Abstract:
A method according to an exemplary aspect of the present disclosure, includes, among other things, at least partially filling a vessel with an abrasive fluid, pressurizing the abrasive fluid, and vibrating a component within the vessel. Further, the method includes gradually adjusting a rate material is removed from the component.

Description:
BACKGROUND 
     Manufactured items, such as components for gas turbine engines, often require surface finishing to achieve certain mechanical properties. Components formed using additive manufacturing, brazing, or welding, as examples, may require surface cleaning (to remove burrs or partially fused particles) before the components can be used in an engine. Components formed using other techniques may also benefit from surface finishing. 
     One known surface finishing technique is known as micromachining. A micromachining process involves the use of an abrasive fluid, which includes a carrier fluid carrying an abrasive media. In this known process, a vessel contains a component to be finished, and the vessel is filled with a first abrasive fluid. The first abrasive fluid is used to finish the component. Following a first surface finishing process, the vessel is drained and a second abrasive fluid fills the vessel. The second abrasive fluid is then used to further finish the component. The process may repeat itself using additional abrasive fluids. Between each step, the vessel is completely drained and refilled with a new abrasive fluid. 
     Another existing surface finishing technique is known as tumbling. In a tumbling process, a component is held in an open-air container, and a plurality of abrasive particles are run over the component. Other known surface finishing techniques use magnetic fields, such as magnetic abrasive finishing, magnetic flow polishing, or magnetorheological finishing techniques. These magnetic techniques typically use open-air containers. 
     SUMMARY 
     A method according to an exemplary aspect of the present disclosure includes, among other things, at least partially filling a vessel with an abrasive fluid, pressurizing the abrasive fluid, and vibrating a component within the vessel. The method further includes gradually adjusting a rate material is removed from the component. 
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings can be briefly described as follows: 
         FIG. 1  schematically illustrates a first example surface finishing system. 
         FIG. 2  schematically illustrates a second example surface finishing system. 
         FIG. 3  is a flowchart representing an example method according to this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a system  20  for finishing a component, or substrate, using an abrasive fluid. In this example, the system  20  includes a vessel  22 , which is enclosed and provides an interior chamber  24 . As will be discussed in detail below, a component is provided in the interior chamber  24 , and the interior chamber  24  is at least partially filled with an abrasive fluid. The abrasive fluid works the exterior surface of the component, and provides a desired surface finish. 
     In one example, a mounting rod  26  supports a component  28  within the interior chamber  24 . The mounting rod  26  is sealed relative to the vessel  22  by a seal  30 . A mounting rod  26  is not required in all examples, as is shown relative to  FIG. 2  (discussed below). 
     The vessel  22  includes upper and lower walls  32 ,  34 . In this example, a first piston  36  and a second piston  38  are provided on opposite ends of the vessel  22  between the upper and lower walls  32 ,  34 . While not illustrated, the pistons  36 ,  38  include seals (such as O-rings) abutting the upper and lower walls  32 ,  34 . Together, the seal  30 , the upper and lower walls  32 ,  34 , and the first and second pistons  36 ,  38  enclose the interior chamber  24 . 
     In this example, the mounting rod  26  is connected to a vibratory device  40  (sometimes spelled “vibritory” device), which may include one or more motors. The vibratory device  40  is operable in response to instructions from a control C, and is configured to vibrate the mounting rod  26 . Ultimately, the vibratory device  40  is configured to vibrate the component  28  within the interior chamber  24 . The vibratory device  40  may be configured to oscillate the mounting rod  26  (and, in turn, the component  28 ) up-and-down (in the Y-direction), side-to-side (in the X-direction), and rotationally (in the R-direction) and any combinations thereof. 
     The control C may be any known type of controller including memory, hardware, and software. The control C is configured to store instructions, and to provide instructions to the various components of the system  20 . The control C may include one or more components. 
     As noted above, the mounting rod  26  is not required in all examples. An alternate arrangement is shown in  FIG. 2 , which illustrates a system  120  corresponding to the system  20  of  FIG. 1 , with like parts having reference numerals preappended with a “1.” In  FIG. 2 , the component  128  is supported within the interior chamber  124  of the vessel  122  by a pedestal  142  extending upwardly from the lower wall  134  of the vessel  122 . 
     In the example of  FIG. 2 , a vibratory device  140  is connected to the vessel  122 . In particular, the vibratory device  140  is connected directly to the lower wall  134  of the vessel  122 , although it could be connected to the vessel  122  at another location. The vibratory device  140 , like the vibratory device  40 , may include one or more motors. The vibratory device  140  is configured to vibrate the vessel  122  which, in turn, vibrates the platform  142  and results in movement of the component  128  within the interior chamber  124 . 
     Turning back to  FIG. 1 , the first and second pistons  36 ,  38  are each in communication with first and second actuators  44 ,  46 . The first and second actuators  44 ,  46  are responsive to instructions from the control C to adjust the position of the pistons  36 ,  38 . The relative position of the pistons  36 ,  38  dictates the size (i.e., volume) of the interior chamber  24 , and changes a pressure of a fluid within the interior chamber  24 . In this example, the pistons  36 ,  38  are moveable in the side-to-side direction (the X-direction) by way of the actuators  44 ,  46 . 
     While two pistons  36 ,  38  and two corresponding actuators  44 ,  46  are illustrated in  FIG. 1 , it should be understood that this disclosure extends to examples having one or more pistons. For instance, in some examples there may only be a single piston. As shown in the system  120  of  FIG. 2 , there is a single piston  136  that is moveable by a corresponding first actuator  144 . Like the first and second pistons  36 ,  38 , the single piston  136  is moveable via the actuator  144  in response to corresponding instructions from the control C. Additionally, while pistons are specifically contemplated in this disclosure, the pressure of the vessel  22  could be adjusted in another known way. 
       FIG. 3  illustrates an example method  48  for finishing a surface of a component. As shown in  FIG. 3 , at  50 , the interior chamber  24  of the vessel  22  is at least partially filled with an abrasive fluid AF W  configured to work the surface of the component  28 . In another example, the interior chamber  24  is completely filled. 
     With joint reference to  FIGS. 1 and 3 , in order to fill the interior chamber  24 , the control C is in communication with an abrasive fluid source  52 . The abrasive fluid source  52  includes at least two sources of abrasive fluids AF 1 , AF 2 . The abrasive fluids AF 1 , AF 2  have different properties. The properties may be different because the abrasive fluids have different carrier fluids, different abrasive media of different sizes, or both. Example abrasive fluids may include carrier fluids provided by acids, such as citric or nitric acid, and may further include an abrasive media provided by cubic boron nitride (CBN) particles or aluminum oxide (Al 2 O 3 ) particles, as examples. 
     In one example, the first abrasive fluid AF 1  provides a lower material removal rate than the second abrasive fluid AF 2 . This may be because the first abrasive fluid AF 1  has a less acidic carrier fluid and/or because the size of the abrasive media (i.e., size of the particles) within the first abrasive fluid AF 1  may be smaller than the size of the abrasive media in the second abrasive fluid AF 2 . 
     The abrasive fluid source  52  may include one or more pumps (not pictured), a plurality of valves (e.g., valves  57 ,  59 ), and is fluidly coupled to an inlet port  54  to the interior chamber  24  by way of an inlet valve  56 . The control C is electrically coupled to the abrasive fluid source  52  (including the individual components). In particular, the control C is operable to selectively adjust valves  57 ,  59  associated with sources of the first and second abrasive fluid AF 1  and the second abrasive fluid AF 2 , respectively. The control C is further electrically coupled to the inlet valve  56 . The control C is operable to provide instructions to these components to establish a flow of fluid from the abrasive fluid source  52  to the inlet port  54  and into the interior chamber  24 . 
     The abrasive fluid AF W  within the interior chamber  24  includes a carrier fluid carrying an abrasive media. In one example, the abrasive media includes a plurality of particles. In this example, again, the source of abrasive fluid  52  includes at least two different abrasive fluids, AF 1  and AF 2  having different material removal rates (because of the different carrier fluids, abrasive media sizes, or both). Depending on the material of the component  28 , which could be steel, ceramic, or some other material, and depending on the desired end finish of the component  28 , the control C is operable to provide an abrasive fluid of a particular material removal rate into the interior chamber  24 . This will be discussed in more detail below. 
     After the vessel  22  is at least partially filled with abrasive fluid AF W , the abrasive fluid AF W  is pressurized, at  58 , by adjusting the relative positions of the first and second pistons  36 ,  38 , for example. Pressurizing the abrasive fluid AF W  increases the coverage, by surface area, between the abrasive fluid AF W  and the exterior surface of the component  28 . 
     Next, at  60 , the component  28  is vibrated within the interior chamber  24  by the vibratory device  40 . Again, as discussed above, the component  28  may be vibrated in one or more directions. As the component is vibrated, at  60 , the abrasive fluid AF W , which is under pressure, works the exterior surface of the component  28 . In particular, the abrasive fluid AF W  removes burrs, polishes the exterior surface, and/or remove excess material. 
     This is disclosure may be particularly useful when the component  28  has been formed using an additive manufacturing process, as many unfused particles may remain on the exterior of the surface. Likewise, if the component has been welded or brazed, the exterior of the component may require smoothing and polishing. Components formed using other techniques can also benefit from this disclosure. 
     During finishing, the rate at which material is removed from the component  28  (i.e., the material removal rate) may require an adjustment. At  62 , if the material removal rate does require an adjustment, a change is made, at  64 , relative to at least one of (1) the pressure of the abrasive fluid AF W , (2) the vibration rate of the component  28 , and (3) the properties of the abrasive fluid AF W  within the interior chamber  24 . It should be understood that each of these adjustments may be made at the same time. It should also be understood that one or more of these adjustments can be made without interrupting the finishing process. 
     In order to increase material removal rate, the amplitude of the oscillations of the vibratory device  40  may be increased. Likewise, to reduce material removal rate, the amplitude of the oscillations may be decreased. Similarly, increasing the pressure of the abrasive fluid AF W  by adjusting the relative position of the pistons  36 ,  38 , for example, will increase the material removal rate. Likewise, decreasing pressure of the abrasive fluid AF W  will reduce material removal rate. 
     Additionally, changing the properties of the abrasive fluid AF W  within the interior chamber  24  will affect material removal rate. This change in properties may be brought about by changes to the carrier fluid or the abrasive media within the interior chamber  24 . In one example, the interior chamber  24  of the vessel  22  is initially filled with the first abrasive fluid AF 1 . In this example, the first abrasive fluid AF 1  includes abrasive media particles having a smaller size (e.g., diameter) than the second abrasive fluid AF 2 . 
     Continuing with this example, if an increase in material removal rate is required, the control C would provide instructions to the system  20  to establish a flow of the second abrasive fluid AF 2  into the interior chamber  24 . The instruction would include, for example, instructions to open valves  56  and  57 . The larger particles of the second abrasive fluid AF 2  would intermix with those of the first abrasive fluid AF 1  already within the interior chamber  24 . As the second abrasive fluid AF 2  is added into the interior chamber  24 , the average particle size within the interior chamber  24  gradually increases, which leads to an increased material removal rate. As the second abrasive fluid AF 2  flows into the interior chamber  24 , a corresponding amount of the intermixed abrasive fluid AF W  is expelled from the interior chamber  24  by an outlet port  66 , which is regulated by an outlet valve  68 , until a desired average particle size within the interior chamber  24  is reached. 
     To reduce the material removal rate after having added the second abrasive fluid AF 2 , the control C could provide an instruction to the system  20  to establish a flow of the first abrasive fluid AF 1  into the interior chamber  24 . The relatively small particles associated with the first abrasive fluid AF 1  would gradually reduce the average particle size within the interior chamber  24 , and reduce the material removal rate. 
     With reference to  FIG. 1 , as the abrasive fluid AF W  works the exterior surface of the component  28 , it will begin to collect material from the component  28 . In one example, the abrasive fluid AF W  flows from the outlet port  66 , downstream of the outlet valve  68 , and to a separator  70 . The separator  70  may include a sifter or a magnetic separator. The separator  70  may separate the material of the component  28 , such as metal, from the abrasive fluid AF W , and return the abrasive fluid AF W  to the abrasive fluid source  52  for further use. Alternatively, the separator  70  can be bypassed and the fluid can be sent to a dump  72  by selective operation of a dump valve  74 . 
     This disclosure provides a material removal rate that is adjustable gradually. Again, the material removal rate can be adjusted without interrupting the finishing process. Further, this disclosure can be used to perform finishing operations that require different material removal rates for different time periods (again, without process interruption). For example, the control C can instruct the system  20  to perform a machining operation using a first abrasive fluid (which provides a first material removal rate) for a first time period, gradually adjust to a second material removal rate by intermixing a second abrasive fluid with the first, and then perform a machining operation for a second time period, and so on. While  FIG. 1  illustrates two abrasive fluids AF 1 , AF 2 , there may be additional sources of abrasive fluid. These additional sources may include carrier fluids having different strengths and/or abrasive media having different sizes. 
     Changes to the abrasive fluid AF W  within the interior chamber  24  can be made concurrent with changes to the vibratory device  40  and the position of the pistons  36 ,  38 . Since these adjustments can be made without interrupting the finishing process, the component  28  can be finished in an expedited manner. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.