolating includes closing an isolation valve to separate the first chamber from the second chamber. 
     In a further non-limiting embodiment of either of the foregoing methods, the method includes opening the isolation valve after the step of drawing the vacuum to reach equilibrium between the first chamber and the second chamber, and after equilibrium is reached, performing the step of communicating the charge of material. 
     In a further non-limiting embodiment of any of the foregoing methods, the method includes actuating a shut-off mechanism to seal the shot tube from a melting system of the die casting system. 
     In a further non-limiting embodiment of any of the foregoing methods, the method includes, after solidification of the component, venting the second chamber and opening an isolation valve to remove the component from the die. 
     A method of manufacturing a component in a die casting cell that includes a die casting system according to another exemplary aspect of the present disclosure includes, among other things, die casting a gas turbine engine component using the die casting system, removing the gas turbine engine component from the die casting system with a robot, delivering the gas turbine engine component to a post-cast station with the robot and performing a secondary operation on the gas turbine engine component at the post-cast station. 
     In a further non-limiting embodiment of the foregoing method, the post-cast station includes a gate cut-off station. 
     In a further non-limiting embodiment of either of the foregoing methods, the post-cast station includes a belt grinding station. 
     In a further non-limiting embodiment of any of the foregoing methods, the post-cast station includes a grit blast station. 
     In a further non-limiting embodiment of any of the foregoing methods, the post-cast station includes an inspection station. 
     The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example die casting system. 
         FIG. 2  illustrates a portion of a die casting system including a die having a die cavity. 
         FIG. 3  illustrates an isolation valve of a die casting system. 
         FIGS. 4A and 4B  illustrate example melting systems for use with a die casting system. 
         FIG. 5  illustrates another example melting system for use with a die casting system. 
         FIG. 6  illustrates another example die casting system. 
         FIG. 7  illustrates an example die casting cell. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a die casting system  10  including a reusable die  12  having a plurality of die elements  14 ,  16  that function to cast one or more components  15  (See  FIG. 2 ). The components  15  could include aeronautical components, such as gas turbine engine blades or vanes, or non-aeronautical components. Although two die elements  14 ,  16  are depicted by  FIG. 1 , it should be understood that the die  12  could include more or fewer die elements, as well as other parts and other configurations. 
     The die  12  is assembled by positioning the die elements  14 ,  16  together and holding the die elements  14 ,  16  at a desired position via a mechanism  18 . The mechanism could include a clamping mechanism that may be powered hydraulically, pneumatically, electromechanically or with other power systems. The mechanism  18  also separates the die elements  14 ,  16  subsequent to casting. 
     The die elements  14 ,  16  include internal surfaces that cooperate to define a die cavity  20  (See  FIG. 2 ). The die cavity  20  defines two cavities  20 A and  20 B, in this example. However, the die cavity  20  could include fewer or additional cavities. 
     A shot tube  24  is in fluid communication with the die cavity  20 . In this example, at least a portion of the shot tube  24  is integral to the die  12 . However, the shot tube  24 , or at least a portion thereof, can also be located external to the die  12 . A shot tube plunger  28  is received within the shot tube  24  and is moveable between a retracted and injected position (in the direction of arrow A) within the shot tube  24  by a mechanism  30 . A shot rod  31  extends between the mechanism  30  and the shot tube plunger  28 . The mechanism  30  could include a hydraulic assembly or other suitable system, including, but not limited to, pneumatic, electromechanical, hydraulic or any combination of systems. 
     The shot tube  24  is positioned to receive a charge of material M from a melting system  32  (shown schematically). Example melting systems are described below. The melting system  32  melts a charge of material M, such as an ingot of metallic material, and delivers molten metal to the shot tube  24 . In this example, the die  12  includes a runner  33  that communicates the charge of material M from the melting system  32  to the shot tube  24 . However, the charge of material M can also be delivered directly to the shot tube  24 , as is discussed in greater detail with respect to  FIG. 6 . 
     A sufficient amount of molten metal is delivered to the shot tube  24  to fill the die cavity  20 . The charge of material M can include, but is not limited to, various metallic materials including nickel-based super alloys, cobalt-based super alloys, titanium alloys, high temperature aluminum alloys, copper-based alloys, iron alloys, molybdenum, tungsten, niobium or other refractory metals. This disclosure is not limited to the disclosed alloys, and other high melting temperature materials may be utilized to die cast a component  15 . As used in this disclosure, the term “high melting temperature material” is intended to include materials having a melting temperature of approximately 1500° F./850° C. and higher. 
     The example die casting system  10  further includes a shut-off mechanism  29  that is selectively retractable between an open position and a closed position (shown in phantom lines) by a mechanism  27 . For example, the shut-off mechanism  29  could include a wedge, a cylinder, a cone or other suitable mechanism for closing off the runner  33 . The shut-off mechanism  29  is actuated to separate the entry point of the charge of material M from the shot tube  24 . In other words, the shut-off mechanism  29  seals the shot tube  24  from the melting system  32 . In this way, a second charge of material M 2  can be prepared for delivery to the shot tube  24  simultaneously with the injection of the first charge of material M to cast a component  15 , thereby reducing cycle time of the die casting system  10 . 
     The shot tube plunger  28  is actuated to inject the charge of material M under pressure from the shot tube  24  to the die cavity  20  to cast the component(s)  15 . In this example, multiple components  15  are cast in a single shot. However, the die casting system  10  could be configured to cast any number of components in a single shot. 
     The die casting system  10  includes a vacuum system  34 . In this example, the vacuum system  34  includes multiple chambers that are separated to facilitate the rapid production of components. In this example, the vacuum system  34  includes a first chamber C 1  and a second chamber C 2 . Although two chambers are shown and described, the vacuum system  34  could include a single chamber or a multitude of chambers. 
     In this example, the first chamber C 1  substantially encloses the melting system  32 , while the second chamber C 2  substantially encloses the die  12 , the shot tube  24  and the shot tube plunger  28 . A portion of melting system  32 , the die  12 , the shot tube  24  or the shot tube plunger  28  may be disposed outside of the first chamber C 1  or second chamber C 2  and still be considered “substantially enclosed.” 
     The vacuum system  34  includes a vacuum source  35  that applies a vacuum to the first chamber C 1  and the second chamber C 2 . In this example, a single vacuum source  35  applies vacuum to both the first chamber C 1  and the second chamber C 2 . Alternatively, separate vacuum sources  35  may be utilized to apply vacuum to the separate chambers C 1 , C 2  of the vacuum system  34 . 
     In one example, the vacuum system  34  selectively applies a pressure of in the range of 5×10 −3  to 1×10 −6  Torr (0.6666 to 0.000133 Pascal) within the first chamber C 1  and the second chamber C 2 . Other pressures are contemplated as within the scope of this disclosure. Each chamber C 1 , C 2  may be maintained at the same or differing vacuum levels. The actual pressure applied by the vacuum system  34  will vary based on the type of component being cast and the alloy being cast, among other conditions and factors. The vacuum source  35  can include a roughing pump, a booster pump, a diffusion and/or turbo pump or other sources for achieving and maintaining a desired vacuum level within the first chamber C 1  and the second chamber C 2 . 
     The vacuum system  34  creates a non-reactive environment that reduces reaction, contamination or other conditions that could detrimentally affect the quality of the cast component, such as excess porosity that could occur from expose to air. In addition, the separate chambers C 1  and C 2  of the vacuum system  34  facilitate the rapid production of cast components by providing the ability to melt a charge of material M in the melting system  32  simultaneously with casting and removal of a component  15  from the die cavity  20 . 
     The example die casting system  10  is a vertical die casting system, although other configurations are contemplated as within the scope of this disclosure (See  FIG. 6 , for example). The first chamber C 1  is positioned vertically above the second chamber C 2 , in this embodiment. In other words, the melting system  32  is positioned vertically above the die  12  to provide a die casting system  10  having a vertical configuration. 
     An isolation valve  36  is positioned between the first chamber C 1  and the second chamber C 2  to separate the two chambers. The isolation valve  36  is selectively actuable to isolate the first chamber C 1  from the second chamber C 2 . The isolation valve  36  can include a plate  38  that is slidable between a first position X (an open position) and a second position X′ (a closed position). Alternatively, the plate  38  could rotate about a pivot point  39  to selectively isolate the first chamber C 1  from the second chamber C 2  (See  FIG. 3 ). 
     A second isolation valve  40  can be positioned between the die  12  and a machine base  42  to provide access to the die cavity  20 , as is discussed in greater detail below. Similar to the isolation valve  36 , the second isolation valve  40  is selectively moveable between an open position and a closed position to provide access to the die cavity  20  of the die  12  for component removal. 
       FIG. 4A  illustrates an example melting system  32  for use with a die casting system, such as the die casting system  10 . The melting system  32  includes an alloy loader  44 , a melting unit  46  and a crucible  48 . The alloy loader  44 , the melting unit  46  and the crucible  48  are each substantially enclosed within the first chamber C 1  of the vacuum system  34 . 
     In one example, the alloy loader  44  is a continuous alloy loader having a conveyor  50  that communicates the charge of material M to the first chamber C 1  and positions the charge of material M relative to the melting unit  46  for melting the charge of material M. The alloy loader  44  could include its own isolation valve to seal any portion of the conveyor  50  that extends exteriorly from the first chamber C 1 . 
     Alternatively, the alloy loader  44  includes an alloy carousel  51  (see  FIG. 4B ) that can be removably positioned within the first chamber C 1  to load multiple charges of material M at once. The alloy carousel  51  rotates to locate each charge of material M at a desired positioning relative to the melting unit  46 . The alloy carousel  51  is removed from the first chamber C 1  when empty and can be loaded with additional charges of material M as needed during the die casting process. 
     In the example illustrated by  FIG. 4A , the melting unit  46  includes a plurality of electron beam melting guns  54 . Two electron beam melting guns  54  are depicted by  FIG. 4A . However, the melting unit  46  could utilize a single electron beam melting gun or a plurality of electron beam melting guns. The electron beam melting guns  54  can include internal isolation valves. Alternatively, separate isolation valves may be positioned within the first chamber C 1  so that each individual electron beam melting gun  54  can be removed from the first chamber C 1  without the need to re-pressurize the entire first chamber C 1 . 
     Prior to melting a charge of material M, the first chamber C 1  is sealed relative to the second chamber C 2  via the isolation valve  36  and vacuum is drawn by the vacuum system  34 . The electron beam melting guns  54  preheat the charge of material M to reduce melt time. After preheating the charge of material M, beams  55  of the electron beam melting guns  54  focus on a tip  56  of the charge of material M. As the charge of material M melts, molten metal is communicated to the crucible  48 , which is positioned beneath the charge of material M. 
     In this example, the crucible  48  is a water cooled copper crucible, although other crucible types are contemplated. The crucible  48  can include a load sensor that detects a weight of the charge of material M. Once the charge of material M is communicated to the crucible  48 , the beams  55  of the electron beam melting guns  54  are directed onto the crucible  48  to superheat the charge of material M once the load sensor indicates that a desired weight is achieved. 
     Once a suitable vacuum is achieved within the first chamber C 1 , the isolation valve  36  is opened so that the first chamber C 1  and the second chamber C 2  reach equilibrium. After equilibrium is reached, the charge of material M is communicated to the shot tube  24 . The shut-off mechanism  29  is then closed. The shot tube plunger  28  is next actuated to force the charge of material M into the die cavity  20  to cast a component  15 . After a sufficient amount of time passes for the component  15  to adequately solidify, the second chamber C 2  is vented and the second isolation valve  40  is opened to allow removal of the component  15  from the die  12 . 
       FIG. 5  illustrates a second example melting system  132 . In this disclosure, like reference numerals signify similar features, and reference numerals identified in multiples of 100 signify slightly modified features. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments within the scope of this disclosure. 
     In this example, the melting system  132  includes a melting unit  146  and a plurality of crucibles  148 . An alloy loader  144  may be used to load charges of material M into the plurality of crucibles  148 . In this example, the melting unit  146  includes an induction melting system having coils  60  for heating the plurality of crucibles  148 . Other melting units are also contemplated as within the scope of this disclosure. The plurality of crucibles  148  are positioned on a rotating platform  58 , such as in a lazy susan configuration, to position each crucible  148  at a desired location within the first chamber C 1  for delivery to the die  12 . 
       FIG. 6  illustrates another example die casting system  110 . In this example, the die casting system  110  is a horizontal die casting system. That is, the first chamber C 1  is axially offset relative to the second chamber C 2  rather than vertically above the second chamber C 2 . A stationary platen  90  divides the first chamber C 1  from the second chamber C 2 . The melting system  32  can direct a charge of material M directly into the shot tube  24 , such as through a pour hole  92 . 
       FIG. 7  illustrates an example die casting cell  70  for manufacturing and performing secondary operations on cast components. The die casting cell  70  includes a die casting system, such as the die casting system  10  or  110 , at least one mechanism  72  and at least one post-cast station  74  for performing a secondary operation on the cast component. 
     Although a single mechanism  72 , such as a robot, is depicted, the die casting cell  70  could include a plurality of robots for performing secondary operations and other tasks associated with the die casting process. The operations the robot  72  can conduct include, but are not limited to, removal of a component from the die  12 , inspection of the die casting system  10 ,  110  via visible light, infrared, ultraviolet or laser light inspection, applying mold release agents to the die  12 , etc. The robot  72  may enter the die casting system  10 ,  110  through the isolation valve  40  to remove a component from the die  12 . 
     The die casting cell  70  includes one or more post-cast stations  74 A- 74 N positioned in relative close proximity to the die casting system  10 ,  110 . In one example, each post cast-station  74 A- 74 N is positioned directly adjacent to the die casting system  10 ,  110  to reduce the travel distance for the robot  72  or other operator. The post-cast stations  74 A- 74 N can include, but are not limited to, one or more of the following post-cast stations: a cooling station, a gate cut-off station, a belt grinding station, a grit blast station and an inspection station. 
     As an example of a potential post-cast procedure, the robot  72  may move the component to a cooling station  74 A once cast and removed from the die  12 . The cooling station  74 A can be stationary or moving, and can include a controlled or uncontrolled thermal gradient. After the component cools, the robot  72  moves the component to the gate cut-off station  74 B. The gate cut-off station  74 B may utilize a dry or wet cut-off wheel, a plasma torch, a wire or plunger electrical discharge machining (EDM), a laser system or any other cut-off system or combination of cut-off systems to remove the gate(s) or other parts from the component. 
     Next, the robot  72  moves the component to the belt grinding station  74 C where cut-off surfaces of the component are smoothed and sharp edges are rounded. After the component is blended to its correct dimensions, the robot  72  moves the component to the grit blast station  74 D to prepare the component for visual and non-destructive testing (NDT) inspections. Finally, the component is moved to the inspection station  74 E. The inspection station  74 E can include dimensional inspection and visual inspection. Other post-cast stations  74 N can also be included. 
     Each of the post-cast stations  74 A- 74 N may be carried out by an individual robot  72  positioned at each station or by a single robot  72  within the die casting cell  70 . The number of robots  72  required will be dictated by the size of the robots  72 , the operating circle of the robots  72  and the load limits of the robots  72 . Alternatively, one or more of the post-cast stations  74 A- 74 N may be operated by a human operator, if desired. 
     The die casting cell  70  could further include a die storage oven  76 , a power supply  78  and a pallet changer  80  for loading the die  12  and/or other parts of the die casting system  10 ,  110 . The power supply  78  supplies power to the die casting cell  70 . The die storage oven  76  is positioned immediately adjacent the pallet changer  80  for ease of die loading. 
     The die storage oven  76  maintains the temperature of the die  12  between 250° F./121° C. and 1500° F./850° C. The die storage oven  76  may operate in air or in an inert atmosphere. Secondary die heating or cooling devices can also be utilized to heat the die parts, including but not limited to, combustible fuel burner systems, re-circulating oil systems, electric cartridge heaters, low temperature resistance heating elements, silicone carbide heating elements, molybdenum discilicide heating elements, graphite heating elements, induction coils or any combination to these or other devices. 
     The example die casting systems  10 ,  110  and the die casting cell  70  described above could include more or fewer sections, stations, parts and/or components. This disclosure extends to all forms of die casting, including but not limited to horizontal, inclined or vertical die casting systems and other die casting configurations. 
     The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.